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1

A Model and Questionnaire of Language Identity in Iran: A Structural Equation Modelling Approach  

ERIC Educational Resources Information Center

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…

Khatib, Mohammad; Rezaei, Saeed

2013-01-01

2

Paper to Electronic Questionnaires: Effects on Structured Questionnaire Forms  

NASA Technical Reports Server (NTRS)

With the use of computers, paper questionnaires are being replaced by electronic questionnaires. The formats of traditional paper questionnaires have been found to effect a subject's rating. Consequently, the transition from paper to electronic format can subtly change results. The research presented begins to determine how electronic questionnaire formats change subjective ratings. For formats where subjects used a flow chart to arrive at their rating, starting at the worst and middle ratings of the flow charts were the most accurate but subjects took slightly more time to arrive at their answers. Except for the electronic paper format, starting at the worst rating was the most preferred. The paper and electronic paper versions had the worst accuracy. Therefore, for flowchart type of questionnaires, flowcharts should start at the worst rating and work their way up to better ratings.

Trujillo, Anna C.

2009-01-01

3

Selective Mutism Questionnaire: Measurement Structure and Validity  

ERIC Educational Resources Information Center

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.

Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.

2008-01-01

4

The Bilevel Structure of the Outcome Questionnaire-45  

ERIC Educational Resources Information Center

The structure of the Outcome Questionnaire-45 (Lambert et al., 2001) was examined in a sample of 1,100 university counseling center clients using confirmatory factor analysis. Specifically, the relative fit of 1-factor, 3-factor orthogonal, 3-factor oblique, 4-factor hierarchical, and 4-factor bilevel models were examined. Although the 3-factor…

Bludworth, Jamie L.; Tracey, Terence J. G.; Glidden-Tracey, Cynthia

2010-01-01

5

Structural Equation Model Trees  

ERIC Educational Resources Information Center

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…

Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

2013-01-01

6

Generalized Multilevel Structural Equation Modeling  

ERIC Educational Resources Information Center

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…

Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

2004-01-01

7

The latent structure of the Peritraumatic Dissociative Experiences Questionnaire.  

PubMed

This paper has been retracted due to a publisher's error: the order of the authors was incorrect. The Editor and Publisher of the Journal of Traumatic Stress apologize to the authors and our readership. The Peritraumatic Dissociative Experiences Questionnaire (PDEQ) is a widely used measure of peritraumatic dissociation, and is presumably a unidimensional construct. Two hundred forty-seven individuals admitted to five hospitals after traumatic injury were administered the Clinician Administered PTSD Scale, the Hospital Anxiety and Depression Scale, and the PDEQ. Factor analysis indicated that the PDEQ involved two factors containing four items each: one factor (altered awareness) indexes alterations in awareness and the other (derealization) reflects distortions in perceptions of the self and the world. Only the derealization factor was associated with acute stress, anxiety, and depression symptoms. Cross-validation with independent data provided only partial support for the 2-factor structure model. These data indicate that peritraumatic dissociation may involve two distinct constructs. PMID:19370700

Brooks, Robert; Bryant, Richard A; Silove, Derrick; Creamer, Mark; O'Donnell, Meaghan; McFarlane, Alexander C; Marmar, Charles R

2009-04-01

8

The latent structure of the Peritraumatic Dissociative Experiences Questionnaire.  

PubMed

The Peritraumatic Dissociative Experiences Questionnaire (PDEQ) is a widely used measure of peritraumatic dissociation, and is presumably a unidimensional construct. Two hundred forty-seven individuals admitted to five hospitals after traumatic injury were administered the Clinician Administered PTSD Scale, the Hospital Anxiety and Depression Scale, and the PDEQ. Factor analysis indicated that the PDEQ involved two factors containing four items each: one factor (altered awareness) indexes alterations in awareness and the other (derealization) reflects distortions in perceptions of the self and the world. Only the derealization factor was associated with acute stress, anxiety, and depression symptoms. Cross-validation with independent data provided only partial support for the 2-factor structure model. These data indicate that peritraumatic dissociation may involve two distinct constructs. PMID:19189282

Bryant, Richard A; Brooks, Robert; Silove, Derrick; Creamer, Mark; O'Donnell, Meaghan; McFarlane, Alexander C; Marmar, Charles R

2009-02-01

9

Confirmatory factor structure and measurement invariance of the Memory Compensation Questionnaire.  

PubMed

Recent research with the Memory Compensation Questionnaire (MCQ) has examined changes, functions, and correlates of compensatory strategy use in older adults. The twofold aim of this study was to test (a) the hypothesized structure of the MCQ and (b) structural equivalence across age, gender, and time. The 7-scale MCQ was designed to measure 5 compensatory mechanisms and 2 general aspects of compensatory awareness. The authors assembled a 3-wave (6-year) sample (N = 521; age = 55-85 years) from the Victoria Longitudinal Study. The results of structural equation modeling supported (a) the a priori structure of the MCQ and (b) the inference of measurement invariance across the 3 dimensions. Accordingly, the MCQ is available for measuring self-reported efforts to compensate for everyday memory losses. PMID:16029104

de Frias, Cindy M; Dixon, Roger A

2005-06-01

10

Factor Structure and Psychometric Properties of the Young Schema Questionnaire (Short Form) in Chinese Undergraduate Students  

ERIC Educational Resources Information Center

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…

Cui, Lixia; Lin, Wenwen; Oei, Tian P. S.

2011-01-01

11

Testing Structural Invariance of the Achievement Goal Questionnaire in American, Chinese, and Dutch College Students  

ERIC Educational Resources Information Center

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…

Sun, Huaping; Hernandez, Diley

2012-01-01

12

Structural Analysis of the Resident Assistant Cultural Diversity Questionnaire  

ERIC Educational Resources Information Center

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…

Johnson, Vanessa D.; Kang, Young-Shin; Thompson, George F.

2011-01-01

13

Confirmatory Factor Structure and Measurement Invariance of the Memory Compensation Questionnaire  

ERIC Educational Resources Information Center

Recent research with the Memory Compensation Questionnaire (MCQ) has examined changes, functions, and correlates of compensatory strategy use in older adults. The twofold aim of this study was to test (a) the hypothesized structure of the MCQ and (b) structural equivalence across age, gender, and time. The 7-scale MCQ was designed to measure 5…

de Frias, Cindy M.; Dixon, Roger A.

2005-01-01

14

Confirmatory Factor Structure and Measurement Invariance of the Memory Compensation Questionnaire  

Microsoft Academic Search

Recent research with the Memory Compensation Questionnaire (MCQ) has examined changes, functions, and correlates of compensatory strategy use in older adults. The twofold aim of this study was to test (a) the hypothesized structure of the MCQ and (b) structural equivalence across age, gender, and time. The 7-scale MCQ was designed to measure 5 compensatory mechanisms and 2 general aspects

Cindy M. de Frias; Roger A. Dixon

2005-01-01

15

The Factorial Structure of the Expectations about Counseling Questionnaire-Brief Form: Some Serious Questions.  

ERIC Educational Resources Information Center

Examines responses of Americans and Icelanders to the Expectations About Counseling Questionnaire-Brief Form (EAC-B) through confirmatory factor analyses. Investigates the validity of and expresses concern for the underlying factor structure of the EAC-B. Argues that a four-factor solution for the EAC-B is too complex and does not fit the student…

Aegisdottir, Stefania; Gerstein, Lawrence H.; Gridley, Betty E.

2000-01-01

16

Temperament Factor Structure in Fragile X Syndrome: The Children's Behavior Questionnaire  

PubMed Central

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

Roberts, Jane E.; Tonnsen, Bridgette L.; Robinson, Marissa; McQuillin, Samuel D.; Hatton, Deborah D.

2014-01-01

17

Factor Structure of the Children's Behavior Questionnaire in Children with Williams Syndrome  

ERIC Educational Resources Information Center

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…

Leyfer, Ovsanna; John, Angela E.; Woodruff-Borden, Janet; Mervis, Carolyn B.

2012-01-01

18

Structural Equation Modeling of Multivariate Time Series  

ERIC Educational Resources Information Center

The covariance structure of a vector autoregressive process with moving average residuals (VARMA) is derived. It differs from other available expressions for the covariance function of a stationary VARMA process and is compatible with current structural equation methodology. Structural equation modeling programs, such as LISREL, may therefore be…

du Toit, Stephen H. C.; Browne, Michael W.

2007-01-01

19

Assessment of structured physical examination skills training using a retro-pre-questionnaire  

PubMed Central

Purpose: The effectiveness of physical examination skills (PES) training is very rarely assessed using the “post-then-pre” approach. In this study, a retro-pre-questionnaire was used to study the effect of structured physical examination skills training (SPEST) imparted to second-year undergraduate medical students. Methods: KIST Medical College (KISTMC) affiliated to Tribhuvan University Nepal admitted its first batch of MBBS students in November 2008. The university curriculum recommends the involvement of Medicine and Surgery Departments in PES training, but the methods for teaching and assessment are not well defined. KISTMC has made training more structured and involved the Medicine, Surgery, Gynaecology and Obstetrics, Orthopaedics, ENT, Ophthalmology, Paediatrics, and Family Medicine Departments. SPEST includes the teaching/learning of basic PES for 210 minutes once a week for 28 weeks. Self-assessment is done by using a retro-pre-questionnaire at the end of the last session of training, and these data are analysed using SPSS. Results: Out of 100 students, 98 participated in the objective structured clinical examination (OSCE); 82 completed the retro-pre-questionnaire. Forty-six skills representing various systems were selected for inclusion in the retro-pre-questionnaire from among the many skills taught in different departments. The average perceived skills score (maximum score, 46×4=184) before training was 15.9 and increased to 116.5 after training. The increase was statistically significant upon the application of a paired t-test. Conclusion: The students perceived that their level of skills improved after the training. The retro-pre- instrument seems to be useful for assessing the learners’ self-reported changes in PES after training if a large number of skills need to be assessed. However, it should be noted that although a retro-pre-questionnaire may reveal valuable information, it is not a substitute for an objective measure or gold standard. PMID:24498473

2013-01-01

20

Psychometric properties and factor structure of an L2 reading motivation questionnaire.  

PubMed

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

Kim, Hee-jung; Choi, Sunhee

2014-01-01

21

Factor Structure of the Iranian Version of 12-Item General Health Questionnaire  

PubMed Central

Background: The 12-Item General Health (GHQ-12) questionnaire is one of the most commonly used instruments in screening studies on mental health. Objectives: The current study aimed to examine the factor structure of the GHQ-12 questionnaire among the students in Iran. Materials and Methods: It was a cross-sectional study in which 428 university students were recruited and completed the GHQ-12. Reliability of the GHQ-12 was evaluated using the Cronbach's alpha and the split-half method by applying the Spearman-Brown coefficient. Factor structure of the questionnaire was extracted by exploratory factor analysis (EFA). Confirmatory factor analysis (CFA) was conducted to assess how well the EFA extracted model fitted the observed data. Results: The mean age of the participants was 22.83 years (SD = 3.09). Most of them were female (56.1%) and 81% were unemployed. The Cronbach’s alpha coefficient for the Iranian version of GHQ-12 was 0.85. Using the split-half method, the alpha for the social dysfunction was found to be 0.77; it was 0.76 for the psychological distress. The principal component analysis revealed a two-factor structure for the questionnaire including social dysfunction and psychological distress that explained 48% of the observed variances. The confirmatory factor analysis was showed fit for the data. Conclusions: The current study findings confirm that the Iranian version of GHQ-12 has a good factor structure and is a reliable and valid instrument to measure psychological distress and social dysfunction.

Rahmati Najarkolaei, Fatemeh; Raiisi, Fatemeh; Rahnama, Parvin; Gholami Fesharaki, Mohammad; Zamani, Omid; Jafari, Mohammad Reza; Montazeri, Ali

2014-01-01

22

Factor structure analysis of the Comprehensive Effects of Alcohol - Spanish questionnaire among adolescents in Mexico  

E-print Network

FACTOR STRUCTURE ANALYSIS OF THE COMPREHENSIVE EFFECTS OF ALCOHOL - SPANISH QUESTIONNAIRE AMONG ADOLESCENTS IN MEXICO A Thesis by CLAUDIA GRACIELA FLATO Submitted to the Office of Graduate Studies of Texas A&M University in partial... IN MEXICO A Thesis by CLAUDIA GRACIELA FLATO Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee...

Flato, Claudia Graciela

2007-09-17

23

[An establishment of theoretical structure of PRO questionnaire in treating chronic liver disease by Chinese medicine].  

PubMed

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

Wang, Li; Zhang, Hua; Yuan, Wei-An; Wang, Yi-Xing; Tang, Jie; Cui, Chen; Zeng, Jin; Miao, Ping; Jiang, Jian

2014-11-01

24

Evaluation of adherence to oral antiviral hepatitis B treatment using structured questionnaires  

PubMed Central

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

Giang, Leesa; Selinger, Christian P; Lee, Alice Unah

2012-01-01

25

French validation of the overexcitability questionnaire 2: psychometric properties and factorial structure.  

PubMed

Overexcitability corresponds to an overall response to stimulations in 5 domains: psychomotor, sensual, intellectual, imaginational, and emotional. The aim of this study was to develop a French version of the Overexcitability Questionnaire 2 (OEQ2) and to expand its psychometric properties. Two studies were conducted: one with a sample of 474 adolescents and another with a sample of 436 adults. Internal consistency, factorial structure, and validity (correlations with intelligence, personality, and alexithymia) were examined. The French OEQ2 showed satisfactory psychometric properties, thus advocating for its use in further research on overexcitability and in clinical practice. PMID:25090583

Botella, Marion; Fürst, Guillaume; Myszkowski, Nils; Storme, Martin; Pereira Da Costa, Maria; Luminet, Olivier

2015-01-01

26

Structural comparison of a translated dental attitude questionnaire: a factor analytic study.  

PubMed

In 1984 the Dental Attitude Questionnaire (DAQ), an instrument for assessing various aspects of a person's attitude toward oral health care, was presented by STOCKWELL & BANTING. The DAQ consists of six content scales, Cynicism, Health Concern, Motivation, Oral Function, Social Aesthetic and Susceptibility, and two validity scales, Halo and Infrequency. A Dutch translation was presented in 1986 by HOOGSTRATEN & BROERS. In order to replicate the factor analysis on the original DAQ as reported by STOCKWELL & BANTING, the present study was undertaken. The results show a change in factor structure from a three factor solution to a two factor solution. A confirmatory factor analysis shows that the original three factor structure of the DAQ is not present in the data collected with the translated version. To account for this change, some possible reasons are discussed. PMID:8871029

Timmerman, E M; Hoogstraten, J; Nauta, M; Meijer, K

1996-08-01

27

Exploring the factor structure of the Food Cravings Questionnaire-Trait in Cuban adults  

PubMed Central

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

Rodríguez-Martín, Boris C.; Molerio-Pérez, Osana

2014-01-01

28

How to compare scores from different depression scales: equating the Patient Health Questionnaire (PHQ) and the ICD-10-Symptom Rating (ISR) using Item Response Theory.  

PubMed

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

Fischer, H Felix; Tritt, Karin; Klapp, Burghard F; Fliege, Herbert

2011-12-01

29

Examination of the Factor Structure of the Schizotypal Personality Questionnaire among British and Trinidadian Adults  

PubMed Central

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.

Barron, David; Swami, Viren; Hutchinson, Gerard

2015-01-01

30

Wording effects and the factor structure of the 12-item General Health Questionnaire (GHQ-12).  

PubMed

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

Molina, J Gabriel; Rodrigo, Maria F; Losilla, Josep-Maria; Vives, Jaume

2014-09-01

31

Generalized Ideal Gas Equations for Structureful Universe  

Microsoft Academic Search

We have derived generalized ideal gas equations for a structureful universe consistingof all forms of matters. We have assumed a universe that contains superclusters. Superclusters arethen made of clusters. Each cluster can be further divided into smaller ones and so on. We havederived an expression for the entropy of such a universe. Our model is rather independent of thegeometry of

Shahid N. Afridi; Khalid Khan

2006-01-01

32

Structural Equation Modeling in Behavioral Research  

Cancer.gov

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

33

Factor structure, reliability, and validity of the Chinese version of the School Bullying Experience Questionnaire.  

PubMed

The aims of this study were to examine the factor structure, internal consistency, 1-month test-retest reliability, and congruent validity of the Chinese version of the School Bullying Experience Questionnaire (C-SBEQ). Study 1, in which 5751 Taiwanese adolescents in Southern Taiwan participated, examined the adequacy of the original four-factor structure of the C-SBEQ using confirmatory factor analysis (CFA) and internal-consistency reliability using Cronbach ?. Study 2, in which 108 adolescents in Southern Taiwan participated, examined the 1-month test-retest reliability using intraclass correlation coefficients (ICCs). We examined the congruent validity of the C-SBEQ by examining the consistency between self-reported and teacher- and classmate-nominated experiences of bullying involvement in Study 2. The results of CFA supported the four-factor structure of the C-SBEQ in Taiwanese adolescents. The test-retest and internal reliability values of all subscales of the C-SBEQ were at acceptable to satisfactory levels. Nominated adolescents had significantly higher self-reported scores on three C-SBEQ subscales than non-nominated ones, and the levels of agreement between self-reported and nominated victims were moderate. The results of this study indicate that the C-SBEQ is appropriate for assessing bullying experiences in Taiwanese adolescents. PMID:22974670

Yen, Cheng-Fang; Kim, Young-Shin; Tang, Tze-Chun; Wu, Yu-Yu; Cheng, Chung-Ping

2012-09-01

34

Examining the factor structures of the five facet mindfulness questionnaire and the self-compassion scale.  

PubMed

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

Williams, Matthew J; Dalgleish, Tim; Karl, Anke; Kuyken, Willem

2014-06-01

35

A Confirmatory Approach to Examining the Factor Structure of the Strengths and Difficulties Questionnaire (SDQ): A Large Scale Cohort Study  

ERIC Educational Resources Information Center

The aim of this study was to examine the factor structure of the Strengths and Difficulties Questionnaire (SDQ) using a Structural Confirmatory Factor Analytic approach. The Danish translation of the SDQ was distributed to 71,840 parents and teachers of 5-7 and 10-12-year-old boys and girls from four large scale cohorts. Three theoretical models…

Niclasen, Janni; Skovgaard, Anne Mette; Andersen, Anne-Marie Nybo; Somhovd, Mikael Julius; Obel, Carsten

2013-01-01

36

Global Structure of Quaternion Polynomial Differential Equations  

NASA Astrophysics Data System (ADS)

In this paper we mainly study the global structure of the quaternion Bernoulli equations {dot q=aq+bq^n} for {qin {mathbb{H}}}, the quaternion field and also some other form of cubic quaternion differential equations. By using the Liouvillian theorem of integrability and the topological characterization of 2-dimensional torus: orientable compact connected surface of genus one, we prove that the quaternion Bernoulli equations may have invariant tori, which possesses a full Lebesgue measure subset of {{mathbb{H}}}. Moreover, if n = 2 all the invariant tori are full of periodic orbits; if n = 3 there are infinitely many invariant tori fulfilling periodic orbits and also infinitely many invariant ones fulfilling dense orbits.

Zhang, Xiang

2011-04-01

37

Structural equation modeling for observational studies  

USGS Publications Warehouse

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.

Grace, J.B.

2008-01-01

38

A Validation Study of the Dutch Childhood Trauma Questionnaire-Short Form: Factor Structure, Reliability, and Known-Groups Validity  

ERIC Educational Resources Information Center

Objective: The 28-item Childhood Trauma Questionnaire-Short Form (CTQ-SF) has been translated into at least 10 different languages. The validity of translated versions of the CTQ-SF, however, has generally not been examined. The objective of this study was to investigate the factor structure, internal consistency reliability, and known-groups…

Thombs, Brett D.; Bernstein, David P.; Lobbestael, Jill; Arntz, Arnoud

2009-01-01

39

Measurement Structure of the Coping Strategies Questionnaire-24 in a Sample of Individuals with Musculoskeletal Pain: A Confirmatory Factor Analysis  

ERIC Educational Resources Information Center

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…

Chiu, Chung-Yi; Jochman, Joseph; Fujikawa, Mayu; Strand, David; Cheing, Gladys; Lee, Gloria; Chan, Fong

2014-01-01

40

Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models  

ERIC Educational Resources Information Center

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…

Song, Xin-Yuan; Xia, Ye-Mao; Pan, Jun-Hao; Lee, Sik-Yum

2011-01-01

41

The Home Situations Questionnaire-PDD Version: Factor Structure and Psychometric Properties  

ERIC Educational Resources Information Center

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).…

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

42

Factor structure and reliability of the Childhood Trauma Questionnaire in a Canadian undergraduate student sample  

Microsoft Academic Search

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 of Psychiatry, 151, 1132–1136; Bernstein, D., & Fink,

Sandra C. Paivio; Kenneth M. Cramer

2004-01-01

43

Psychometric Evidence for the Leisure Interest Questionnaire and Analyses of the Structure of Leisure Interests  

Microsoft Academic Search

This study provides evidence of reliability and validity for the Leisure Interest Questionnaire (LIQ; J. C. Hansen, 1998). Undergraduate students completed the LIQ and Strong Interest Inventory (SII; E. K. Strong Jr., 1927) at Time 1 and the LIQ 5 weeks later. The internal consistency and test-retest reliability of the LIQ scales were calculated. Evidence of construct validity was inferred

Jo-Ida C. Hansen; Mark G. Scullard

2002-01-01

44

Psychometric Evidence for the Leisure Interest Questionnaire and Analyses of the Structure of Leisure Interests  

ERIC Educational Resources Information Center

This study provides evidence of reliability and validity for the Leisure Interest Questionnaire (LIQ; J. C. Hansen, 1998). Undergraduate students completed the LIQ and Strong Interest Inventory (SII; E. K. Strong Jr., 1927) at Time 1 and the LIQ 5 weeks later. The internal consistency and test-retest reliability of the LIQ scales were calculated.…

Hansen, Jo-Ida C.; Scullard, Mark G.

2002-01-01

45

The Adult Reading History Questionnaire (ARHQ) in Icelandic: Psychometric Properties and Factor Structure  

ERIC Educational Resources Information Center

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…

Bjornsdottir, Gyda; Halldorsson, Jonas G.; Steinberg, Stacy; Hansdottir, Ingunn; Kristjansson, Kristleifur; Stefansson, Hreinn; Stefansson, Kari

2014-01-01

46

Component Structure, Reliability, and Stability of Lawrence's Self-Esteem Questionnaire (LAWSEQ)  

ERIC Educational Resources Information Center

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…

Rae, Gordon; Dalto, Georgia; Loughrey, Dolores; Woods, Caroline

2011-01-01

47

Saudi mothers' preferences about breaking bad news concerning newborns: a structured verbal questionnaire  

PubMed Central

Background Breaking bad news (BBN) to parents whose newborn has a major disease is an ethical dilemma. In Saudi Arabia, BBN about newborns is performed according to the parental preferences that have been reported from non-Arabic/non-Islamic countries. Saudi mothers' preferences about BBN have not yet been studied. Therefore, we aimed to elicit the preferences of Saudi mothers about BBN concerning newborns. Methods We selected a convenience sample of 402 Saudi mothers, aged 18-50 years, who had no previous experience with BBN. We selected them via a simple number-randomization scheme from the premises of a level III Saudi hospital between October of 2009 and January of 2011. We used a hypothetical situation (BBN about trisomy 21) to elicit their preferences about BBN concerning newborns via a structured verbal questionnaire composed of 12 multiple-choice questions. We expressed their preferences as percentages (95% confidence interval), and we used the Kendall's W test (W) to assess the degree of agreement in preferences. Results The Saudi mothers preferred that BBN be conducted with both parents together (64% [60-69]), albeit with weak levels of agreement (W = 0.29). They showed moderate agreement in their preferences that BBN should be conducted early (79% [75-83], W = 0.48), in detail (81% [77-85], W = 0.52), in person (88% [85-91], W = 0.58), and in a quiet setting (86% [83-90], W = 0.53). With extremely weak agreement, they preferred to have a known person present for support during BBN (56% [51-61], W = 0.01), to have close bodily contact with their babies (66% [61-70], W = 0.10), and to have no another patients present (64% [59-68], W = 0.08). They showed moderate levels of agreement in their desires to detail, in advance, their preferences about process of BBN by giving a reversible, written informed consent that could be utilized for guidance, if needed (80% [76-84], W = 0.36). Conclusions In our experience, Saudi mothers' preferences about BBN concerning newborns are varied, suggesting that a "one-size-fits-all" approach is inappropriate. A reversible, written informed consent detailing their preferences about BBN that would be kept in their medical records and utilized for guidance, if needed, may be the best solution, given this level of diversity. These findings merit further study. PMID:21861876

2011-01-01

48

The structure of the perceived sociocultural influences on body image and body change questionnaire  

Microsoft Academic Search

This article is concerned with the development and evaluation of the Perceived Sociocultural Influences on Body Image and\\u000a Body Change Questionnaire. The scale was designed to assess the perceived nature of feedback received from mother, father,\\u000a best male friend, and best female friend togain weight, lose weight, and increase muscle tone. The perceived feedback from\\u000a the media on each of

Marita P. McCabe; Lina A. Ricciardelli

2001-01-01

49

Atomic Structure Schrdinger equation has approximate solutions for multi-  

E-print Network

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

Zakarian, Armen

50

Fermionic covariant prolongation structure theory for supernonlinear evolution equation  

NASA Astrophysics Data System (ADS)

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 Schrödinger equation is analyzed in the framework of this fermionic covariant prolongation structure theory. We obtain its Lax pairs and Bäcklund transformation.

Cheng, Ji-Peng; Wang, Shi-Kun; Wu, Ke; Zhao, Wei-Zhong

2010-09-01

51

Structured Matrices, Multigrid Methods, and the Helmholtz Equation  

E-print Network

Structured Matrices, Multigrid Methods, and the Helmholtz Equation Rainer Fischer 1 , Thomas Huckle 2 Technical University of Munich, Germany Abstract Discretization of the Helmholtz equation with the methods from [13] to construct a faster and more robust multigrid solver. Key words: Helmholtz equation

Cengarle, María Victoria

52

Clarification of the factor structure of the 12-item General Health Questionnaire among Japanese adolescents and associated sleep status.  

PubMed

If the factors affecting the mental health status of adolescents and their association with sleep status could be clarified, this information would be helpful for formulating lifestyle and healthcare guidance for the promotion of healthy growth and the prevention of mental problems in these individuals. The purpose of this study was to clarify (1) the factor structure of the 12-item General Health Questionnaire (GHQ-12), and (2) the associations between the factors extracted from this questionnaire and lifestyle, in particular sleep status, by using a representative sample population of Japanese adolescents. One hundred three thousand sixty hundred fifty self-administered questionnaires were collected from students enrolled in junior high and high schools in Japan. Of these questionnaires, 99,668 were analyzed. Sleep duration, subjective sleep assessment, bedtime, and insomnia symptoms of these students over the past month were studied to investigate sleep status. The factor analyses yielded two factors: depression/anxiety and loss of positive emotion. Sleep duration of less than 7h was found to be associated with both depression/anxiety and loss of positive emotion, whereas sleep duration of 8h or more was associated only with loss of positive emotion. Subjective sleep assessment and insomnia symptoms were associated with both depression/anxiety and loss of positive emotion. It was demonstrated that two underlying factors of mental health status were associated with differences in sleep status. In order to improve the mental health status of adolescents, it is important to provide guidance about sleep and lifestyle habits according to the mental health status of the individual. PMID:21145596

Suzuki, Hiroyuki; Kaneita, Yoshitaka; Osaki, Yoneatsu; Minowa, Masumi; Kanda, Hideyuki; Suzuki, Kenji; Wada, Kiyoshi; Hayashi, Kenji; Tanihata, Takeo; Ohida, Takashi

2011-06-30

53

The Everyday Feeling Questionnaire: the structure and validation of a measure of general psychological well-being and distress  

Microsoft Academic Search

Background  Psychological distress and well-being underlie the continuum of susceptibility to common mental disorders. Our objective was\\u000a to provide a simple and acceptable measure of psychological distress and well-being to collect information from subjects and\\u000a informants in non-clinical samples, to explore its internal structure, concurrent and external validity.\\u000a \\u000a \\u000a \\u000a \\u000a Method  Self and partner versions of the ten-item Everyday Feeling Questionnaire (EFQ) were administered

Rudolf Uher; Robert Goodman

2010-01-01

54

A Structural Equation Modeling Analysis of Influences on Juvenile Delinquency  

ERIC Educational Resources Information Center

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…

Barrett, David E.; Katsiyannis, Antonis; Zhang, Dalun; Zhang, Dake

2014-01-01

55

Fitting ARMA Time Series by Structural Equation Models.  

ERIC Educational Resources Information Center

This paper outlines how the stationary ARMA (p,q) model (G. Box and G. Jenkins, 1976) can be specified as a structural equation model. Maximum likelihood estimates for the parameters in the ARMA model can be obtained by software for fitting structural equation models. The method is applied to three problem types. (SLD)

van Buuren, Stef

1997-01-01

56

Fitting Multivariate Normal Finite Mixtures Subject to Structural Equation Modeling.  

ERIC Educational Resources Information Center

Discusses fitting multivariate normal mixture distributions to structural equation modeling. The model used is a LISREL submodel that includes confirmatory factor and structural equation models. Two approaches to maximum likelihood estimation are used. A simulation study compares confidence intervals based on the observed information and…

Dolan, Conor V.; van der Maas, Han L. J.

1998-01-01

57

Sensitivity of rocky planet structures to the equation of state  

E-print Network

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.

Swift, Damian C

2009-01-01

58

Sensitivity of rocky planet structures to the equation of state  

SciTech Connect

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.

Swift, D C

2009-06-10

59

The Adult Reading History Questionnaire (ARHQ) in Icelandic: Psychometric Properties and Factor Structure.  

PubMed

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 (Cronbach's alpha = .92) and test-retest reliability (r = .93). Validity was established by comparing scores of adults who as children received ICD-10 diagnoses of specific reading disorder (F81.0; n = 419) to those of adults defined as nondyslexics (n = 679). ROC curve analysis resulted in an area under the curve of .92 (95% CI = .90, .93, p < .001) and a cutoff score of .43 with sensitivity of 84.5% and specificity of 83.7%. An exploratory factor analysis (n = 2,187) suggested three subscales, Dyslexia Symptoms, Current Reading, and Memory, the mean scores of which differed significantly among diagnosed dyslexics, relatives of dyslexics, and population controls. Our results support the applicability of the ARHQ in Icelandic as a self-report screening tool for adult dyslexia in Iceland. PMID:23456983

Bjornsdottir, Gyda; Halldorsson, Jonas G; Steinberg, Stacy; Hansdottir, Ingunn; Kristjansson, Kristleifur; Stefansson, Hreinn; Stefansson, Kari

2014-01-01

60

Static Analysis of Tensegrity Structures Part 1. Equilibrium Equations  

E-print Network

Static Analysis of Tensegrity Structures Part 1. Equilibrium Equations Julio Correa Joseph Duffy of an antiprism tensegrity structure subjected to a wide variety of external loads is addressed. The virtual work. Introduction Tensegrity structures are spatial structures formed by a combination of rigid elements (the struts

Florida, University of

61

Integrable structures for a generalized Monge-Ampère equation  

NASA Astrophysics Data System (ADS)

We consider a third-order generalized Monge-Ampère equation uyyy - u{xxy/ 2 } + uxxxuxyy = 0, which is closely related to the associativity equation in two-dimensional topological field theory. We describe all integrable structures related to it: Hamiltonian, symplectic, and also recursion operators. We construct infinite hierarchies of symmetries and conservation laws.

Verbovetsky, A. M.; Vitolo, R.; Kersten, P.; Krasil'shchik, I. S.

2012-05-01

62

A general non-linear multilevel structural equation mixture model  

PubMed Central

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

Kelava, Augustin; Brandt, Holger

2014-01-01

63

A general non-linear multilevel structural equation mixture model.  

PubMed

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

Kelava, Augustin; Brandt, Holger

2014-01-01

64

Stellar structure equations in extended Palatini gravity  

NASA Astrophysics Data System (ADS)

We consider static spherically symmetric stellar configurations in Palatini theories of gravity in which the Lagrangian is an unspecified function of the form f(R,R??R??). We obtain the Tolman-Oppenheimer-Volkov equations corresponding to this class of theories and show that they recover those of f(R) theories and general relativity in the appropriate limits. We show that the exterior vacuum solutions are of Schwarzschild-de Sitter type and comment on the possible expected modifications, as compared to general relativity, of the interior solutions.

Olmo, Gonzalo J.; Sanchis-Alepuz, Hèlios; Tripathi, Swapnil

2012-11-01

65

Quantifying parsimony in structural equation modeling  

E-print Network

that the number of free model parameters influences FP, but other facets of FP are routinely excluded from consideration. It is shown that models possessing the same number of free parameters but different structures may exhibit different FPs. The consequences...

Preacher, K. J.

2006-01-01

66

Examining the cognitive model of caregiving--a structural equation modelling approach.  

PubMed

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

Hesse, Klaus; Klingberg, Stefan

2014-07-30

67

The Factor Structure and Factorial Invariance of the 12-Item General Health Questionnaire (GHQ-12) across Time: Evidence from Two Community-Based Samples  

ERIC Educational Resources Information Center

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…

Makikangas, Anne; Feldt, Taru; Kinnunen, Ulla; Tolvanen, Asko; Kinnunen, Marja-Liisa; Pulkkinen, Lea

2006-01-01

68

Case Residuals in Structural Equation Modeling  

ERIC Educational Resources Information Center

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…

Cardinale, John

2011-01-01

69

Structural Equation Modelling: A Primer for Music Education Researchers  

ERIC Educational Resources Information Center

Structural equation modelling (SEM) is a method for analysis of multivariate data from both non-experimental and experimental research. The method combines a structural model linking latent variables and a measurement model linking observed variables with latent variables. Its use in social science and educational research has grown since the…

Teo, Timothy

2010-01-01

70

PERIODIC STRUCTURE IN TWODIMENSIONAL RIEMANN PROBLEMS FOR HAMILTONJACOBI EQUATIONS \\Lambda  

E-print Network

to more general problems, in particular, for numerical construction using methods such as front tracking contain closed characteristic orbits, enclosing furthermore a periodic sonic structure, which in turn structure. Key words. Riemann problem, Hamilton­Jacobi equation, conservation law, sonic shock, delay

New York at Stoney Brook, State University of

71

Cross-cultural invariance of the factor structure of the Schizotypal Personality Questionnaire across Spanish and American college students.  

PubMed

The main goal of this study was to examine the cross-cultural invariance of the factor structure of the Schizotypal Personality Questionnaire (SPQ) (Raine, 1991) in two large samples of Spanish and American young adults. The final sample was made up of 2313 college students (508 men, 22%). Their mean age was 20.5 years (S.D.=3.2). The results indicated that the Stefanis et al. (2004) four-factor model yielded the best goodness-of-fit indices compared to alternative models. Moreover, the results support configural, metric, and partial measurement invariance of the covariances of the SPQ across the two samples. The finding of measurement equivalence across cultures provides essential evidence of construct validity for the schizotypy dimensions and of the cross-cultural validity of SPQ scores. The finding of comparable dimensional structures in cross-cultural samples lends further support to the continuum model of schizotypy and schizophrenia spectrum disorders. Future studies should continue to examine the validity of scores on the SPQ and other schizotypy measures and their variation or consistency across cultures. PMID:25412981

Fonseca-Pedrero, Eduardo; Compton, Michael T; Tone, Erin B; Ortuño-Sierra, Javier; Paino, Mercedes; Fumero, Ascensión; Lemos-Giráldez, Serafín

2014-08-13

72

Post-partum blues among Korean mothers: a structural equation modelling approach.  

PubMed

The objective of this study was to propose the post-partum blues (PPB) model and to estimate the effects of self-esteem, social support, antenatal depression, and stressful events during pregnancy on PPB. Data were collected from 249 women post-partum during their stay in the maternity units of three hospitals in Korea using a self-administered questionnaire. A structural equation modelling approach using the Analysis of Moments Structure program was used to identify the direct and indirect effects of the variables on PPB. The full model had a good fit and accounted for 70.3% of the variance of PPB. Antenatal depression and stressful events during pregnancy had strong direct effects on PPB. Household income showed indirect effects on PPB via self-esteem and antenatal depression. Social support indirectly affected PPB via self-esteem, antenatal depression, and stressful events during pregnancy. PMID:23009567

Chung, Sung Suk; Yoo, Il Young; Joung, Kyoung Hwa

2013-08-01

73

On third Poisson structure of KdV equation  

SciTech Connect

The third Poisson structure of the KdV equation in terms of canonical {open_quote}free fields{close_quote} and the reduced WZNW model is discussed. We prove that it is {open_quotes}diagonalized{close_quotes} in the Lagrange variables which were used before in the formulation of 2d gravity. We propose a quantum path integral for the KdV equation based on this representation.

Gorsky, A.; Marshakov, A.; Orlov, A. [Inst. of Theoretical Physics, Moscow (Russian Federation)] [and others

1995-12-01

74

Adjustment to College as Measured by the Student Adaptation to College Questionnaire: A Quantitative Review of Its Structure and Relationships with Correlates and Consequences  

ERIC Educational Resources Information Center

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…

Crede, Marcus; Niehorster, Sarah

2012-01-01

75

Factor Structure of the Reactive-Proactive Aggression Questionnaire in Turkish Children and Gender, Grade-Level, and Socioeconomic Status Differences in Reactive and Proactive Aggression  

ERIC Educational Resources Information Center

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…

Uz Bas, Asli; Yurdabakan, Irfan

2012-01-01

76

Consistent Partial Least Squares for nonlinear structural equation models.  

PubMed

Partial Least Squares as applied to models with latent variables, measured indirectly by indicators, is well-known to be inconsistent. The linear compounds of indicators that PLS substitutes for the latent variables do not obey the equations that the latter satisfy. We propose simple, non-iterative corrections leading to consistent and asymptotically normal (CAN)-estimators for the loadings and for the correlations between the latent variables. Moreover, we show how to obtain CAN-estimators for the parameters of structural recursive systems of equations, containing linear and interaction terms, without the need to specify a particular joint distribution. If quadratic and higher order terms are included, the approach will produce CAN-estimators as well when predictor variables and error terms are jointly normal. We compare the adjusted PLS, denoted by PLSc, with Latent Moderated Structural Equations (LMS), using Monte Carlo studies and an empirical application. PMID:24306555

Dijkstra, Theo K; Schermelleh-Engel, Karin

2014-10-01

77

Robust Structural Equation Modeling with Missing Data and Auxiliary Variables  

ERIC Educational Resources Information Center

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…

Yuan, Ke-Hai; Zhang, Zhiyong

2012-01-01

78

Structural Equation Modeling: Foundations and Extensions [book review].  

ERIC Educational Resources Information Center

This book, which is designed for those already familiar with the basic principles of structural equation modeling (SEM), discusses the progress and unfolding of SEM since the 1990s. After a compact treatment of underlying theory, the author illustrates many such issues with a discussion of his own SEM research. (SLD)

Boomsma, Anne

2003-01-01

79

Customer repurchase intention : A general structural equation model  

Microsoft Academic Search

This paper develops a general service sector model of repurchase intention from the consumer theory literature. A key contribution of the structural equation model is the incorporation of customer perceptions of equity and value and customer brand preference into an integrated repurchase intention analysis. The model describes the extent to which customer repurchase intention is influenced by seven important factors

Phillip K. Hellier; Gus M. Geursen; Rodney A. Carr; John A. Rickard

2003-01-01

80

Sensitivity Analysis in Structural Equation Models: Cases and Their Influence  

ERIC Educational Resources Information Center

The detection of outliers and influential observations is routine practice in linear regression. Despite ongoing extensions and development of case diagnostics in structural equation models (SEM), their application has received limited attention and understanding in practice. The use of case diagnostics informs analysts of the uncertainty of model…

Pek, Jolynn; MacCallum, Robert C.

2011-01-01

81

A Structural Equation Model of Conceptual Change in Physics  

ERIC Educational Resources Information Center

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…

Taasoobshirazi, Gita; Sinatra, Gale M.

2011-01-01

82

Bayesian Data-Model Fit Assessment for Structural Equation Modeling  

ERIC Educational Resources Information Center

Bayesian approaches to modeling are receiving an increasing amount of attention in the areas of model construction and estimation in factor analysis, structural equation modeling (SEM), and related latent variable models. However, model diagnostics and model criticism remain relatively understudied aspects of Bayesian SEM. This article describes…

Levy, Roy

2011-01-01

83

Analyzing Mixed-Dyadic Data Using Structural Equation Models  

ERIC Educational Resources Information Center

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…

Peugh, James L.; DiLillo, David; Panuzio, Jillian

2013-01-01

84

Multiple Imputation Strategies for Multiple Group Structural Equation Models  

ERIC Educational Resources Information Center

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…

Enders, Craig K.; Gottschall, Amanda C.

2011-01-01

85

A Bayesian Approach for Analyzing Longitudinal Structural Equation Models  

ERIC Educational Resources Information Center

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…

Song, Xin-Yuan; Lu, Zhao-Hua; Hser, Yih-Ing; Lee, Sik-Yum

2011-01-01

86

Habitat fragmentation and reproductive success: a structural equation modelling approach  

E-print Network

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

Helle, Samuli

87

Global solutions to the compressible Euler equations with geometrical structure  

Microsoft Academic Search

We prove the existence of global solutions to the Euler equations of compressible isentropic gas dynamics with geometrical structure, including transonic nozzle flow and spherically symmetric flow. Due to the presence of the geometrical source terms, the existence results themselves are new, especially as they pertain to radial flow in an unbounded region,\\u000a

Gui-Qiang Chen; James Glimm

1996-01-01

88

Local Influence Analysis of Nonlinear Structural Equation Models  

ERIC Educational Resources Information Center

By regarding the latent random vectors as hypothetical missing data and based on the conditional expectation of the complete-data log-likelihood function in the EM algorithm, we investigate assessment of local influence of various perturbation schemes in a nonlinear structural equation model. The basic building blocks of local influence analysis…

Lee, Sik-Yum; Tang, Nian-Sheng

2004-01-01

89

Principles and practice in reporting structural equation analyses  

Microsoft Academic Search

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

Roderick P. McDonald; Moon-Ho Ringo Ho

2002-01-01

90

Canonical structure of the coupled Korteweg-de Vries equations  

NASA Astrophysics Data System (ADS)

The inverse problem of variational calculus is solved for the coupled Korteweg-de Vries equations resulting from a complex Lax pair. The system is found to be characterized by a second-order degenerate Lagrangian density having some common feature with the well-known Morse-Feshbach Lagrangian. The Hamiltonian structure is examined using Dirac's theory of constraints.

Talukdar, B.; Ghosh, S.; Shamanna, J.

2004-06-01

91

A Structural Equation Model of Expertise in College Physics  

ERIC Educational Resources Information Center

A model of expertise in physics was tested on a sample of 374 college students in 2 different level physics courses. Structural equation modeling was used to test hypothesized relationships among variables linked to expert performance in physics including strategy use, pictorial representation, categorization skills, and motivation, and these…

Taasoobshirazi, Gita; Carr, Martha

2009-01-01

92

Motives for choosing growth-enhancing hormone treatment in adolescents with idiopathic short stature: a questionnaire and structured interview study  

PubMed Central

Background Growth-enhancing hormone treatment is considered a possible intervention in short but otherwise healthy adolescents. Although height gain is an obvious measure for evaluating hormone treatment, this may not be the ultimate goal for the person, but rather a means to reach other goals such as the amelioration of current height-related psychosocial problems or the enhancement of future prospects in life and society. The aim of our study was to clarify the motives of adolescents and their parents when choosing to participate in a growth-enhancing trial combining growth hormone and puberty-delaying hormone treatment. Methods Participants were early pubertal adolescents (25 girls, 13 boys) aged from 11 to 13 years (mean age 11.5 years) with a height standard deviation score (SDS) ranging from -1.03 to -3.43. All had been classified as idiopathic short stature or persistent short stature born small for the gestational age (intrauterine growth retardation) on the basis of a height SDS below -2, or had a height SDS between -1 and -2 and a predicted adult height SDS below -2. The adolescents and their parents completed questionnaires and a structured interview on the presence of height-related stressors, parental worries about their child's behavior and future prospects, problems in psychosocial functioning, and treatment expectations. Questionnaire scores were compared to norms of the general Dutch population. Results The adolescents reported normal psychosocial functioning and highly positive expectations of the treatment in terms of height gain, whereas the parents reported that their children encountered some behavioral problems (being anxious/depressed, and social and attention problems) and height-related stressors (being teased and juvenilized). About 40% of the parents were worried about their children's future prospects for finding a spouse or job. The motives of the adolescents and their parents exhibited rather different profiles. The most prevalent parental worries related to the current or future functioning of their children, while a few cases were characterized by no observed motives or by psychosocial problems only reported by the adolescents themselves. Conclusion The motives for participating in a growth-enhancing hormone trial are more obvious in the parents than in the adolescents themselves. Two out of three parents report worries about the future opportunities or observe modest current psychosocial problems in their children. The adolescents want to gain height, but the motivation underlying this remains unclear. Few of the adolescents experience psychosocial problems. Our analyses revealed differences among individuals in terms of motives, which implies that in an evaluation of hormone treatment, the importance of divergent outcome variables will also differ among individuals. Effectiveness evaluations of hormone treatment to increase height and the consequential fulfillment of other goals must be awaited. PMID:15943869

Visser – van Balen, Hanneke; Geenen, Rinie; Kamp, Gerdine A; Huisman, Jaap; Wit, Jan M; Sinnema, Gerben

2005-01-01

93

Selected Neurophysiological, Psychological, and Behavioral Influences on Subjective Sleep Quality in Nurses: A Structure Equation Model  

PubMed Central

Few studies have examined relationships among neurophysiological, psychological, and behavioral factors with regard to their effects on sleep quality. We used a structure equation model to investigate behavioral and psychological factors that influence neurophysiological regulation of sleep in shift workers. Using a cross-sectional study design, we tested the model with a sample of 338 female nurses working rotating shifts at an urban regional hospital. The Morningness-Eveningness Questionnaire (MEQ) and short-form Menstrual Distress Questionnaire (MDQ) were used to measure neurophysiological factors involved in morningness-eveningness and menstrual distress. The Sleep Hygiene Awareness and Practice Scale (SHAPS) and Profile of Mood States Short Form (POMS-SF) were completed to measure behavioral factors of sleep hygiene practices and psychological factors of mood states. In addition, the Pittsburgh Sleep Quality Index (PSQI) measured participant's self-reported sleep quality. The results revealed that sleep hygiene practices and mood states mediated the effects of morningness-eveningness and menstrual distress on sleep quality. Our findings provide support for developing interventions to enhance sleep hygiene and maintain positive mood states to reduce the influence of neurophysiological factors on sleep quality among shift workers. PMID:24278145

Chung, Min-Huey; Liu, Wen-I; Lee, Hui-Ling; Hsu, Nanly

2013-01-01

94

Multidisciplinary optimization of controlled space structures with global sensitivity equations  

NASA Technical Reports Server (NTRS)

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.

Padula, Sharon L.; James, Benjamin B.; Graves, Philip C.; Woodard, Stanley E.

1991-01-01

95

The feeding practices and structure questionnaire: construction and initial validation in a sample of Australian first-time mothers and their 2-year olds  

PubMed Central

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

2014-01-01

96

Examining the Factor Structure and Discriminant Validity of the 12-Item General Health Questionnaire (GHQ-12) Among Spanish Postpartum Women  

ERIC Educational Resources Information Center

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.…

Aguado, Jaume; Campbell, Alistair; Ascaso, Carlos; Navarro, Purificacion; Garcia-Esteve, Lluisa; Luciano, Juan V.

2012-01-01

97

Factor Structure and Reliability of the Childhood Trauma Questionnaire and Prevalence Estimates of Trauma for Male and Female Street Youth  

ERIC Educational Resources Information Center

This study examines the psychometric properties of the Childhood Trauma Questionnaire short form (CTQ-SF) with street youth who have run away or been expelled from their homes (N = 397). Internal reliability coefficients for the five clinical scales ranged from 0.65 to 0.95. Confirmatory Factor Analysis (CFA) was used to test the five-factor…

Forde, David R.; Baron, Stephen W.; Scher, Christine D.; Stein, Murray B.

2012-01-01

98

Extended Navier–Stokes equations, ultrasonic absorption and shock structure  

NASA Astrophysics Data System (ADS)

The Navier-Stokes (N-S) equations for a steady or unsteady, compressible, continuum flow are modified. The extension is based on a Stokesian fluid with a single nonlinear term in an isotropic stress, rate-of-deformation relation. This is the simplest possible nonlinear extension that also satisfies the second law of thermodynamics. The transport coefficient of this term is referred to as the third viscosity coefficient. In the extended version, the momentum and energy equations each contain a nonlinear term that is proportional to this new coefficient. These terms are significant only when the velocity gradient is extremely large. They are inconsequential, e.g., in a laminar boundary layer. Nevertheless, there are flows where the extended version of the N-S equations is relevant. The first of these is an ultrasonic, unsteady, one-dimensional flow, which is used for evaluating the bulk viscosity. In this case, the linearized N-S equations become singular as the ultrasonic frequency increases toward infinity. When the frequency is sufficiently large, nonlinear terms in the extended N-S equations need to be retained. The terms that are proportional to the third viscosity coefficient increase in importance, relative to linear terms, as the fourth power of the frequency. A second example is shock wave structure. A model is established and numerically solved for the normalized density derivative. Results are compared with corresponding measurements for argon when the upstream Mach number is 1.058 and 1.23. Good agreement between the extended N-S predictions and measurements is obtained for both Mach numbers with a single, but extremely small, value for the third viscosity coefficient. An important difference between conventional and extended N-S shock structure solutions is that the extended-model solution depends on the upstream pressure, whereas the conventional solution does not.

Emanuel, G.

2015-01-01

99

Factor structure of the General Health Questionnaire (GHQ12) in subjects who had suffered from the 2004 Niigata-Chuetsu Earthquake in Japan: a community-based study  

Microsoft Academic Search

BACKGROUND: Factor structure of the 12-item General Health Questionnaire (GHQ-12) was studied by a survey of subjects who had experienced the 2004 Niigata-Chuetsu earthquake (6.8 on the Richter scale) in Japan. METHODS: Psychological distress was measured at two years after the earthquake by using GHQ-12 in 2,107 subjects (99.0% response rate) who suffered the earthquake. GHQ-12 was scored by binary,

Shin-ichi Toyabe; Toshiki Shioiri; Kuriko Kobayashi; Hideki Kuwabara; Masataka Koizumi; Taro Endo; Miki Ito; Hiroko Honma; Noboru Fukushima; Toshiyuki Someya; Kouhei Akazawa

2007-01-01

100

Assessment of the factor structure and reliability of the 28 item version of the General Health Questionnaire (GHQ28) in El Salvador  

Microsoft Academic Search

We wished to assess both the factor structure and the reliability of the 28-item version of the General Health Questionnaire (GHQ-28) in a non-clinical population in El Salvador. The GHQ-28 was applied to a large sample (n = 714) of university students in El Salvador. A principal components analysis was applied and a four-factor solution selected. A sub-group of the

Pat Gibbons; Hilda Flores de Arévalo; Mauricio Mónico

2004-01-01

101

Structure of the field equations in N = 1 chiral supergravity  

E-print Network

We study the structure of linearized field equations in $N = 1$ chiral supergravity (SUGRA) with a complex tetrad, as a preliminary to introducing additional auxiliary fields in order that the supersymmetry (SUSY) algebra close off shell. We follow the first-order formulation we have recently constructed using the method of the usual $N = 1$ SUGRA. In particular, we see how the real and imaginary parts of the complex tetrad are coupled to matter fields in the weak field approximation. Starting from the linearized (free) theory of $N = 1$ chiral SUGRA, we then construct a Lagrangian which is invariant under local SUSY transformations to zeroth order of the gravitational constant, and compare the results with the linearized field equations.

M. Tsuda; T. Shirafuji

1996-10-16

102

Evaluation of Existing Structure and Civil Protection Management Framework in Greek Local Authorities: A Questionnaire Survey Demonstrates Why Prevention Fails  

NASA Astrophysics Data System (ADS)

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.

Papanikolaou, Dimitrios; Papanikolaou, Ioannis; Diakakis, Michalis; Deligiannakis, Georgios

2013-04-01

103

Reporting Multiple-Group Mean and Covariance Structure across Occasions with Structural Equation Modeling  

ERIC Educational Resources Information Center

Objectives: Using baseline and second wave data, the study evaluated the measurement and structural properties of parenting stress, personal mastery, and economic strain with N = 381 lower income parents who decided to join and those who did not join in a child development savings account program. Methods: Structural equation modeling mean and…

Okech, David

2012-01-01

104

Structural Stability for Fractional Differential Equations as Boundary Value Problems  

NASA Astrophysics Data System (ADS)

In this paper we aim to construct reliable numerical schemes for the approximation of solutions to fractional boundary value problems. We focus on equations of the form D*?y(t) = f(t,y(t)), y(a) = y1, where D*? denotes the fractional derivative of Caputo type, the order ? satisfies 0 < ? < 1 and f is a suitably behaved function. We seek solutions over a finite interval [0,T] and 0 < a < T. We investigate the structural stability of the underlying problem and discuss the numerical stability of the numerical methods we construct.

Ford, Neville J.; Morgado, M. L.

2010-09-01

105

The Survey Questionnaire  

ERIC Educational Resources Information Center

Internet-based surveys are still relatively new, and researchers are just beginning to articulate best practices for questionnaire design. Online questionnaire design has generally been guided by the principles applying to other self-administered instruments, such as paper-based questionnaires. Web-based questionnaires, however, have the potential…

Ritter, Lois A. Ed.; Sue, Valerie M., Ed.

2007-01-01

106

The Interface Between Theory and Data in Structural Equation Models  

USGS Publications Warehouse

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.

Grace, James B.; Bollen, Kenneth A.

2006-01-01

107

Structural Equation Modeling: Applications in Ecological and Evolutionary Biology Research  

USGS Publications Warehouse

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.

Pugesek, Bruce H.; von Eye, Alexander; Tomer, Adrian

2003-01-01

108

A Hierarchy of New Nonlinear Evolution Equations and Their Bi-Hamiltonian Structures  

NASA Astrophysics Data System (ADS)

A hierarchy of new nonlinear evolution equations associated with a 3 × 3 matrix spectral problem with four potentials is proposed, in which two typical members are a new coupled Burgers equation and a new coupled KdV equation. The bi-Hamiltonian structures for the hierarchy of nonlinear evolution equations are established by using the trace identity.

Geng, Xian-Guo; Wang, Hui

2014-07-01

109

Structural equation modeling in medical research: a primer  

PubMed Central

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

2010-01-01

110

Structural equation models of VMT growth in US urbanised areas.  

USGS Publications Warehouse

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.

Ewing, Reid; Hamidi, Shima; Gallivan, Frank; Nelson, Arthur C.; Grace, James B.

2014-01-01

111

Conversion of Questionnaire Data  

SciTech Connect

During the survey, respondents are asked to provide qualitative answers (well, adequate, needs improvement) on how well material control and accountability (MC&A) functions are being performed. These responses can be used to develop failure probabilities for basic events performed during routine operation of the MC&A systems. The failure frequencies for individual events may be used to estimate total system effectiveness using a fault tree in a probabilistic risk analysis (PRA). Numeric risk values are required for the PRA fault tree calculations that are performed to evaluate system effectiveness. So, the performance ratings in the questionnaire must be converted to relative risk values for all of the basic MC&A tasks performed in the facility. If a specific material protection, control, and accountability (MPC&A) task is being performed at the 'perfect' level, the task is considered to have a near zero risk of failure. If the task is performed at a less than perfect level, the deficiency in performance represents some risk of failure for the event. As the degree of deficiency in performance increases, the risk of failure increases. If a task that should be performed is not being performed, that task is in a state of failure. The failure probabilities of all basic events contribute to the total system risk. Conversion of questionnaire MPC&A system performance data to numeric values is a separate function from the process of completing the questionnaire. When specific questions in the questionnaire are answered, the focus is on correctly assessing and reporting, in an adjectival manner, the actual performance of the related MC&A function. Prior to conversion, consideration should not be given to the numeric value that will be assigned during the conversion process. In the conversion process, adjectival responses to questions on system performance are quantified based on a log normal scale typically used in human error analysis (see A.D. Swain and H.E. Guttmann, 'Handbook of Human Reliability Analysis with Emphasis on Nuclear Power Plant Applications,' NUREG/CR-1278). This conversion produces the basic event risk of failure values required for the fault tree calculations. The fault tree is a deductive logic structure that corresponds to the operational nuclear MC&A system at a nuclear facility. The conventional Delphi process is a time-honored approach commonly used in the risk assessment field to extract numerical values for the failure rates of actions or activities when statistically significant data is absent.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL

2011-01-01

112

Shock wave structure using nonlinear model Boltzmann equations  

NASA Technical Reports Server (NTRS)

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.

Segal, Ben Maurice

1971-01-01

113

Measuring Metacognition in Cancer: Validation of the Metacognitions Questionnaire 30 (MCQ-30)  

PubMed Central

Objective The Metacognitions Questionnaire 30 assesses metacognitive beliefs and processes which are central to the metacognitive model of emotional disorder. As recent studies have begun to explore the utility of this model for understanding emotional distress after cancer diagnosis, it is important also to assess the validity of the Metacognitions Questionnaire 30 for use in cancer populations. Methods 229 patients with primary breast or prostate cancer completed the Metacognitions Questionnaire 30 and the Hospital Anxiety and Depression Scale pre-treatment and again 12 months later. The structure and validity of the Metacognitions Questionnaire 30 were assessed using factor analyses and structural equation modelling. Results Confirmatory and exploratory factor analyses provided evidence supporting the validity of the previously published 5-factor structure of the Metacognitions Questionnaire 30. Specifically, both pre-treatment and 12 months later, this solution provided the best fit to the data and all items loaded on their expected factors. Structural equation modelling indicated that two dimensions of metacognition (positive and negative beliefs about worry) were significantly associated with anxiety and depression as predicted, providing further evidence of validity. Conclusions These findings provide initial evidence that the Metacognitions Questionnaire 30 is a valid measure for use in cancer populations. PMID:25215527

Cook, Sharon A.; Salmon, Peter; Dunn, Graham; Fisher, Peter

2014-01-01

114

Linking impulsivity to dysfunctional thought control and insomnia: a structural equation model.  

PubMed

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

Schmidt, Ralph E; Gay, Philippe; Ghisletta, Paolo; VAN DER Linden, Martial

2010-03-01

115

Executive functions, impulsivity, and inhibitory control in adolescents: A structural equation model  

PubMed Central

Background. Adolescence represents a critical period for brain development, addressed by neurodevelopmental models to frontal, subcortical-limbic, and striatal activation, a pattern associated with rise of impulsivity and deficits in inhibitory control. The present study aimed at studying the association between self-report measures of impulsivity and inhibitory control with executive function in adolescents, employing structural equation modeling. Method. Tests were administered to 434 high school students. Acting without thinking was measured through the Barratt Impulsiveness Scale and the Dickman Impulsivity Inventory, reward sensitivity through the Behavioral Activation System, and sensation seeking through the Zuckerman–Kuhlman–Aluja Personali- ty Questionnaire. Inhibitory control was assessed through the Behavioral Inhibition System. The performance at the Wisconsin Card Sorting Task indicated executive function. Three models were specified using Sample Covariance Matrix, and the estimated parameters using Maximum Likelihood. Results. In the final model, impulsivity and inhibitory control predicted executive function, but sensation seeking did not. The fit of the model to data was excellent. Conclusions. The hypothesis that inhibitory control and impulsivity are predictors of executive function was supported. Our results appear informative of the validity of self-report measures to examine the relation between impulsivity traits rather than others to regulatory function of cognition and behavior. PMID:25157298

Fino, Emanuele; Melogno, Sergio; Iliceto, Paolo; D’Aliesio, Sara; Pinto, Maria Antonietta; Candilera, Gabriella; Sabatello, Ugo

2014-01-01

116

Predictors of Quality of Life in Portuguese Obese Patients: A Structural Equation Modeling Application  

PubMed Central

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

Vilhena, Estela; Pais-Ribeiro, José; Silva, Isabel; Cardoso, Helena; Mendonça, Denisa

2014-01-01

117

Reassessment of the Psychometric Characteristics and Factor Structure of the ‘Perceived Stress Questionnaire’ (PSQ): Analysis in a Sample of Dental Students  

PubMed Central

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

Montero-Marin, Jesús; Piva Demarzo, Marcelo Marcos; Pereira, Joao Paulo; Olea, Marina; García-Campayo, Javier

2014-01-01

118

Using structural equation modeling to investigate relationships among ecological variables  

USGS Publications Warehouse

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.

Malaeb, Z.A.; Kevin, Summers J.; Pugesek, B.H.

2000-01-01

119

On the specification of structural equation models for ecological systems  

USGS Publications Warehouse

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.

Grace, J.B.; Michael, Anderson T.; Han, O.; Scheiner, S.M.

2010-01-01

120

Clarification of the factor structure of the 12-item General Health Questionnaire among Japanese adolescents and associated sleep status  

Microsoft Academic Search

If the factors affecting the mental health status of adolescents and their association with sleep status could be clarified, this information would be helpful for formulating lifestyle and healthcare guidance for the promotion of healthy growth and the prevention of mental problems in these individuals. The purpose of this study was to clarify (1) the factor structure of the 12-item

Hiroyuki Suzuki; Yoshitaka Kaneita; Yoneatsu Osaki; Masumi Minowa; Hideyuki Kanda; Kenji Suzuki; Kiyoshi Wada; Kenji Hayashi; Takeo Tanihata; Takashi Ohida

2011-01-01

121

Confirming the Structure of the "Why Do You Smoke?" Questionnaire: A Community Resource for Adolescent Tobacco Cessation  

ERIC Educational Resources Information Center

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…

Smith, Dennis W.; Lee, Jay T.; Colwell, Brian; Stevens-Manser, Stacey

2008-01-01

122

Development and Validation of the Cognitive Behavioral Physical Activity Questionnaire.  

PubMed

Abstract 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

Schembre, Susan M; Durand, Casey P; Blissmer, Bryan J; Greene, Geoffrey W

2014-08-27

123

Shock capturing approximations to the compressible Euler equations with geometric structure and related equations  

Microsoft Academic Search

In this paper we analyze a shock capturing method, developed by Chen-Glimm (4), to construct approximate solutions of the transonic nozzle flow and the spherically symmet- ric flow for the compressible Euler equations and related equations. The L 1 {stability, H 1 { compactness, and convergence of the approximate solutions are proved for any adiabatic exponent >1 for the isentropic

Gui-Qiang Chen; Dehua Wang

1998-01-01

124

Structural equation modeling of pesticide poisoning, depression, safety, and injury.  

PubMed

The role of pesticide poisoning in risk of injuries may operate through a link between pesticide-induced depressive symptoms and reduced engagement in safety behaviors. The authors conducted structural equation modeling of cross-sectional data to examine the pattern of associations between pesticide poisoning, depressive symptoms, safety knowledge, safety behaviors, and injury. Interviews of 1637 Colorado farm operators and their spouses from 964 farms were conducted during 1993-1997. Pesticide poisoning was assessed based on a history of ever having been poisoned. The Center for Epidemiologic Studies-Depression scale was used to assess depressive symptoms. Safety knowledge and safety behaviors were assessed using ten items for each latent variable. Outcomes were safety behaviors and injuries. A total of 154 injuries occurred among 1604 individuals with complete data. Pesticide poisoning, financial problems, health, and age predicted negative affect/somatic depressive symptoms with similar effect sizes; sex did not. Depression was more strongly associated with safety behavior than was safety knowledge. Two safety behaviors were significantly associated with an increased risk of injury. This study emphasizes the importance of financial problems and health on depression, and provides further evidence for the link between neurological effects of past pesticide poisoning on risk-taking behaviors and injury. PMID:24125049

Beseler, Cheryl L; Stallones, Lorann

2013-01-01

125

The Factor Structure of the General Health Questionnaire in a Japanese High School and University Student Sample  

Microsoft Academic Search

Factor structures of the 60- and 30-item versions of the General Health Question naire (GHQ) were explored, using data collected from 236 Japanese high-school and university students. The 60-item version produced factors interpretable as social functioning, anxiety, somatic symptoms, and severe depression; the 30-item version produced general dysphoria, social functioning, depressive thoughts, difficulty in concentration and insomnia. Although the two

Mika Takeuchi; Toshinori Kitamura

1991-01-01

126

Factor structure and internal consistency of the 12-item General Health Questionnaire (GHQ12) and the Subjective Vitality Scale (VS), and the relationship between them: a study from France  

Microsoft Academic Search

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

Mareï Salama-Younes; Ali Montazeri; Amany Ismaïl; Charles Roncin

2009-01-01

127

Hard ellipses: Equation of state, structure, and self-diffusion.  

PubMed

Despite their fundamental and practical interest, the physical properties of hard ellipses remain largely unknown. In this paper, we present an event-driven molecular dynamics study for hard ellipses and assess the effects of aspect ratio and area fraction on their physical properties. For state points in the plane of aspect ratio (1 ? k ? 9) and area fraction (0.01 ? ? ? 0.8), we identify three different phases, including isotropic, plastic, and nematic states. We analyze in detail the thermodynamic, structural, and self-diffusive properties in the formed various phases of hard ellipses. The equation of state (EOS) is shown for a wide range of aspect ratios and is compared with the scaled particle theory (SPT) for the isotropic states. We find that SPT provides a good description of the EOS for the isotropic phase of hard ellipses. At large fixed ?, the reduced pressure p increases with k in both the isotropic and the plastic phases and, interestingly, its dependence on k is rather weak in the nematic phase. We rationalize the thermodynamics of hard ellipses in terms of particle motions. The static structures of hard ellipses are then investigated both positionally and orientationally in the different phases. The plastic crystal is shown to form for aspect ratios up to k = 1.4, while appearance of the stable nematic phase starts approximately at k = 3. We quantitatively determine the locations of the isotropic-plastic (I-P) transition and the isotropic-nematic (I-N) transition by analyzing the bond-orientation correlations and the angular correlations, respectively. As expected, the I-P transition point is found to increase with k, while a larger k leads to a smaller area fraction where the I-N transition takes place. Moreover, our simulations strongly support that the two-dimensional nematic phase in hard ellipses has only quasi-long-range orientational order. The self-diffusion of hard ellipses is further explored and connections are revealed between the structure and the self-diffusion. We discuss the relevance of our results to the glass transition in hard ellipses. Finally, the results of the isodiffusivity lines are evaluated for hard ellipses and we discuss the effect of spatial dimension on the diffusive dynamics of hard ellipsoidal particles. PMID:23862947

Xu, Wen-Sheng; Li, Yan-Wei; Sun, Zhao-Yan; An, Li-Jia

2013-07-14

128

System Characteristics, Satisfaction and E-Learning Usage: A Structural Equation Model (SEM)  

ERIC Educational Resources Information Center

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…

Ramayah, T.; Lee, Jason Wai Chow

2012-01-01

129

Efficient Surface Integral Equation Methods for the Analysis of Complex Metamaterial Structures  

E-print Network

Efficient Surface Integral Equation Methods for the Analysis of Complex Metamaterial Structures equivalence principle algorithm, are applied to analyze complex three-dimensional metamaterial structures. The efficiency and performance of these methods are studied and discussed. I. INTRODUCTION Metamaterials

Gürel, Levent

130

Hard ellipses: Equation of state, structure and self-diffusion  

E-print Network

We present an event-driven molecular dynamics study for hard ellipses and assess the effects of aspect ratio and area fraction on their physical properties. For state points in the plane of aspect ratio (k=1-9) and area fraction (phi=0.01-0.8), we identify three different phases, including isotropic, plastic and nematic states. The equation of state (EOS) is shown for a wide range of aspect ratios and is compared with the scaled particle theory (SPT) for the isotropic states. We find that SPT provides a good description of the EOS for the isotropic phase of hard ellipses. At large fixed phi, the reduced pressure p increases with k in both the isotropic and the plastic phases, and interestingly, its dependence on k is rather weak in the nematic phase. We rationalize the thermodynamics of hard ellipses in terms of particle motions. The plastic crystal is shown to form for aspect ratios up to k=1.4, while appearance of the stable nematic phase starts approximately at k=3. We quantitatively determine the locations of the isotropic-plastic (I-P) transition and the isotropic-nematic (I-N) transition by analyzing the bond-orientation correlations and the angular correlations, respectively. As expected, the I-P transition point is found to increase with k, while a larger k leads to a smaller area fraction where the I-N transition takes place. Moreover, our simulations strongly support that the two-dimensional nematic phase in hard ellipses has only quasi-long-range orientational order. The self-diffusion of hard ellipses is further explored and connections are revealed between the structure and the self-diffusion. We discuss the relevance of our results to the glass transition in hard ellipses. Finally, the results of the isodiffusivity lines are evaluated for hard ellipses and we discuss the effect of spatial dimension on the diffusive dynamics of hard ellipsoidal particles.

Wen-Sheng Xu; Yan-Wei Li; Zhao-Yan Sun; Li-Jia An

2012-12-28

131

Estimating and Interpreting Latent Variable Interactions: A Tutorial for Applying the Latent Moderated Structural Equations Method  

ERIC Educational Resources Information Center

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)…

Maslowsky, Julie; Jager, Justin; Hemken, Douglas

2015-01-01

132

A Maximum Likelihood Approach for Multisample Nonlinear Structural Equation Models with Missing Continuous and Dichotomous Data  

ERIC Educational Resources Information Center

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.…

Song, Xin-Yuan; Lee, Sik-Yum

2006-01-01

133

An EM Algorithm for Fitting Two-Level Structural Equation Models  

ERIC Educational Resources Information Center

Maximum likelihood is an important approach to analysis of two-level structural equation models. Different algorithms for this purpose have been available in the literature. In this paper, we present a new formulation of two-level structural equation models and develop an EM algorithm for fitting this formulation. This new formulation covers a…

Liang, Jiajuan; Bentler, Peter M.

2004-01-01

134

General structure of the gravitational equations of motion in conformal Weyl gravity  

NASA Technical Reports Server (NTRS)

A general method for determining the structure of the gravitational equations of motion is presented in the fourth-order theory of gravity based on local conformal Weyl invariance of the gravitational action. The explicit structure for these equations is given for a time-dependent, spherically symmetric geometry.

Kazanas, Demosthenes; Mannheim, Philip D.

1991-01-01

135

Evaluation of Structural Equation Mixture Models: Parameter Estimates and Correct Class Assignment  

ERIC Educational Resources Information Center

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…

Tueller, Stephen; Lubke, Gitta

2010-01-01

136

Applications of structural equation modeling in marketing and consumer research: A review  

Microsoft Academic Search

This paper reviews prior applications of structural equation modeling in four major marketing journals (the Journal of Marketing, Journal of Marketing Research, International Journal of Research in Marketing, and the Journal of Consumer Research) between 1977 and 1994. After documenting and characterizing the number of applications over time, we discuss important methodological issues related to structural equation modeling and assess

Hans Baumgartner; Christian Homburg

1996-01-01

137

Static and dynamic analyses of tensegrity structures. Part 1. Nonlinear equations of motion  

Microsoft Academic Search

In order to present basic equations for static and dynamic analyses of a class of truss structures called tensegrity structures, large-deformation kinematics and kinetics were presented in both Eulerian and Lagrangian formulations. The two sets of equations of motion yield the same values even if different stress and strain measures were employed for their computation. The Eulerian formulation was implemented

Hidenori Murakami

2001-01-01

138

Wesleyan University Student Questionnaire.  

ERIC Educational Resources Information Center

This questionnaire assesses marijuana use practices in college students. The 30 items (multiple choice or free response) are concerned with personal and demographic data, marijuana smoking practices, use history, effects from smoking marijuana, present attitude toward the substance, and use of other drugs. The Questionnaire is untimed and…

Haagen, C. Hess

139

Hamiltonian structure of propagation equations for ultrashort optical pulses  

Microsoft Academic Search

A Hamiltonian framework is developed for a sequence of ultrashort optical pulses propagating in a nonlinear dispersive medium. To this end a second-order nonlinear wave equation for the electric field is transformed into a first-order propagation equation for a suitably defined complex electric field. The Hamiltonian formulation is then introduced in terms of normal variables, i.e., classical complex fields referring

Sh. Amiranashvili; A. Demircan

2010-01-01

140

Automatic algebraic computation of basic kinematic equations of tree structure robot arms: application to human arms.  

PubMed

Tree structure robot arms have been very little studied due to the complexity of their topological structure compared with those of the simple chain type. This paper presents a symbolic computation of the basic kinematic equations of these tree structure robot arms. This leads to the calculation of the homogeneous transformation matrices (HTMs) of the tree branches. These computations are arranged to need the smallest possible number of arithmetic operations. A computer program MGLAT is developed in Pascal to generate such equations in symbolic form. The human arm which consists of the forearm, a wrist and fingers is a very good example of such a structure. A simplified model of 25 degrees of mobility of such an arm is presented. Its basic kinematic equations need 358 multiplications, 214 additions and 252 equations. These equations are useful for improving the existing designs of the artificial arms for handicapped persons and for designing new robot hands for delicate tasks. PMID:1823787

Megahed, S M

1991-01-01

141

General non-markovian structure of gaussian master and stochastic schrödinger equations.  

PubMed

General open quantum systems display memory features, their master equations are non-Markovian. We show that the subclass of Gaussian non-Markovian open system dynamics is tractable in a depth similar to the Markovian class. The structure of master equations exhibits a transparent generalization of the Lindblad structure. We find and parametrize the class of stochastic Schrödinger equations that unravel a given master equation, such a class was previously known for Markovian systems only. We show that particular non-Markovian unravelings known in the literature are special cases of our class. PMID:25432028

Diósi, L; Ferialdi, L

2014-11-14

142

Hamiltonian structure of propagation equations for ultrashort optical pulses  

SciTech Connect

A Hamiltonian framework is developed for a sequence of ultrashort optical pulses propagating in a nonlinear dispersive medium. To this end a second-order nonlinear wave equation for the electric field is transformed into a first-order propagation equation for a suitably defined complex electric field. The Hamiltonian formulation is then introduced in terms of normal variables, i.e., classical complex fields referring to the quantum creation and annihilation operators. The derived z-propagated Hamiltonian accounts for forward and backward waves, arbitrary medium dispersion, and four-wave mixing processes. As a simple application we obtain integrals of motion for the pulse propagation. The integrals reflect time-averaged fluxes of energy, momentum, and photons transferred by the pulse. Furthermore, pulses in the form of stationary nonlinear waves are considered. They yield extremal values of the momentum flux for a given energy flux. Simplified propagation equations are obtained by reduction of the Hamiltonian. In particular, the complex electric field reduces to an analytic signal for the unidirectional propagation. Solutions of the full bidirectional model are numerically compared to the predictions of the simplified equation for the analytic signal and to the so-called forward Maxwell equation. The numerics is effectively tested by examining the conservation laws.

Amiranashvili, Sh.; Demircan, A. [Weierstrass Institute for Applied Analysis and Stochastics, Mohrenstrasse 39, D-10117 Berlin (Germany)

2010-07-15

143

On the Lagrangian Structure of Integrable Quad-Equations  

NASA Astrophysics Data System (ADS)

The new idea of flip invariance of action functionals in multidimensional lattices was recently highlighted as a key feature of discrete integrable systems. Flip invariance was proved for several particular cases of integrable quad-equations by Bazhanov, Mangazeev and Sergeev and by Lobb and Nijhoff. We provide a simple and case-independent proof for all integrable quad-equations. Moreover, we find a new relation for Lagrangians within one elementary quadrilateral which seems to be a fundamental building block of the various versions of flip invariance.

Bobenko, Alexander I.; Suris, Yuri B.

2010-04-01

144

Integral equations of the electrodynamics of three-dimensional structures and iterative methods for solving them (Review)  

NASA Astrophysics Data System (ADS)

Integral equations describing problems of electromagnetic wave diffraction by 3-D structures are examined, and it is shown that these equations can be effectively solved by iterative methods. Iterative methods are applicable to the study of diffraction by 3-D structures described by volume singular integral equations for a dielectric body and by surface hypersingular integral equations for a perfectly conducting surface.

Samokhin, A. B.

1993-08-01

145

The Shorter PROMIS Questionnaire  

Microsoft Academic Search

There is both a theoretical and clinical need to develop a questionnaire that assesses a range of addictive behaviours. The Shorter PROMIS Questionnaire (SPQ) is a 16-scale self-report instrument assessing the use of nicotine, recreational drugs, prescription drugs, gambling, sex, caffeine, food bingeing, food starving, exercise, shopping, work, relationships dominant and submissive, and compulsive helping dominant and submissive. Clinical cut-off

George Christo; Susan L Jones; Samantha Haylett; Geoffrey M Stephenson; Robert M. H Lefever; Robin Lefever

2003-01-01

146

Psychometric properties of the Trait Emotional Intelligence Questionnaire: factor structure, reliability, construct, and incremental validity in a French-speaking population.  

PubMed

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 independent of age; (d) there was preliminary evidence of convergent/discriminant validity, with TEIQue scores being independent of nonverbal reasoning (Raven's [1976] matrices) but positively related to some personality dimensions (optimism, agreeableness, openness, conscientiousness) as well as inversely related to others (alexithymia, neuroticism); (e) there was also preliminary evidence of criterion validity, with TEIQue scores predicting depression, anxiety, and social support as well as future state affectivity and emotional reactivity in neutral and stressful situations; (f) TEIQue scores were susceptible to socially desirable responding; however, (g) TEIQue scores had incremental validity to predict emotional reactivity over and above social desirability, alexithymia, and the Five-factor model of personality. Such results constitute encouraging preliminary findings in favor of the use of the TEIQue. PMID:17518555

Mikolajczak, Moira; Luminet, Olivier; Leroy, Cecile; Roy, Emmanuel

2007-06-01

147

On the structure of nonlinear constitutive equations for fiber reinforced composites  

NASA Technical Reports Server (NTRS)

The structure of constitutive equations for nonlinear multiaxial behavior of transversely isotropic fiber reinforced metal matrix composites subject to proportional loading was investigated. Results from an experimental program were combined with numerical simulations of the composite behavior for complex stress to reveal the full structure of the equations. It was found that the nonlinear response can be described by a quadratic flow-potential, based on the polynomial stress invariants, together with a hardening rule that is dominated by two different hardening mechanisms.

Jansson, Stefan

1992-01-01

148

Generalized pulse equations for through-transmission evaluation of arbitrary multilayered structures  

NASA Technical Reports Server (NTRS)

Generalized transit time and pulse amplitude equations were derived for modelling the ultrasonic through-transmission wave propagation of an arbitrary n-layered structure. The equations can be programmed into an expert system and used to identify and predict the through-transmission pulse signals from the critical interfaces of a multilayered structure. To test the formulas, the through transmission was measured from one- and three-layered configurations in the laboratory. The experimental measurements were compared with computer-generated data determined using the derived equations. The results verify the validity of the formulas.

Chern, E. James; Nielsen, Hatsumi T. C.

1990-01-01

149

Generalized pulse equations for through-transmission evaluation of arbitrary multilayered structures  

NASA Technical Reports Server (NTRS)

Generalized transit-time and pulse-amplitude equations have been derived for modeling the ultrasonic through-transmission wave propagation of an arbitrary n-layered structure. The equations can be programmed into an expert system and used to identify and predict the through-transmission pulse signals from the critical interfaces of a multilayered structure. To test the formulas, the through-transmission responses from one- and three-layered configurations were measured in the laboratory and compared with computer-generated data that were determined using the derived equations. The results verify the validity of the formulas.

Chern, E. James; Nielsen, Hatsumi T. C.

1990-01-01

150

Impaired self-awareness after traumatic brain injury: inter-rater reliability and factor structure of the Dysexecutive Questionnaire (DEX) in patients, significant others and clinicians  

PubMed Central

Aims: This study sought to address two questions: (1) what is the inter-rater reliability of the Dysexecutive Questionnaire (DEX) when completed by patients, their significant others, and clinicians; and (2) does the factor structure of the DEX vary for these three groups? Methods: We obtained DEX ratings for 113 patients with an acquired brain injury from two brain injury services in the UK and two services in Ireland. We gathered data from two groups of raters—“significant others” (DEX-SO) such as partners and close family members and “clinicians” (DEX-C), who were psychologists or rehabilitation physicians working closely with the patient and who were able to provide an opinion about the patient’s level of everyday executive functioning. Intra-class correlation coefficients and their 95% confidence intervals were calculated between each of the three groups (self, significant other, clinician). Principal axis factor (PAF) analyses were also conducted for each of the three groups. Results: The factor analysis revealed a consistent one-factor model for each of the three groups of raters. However, the inter-rater reliability analyses showed a low level of agreement between the self-ratings and the ratings of the two groups of independent raters. We also found low agreement between the significant others and the clinicians. Conclusion: Although there was a consistent finding of a single factor solution for each of the three groups, the low level of agreement between significant others and clinicians raises a question about the reliability of the DEX. PMID:25346668

McGuire, Brian E.; Morrison, Todd G.; Barker, Lynne A.; Morton, Nicholas; McBrinn, Judith; Caldwell, Sheena; Wilson, Colin F.; McCann, John; Carton, Simone; Delargy, Mark; Walsh, Jane

2014-01-01

151

$R$-matrices and Hamiltonian Structures for Certain Lax Equations  

E-print Network

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.

Chao-Zhong Wu

2013-05-06

152

The Depression Coping Questionnaire.  

ERIC Educational Resources Information Center

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,…

Kleinke, Chris L.

153

Diet History Questionnaire  

Cancer.gov

NATIONAL INSTITUTES OF HEALTH Diet History Questionnaire Today's date: MONTH DAY YEAR |___|___| 0 0 1 1 2 2 3 3 4 5 6 7 8 01 Jan 02 Feb 03 Mar 04 Apr 05 May 06 Jun 07 Jul 08 Aug 09 Sep 10 Oct 11 Nov 12

154

Exploratory Structural Equation Modeling, Integrating CFA and EFA: Application to Students' Evaluations of University Teaching  

Microsoft Academic Search

This study is a methodological-substantive synergy, demonstrating the power and flexibility of exploratory structural equation modeling (ESEM) methods that integrate confirmatory and exploratory factor analyses (CFA and EFA), as applied to substantively important questions based on multidimentional students' evaluations of university teaching (SETs). For these data, there is a well established ESEM structure but typical CFA models do not fit

Herbert W. Marsh; Bengt Muthén; Tihomir Asparouhov; Oliver Lüdtke; Alexander Robitzsch; Alexandre J. S. Morin; Ulrich Trautwein

2009-01-01

155

Fitting Data to Model: Structural Equation Modeling Diagnosis Using Two Scatter Plots  

ERIC Educational Resources Information Center

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…

Yuan, Ke-Hai; Hayashi, Kentaro

2010-01-01

156

Application of Exploratory Structural Equation Modeling to Evaluate the Academic Motivation Scale  

ERIC Educational Resources Information Center

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…

Guay, Frédéric; Morin, Alexandre J. S.; Litalien, David; Valois, Pierre; Vallerand, Robert J.

2015-01-01

157

On soliton structure of the Vakhnenko equation with a 'dissipative' term: a peculiar fission phenomenon  

E-print Network

In the present work, we investigate the soliton structure of the Vakhnenko equation with a 'dissipative' term, by means of the Hirota's method. As a result, we unearth three kinds of soliton solutions depending upon the dissipation parameter. We further find that the scattering behavior among such structures exhibits a peculiar feature that may be the fission phenomenon.

Kuetche Kamgang Victor; Bouetou Bouetou Thomas; Timoleon Crepin Kofane

2007-09-20

158

Direct and Indirect Effects of Parental Influence upon Adolescent Alcohol Use: A Structural Equation Modeling Analysis  

ERIC Educational Resources Information Center

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…

Kim, Young-Mi; Neff, James Alan

2010-01-01

159

Using Structural Equation Modeling to Examine Group Differences in Assessment Booklet Designs with Sparse Data  

ERIC Educational Resources Information Center

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…

Willse, John T.; Goodman, Joshua T.; Allen, Nancy; Klaric, John

2008-01-01

160

Multilevel Structural Equation Models for the Analysis of Comparative Data on Educational Performance  

ERIC Educational Resources Information Center

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…

Goldstein, Harvey; Bonnet, Gerard; Rocher, Thierry

2007-01-01

161

OpenMx: An Open Source Extended Structural Equation Modeling Framework  

ERIC Educational Resources Information Center

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…

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

162

Structural Equation Modeling in Assessing Students' Understanding of the State Changes of Matter  

ERIC Educational Resources Information Center

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,…

Stamovlasis, Dimitrios; Tsitsipis, Georgios; Papageorgiou, George

2012-01-01

163

Distinct variants of the KdV equation with compact and noncompact structures  

Microsoft Academic Search

In this paper we examine three distinct variants of the generalized KdV equation. Both the compact and the noncompact structures are treated for these variants. We also emphasize the different physical structures of the two classes: the focusing branch and the defocusing branch.

Abdul-Majid Wazwaz

2004-01-01

164

Structure-function hierarchies and von Kármán-Howarth relations for turbulence in magnetohydrodynamical equations.  

PubMed

We generalize the method of A. M. Polyakov, [ Phys. Rev. E 52 6183 (1995)] for obtaining structure-function relations in turbulence in the stochastically forced Burgers equation, to develop structure-function hierarchies for turbulence in three models for magnetohydrodynamics (MHD). These are the Burgers analogs of MHD in one dimension [ Eur. Phys. J. B 9 725 (1999)], and in three dimensions (3DMHD and 3D Hall MHD). Our study provides a convenient and unified scheme for the development of structure-function hierarchies for turbulence in a variety of coupled hydrodynamical equations. For turbulence in the three sets of MHD equations mentioned above, we obtain exact relations for third-order structure functions and their derivatives; these expressions are the analogs of the von Kármán-Howarth relations for fluid turbulence. We compare our work with earlier studies of such relations in 3DMHD and 3D Hall MHD. PMID:24580182

Basu, Abhik; Naji, Ali; Pandit, Rahul

2014-01-01

165

Discrete Kalman filtering equations of second-order form for control-structure interaction simulations  

NASA Technical Reports Server (NTRS)

A second-order form of discrete Kalman filtering equations is proposed as a candidate state estimator for efficient simulations of control-structure interactions in coupled physical coordinate configurations as opposed to decoupled modal coordinates. The resulting matrix equation of the present state estimator consists of the same symmetric, sparse N x N coupled matrices of the governing structural dynamics equations as opposed to unsymmetric 2N x 2N state space-based estimators. Thus, in addition to substantial computational efficiency improvement, the present estimator can be applied to control-structure design optimization for which the physical coordinates associated with the mass, damping and stiffness matrices of the structure are needed instead of modal coordinates.

Park, K. C.; Alvin, K. F.; Belvin, W. Keith

1991-01-01

166

The Peer Interaction in Primary School Questionnaire: Testing for Measurement Equivalence and Latent Mean Differences in Bullying between Gender in Egypt, Saudi Arabia and the USA  

ERIC Educational Resources Information Center

The Peer Interaction in Primary School Questionnaire (PIPSQ) was developed to assess individuals' levels of bullying and victimization. This study used the approach of latent means analysis (LMA) within the framework of structural equation modeling (SEM) to explore the factor structure and gender differences associated with the PIPSQ in a sample…

Hussein, Mohamed Habashy

2010-01-01

167

Structural Response of Triangular Tension Leg Platform Using Dynamic Morison Equation  

NASA Astrophysics Data System (ADS)

Structural response behavior of Tension Leg Platforms (TLPs) used in deep sea oil exploration is nonlinear due to large displacements and fluid-structure interaction. Their relative insensitivity in deep sea and excellent station keeping characteristics make them suitable for deep waters, apart from being cost-effective. This study investigates response behavior of TLP with triangular geometry using Dynamic Morison equation; nonlinearities associated with vortex shedding effects are considered in contrast to the standard Morison equation that has undesirable features in this respect. Numerical studies conducted on TLPs under regular waves with varying hydrodynamic coefficients show that the coupled responses in active degrees-of-freedom namely surge, heave and pitch response obtained using Dynamic Morison equation are lesser in comparison to those obtained using standard Morison equation.

Chandak, N. R.; Chandrasekaran, S.

2010-05-01

168

Structure-preserving model reduction of partially observed dierential equations: molecular dynamics and beyond  

Microsoft Academic Search

Model reduction is a major issue for control, optimization and simulation of large-scale systems. We present a formal procedure for model reduction of per- turbed linear second-order dierential equations. Second-order equations appear in a variety of physical contexts, e.g., in molecular dynamics or structural mechan- ics to mention just a few. Common spatial decomposition methods such as Proper Orthogonal Decomposition,

Carsten Hartmann; M. Vulcanov; Ch. Schutte

169

Assessment of DSM-IV personality disorders in obsessive-compulsive disorder: Comparison of clinical diagnosis, self-report questionnaire and semi-structured interview. [IF 1.7  

Microsoft Academic Search

In patients with obsessive-compulsive disorder, personality disorders are not many times assessed according to DSM-IV criteria. The purpose of the present study is to examine the prevalence of personality disorders diagnosed according to the DSM-IV in a severely disordered OCD popula- tion (n = 65) with three different methods of assessing personality disor- ders (structured interview, questionnaire, and clinical diagnoses).

N. H. Tenneij; Chris K. W. Schotte; Damiaan A. J. P. Denys; Megen van H. J. G. M; Herman G. M. Westenberg

2003-01-01

170

Influence of Psychosocial Classroom Environment on Students' Motivation and Self-Regulation in Science Learning: A Structural Equation Modeling Approach  

NASA Astrophysics Data System (ADS)

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.

Velayutham, Sunitadevi; Aldridge, Jill M.

2013-04-01

171

Cosmological structure formation under MOND. A new numerical solver for the Poisson's equation  

NASA Astrophysics Data System (ADS)

We present a novel solver for an analogue to Poisson's equation in the framework of modified Newtonian dynamics (MOND). This equation is highly non-linear and hence standard codes based upon tree structures and/or FFT's in general are not applicable; one needs to defer to multi-grid relaxation techniques. We present results from the first cosmological simulations we made to compare cosmological structure formation of in the two paradigms. We found compatible results between the two simulations, at least at redshift z = 0.

Llinares, C.; Knebe, A.; Zhao, H.

2011-01-01

172

Developing Written Questionnaires: Determining if Questionnaires Should be Used  

NSDL National Science Digital Library

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.

Daniel R. Zalles

173

The relativistic equations of stellar structure and evolution. Stars with degenerate neutron cores. 1: Structure of equilibrium models  

NASA Technical Reports Server (NTRS)

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."

Thorne, K. S.; Zytkow, A. N.

1976-01-01

174

Thermodynamics and structure of a two-dimensional electrolyte by integral equation theory  

SciTech Connect

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.

Aupic, Jana; Urbic, Tomaz, E-mail: tomaz.urbic@fkkt.uni-lj.si [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ašker?eva 5, SI-1000 Ljubljana (Slovenia)] [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ašker?eva 5, SI-1000 Ljubljana (Slovenia)

2014-05-14

175

Hints for Designing Effective Questionnaires  

NSDL National Science Digital Library

The purpose of this article is to offer tips in designing quality questionnaires and on avoiding common errors. Some of the more prevalent problems in questionnaire development are identified and suggestions of ways to avoid them are offered.

Frary, Robert

176

Evaluation of structural equation mixture models Parameter estimates and correct class assignment  

PubMed Central

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 one 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 investigated in a large scale simulation study. Design factors of the simulation study are (im)balanced class proportions, (im)balanced factor variances, sample size, and class separation. We compare the fit of models with correct and misspecified within-class structural relations. In addition, we investigate the potential to fit SEMMs with binary indicators. The structure of within-class distributions can be recovered under a wide variety of conditions, indicating the general potential and flexibility of SEMMs to test complex within-class models. Correct class assignment is limited. PMID:20582328

Tueller, Stephen; Lubke, Gitta

2009-01-01

177

Questioning Newton's second law: What is the structure of equations of motion?  

E-print Network

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.

Lämmerzahl, Claus

2009-01-01

178

Does Method of Handling Missing Data Affect Results of a Structural Equation Model?  

ERIC Educational Resources Information Center

The influence of method of handling missing data on estimates produced by a structural equation model of the effects of part-time work on high-school student achievement was investigated. Missing data methods studied were listwise deletion, pairwise deletion, the expectation maximization (EM) algorithm, regression, and response pattern. The 26…

Witta, E. Lea

179

Exploratory Structural Equation Modeling, Integrating CFA and EFA: Application to Students' Evaluations of University Teaching  

ERIC Educational Resources Information Center

This study is a methodological-substantive synergy, demonstrating the power and flexibility of exploratory structural equation modeling (ESEM) methods that integrate confirmatory and exploratory factor analyses (CFA and EFA), as applied to substantively important questions based on multidimentional students' evaluations of university teaching…

Marsh, Herbert W.; Muthen, Bengt; Asparouhov, Tihomir; Ludtke, Oliver; Robitzsch, Alexander; Morin, Alexandre J. S.; Trautwein, Ulrich

2009-01-01

180

Hypothesis Testing and Model Comparison in Two-Level Structural Equation Models.  

ERIC Educational Resources Information Center

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)

Lee, Sik-Yum; Song, Xin-Yuan

2001-01-01

181

Evaluating Small Sample Approaches for Model Test Statistics in Structural Equation Modeling.  

ERIC Educational Resources Information Center

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…

Nevitt, Jonathan

182

Psychological Separation, Attachment Security, Vocational Self-Concept Crystallization, and Career Indecision: A Structural Equation Analysis.  

ERIC Educational Resources Information Center

Structural equation modeling was used to test theoretically based models in which psychological separation and attachment security variables were related to career indecision and those relations were mediated through vocational self-concept crystallization. Results indicated that some components of separation and attachment security did relate to…

Tokar, David M.; Withrow, Jason R.; Hall, Rosalie J.; Moradi, Bonnie

2003-01-01

183

Internal null-controllability for a structurally damped beam equation, Version 4.0  

E-print Network

Internal null-controllability for a structurally damped beam equation, Version 4.0 Julian Edward with internal damping to prove boundary null-controllability in time T for any and Louis Tebou March 10, 2005 Abstract In this paper we study the null-controllability of a beam equa- tion

Edward, Julian

184

Comparison of Approaches to Constructing Confidence Intervals for Mediating Effects Using Structural Equation Models  

ERIC Educational Resources Information Center

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…

Cheung, Mike W. L.

2007-01-01

185

Equivalence and Differences between Structural Equation Modeling and State-Space Modeling Techniques  

ERIC Educational Resources Information Center

State-space modeling techniques have been compared to structural equation modeling (SEM) techniques in various contexts but their unique strengths have often been overshadowed by their similarities to SEM. In this article, we provide a comprehensive discussion of these 2 approaches' similarities and differences through analytic comparisons and…

Chow, Sy-Miin; Ho, Moon-ho R.; Hamaker, Ellen L.; Dolan, Conor V.

2010-01-01

186

Anti-Transgender Prejudice: A Structural Equation Model of Associated Constructs  

ERIC Educational Resources Information Center

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.…

Tebbe, Esther N.; Moradi, Bonnie

2012-01-01

187

A Confirmatory Structural Equation Model of Achievement Estimated by Dichotomous Attitudes, Interest, and Conceptual Understanding  

ERIC Educational Resources Information Center

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):…

Kim, Minkee; Song, Jinwoong

2010-01-01

188

University Students' Behaviors Pertaining to Sustainability: A Structural Equation Model with Sustainability-Related Attributes  

ERIC Educational Resources Information Center

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…

Sahin, Elvan; Ertepinar, Hamide; Teksoz, Gaye

2012-01-01

189

Testing Mediation Using Multiple Regression and Structural Equation Modeling Analyses in Secondary Data  

Microsoft Academic Search

Mediation analysis in child and adolescent development research is possible using large secondary data sets. This article provides an overview of two statistical methods commonly used to test mediated effects in secondary analysis: multiple regression and structural equation modeling (SEM). Two empirical studies are presented to illustrate the respective circumstances in which the two methods are most useful. One study

Spencer D. Li

2011-01-01

190

An Assessment of the Use of Partial Least Squares Structural Equation Modeling in Marketing Research  

Microsoft Academic Search

Most methodological fields undertake regular critical reflections to ensure rigorous research and publication practices, and, consequently, acceptance in their domain. Interestingly, relatively little attention has been paid to assessing the use of partial least squares structural equation modeling (PLS-SEM) in marketing research?despite its increasing popularity in recent years. To fill this gap, we conducted an extensive search in the 30

Joe F. Hair; Marko Sarstedt; Christian M. Ringle; Jeannette A. Mena

2012-01-01

191

Some Cautionary Notes on the Specification and Interpretation of LISREL-type Structural Equation Models.  

ERIC Educational Resources Information Center

LISREL-type structural equation modeling is a powerful statistical technique that seems appropriate for social science variables which are complex and difficult to measure. The literature on the specification, estimation, and testing of such models is voluminous. The greatest proportion of this literature, however, focuses on the technical aspects…

Baldwin, Beatrice

192

An Illustration of a Longitudinal Cross-Lagged Design for Larger Structural Equation Models. Teacher's Corner.  

ERIC Educational Resources Information Center

Tested a model of HIV behavior risk, using a fully cross-lagged, longitudinal design to illustrate the analysis of larger structural equation models. Data from 527 women who completed a survey at three time points show excellent fit of the model to the data. (SLD)

Burkholder, Gary J.; Harlow, Lisa L.

2003-01-01

193

Vocabulary and Grammar Knowledge in Second Language Reading Comprehension: A Structural Equation Modeling Study  

ERIC Educational Resources Information Center

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);…

Zhang, Dongbo

2012-01-01

194

Inference of gene regulatory networks with sparse structural equation models exploiting genetic perturbations  

E-print Network

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

Giannakis, Georgios

195

A Polychoric Instrumental Variable (PIV) Estimator for Structural Equation Models with Categorical Variables  

ERIC Educational Resources Information Center

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…

Bollen, Kenneth A.; Maydeu-Olivares, Albert

2007-01-01

196

Rumination and Distraction Among Chronic Depressives in Treatment: A Structural Equation Analysis  

Microsoft Academic Search

Response Styles Theory hypothesizes that rumination about one's symptoms amplifies and prolongs depressed mood, whereas distraction has the opposite effect. Response styles are also hypothesized to be trait-like dispositions. The generalizability of Response Styles Theory, as well as the linkages that may account for correlations between rumination, distraction, and depression, were explored with structural equation modeling in a sample of

Bruce A. Arnow; Diane Spangler; Daniel N. Klein; David D. Burns

2004-01-01

197

Structural Equation Modelling of Multiple Facet Data: Extending Models for Multitrait-Multimethod Data  

ERIC Educational Resources Information Center

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…

Bechger, Timo M.; Maris, Gunter

2004-01-01

198

Relationships among Adolescents' Leisure Motivation, Leisure Involvement, and Leisure Satisfaction: A Structural Equation Model  

ERIC Educational Resources Information Center

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…

Chen, Ying-Chieh; Li, Ren-Hau; Chen, Sheng-Hwang

2013-01-01

199

Personality traits and general intelligence as predictors of academic performance: A structural equation modelling approach  

Microsoft Academic Search

The aim of the present study was to investigate the extent to which personality traits, after controlling for general intelligence, predict academic performance in different school subjects. Upper secondary school students in Sweden (N=315) completed the Wonderlic IQ test (Wonderlic, 1992) and the IPIP-NEO-PI test (Goldberg, 1999). A series of hierarchical structural equation models showed that general intelligence, Conscientiousness, Extraversion

Pia Rosander; Martin Bäckström; Georg Stenberg

2011-01-01

200

How to Use Structural Equation Modeling in Medical Education Research: A Brief Guide  

Microsoft Academic Search

Background: Structural equation modeling (SEM) is a family of statistical techniques used for the analysis of multivariate data to measure latent variables and their interrelationships. SEM has potential to advance theory and research in medical education.Purpose: The purpose of this article is to introduce SEM to medical education researchers and provide procedural information for applying SEM.Methods: We outline the basic

Claudio Violato; Kent G. Hecker

2007-01-01

201

Teacher's Corner: Structural Equation Modeling with the Sem Package in R  

ERIC Educational Resources Information Center

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…

Fox, John

2006-01-01

202

Structural Equation Models of Latent Interactions: Clarification of Orthogonalizing and Double-Mean-Centering Strategies  

ERIC Educational Resources Information Center

The purpose of this investigation is to compare a new (double-mean-centering) strategy to estimating latent interactions in structural equation models with the (single) mean-centering strategy (Marsh, Wen, & Hau, 2004, 2006) and the orthogonalizing strategy (Little, Bovaird, & Widaman, 2006; Marsh et al., 2007). A key benefit of the…

Lin, Guan-Chyun; Wen, Zhonglin; Marsh, Herbert W.; Lin, Huey-Shyan

2010-01-01

203

Merged Structural Equation Model of Online Retailer's Customer Preference and Stickiness  

Microsoft Academic Search

Rapid explosion of the number of online retailers as well as online customers has been observed in these past few years. Comparable growth in sellers and buyers means that Internet retailers have to understand how to make customers prefer them to the competitors and make the customers loyal to their stores. Previous structural equation modeling study of customer preference and

Sri Hastuti Kurniawan

2000-01-01

204

Structural Equation Models of Latent Interactions: An Appropriate Standardized Solution and Its Scale-Free Properties  

ERIC Educational Resources Information Center

Standardized parameter estimates are routinely used to summarize the results of multiple regression models of manifest variables and structural equation models of latent variables, because they facilitate interpretation. Although the typical standardization of interaction terms is not appropriate for multiple regression models, straightforward…

Wen, Zhonglin; Marsh, Herbert W.; Hau, Kit-Tai

2010-01-01

205

Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety  

ERIC Educational Resources Information Center

Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.…

Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

2013-01-01

206

A structural equations modeling approach to the general linear mixed model  

Microsoft Academic Search

(from the chapter) This chapter presents a method based on a structural equation modeling (SEM) framework for estimating models representing specific instances of the general linear mixed model (GLMM; Laird and Ware, 1982). The authors state their choice of the GLMM as a starting point, firstly, because it can be considered the basis of the general multilevel modeling approach; and

P. C. M. Molenaar; M. J. Rovine

2001-01-01

207

Performance and scaling of locally-structured grid methods forpartial differential equations  

SciTech Connect

In this paper, we discuss some of the issues in obtaining high performance for block-structured adaptive mesh refinement software for partial differential equations. We show examples in which AMR scales to thousands of processors. We also discuss a number of metrics for performance and scalability that can provide a basis for understanding the advantages and disadvantages of this approach.

Colella, Phillip; Bell, John; Keen, Noel; Ligocki, Terry; Lijewski, Michael; Van Straalen, Brian

2007-07-19

208

Estimation of health effects of prenatal methylmercury exposure using structural equation models  

Microsoft Academic Search

BACKGROUND: Observational studies in epidemiology always involve concerns regarding validity, especially measurement error, confounding, missing data, and other problems that may affect the study outcomes. Widely used standard statistical techniques, such as multiple regression analysis, may to some extent adjust for these shortcomings. However, structural equations may incorporate most of these considerations, thereby providing overall adjusted estimations of associations. This

Esben Budtz-Jørgensen; Niels Keiding; Philippe Grandjean; Pal Weihe

2002-01-01

209

A Robust Bayesian Approach for Structural Equation Models with Missing Data  

ERIC Educational Resources Information Center

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…

Lee, Sik-Yum; Xia, Ye-Mao

2008-01-01

210

Compactons and solitary patterns structures for variants of the KdV and the KP equations  

Microsoft Academic Search

In this paper we discuss mathematical variants in higher dimensions of the KdV and the KP equations. It is shown that the focusing branches of these variants exhibit compactons: solitons with finite wavelength, whereas the defocusing branches support solitary patterns solutions with infinite slopes or cusps. The study presents a fairly complete understanding of the compact and noncompact dispersive structures.

A. M. Wazwaz

2003-01-01

211

Variants of the generalized KdV equation with compact and noncompact structures  

Microsoft Academic Search

In this paper, nonlinear dispersive variants of the generalized KdV equation are investigated. The compact and the noncompact physical structures are studied. Two general formulas for the focusing branch and the defocusing branch, that are of substantial interest, are formally derived.

A.-M Wazwaz

2004-01-01

212

Finite-stage stochastic decision processes with recursive reward structure I: optimality equations and deterministic strategies  

Microsoft Academic Search

In this paper we examine an N-stage stochastic decision model with a recursive reward structure whose state and action spaces are standard Borel ones. The central results relate to the validity of the optimality equations and to the sufficiency of deterministic strategies. The results expand statements known for classical dynamic programming problems with additive total rewards to a wide class

H. D. Dahlke

1992-01-01

213

IQ heritability estimation: Analyzing genetically-informative data with structural equation models  

Microsoft Academic Search

When analyzing genetic data, Structural Equations Modeling (SEM) provides a straightforward me- thodology to decompose phenotypic variance using a model-based approach. Furthermore, several mo- dels can be easily implemented, tested, and compared using SEM, allowing the researcher to obtain va- luable information about the sources of variability. This methodology is briefly described and applied to re-analyze a Spanish set of

David Gallardo Pujol; Carlos García-Forero; Uwe Kramp; Albert Maydeu-Olivares; Antonio Andrés-Pueyo

2007-01-01

214

The Issue of Isopower in Power Analysis for Tests of Structural Equation Models  

ERIC Educational Resources Information Center

Two general frameworks have been proposed for evaluating statistical power of tests of model fit in structural equation modeling (SEM). Under the Satorra-Saris (1985) approach, to evaluate the power of the test of fit of Model A, a Model B, within which A is nested, is specified as the alternative hypothesis and considered as the true model. We…

MacCallum, Robert; Lee, Taehun; Browne, Michael W.

2010-01-01

215

Using a Multilevel Structural Equation Modeling Approach to Explain Cross-Cultural Measurement Noninvariance  

Microsoft Academic Search

Testing for invariance of measurements across groups (such as countries or time points) is essential before meaningful comparisons may be conducted. However, when tested, invariance is often absent. As a result, comparisons across groups are potentially problematic and may be biased. In the current study, we propose utilizing a multilevel structural equation modeling (SEM) approach to provide a framework to

Eldad Davidov; Hermann Dülmer; Elmar Schlüter; Peter Schmidt; Bart Meuleman

2012-01-01

216

Spiritual Leadership and Organizational Culture: A Study of Structural Equation Modeling  

ERIC Educational Resources Information Center

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…

Karadag, Engin

2009-01-01

217

Organizational Cynicism, School Culture, and Academic Achievement: The Study of Structural Equation Modeling  

ERIC Educational Resources Information Center

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…

Karadag, Engin; Kilicoglu, Gökhan; Yilmaz, Derya

2014-01-01

218

A Structural Equation Model of Parental Involvement, Motivational and Aptitudinal Characteristics, and Academic Achievement  

Microsoft Academic Search

The authors used the structural equation model (SEM) approach to test a model hypothesizing the influence of parental involvement on students' academic aptitudes, self-concept, and causal attributions, as well as the influence of the 3 variables on academic achievement. The theoretical model was contrasted in a group of 12- to 18-year-old adolescents (N = 261) attending various educational centers. The

Julio Antonio Gonzalez-pienda; Jose Carlos Nunez; Soledad Gonzalez-pumariega; Luis Alvarez; Cristina Roces; Marta Garcia

2002-01-01

219

Self-Conscious Emotions in Response to Perceived Failure: A Structural Equation Model  

ERIC Educational Resources Information Center

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…

Bidjerano, Temi

2010-01-01

220

Testing Mediation Using Multiple Regression and Structural Equation Modeling Analyses in Secondary Data  

ERIC Educational Resources Information Center

Mediation analysis in child and adolescent development research is possible using large secondary data sets. This article provides an overview of two statistical methods commonly used to test mediated effects in secondary analysis: multiple regression and structural equation modeling (SEM). Two empirical studies are presented to illustrate the…

Li, Spencer D.

2011-01-01

221

Multilevel Modeling of Two Cyclical Processes: Extending Differential Structural Equation Modeling to Nonlinear Coupled Systems  

ERIC Educational Resources Information Center

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…

Butner, Jonathan; Amazeen, Polemnia G.; Mulvey, Genna M.

2005-01-01

222

Survey and Questionnaire Tutorial  

NSDL National Science Digital Library

What are the important factors to consider when designing a survey? Would it be best conducted via telephone? Or would it be better to have a face-to-face meeting? These are but a few of the topics covered on this site created as a public service by the StatPac group. Visitors can elect to download the entire report on survey design here, or they can just click through the topics that interest them. Each topic includes a brief discussion of its relative importance, and the areas covered include questionnaire length, time considerations, question wording, and sampling methods. It's a thoughtful and helpful resource overall, and it's one that might be put to good use in an introductory statistics course in college.

223

General features and master equations for structurization in complex dusty plasmas  

SciTech Connect

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.

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

224

Self-Assembly of Nanocomponents into Composite Structures: Derivation and Simulation of Langevin Equations  

E-print Network

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.

Stephen Pankavich; Zeina Shreif; Yinglong Miao; Peter Ortoleva

2010-03-08

225

Quantization of wave equations and hermitian structures in partial differential varieties  

PubMed Central

Sufficiently close to 0, the solution variety of a nonlinear relativistic wave equation—e.g., of the form ?? + m2? + g?p = 0—admits a canonical Lorentz-invariant hermitian structure, uniquely determined by the consideration that the action of the differential scattering transformation in each tangent space be unitary. Similar results apply to linear time-dependent equations or to equations in a curved asymptotically flat space-time. A close relation of the Riemannian structure to the determination of vacuum expectation values is developed and illustrated by an explicit determination of a perturbative 2-point function for the case of interaction arising from curvature. The theory underlying these developments is in part a generalization of that of M. G. Krein and collaborators concerning stability of differential equations in Hilbert space and in part a precise relation between the unitarization of given symplectic linear actions and their full probabilistic quantization. The unique causal structure in the infinite symplectic group is instrumental in these developments. PMID:16592923

Paneitz, S. M.; Segal, I. E.

1980-01-01

226

A two-stage estimation of structural equation models with continuous and polytomous variables.  

PubMed

This paper develops a computationally efficient procedure for analysis of structural equation models with continuous and polytomous variables. A partition maximum likelihood approach is used to obtain the first stage estimates of the thresholds and the polyserial and polychoric correlations in the underlying correlation matrix. Then, based on the joint asymptotic distribution of the first stage estimator and an appropriate weight matrix, a generalized least squares approach is employed to estimate the structural parameters in the correlation structure. Asymptotic properties of the estimators are derived. Some simulation studies are conducted to study the empirical behaviours and robustness of the procedure, and compare it with some existing methods. PMID:8527346

Lee, S Y; Poon, W Y; Bentler, P M

1995-11-01

227

Solution of quadratic matrix equations for free vibration analysis of structures.  

NASA Technical Reports Server (NTRS)

An efficient digital computer procedure and the related numerical algorithm are presented herein for the solution of quadratic matrix equations associated with free vibration analysis of structures. Such a procedure enables accurate and economical analysis of natural frequencies and associated modes of discretized structures. The numerically stable algorithm is based on the Sturm sequence method, which fully exploits the banded form of associated stiffness and mass matrices. The related computer program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be substantially more accurate and economical than other existing procedures of such analysis. Numerical examples are presented for two structures - a cantilever beam and a semicircular arch.

Gupta, K. K.

1973-01-01

228

Travelling waves in a nonlocal reaction-diffusion equation as a model for a population structured by a space variable  

E-print Network

Travelling waves in a nonlocal reaction-diffusion equation as a model for a population structured by a space variable and a phenotypical trait Matthieu Alfaro 1 , Jérôme Coville 2 and Gaël Raoul 3 . Abstract We consider a nonlocal reaction-diffusion equation as a model for a population structured by a space

Paris-Sud XI, Université de

229

Derivation of the equations of motion for complex structures by symbolic manipulation  

NASA Technical Reports Server (NTRS)

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.

Hale, A. L.; Meirovitch, L.

1978-01-01

230

Structure-function hierarchies and von Kármán-Howarth relations for turbulence in magnetohydrodynamical equations  

NASA Astrophysics Data System (ADS)

We generalize the method of A. M. Polyakov, [Phys. Rev. E 52, 6183 (1995), 10.1103/PhysRevE.52.6183] for obtaining structure-function relations in turbulence in the stochastically forced Burgers equation, to develop structure-function hierarchies for turbulence in three models for magnetohydrodynamics (MHD). These are the Burgers analogs of MHD in one dimension [Eur. Phys. J. B 9, 725 (1999), 10.1007/s100510050817], and in three dimensions (3DMHD and 3D Hall MHD). Our study provides a convenient and unified scheme for the development of structure-function hierarchies for turbulence in a variety of coupled hydrodynamical equations. For turbulence in the three sets of MHD equations mentioned above, we obtain exact relations for third-order structure functions and their derivatives; these expressions are the analogs of the von Kármán-Howarth relations for fluid turbulence. We compare our work with earlier studies of such relations in 3DMHD and 3D Hall MHD.

Basu, Abhik; Naji, Ali; Pandit, Rahul

2014-01-01

231

CROSS-CULTURAL EQUIVALENCE OF FEEDING BELIEFS AND PRACTICES: THE PSYCHOMETRIC PROPERTIES OF THE CHILD FEEDING QUESTIONNAIRE AMONG BLACKS AND HISPANICS  

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...

232

How Structure Sense for Algebraic Expressions or Equations Is Related to Structure Sense for Abstract Algebra  

ERIC Educational Resources Information Center

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…

Novotna, Jarmila; Hoch, Maureen

2008-01-01

233

On the minimal set of conservation laws and the Hamiltonian structure of the Whitham equations  

E-print Network

We consider the questions connected with the Hamiltonian properties of the Whitham equations in case of several spatial dimensions. An essential point of our approach here is a connection of the Hamiltonian structure of the Whitham system with the finite-dimensional Poisson bracket defined on the space of periodic or quasi-periodic solutions. From our point of view, this approach gives a possibility to construct the Hamiltonian structure of the Whitham equations under minimal requirements on the properties of the initial system. The Poisson bracket for the Whitham system can be considered here as a deformation of the finite-dimensional bracket with the aid of the Dubrovin - Novikov procedure of bracket averaging. At the end, we consider the examples where the constructions of the paper play an essential role for the construction of the Poisson bracket for the Whitham system.

A. Ya. Maltsev

2014-09-29

234

metaSEM: an R package for meta-analysis using structural equation modeling  

PubMed Central

The metaSEM package provides functions to conduct univariate, multivariate, and three-level meta-analyses using a structural equation modeling (SEM) approach via the OpenMx package in the R statistical platform. It also implements the two-stage SEM approach to conducting fixed- and random-effects meta-analytic SEM on correlation or covariance matrices. This paper briefly outlines the theories and their implementations. It provides a summary on how meta-analyses can be formulated as structural equation models. The paper closes with a conclusion on several relevant topics to this SEM-based meta-analysis. Several examples are used to illustrate the procedures in the supplementary material. PMID:25601849

Cheung, Mike W.-L.

2015-01-01

235

Numerical solution of quadratic matrix equations for free vibration analysis of structures  

NASA Technical Reports Server (NTRS)

This paper is concerned with the efficient and accurate solution of the eigenvalue problem represented by quadratic matrix equations. Such matrix forms are obtained in connection with the free vibration analysis of structures, discretized by finite 'dynamic' elements, resulting in frequency-dependent stiffness and inertia matrices. The paper presents a new numerical solution procedure of the quadratic matrix equations, based on a combined Sturm sequence and inverse iteration technique enabling economical and accurate determination of a few required eigenvalues and associated vectors. An alternative procedure based on a simultaneous iteration procedure is also described when only the first few modes are the usual requirement. The employment of finite dynamic elements in conjunction with the presently developed eigenvalue routines results in a most significant economy in the dynamic analysis of structures.

Gupta, K. K.

1975-01-01

236

High Risk Sexual Behaviors for HIV among the In-School Youth in Swaziland: A Structural Equation Modeling Approach  

PubMed Central

Background Global efforts in response to the increased prevalence of the human immunodeficiency virus (HIV) are mainly aimed at reducing high risk sexual behaviors among young people. However, knowledge regarding intentions of young people to engage in protective sexual behaviors is still lacking in many countries around the world, especially in Sub-Saharan Africa where prevalence of human immunodeficiency virus is the highest. The objective of this study was to test the theory of planned behavior (TPB) for predicting factors associated with protective sexual behaviors, including sexual abstinence and condom use, among in-school youths aged between 15 and 19 years in Swaziland. Methods This cross-sectional survey was conducted using a anonymous questionnaire. A two-stage stratified and cluster random sampling method was used. Approximately one hundred pupils from each of four schools agreed to participate in the study, providing a total sample size of 403 pupils of which 369 were ultimately included for data analysis. The response rate was 98%. Structural equation modeling was used to analyse hypothesized paths. Results The TPB model used in this study was effective in predicting protective sexual behavior among Swazi in-school youths, as shown by model fit indices. All hypothesized constructs significantly predicted intentions for abstinence and condom use, except perceived abstinence controls. Subjective norms were the strongest predictors of intention for premarital sexual abstinence; however, perceived controls for condom use were the strongest predictors of intention for condom use. Conclusions Our findings support application of the model in predicting determinants of condom use and abstinence intentions among Swazi in-school youths. PMID:23861756

Chu, Hsin; Liao, Yuan-Mei; Chen, Chiung-Hua; Ou, Keng-Liang; Chang, Lu-I; Chou, Kuei-Ru

2013-01-01

237

The Trauma Outcome Process Assessment Model: A Structural Equation Model Examination of Adjustment  

Microsoft Academic Search

This investigation sought to operationalize a comprehensive theoretical model, the Trauma Outcome Process Assessment, and test it empirically with structural equation modeling. The Trauma Outcome Process Assessment reflects a robust body of research and incorporates known ecological factors (e.g., family dynamics, social support) to explain internalizing distress (e.g., anxiety, depression), externalizing distress (e.g., aggression), and recovery outcomes following traumatic events.

Susan E. Borja; Jennifer L. Callahan

2009-01-01

238

Structural equation modeling in practice: A review and recommended two-step approach  

Microsoft Academic Search

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,

James C. Anderson; David W. Gerbing

1988-01-01

239

Organizational Learning and Performance in Two National Cultures: A Multi-group Structural Equation Modeling Approach  

Microsoft Academic Search

\\u000a This chapter examines the impact of organizational learning on organizational performance in two countries. Using a multi-group\\u000a structural equation modeling approach on data from 203 Slovenian and 202 Croatian companies, it tests the impact of the organizational\\u000a learning process on financial and non-financial performance (NFP). The results show consistent findings between both countries\\u000a under investigation (which vary only in terms

Miha Škerlavaj; Vlado Dimovski

240

Anomalous wave structure in magnetized materials described by non-convex equations of state  

SciTech Connect

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.

Serna, Susana, E-mail: serna@mat.uab.es [Departament de Matematiques, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)] [Departament de Matematiques, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Marquina, Antonio, E-mail: marquina@uv.es [Departamento de Matematicas, Universidad de Valencia, 46100 Burjassot, Valencia (Spain)] [Departamento de Matematicas, Universidad de Valencia, 46100 Burjassot, Valencia (Spain)

2014-01-15

241

Cosmological structure formation under MOND: a new numerical solver for Poisson's equation  

NASA Astrophysics Data System (ADS)

We present a novel solver for an analogue to Poisson's equation in the framework of modified Newtonian dynamics (MOND). This equation is highly non-linear and hence standard codes based upon tree structures and/or fast Fourier transforms in general are not applicable; one needs to defer to multigrid relaxation techniques. After a detailed description of the necessary modifications to the cosmological N-body code AMIGA (formerly known as MLAPM) we utilize the new code to revisit the issue of cosmic structure formation under MOND. We find that the proper (numerical) integration of a MONDian Poisson's equation has some noticeable effects on the final results when compared against simulations of the same kind but based upon rather ad hoc assumptions about the properties of the MONDian force field. Namely, we find that the large-scale structure evolution is faster in our revised MOND model leading to an even stronger clustering of galaxies, especially when compared to the standard ? cold dark matter paradigm.

Llinares, Claudio; Knebe, Alexander; Zhao, Hongsheng

2008-12-01

242

Analysis of frequency band structure in one-dimensional sonic crystal using Webster horn equation  

NASA Astrophysics Data System (ADS)

Sound propagation through periodic arrangement of scatterers lead to formation of bands of frequencies, known as band gaps, where sound cannot propagate though the structure. We propose a method based on Webster horn equation, along with Floquet theorem, to predict the band gap of a one-dimensional periodic structure made of hard sound-scatterers. The method is further modified to obtain the complex wave numbers, which give the decay constants. The decay constant is used to predict the sound attenuation of the evanescent wave in the finite sonic crystal. The theoretical prediction is verified with experimental measurements.

Gupta, A.; Lim, K. M.; Chew, C. H.

2011-05-01

243

Ridge structural equation modelling with correlation matrices for ordinal and continuous data.  

PubMed

This paper develops a ridge procedure for structural equation modelling (SEM) with ordinal and continuous data by modelling the polychoric/polyserial/product-moment correlation matrix R. Rather than directly fitting R, the procedure fits a structural model to R(a) =R+aI by minimizing the normal distribution-based discrepancy function, where a > 0. Statistical properties of the parameter estimates are obtained. Four statistics for overall model evaluation are proposed. Empirical results indicate that the ridge procedure for SEM with ordinal data has better convergence rate, smaller bias, smaller mean square error, and better overall model evaluation than the widely used maximum likelihood procedure. PMID:21506947

Yuan, Ke-Hai; Wu, Ruilin; Bentler, Peter M

2011-02-01

244

Improving the correlation structure selection approach for generalized estimating equations and balanced longitudinal data.  

PubMed

Generalized estimating equations are commonly used to analyze correlated data. Choosing an appropriate working correlation structure for the data is important, as the efficiency of generalized estimating equations depends on how closely this structure approximates the true structure. Therefore, most studies have proposed multiple criteria to select the working correlation structure, although some of these criteria have neither been compared nor extensively studied. To ease the correlation selection process, we propose a criterion that utilizes the trace of the empirical covariance matrix. Furthermore, use of the unstructured working correlation can potentially improve estimation precision and therefore should be considered when data arise from a balanced longitudinal study. However, most previous studies have not allowed the unstructured working correlation to be selected as it estimates more nuisance correlation parameters than other structures such as AR-1 or exchangeable. Therefore, we propose appropriate penalties for the selection criteria that can be imposed upon the unstructured working correlation. Via simulation in multiple scenarios and in application to a longitudinal study, we show that the trace of the empirical covariance matrix works very well relative to existing criteria. We further show that allowing criteria to select the unstructured working correlation when utilizing the penalties can substantially improve parameter estimation. PMID:24504841

Westgate, Philip M

2014-06-15

245

Working conditions, self-perceived stress, anxiety, depression and quality of life: A structural equation modelling approach  

PubMed Central

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

Rusli, Bin Nordin; Edimansyah, Bin Abdin; Naing, Lin

2008-01-01

246

Subdiffusive master equation with space-dependent anomalous exponent and structural instability  

NASA Astrophysics Data System (ADS)

We derive the fractional master equation with space-dependent anomalous exponent. We analyze the asymptotic behavior of the corresponding lattice model both analytically and by Monte Carlo simulation. We show that the subdiffusive fractional equations with constant anomalous exponent ? in a bounded domain [0,L] are not structurally stable with respect to the nonhomogeneous variations of parameter ?. In particular, the Gibbs-Boltzmann distribution is no longer the stationary solution of the fractional Fokker-Planck equation whatever the space variation of the exponent might be. We analyze the random distribution of ? in space and find that in the long-time limit, the probability distribution is highly intermediate in space and the behavior is completely dominated by very unlikely events. We show that subdiffusive fractional equations with the nonuniform random distribution of anomalous exponent is an illustration of a “Black Swan,” the low probability event of the small value of the anomalous exponent that completely dominates the long-time behavior of subdiffusive systems.

Fedotov, Sergei; Falconer, Steven

2012-03-01

247

Structure and decay constant of the {rho} meson within the Bethe-Salpeter equation  

SciTech Connect

In this article, we study the structure of the {rho} meson in the framework of the coupled rainbow Schwinger-Dyson equation and ladder Bethe-Salpeter equation with a confining effective potential. The u and d quark propagators get significantly modified, the mass poles are absent in the timelike region, which implements confinement naturally. The Bethe-Salpeter amplitudes of the {rho} meson center around zero momentum and extend to the energy scale about q{sup 2}=1 GeV{sup 2}, which happens to be the energy scale of chiral symmetry breaking, strong interactions in the infrared region result in bound state. The numerical results of the mass and decay constant of the {rho} meson are in agreement with the experimental data.

Wang, Z. G. [Department of Physics, North China Electric Power University, Baoding 071003 (China); Wan, S. L. [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

2007-08-15

248

OpenMx: An Open Source Extended Structural Equation Modeling Framework  

PubMed Central

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

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

249

Psychosocial Problems Among Truant Youth: A Multi-Group, Exploratory Structural Equation Modeling Analysis  

PubMed Central

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

Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C.; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven

2012-01-01

250

The evolution of anisotropic structures and turbulence in the multi-dimensional Burgers equation  

E-print Network

The goal of the present paper is the investigation of the evolution of anisotropic regular structures and turbulence at large Reynolds number in the multi-dimensional Burgers equation. We show that we have local isotropization of the velocity and potential fields at small scale inside cellular zones. For periodic waves, we have simple decay inside of a frozen structure. The global structure at large times is determined by the initial correlations, and for short range correlated field, we have isotropization of turbulence. The other limit we consider is the final behavior of the field, when the processes of nonlinear and harmonic interactions are frozen, and the evolution of the field is determined only by the linear dissipation.

S. N. Gurbatov; A. Yu. Moshkov; A. Noullez

2008-08-20

251

Multidisciplinary Treatment Planning Questionnaire  

Cancer.gov

Multidisciplinary care, which incorporates Multidisciplinary Treatment Planning (MTP), is increasingly being adopted within oncology care settings with the intent of enhancing the quality of care delivered to patients. However, what is not known is its impact on improving patient outcomes and the quality of care being delivered. A targeted review of the literature was conducted to examine the organization and operation of the Multidisciplinary Care (MDC) team structure1. Findings revealed that a variety of implementation models exist within the health care system.

252

An investigation of multi-block structured algorithms for parallel CFD applications by a solution of 1D Burgers equation  

NASA Astrophysics Data System (ADS)

The application of a multiblock structured approach for the solution of the 1D (one dimensional) Burgers equation in distributed memory parallel architectures is illustrated. Numerical results and parallel performance concerning the use of two explicit methods and one implicit method to solve the Euler/Navier-Stokes equations are compared.

Denicola, C.; Paparone, L.; Tognaccini, R.

253

Two reliable methods for solving variants of the KdV equation with compact and noncompact structures  

Microsoft Academic Search

In this work we use the sine–cosine and the tanh methods for solving variants of the KdV equation. Compact and noncompact physical solutions for these variants with dispersive effects are formally derived. The study also examines the role of coefficients of the derivatives of the equation and its exponents in affecting the physical structures of the solutions.

Abdul-Majid Wazwaz

2006-01-01

254

Using Structural Equation Modeling to Assess Functional Connectivity in the Brain: Power and Sample Size Considerations  

PubMed Central

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

Sideridis, Georgios; Simos, Panagiotis; Papanicolaou, Andrew; Fletcher, Jack

2014-01-01

255

Health belief structural equation model predicting sleep behavior of employed college students.  

PubMed

Adequate sleep comprising 7 to 8 hours per day is vital for health and effective functioning for all adults. The purpose of this study was to specify a health belief model to measure and predict the sleep behavior of employed college students. A 52-item instrument was developed with acceptable validity and reliability. A cross-sectional, convenience sample of 188 students was recruited for this study. Structural equation modeling was used to build models. The health belief model explained 34% of the variance in sleep behavior, with perceived severity, perceived barriers, cues to action, and self-efficacy identified as significant predictors. PMID:25167067

Knowlden, Adam P; Sharma, Manoj

2014-01-01

256

Alternative Lax Pair, Bi-Hamiltonian Structure, and Constrained Flows for the ?-DYNAMIC of Nls Equation  

NASA Astrophysics Data System (ADS)

Nonlinear equations describing the ?-dynamics of the NLS problem are analyzed with the help of small amplitude expansion and Fourier analysis. An alternative form of Lax problem is deduced which is a (2×2) matrix function in contrast to the (3×3) form suggested by Dodd. et al. We also derive the form of the implectic operators giving bi-Hamiltonian structure. Lastly, the Bargmann type constraint is shown to yield nonlinear dynamical systems which is also integrable in the Liouville sense.

Das, Chandan Kr.; Chowdhury, A. Roy

257

Structural equation model-based genome scan for the metabolic syndrome  

PubMed Central

Background The metabolic syndrome is characterized by the clustering of several traits, including obesity, hypertension, decreased levels of HDL cholesterol, and increased levels of glucose and triglycerides. Because these traits cluster, there are likely common genetic factors involved. Results We used a multivariate structural equation model (SEM) approach to scan the genome for loci involved in the metabolic syndrome. We found moderate evidence for linkage on chromosomes 2, 3, 11, 13, and 15, and these loci appear to have different relative effects on the component traits of the metabolic syndrome. Conclusion Our results suggest that the metabolic syndrome components, diabetes, obesity, and hypertension, are under the pleiotropic control of several loci. PMID:14975167

Stein, Catherine M; Song, Yeunjoo; Elston, Robert C; Jun, Gyungah; Tiwari, Hemant K; Iyengar, Sudha K

2003-01-01

258

Analysis of factors affecting satisfaction level on problem based learning approach using structural equation modeling  

NASA Astrophysics Data System (ADS)

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.

Hussain, Nur Farahin Mee; Zahid, Zalina

2014-12-01

259

Physical Activity Questionnaire Search Results  

Cancer.gov

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?

260

Structure properties of one-mode collaboration network model based on rate equation approach  

NASA Astrophysics Data System (ADS)

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.

Wang, Long; Ma, Yinghong

2014-12-01

261

The MPC&A Questionnaire  

SciTech Connect

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.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL

2011-01-01

262

Job and Professional Leaving Among Newly Licensed RNs: A Structural Equation Model.  

PubMed

With more than 50% of the nursing workforce close to retirement, it is especially important to keep younger nurses in nursing jobs and careers. This study empirically tests a structural equation model of registered nurse (RN) intent to leave the job and profession using data from a survey of newly licensed RNs (NLRNs). Job demands, difficulties and control, intent to leave the job, and intent to leave the profession were latent variables. A number of direct, indirect, and mediating relationships were modeled. Measurement models for all latent variables and the structural model had good fit. The final model showed a path from job demands, difficulties, and control to job satisfaction to intent to leave the job to intent to leave the profession. The results suggest that the process of an NLRN intending to leave the job and profession involves a number of mediators between the work environment and this intent. PMID:25433000

Unruh, Lynn; Zhang, Ning Jackie; Chisolm, Latarsha

2014-11-27

263

Adjoint design sensitivity analysis of reduced atomic systems using generalized Langevin equation for lattice structures  

SciTech Connect

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.

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

264

Normal forms for semilinear equations with non-dense domain with applications to age structured models  

NASA Astrophysics Data System (ADS)

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.

Liu, Zhihua; Magal, Pierre; Ruan, Shigui

2014-08-01

265

Guidelines for a graph-theoretic implementation of structural equation modeling  

USGS Publications Warehouse

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.

Grace, James B.; Schoolmaster, Donald R.; Guntenspergen, Glenn R.; Little, Amanda M.; Mitchell, Brian R.; Miller, Kathryn M.; Schweiger, E. William

2012-01-01

266

Representing general theoretical concepts in structural equation models: The role of composite variables  

USGS Publications Warehouse

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.

Grace, J.B.; Bollen, K.A.

2008-01-01

267

Actinide electronic structure based on the Dirac equation and density functional theory  

NASA Astrophysics Data System (ADS)

Density functional theory (DFT) provides a formally predictive basis for predicting the structural properties of actinides. Although available approximations to the exchange/correlation functional provide accurate predictions for many materials, they fail qualitatively and sometimes quantitatively when applied to actinides. Major contributors to this deficiency are an inadequate treatment of confinement physics and an incomplete treatment of relativity in the underlying equations. The development of a functional correctly incorporating confinement physics with a proper treatment of relativity would provide definitive, internally consistent predictions of actinide properties. To enable the development of such a functional and quantify the predictions of currently available functionals, we have developed an efficient first-principles electronic structure method based on the Dirac equation. Results are compared with current methods, and the implications for relativistic density functionals discussed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Wills, John M.; Mattsson, Ann E.

2013-03-01

268

An extended structure-based model based on a stochastic eddy-axis evolution equation  

NASA Technical Reports Server (NTRS)

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.

Kassinos, S. C.; Reynolds, W. C.

1995-01-01

269

Attitudes and doping: a structural equation analysis of the relationship between athletes' attitudes, sport orientation and doping behaviour  

PubMed Central

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

2007-01-01

270

The Eating Attitudes Test-26 revisited using exploratory structural equation modeling.  

PubMed

Most previous studies have failed to replicate the original factor structure of the 26-item version of the Eating Attitudes Test (EAT-26) among community samples of adolescents. The main objective of the present series of four studies (n?=?2178) was to revisit the factor structure of this instrument among mixed gender community samples of adolescents using both exploratory structural equation modeling (ESEM) and confirmatory factor analysis (CFA). First, results from the ESEM analyses provided satisfactory goodness-of-fit statistics and reliability coefficients for a six-factor model of the EAT with 18 items (EAT-18) closely corresponding to the original seven-factor structure proposed for the 40-item version of the EAT. Second, these analyses were satisfactorily replicated among a new sample of community adolescents using CFA. The results confirmed the factor loading and intercept invariance of this model across gender and age groups (i.e., early and late adolescence), as well as the complete invariance of the EAT-18 measurement model between ethnicities (i.e., European versus African origins) and across weight categories (i.e., underweight, normal weight and overweight). Finally, the last study provided support for convergent validity of the EAT-18 with the Eating Disorder Inventory and with instruments measuring global self-esteem, physical appearance, social physique anxiety and fear of negative appearance evaluation. PMID:23344702

Maïano, Christophe; Morin, Alexandre J S; Lanfranchi, Marie-Christine; Therme, Pierre

2013-07-01

271

Thalamic-insular dysconnectivity in schizophrenia: evidence from structural equation modeling.  

PubMed

Structural and functional studies have shown that schizophrenia is often associated with frontolimbic abnormalities in the prefrontal and mediotemporal regions. It is still unclear, however, if such dysfunctional interaction extends as well to relay regions such as the thalamus and the anterior insula. Here, we measured gray matter volumes of five right-hemisphere regions in 68 patients with schizophrenia and 77 matched healthy subjects. The regions were amygdala, thalamus, and entorhinal cortex (identified as anomalous by prior studies on the same population) and dorsolateral prefrontal cortex and anterior insula (isolated by voxel-based morphometry analysis). We used structural equation modeling and found altered path coefficients connecting the thalamus to the anterior insula, the amygdala to the DLPFC, and the entorhinal cortex to the DLPFC. In particular, patients exhibited a stronger thalamus-insular connection than healthy controls. Instead, controls showed positive entorhinal-DLPFC and negative amygdalar-DLPFC connections, both of which were absent in the clinical population. Our data provide evidence that schizophrenia is characterized by an impaired right-hemisphere network, in which intrahemispheric communication involving relay structures may play a major role in sustaining the pathophysiology of the disease. PMID:21484952

Corradi-Dell'Acqua, Corrado; Tomelleri, Luisa; Bellani, Marcella; Rambaldelli, Gianluca; Cerini, Roberto; Pozzi-Mucelli, Roberto; Balestrieri, Matteo; Tansella, Michele; Brambilla, Paolo

2012-03-01

272

a Two-Level Second-Order Finite Difference Scheme for the Single Term Structure Equation  

NASA Astrophysics Data System (ADS)

In the paper [6] the classical single factor term structure equation for models that predict non-negative interest rates is numerically studied. For these models the authors proposed a second order accurate three-level finite difference scheme (FDs) using the appropriate boundary conditions at zero. For the same problem we propose a two-level second-order accurate FDs. We also propose an effective algorithm for solving the difference schemes, for which also follows the positivity of the numerical solution. The flexibility of our FDs makes it easy to change the drift and diffusion terms in the model. The numerical experiments confirm the second-order of accuracy of the scheme and the positivity-convexity property.

Chernogorova, T.; Valkov, R.

2011-12-01

273

IT vendor selection model by using structural equation model & analytical hierarchy process  

NASA Astrophysics Data System (ADS)

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.

Maitra, Sarit; Dominic, P. D. D.

2012-11-01

274

Should researchers use single indicators, best indicators, or multiple indicators in structural equation models?  

PubMed Central

Background Structural equation modeling developed as a statistical melding of path analysis and factor analysis that obscured a fundamental tension between a factor preference for multiple indicators and path modeling’s openness to fewer indicators. Discussion Multiple indicators hamper theory by unnecessarily restricting the number of modeled latents. Using the few best indicators – possibly even the single best indicator of each latent – encourages development of theoretically sophisticated models. Additional latent variables permit stronger statistical control of potential confounders, and encourage detailed investigation of mediating causal mechanisms. Summary We recommend the use of the few best indicators. One or two indicators are often sufficient, but three indicators may occasionally be helpful. More than three indicators are rarely warranted because additional redundant indicators provide less research benefit than single indicators of additional latent variables. Scales created from multiple indicators can introduce additional problems, and are prone to being less desirable than either single or multiple indicators. PMID:23088287

2012-01-01

275

An informant questionnaire for detecting Alzheimer's disease: are some items better than others?  

PubMed

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

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

276

High-pressure structural behavior and equation of state of NaZnF{sub 3}  

SciTech Connect

We report the results of density functional theory ab-initio calculations and monochromatic synchrotron X-ray diffraction study carried out for orthorhombic NaZnF{sub 3} in the pressure range 0-40 GPa. Perovskite-to-postperovskite phase transition was anticipated by first-principles computations and then observed in high-pressure diamond anvil cell synchrotron diffraction experiment between 14 and 22 GPa. Above 25 GPa postperovskite structure (CaIrO{sub 3} type, space group Cmcm) coexists with another phase, yet unidentified. On decompression, pure postperovskite-type structure was found to be stable down to 4 GPa; below this pressure sample contained both perovskite and postperovskite modifications. Fit of experimental P-V data to the third-order Birch-Murnaghan equation of state gave bulk moduli, K{sub P,0} 64.98+-2.67 and 69.88+-3.69 GPa for perovskite and postperovskite modifications, respectively. Both phases demonstrated strong anisotropy of compressibility. For postperovskite NaZnF{sub 3}, the highest compression was observed along the direction perpendicular to the planes of ZnF{sub 6} octahedra arrangement. - Graphical Abstract: Fit of P-V data obtained from high-pressure X-ray diffraction study of perovskite and postperovskite NaZnF{sub 3} to the third-order Birch-Murnaghan equation of state (solid line). Open and closed symbols represent experimental data corresponding to compression and decompression, respectively. Bulk moduli, K{sub 0,P}, of perovskite and postperovskite phases are 64.98+-2.67 and 69.88+-3.69 GPa.

Yakovlev, Sergey, E-mail: s.yakovlev@tnw.utwente.n [Bragg Institute, Australian Nuclear Science and Technology Organisation, 1 PBM, Menai, NSW 2234 (Australia); Avdeev, Maxim [Bragg Institute, Australian Nuclear Science and Technology Organisation, 1 PBM, Menai, NSW 2234 (Australia); Mezouar, Mohamed [ID-27, European Synchrotron Radiation Facility (ESRF), 6 rue Jules Horowitz, PB220, 38043 Grenoble CEDEX (France)

2009-06-15

277

Factor Structure of the Primary Scales of the Inventory of Personality Organization in a Nonclinical Sample Using Exploratory Structural Equation Modeling  

ERIC Educational Resources Information Center

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,…

Ellison, William D.; Levy, Kenneth N.

2012-01-01

278

Physical Activity Questionnaire Search Results  

Cancer.gov

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)?

279

Energy Balance Survey: Adult Questionnaire  

Cancer.gov

The Physician Survey of Practices on Diet, Physical Activity, and Weight Control -- Adult Questionnaire is sponsored by the National Cancer Institute in collaboration with the Office of Behavioral and Social Sciences Research, the National Institute of Child Health and Human Development, the National Institute of Diabetes and Digestive and Kidney Diseases, and the Centers for Disease Control and Prevention.

280

Preschool Parent's Questionnaire: An Analysis.  

ERIC Educational Resources Information Center

The Preschool Parent's Questionnaire (PPQ) was administered, in English and Spanish, to 120 parents (95 Black, 25 Mexican) of preschool children enrolled in child care programs, to ascertain the parents' attitudes regarding four basic issues: (1) parent's relationship to the child care program, (2) parent's attitudes toward teachers, (3) parent's…

Smith, Rutha L.

281

Physical Activity Questionnaire Search Results  

Cancer.gov

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?

282

Physical Activity Questionnaire Search Results  

Cancer.gov

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?

283

Measuring interrelating within couples : The Couple's Relating to Each Other Questionnaires (CREOQ)  

Microsoft Academic Search

The Couple's Relating to Each Other Questionnaires (CREOQ) are a set of four questionnaires for measuring negative forms of interrelating within couples. They enable each partner to rate his\\/her relating to the other and the other's relating to him\\/her. They are based upon the theoretical structure called the interpersonal octagon, and each questionnaire has eight scales. They are usually accompanied

John Birtchnell; Stijn Voortman; C. A. J. de Jong; Deidre Gordon

2006-01-01

284

A structural equation model of plant species richness and its application to a coastal wetland  

USGS Publications Warehouse

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.

Grace, J.B.; Pugesek, B.H.

1997-01-01

285

The Dirac equation in electronic structure calculations: Accurate evaluation of DFT predictions for actinides  

SciTech Connect

Brooks, Johansson, and Skriver, using the LMTO-ASA method and considerable insight, were able to explain many of the ground state properties of the actinides. In the many years since this work was done, electronic structure calculations of increasing sophistication have been applied to actinide elements and compounds, attempting to quantify the applicability of DFT to actinides and actinide compounds and to try to incorporate other methodologies (i.e. DMFT) into DFT calculations. Through these calculations, the limits of both available density functionals and ad hoc methodologies are starting to become clear. However, it has also become clear that approximations used to incorporate relativity are not adequate to provide rigorous tests of the underlying equations of DFT, not to mention ad hoc additions. In this talk, we describe the result of full-potential LMTO calculations for the elemental actinides, comparing results obtained with a full Dirac basis with those obtained from scalar-relativistic bases, with and without variational spin-orbit. This comparison shows that the scalar relativistic treatment of actinides does not have sufficient accuracy to provide a rigorous test of theory and that variational spin-orbit introduces uncontrolled errors in the results of electronic structure calculations on actinide elements.

Wills, John M [Los Alamos National Laboratory; Mattsson, Ann E [Sandia National Laboratories

2012-06-06

286

Modeling Alcohol Use Disorder Severity: An Integrative Structural Equation Modeling Approach  

PubMed Central

Background: Alcohol dependence is a complex psychological disorder whose phenomenology changes as the disorder progresses. Neuroscience has provided a variety of theories and evidence for the development, maintenance, and severity of addiction; however, clinically, it has been difficult to evaluate alcohol use disorder (AUD) severity. Objective: This study seeks to evaluate and validate a data-driven approach to capturing alcohol severity in a community sample. Method: Participants were non-treatment seeking problem drinkers (n?=?283). A structural equation modeling approach was used to (a) verify the latent factor structure of the indices of AUD severity; and (b) test the relationship between the AUD severity factor and measures of alcohol use, affective symptoms, and motivation to change drinking. Results: The model was found to fit well, with all chosen indices of AUD severity loading significantly and positively onto the severity factor. In addition, the paths from the alcohol use, motivation, and affective factors accounted for 68% of the variance in AUD severity. Greater AUD severity was associated with greater alcohol use, increased affective symptoms, and higher motivation to change. Conclusion: Unlike the categorical diagnostic criteria, the AUD severity factor is comprised of multiple quantitative dimensions of impairment observed across the progression of the disorder. The AUD severity factor was validated by testing it in relation to other outcomes such as alcohol use, affective symptoms, and motivation for change. Clinically, this approach to AUD severity can be used to inform treatment planning and ultimately to improve outcomes. PMID:23908635

Moallem, Nathasha R.; Courtney, Kelly E.; Bacio, Guadalupe A.; Ray, Lara A.

2013-01-01

287

Parallel Workflows for Data-Driven Structural Equation Modeling in Functional Neuroimaging  

PubMed Central

We present a computational framework suitable for a data-driven approach to structural equation modeling (SEM) and describe several workflows for modeling functional magnetic resonance imaging (fMRI) data within this framework. The Computational Neuroscience Applications Research Infrastructure (CNARI) employs a high-level scripting language called Swift, which is capable of spawning hundreds of thousands of simultaneous R processes (R Development Core Team, 2008), consisting of self-contained SEMs, on a high performance computing system (HPC). These self-contained R processing jobs are data objects generated by OpenMx, a plug-in for R, which can generate a single model object containing the matrices and algebraic information necessary to estimate parameters of the model. With such an infrastructure in place a structural modeler may begin to investigate exhaustive searches of the model space. Specific applications of the infrastructure, statistics related to model fit, and limitations are discussed in relation to exhaustive SEM. In particular, we discuss how workflow management techniques can help to solve large computational problems in neuroimaging. PMID:19876406

Kenny, Sarah; Andric, Michael; Boker, Steven M.; Neale, Michael C.; Wilde, Michael; Small, Steven L.

2009-01-01

288

Anti-transgender prejudice: a structural equation model of associated constructs.  

PubMed

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. Social desirability was controlled as a covariate in the model. Analyses of data from 250 undergraduate students indicated that anti-LGB prejudice, traditional gender role attitudes, and need for closure each had positive unique relations with anti-transgender prejudice beyond the negative association of social desirability with such prejudice. By contrast, social dominance orientation was not related uniquely to anti-transgender prejudice. Additional analyses indicated that women's mean level of anti-transgender prejudice was lower than that of men's, but the pattern of relations between the predictor variables and anti-transgender prejudice did not differ between women and men. A confirmatory factor analysis also supported the unidimensional structure of anti-transgender prejudice as operationalized by Nagoshi et al.'s (2008) Transphobia Scale. PMID:22329343

Tebbe, Esther N; Moradi, Bonnie

2012-04-01

289

STRUCTURALLY DAMPED PLATE AND WAVE EQUATIONS WITH RANDOM POINT FORCE IN ARBITRARY SPACE  

E-print Network

for solutions in Lq (S) with q (1, 2); in fact, we need q (1, d/(d - 1)) for the plate equation and q (1, 2d/(2d - 1)) for the wave equation. In the non-damped situation the stochastic wave equation and plate Organization for Scientific Research (NWO). 1 #12;2 ROLAND SCHNAUBELT AND MARK VERAAR wave equations have been

Veraar, Mark C.

290

Full Equations (FEQ) model for the solution of the full, dynamic equations of motion for one-dimensional unsteady flow in open channels and through control structures  

USGS Publications Warehouse

The Full EQuations (FEQ) model is a computer program for solution of the full, dynamic equations of motion for one-dimensional unsteady flow in open channels and through control structures. A stream system that is simulated by application of FEQ is subdivided into stream reaches (branches), parts of the stream system for which complete information on flow and depth are not required (dummy branches), and level-pool reservoirs. These components are connected by special features; that is, hydraulic control structures, including junctions, bridges, culverts, dams, waterfalls, spillways, weirs, side weirs, and pumps. The principles of conservation of mass and conservation of momentum are used to calculate the flow and depth throughout the stream system resulting from known initial and boundary conditions by means of an implicit finite-difference approximation at fixed points (computational nodes). The hydraulic characteristics of (1) branches including top width, area, first moment of area with respect to the water surface, conveyance, and flux coefficients and (2) special features (relations between flow and headwater and (or) tail-water elevations, including the operation of variable-geometry structures) are stored in function tables calculated in the companion program, Full EQuations UTiLities (FEQUTL). Function tables containing other information used in unsteady-flow simulation (boundary conditions, tributary inflows or outflows, gate settings, correction factors, characteristics of dummy branches and level-pool reservoirs, and wind speed and direction) are prepared by the user as detailed in this report. In the iterative solution scheme for flow and depth throughout the stream system, an interpolation of the function tables corresponding to the computational nodes throughout the stream system is done in the model. FEQ can be applied in the simulation of a wide range of stream configurations (including loops), lateral-inflow conditions, and special features. The accuracy and convergence of the numerical routines in the model are demonstrated for the case of laboratory measurements of unsteady flow in a sewer pipe. Verification of the routines in the model for field data on the Fox River in northeastern Illinois also is briefly discussed. The basic principles of unsteady-flow modeling and the relation between steady flow and unsteady flow are presented. Assumptions and the limitations of the model also are presented. The schematization of the stream system and the conversion of the physical characteristics of the stream reaches and a wide range of special features into function tables for model applications are described. The modified dynamic-wave equation used in FEQ for unsteady flow in curvilinear channels with drag on minor hydraulic structures and channel constrictions determined from an equivalent energy slope is developed. The matrix equation relating flows and depths at computational nodes throughout the stream system by the continuity (conservation of mass) and modified dynamic-wave equations is illustrated for four sequential examples. The solution of the matrix equation by Newton's method is discussed. Finally, the input for FEQ and the error messages and warnings issued are presented.

Franz, Delbert D.; Melching, Charles S.

1997-01-01

291

Significant progress in solution of nonlinear equations at displacement of structure and heat transfer extended surface by new AGM approach  

NASA Astrophysics Data System (ADS)

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.

Akbari, M. R.; Ganji, D. D.; Nimafar, M.; Ahmadi, A. R.

2014-12-01

292

Filipino Nursing Students' Behavioral Intentions toward Geriatric Care: A Structural Equation Model (SEM)  

ERIC Educational Resources Information Center

Anchored on the key constucts of Ajzen's Theory of Planned Behavior (1985), this paper seeks to test a model that explores the influence of knowledge, attitude, and caring behavior on nursing students' behavioral intention toward geriatric care. A five-part survey-questionnaire was administered to 839 third and fourth year nursing students from a…

de Guzman, Allan B.; Jimenez, Benito Christian B.; Jocson, Kathlyn P.; Junio, Aileen R.; Junio, Drazen E.; Jurado, Jasper Benjamin N.; Justiniano, Angela Bianca F.

2013-01-01

293

Development of a "Steps Questionnaire".  

PubMed

Thousands of men and women have begun their recovery from alcoholism through the support of Alcoholics Anonymous (AA) and its well-known "12-Step" program. The purpose of the present study was to develop a scale to measure alcoholics' levels of agreement with the first three of AA's 12 Steps and to test the relationship between sobriety and belief in these three steps. Using both factor analysis and Rasch analysis, two versions of a "Steps Questionnaire" were developed. A 96-member subset of the original subject pool was assessed quarterly for 1 year following inpatient treatment to determine the predictive validity of the questionnaire. The results of this study suggested that agreement with AA's first three steps can be measured and that agreement with AA's first step correlates with number of sober days posttreatment. The dichotomization of Steps Questionnaire scores into total agreement versus partial agreement with Step 1, and from this the reduction of uncertainty in the prediction of abstention over a lengthy follow-up period, provides support for AA's contention that total surrender to one's powerlessness over alcohol is part of the process of achieving abstention. PMID:1875709

Gilbert, F S

1991-07-01

294

Validation of the Dutch Eating Behavior Questionnaire (DEBQ) in a sample of Spanish women.  

PubMed

The Dutch Eating Behavior Questionnaire (DEBQ) was developed to measure eating styles that may contribute to or attenuate the development of overweight. It comprises three scales that measure emotional, external and restrained eating. The main goal of this study is to evaluate the internal structure of the Spanish version of the DEBQ using updated psychometric techniques in a sample of women. A sample of 647 Spanish females answered the questionnaire. Both exploratory structural equation modeling and confirmatory factor analysis were used to evaluate the factor structure of the DEBQ. Reliabilities were estimated with Cronbach's alpha. The relations between the subscales of the DEBQ and age, BMI, and scores on the Eating Attitude Test-26 (EAT) and the Restrained Scale-Revised (RS) were computed with Pearson correlations. Results showed that the internal structure was similar to the theoretical proposal, although items associated with boredom and idleness presented cross-loading problems. The reliability estimates were satisfactory. The Emotional and External Eating factors correlated with the BMI, and External Eating was negatively correlated with age. The Restraint factor of the DEBQ showed significant relationships with scales of the EAT-26 and RS. The dimensional validity of the DEBQ is reproduced in a Spanish sample, and the DEBQ seems to be an effective instrument for research in Spanish females. Minor modifications to the DEBQ are recommended. PMID:24177441

Cebolla, A; Barrada, J R; van Strien, T; Oliver, E; Baños, R

2014-02-01

295

Structural Equation Modeling of Relationships Among Developmental Skills and Writing Skills in Primary and Intermediate-Grade Writers  

Microsoft Academic Search

We used multiple-group structural equation modeling to analyze structural relationships between latent factors underlying writing-related developmental skills and component writing skills in Grades 1–6. For handwriting, both motor skills and orthographic coding contributed to the model fit, but only the path from orthographic coding was significant at all grade levels. For spelling, only the path from orthographic coding was significant

Robert D. Abbott; Virginia W. Berninger

1993-01-01

296

Three Approaches to Using Lengthy Ordinal Scales in Structural Equation Models: Parceling, Latent Scoring, and Shortening Scales  

ERIC Educational Resources Information Center

Lengthy scales or testlets pose certain challenges for structural equation modeling (SEM) if all the items are included as indicators of a latent construct. Three general approaches to modeling lengthy scales in SEM (parceling, latent scoring, and shortening) have been reviewed and evaluated. A hypothetical population model is simulated containing…

Yang, Chongming; Nay, Sandra; Hoyle, Rick H.

2010-01-01

297

Review of Sample Size for Structural Equation Models in Second Language Testing and Learning Research: A Monte Carlo Approach  

ERIC Educational Resources Information Center

The importance of sample size, although widely discussed in the literature on structural equation modeling (SEM), has not been widely recognized among applied SEM researchers. To narrow this gap, we focus on second language testing and learning studies and examine the following: (a) Is the sample size sufficient in terms of precision and power of…

In'nami, Yo; Koizumi, Rie

2013-01-01

298

Effects of Assets and Deficits on the Social Control of At-Risk Behavior among Youth: A Structural Equations Approach.  

ERIC Educational Resources Information Center

Tested control theory using protective effects of personal and social assets and risk effects of personal deficits on deviant behaviors of drug use, delinquency, truancy, and weapons possession. Analyzed data from students in grades 6-12 using structural equations modeling. Second order factors of assets and deficits explained deviant behavior.…

Dukes, Richard L.; Stein, Judith A.

2001-01-01

299

On soliton structure of higher order (2+1)-dimensional equations of a relaxing medium beneath high-frequency perturbations  

E-print Network

We investigate the soliton structure of novel (2+1)-dimensional nonlinear partial differential evolution(NLPDE) equations which may govern the behavior of a barothropic relaxing medium beneath high-frequency perturbations. As a result, we may derive some soliton solutions amongst which three typical pattern formations with loop-, cusp- and hump-like shapes.

Kuetche Kamgang Victor; Bouetou Bouetou Thomas; Timoleon Crepin Kofane

2007-09-27

300

Structural Equation Modeling (SEM) for Satisfaction and Dissatisfaction Ratings; Multiple Group Invariance Analysis across Scales with Different Response Format  

ERIC Educational Resources Information Center

The current study evaluates three hypothesized models on subjective well-being, comprising life domain ratings (LDR), overall satisfaction with life (OSWL), and overall dissatisfaction with life (ODWL), using structural equation modeling (SEM). A sample of 1,310 volunteering students, randomly assigned to six conditions, rated their overall life…

Mazaheri, Mehrdad; Theuns, Peter

2009-01-01

301

Accuracy in Parameter Estimation for Targeted Effects in Structural Equation Modeling: Sample Size Planning for Narrow Confidence Intervals  

ERIC Educational Resources Information Center

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…

Lai, Keke; Kelley, Ken

2011-01-01

302

Doubly-Latent Models of School Contextual Effects: Integrating Multilevel and Structural Equation Approaches to Control Measurement and Sampling Error  

ERIC Educational Resources Information Center

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)…

Marsh, Herbert W.; Ludtke, Oliver; Robitzsch, Alexander; Trautwein, Ulrich; Asparouhov, Tihomir; Muthen, Bengt; Nagengast, Benjamin

2009-01-01

303

Structural Equation Modeling of the Relationships Between Pesticide Poisoning, Depressive Symptoms and Safety Behaviors Among Colorado Farm Residents  

Microsoft Academic Search

Purpose: To use structural equation modeling (SEM) to test the theory that a past pesticide poisoning may act as a mediator in the relationship between depression and safety practices. Depression has been associated with pesticide poisoning and was more strongly associated with safety behaviors than workload, social support or health status of farm residents in a previously published report.Methods: A

Cheryl Lynn Beseler; Lorann Stallones

2006-01-01

304

Modeling the Relationships among Topical Knowledge, Anxiety, and Integrated Speaking Test Performance: A Structural Equation Modeling Approach  

ERIC Educational Resources Information Center

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…

Huang, Heng-Tsung Danny

2010-01-01

305

Investigating perturbed pathway modules from gene expression data via structural equation models  

PubMed Central

Background It is currently accepted that the perturbation of complex intracellular networks, rather than the dysregulation of a single gene, is the basis for phenotypical diversity. High-throughput gene expression data allow to investigate changes in gene expression profiles among different conditions. Recently, many efforts have been made to individuate which biological pathways are perturbed, given a list of differentially expressed genes (DEGs). In order to understand these mechanisms, it is necessary to unveil the variation of genes in relation to each other, considering the different phenotypes. In this paper, we illustrate a pipeline, based on Structural Equation Modeling (SEM) that allowed to investigate pathway modules, considering not only deregulated genes but also the connections between the perturbed ones. Results The procedure was tested on microarray experiments relative to two neurological diseases: frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U) and multiple sclerosis (MS). Starting from DEGs and dysregulated biological pathways, a model for each pathway was generated using databases information biological databases, in order to design how DEGs were connected in a causal structure. Successively, SEM analysis proved if pathways differ globally, between groups, and for specific path relationships. The results confirmed the importance of certain genes in the analyzed diseases, and unveiled which connections are modified among them. Conclusions We propose a framework to perform differential gene expression analysis on microarray data based on SEM, which is able to: 1) find relevant genes and perturbed biological pathways, investigating putative sub-pathway models based on the concept of disease module; 2) test and improve the generated models; 3) detect a differential expression level of one gene, and differential connection between two genes. This could shed light, not only on the mechanisms affecting variations in gene expression, but also on the causes of gene-gene relationship modifications in diseased phenotypes. PMID:24885496

2014-01-01

306

Empirical Correction to the Likelihood Ratio Statistic for Structural Equation Modeling with Many Variables.  

PubMed

Survey data typically contain many variables. Structural equation modeling (SEM) is commonly used in analyzing such data. The most widely used statistic for evaluating the adequacy of a SEM model is T ML, a slight modification to the likelihood ratio statistic. Under normality assumption, T ML approximately follows a chi-square distribution when the number of observations (N) is large and the number of items or variables (p) is small. However, in practice, p can be rather large while N is always limited due to not having enough participants. Even with a relatively large N, empirical results show that T ML rejects the correct model too often when p is not too small. Various corrections to T ML have been proposed, but they are mostly heuristic. Following the principle of the Bartlett correction, this paper proposes an empirical approach to correct T ML so that the mean of the resulting statistic approximately equals the degrees of freedom of the nominal chi-square distribution. Results show that empirically corrected statistics follow the nominal chi-square distribution much more closely than previously proposed corrections to T ML, and they control type I errors reasonably well whenever N?max(50,2p). The formulations of the empirically corrected statistics are further used to predict type I errors of T ML as reported in the literature, and they perform well. PMID:24327067

Yuan, Ke-Hai; Tian, Yubin; Yanagihara, Hirokazu

2013-12-11

307

Bayesian model comparison of nonlinear structural equation models with missing continuous and ordinal categorical data.  

PubMed

Missing data are very common in behavioural and psychological research. In this paper, we develop a Bayesian approach in the context of a general nonlinear structural equation model with missing continuous and ordinal categorical data. In the development, the missing data are treated as latent quantities, and provision for the incompleteness of the data is made by a hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm. We show by means of a simulation study that the Bayesian estimates are accurate. A Bayesian model comparison procedure based on the Bayes factor and path sampling is proposed. The required observations from the posterior distribution for computing the Bayes factor are simulated by the hybrid algorithm in Bayesian estimation. Our simulation results indicate that the correct model is selected more frequently when the incomplete records are used in the analysis than when they are ignored. The methodology is further illustrated with a real data set from a study concerned with an AIDS preventative intervention for Filipina sex workers. PMID:15171804

Lee, Sik-Yum; Song, Xin-Yuan

2004-05-01

308

Stress and Resilience in Functional Somatic Syndromes – A Structural Equation Modeling Approach  

PubMed Central

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

Fischer, Susanne; Lemmer, Gunnar; Gollwitzer, Mario; Nater, Urs M.

2014-01-01

309

Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety  

PubMed Central

Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb. This study used Monte Carlo data simulation techniques to evaluate sample size requirements for common applied SEMs. Across a series of simulations, we systematically varied key model properties, including number of indicators and factors, magnitude of factor loadings and path coefficients, and amount of missing data. We investigated how changes in these parameters affected sample size requirements with respect to statistical power, bias in the parameter estimates, and overall solution propriety. Results revealed a range of sample size requirements (i.e., from 30 to 460 cases), meaningful patterns of association between parameters and sample size, and highlight the limitations of commonly cited rules-of-thumb. The broad “lessons learned” for determining SEM sample size requirements are discussed.

Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

2015-01-01

310

Modelling Pathways to Rubisco Degradation: A Structural Equation Network Modelling Approach  

PubMed Central

‘Omics analysis (transcriptomics, proteomics) quantifies changes in gene/protein expression, providing a snapshot of changes in biochemical pathways over time. Although tools such as modelling that are needed to investigate the relationships between genes/proteins already exist, they are rarely utilised. We consider the potential for using Structural Equation Modelling to investigate protein-protein interactions in a proposed Rubisco protein degradation pathway using previously published data from 2D electrophoresis and mass spectrometry proteome analysis. These informed the development of a prior model that hypothesised a pathway of Rubisco Large Subunit and Small Subunit degradation, producing both primary and secondary degradation products. While some of the putative pathways were confirmed by the modelling approach, the model also demonstrated features that had not been originally hypothesised. We used Bayesian analysis based on Markov Chain Monte Carlo simulation to generate output statistics suggesting that the model had replicated the variation in the observed data due to protein-protein interactions. This study represents an early step in the development of approaches that seek to enable the full utilisation of information regarding the dynamics of biochemical pathways contained within proteomics data. As these approaches gain attention, they will guide the design and conduct of experiments that enable ‘Omics modelling to become a common place practice within molecular biology. PMID:24498339

Tétard-Jones, Catherine; Gatehouse, Angharad M. R.; Cooper, Julia; Leifert, Carlo; Rushton, Steven

2014-01-01

311

Network inference of AP pattern formation system in D.melanogaster by structural equation modeling  

NASA Astrophysics Data System (ADS)

Within the field of systems biology, revealing the control systems functioning during embryogenesis is an important task. To clarify the mechanisms controlling sequential events, the relationships between various factors and the expression of specific genes should be determined. In this study, we applied a method based on Structural Equation Modeling (SEM), combined with factor analysis. SEM can include the latent variables within the constructed model and infer the relationships among the latent and observed variables, as a network model. We improved a method for the construction of initial models for the SEM calculation, and applied our approach to estimate the regulatory network for Antero-Posterior (AP) pattern formation in D. melanogaster embryogenesis. In this new approach, we combined cross-correlation and partial correlation to summarize the temporal information and to extract the direct interactions from the gene expression profiles. In the inferred model, 18 transcription factor genes were regulated by not only the expression of other genes, but also the estimated factors. Since each factor regulated the same type of genes, these factors were considered to be involved in maternal effects or spatial morphogen distributions. The interpretation of the inferred network model allowed us to reveal the regulatory mechanism for the patterning along the head to tail axis in D. melanogaster.

Aburatani, S.; Toh, H.

2014-03-01

312

Mediation analysis with intermediate confounding: structural equation modeling viewed through the causal inference lens.  

PubMed

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

De Stavola, Bianca L; Daniel, Rhian M; Ploubidis, George B; Micali, Nadia

2015-01-01

313

The Neo Personality Inventory-Revised: Factor Structure and Gender Invariance from Exploratory Structural Equation Modeling Analyses in a High-Stakes Setting  

ERIC Educational Resources Information Center

This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM)…

Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z.; Chamorro-Premuzic, Tomas

2013-01-01

314

Criteria for the Design of Mail Questionnaires.  

ERIC Educational Resources Information Center

Describes the elements required for a well-designed questionnaire, including appearance, question writing, organization, and cover letter. A checklist for effective questionnaire design is provided, as well as seven references. (BK)

Swisher, Robert

1980-01-01

315

Structural equation modeling of the proximal–distal continuum of adherence drivers  

PubMed Central

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

McHorney, Colleen A; Zhang, Ning Jackie; Stump, Timothy; Zhao, Xiaoquan

2012-01-01

316

Analysing the socioeconomic determinants of hypertension in South Africa: a structural equation modelling approach  

PubMed Central

Background Epidemiological research has long observed a varying prevalence of hypertension across socioeconomic strata. However, patterns of association and underlying causal mechanisms are poorly understood in sub-Saharan Africa. Using education and income as indicators, we investigated the extent to which socioeconomic status is linked to blood pressure in the first wave of the National Income Dynamics Study — a South African longitudinal study of more than 15000 adults – and whether bio-behavioural risk factors mediate the association. Methods In a cross-sectional analysis, structural equation modelling was employed to estimate the effect of socioeconomic status on systolic and diastolic blood pressure and to assess the role of a set of bio-behavioural risk factors in explaining the observed relationships. Results After adjustment for age, race and antihypertensive treatment, higher education and income were independently associated with higher diastolic blood pressure in men. In women higher education predicted lower values of both diastolic and systolic blood pressure while higher income predicted lower systolic blood pressure. In both genders, body mass index was a strong mediator of an adverse indirect effect of socioeconomic status on blood pressure. Together with physical exercise, alcohol use, smoking and resting heart rate, body mass index therefore contributed substantially to mediation of the observed relationships in men. By contrast, in women unmeasured factors played a greater role. Conclusion In countries undergoing epidemiological transition, effects of socioeconomic status on blood pressure may vary by gender. In women, factors other than those listed above may have substantial role in mediating the association and merit investigation. PMID:24885860

2014-01-01

317

Species richness and soil properties in Pinus ponderosa forests: A structural equation modeling analysis  

USGS Publications Warehouse

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.

Laughlin, D.C.; Abella, S.R.; Covington, W.W.; Grace, J.B.

2007-01-01

318

THE RELATIONSHIP BETWEEN MEASURES OF IMPULSIVITY AND ALCOHOL MISUSE: AN INTEGRATIVE STRUCTURAL EQUATION MODELING APPROACH  

PubMed Central

Background Higher levels of impulsivity have been implicated in the development of alcohol use disorders. Recent findings suggest that impulsivity is not a unitary construct, highlighted by the diverse ways in which the various measures of impulsivity relate to alcohol use outcomes. This study simultaneously tested the following dimensions of impulsivity as determinants of alcohol use and alcohol problems: risky decision-making, self-reported risk attitudes, response inhibition, and impulsive decision-making. Method Participants were a community sample of non-treatment seeking problem drinkers (N = 158). Structural Equation Modeling (SEM) analyses employed behavioral measures of impulsive decision-making (Delay Discounting Task, DDT), response inhibition (Stop Signal Task, SST), and risky decision-making (Balloon Analogue Risk Task, BART), and a self-report measure of risk attitudes (Domain-specific Risk-attitude Scale, DOSPERT), as predictors of alcohol use and of alcohol-related problems in this sample. Results The model fit well, accounting for 38% of the variance in alcohol problems, and identified two impulsivity dimensions that significantly loaded onto alcohol outcomes: (1) impulsive decision-making, indexed by the DDT; and (2) risky decision-making, measured by the BART. Conclusions The impulsive decision-making dimension of impulsivity, indexed by the DDT, was the strongest predictor of alcohol use and alcohol pathology in this sample of problem drinkers. Unexpectedly, a negative relationship was found between risky decision-making and alcohol problems. The results highlight the importance of considering the distinct facets of impulsivity in order to elucidate their individual and combined effects on alcohol use initiation, escalation, and dependence. PMID:22091877

Courtney, Kelly E.; Arellano, Ryan; Barkley-Levenson, Emily; Gálvan, Adriana; Poldrack, Russell A.; MacKillop, James; Jentsch, J. David; Ray, Lara A.

2011-01-01

319

A Structural Equation Model Analysis of Relationships among ENSO, Seasonal Descriptors and Wildfires  

PubMed Central

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

320

Biomarkers and neurodevelopment in perinatally HIV-infected or exposed youth: a structural equation model analysis  

PubMed Central

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

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

321

Examining the Link between Patient Satisfaction and Adherence to HIV Care: A Structural Equation Model  

PubMed Central

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

Dang, Bich N.; Westbrook, Robert A.; Black, William C.; Rodriguez-Barradas, Maria C.; Giordano, Thomas P.

2013-01-01

322

Neurocognition, Insight and Medication Nonadherence in Schizophrenia: A Structural Equation Modeling Approach  

PubMed Central

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

Boyer, Laurent; Cermolacce, Michel; Dassa, Daniel; Fernandez, Jessica; Boucekine, Mohamed; Richieri, Raphaelle; Vaillant, Florence; Dumas, Remy; Auquier, Pascal; Lancon, Christophe

2012-01-01

323

Evaluation of trip-inducing effects of new freeways using a structural equations model system of commuters’ time use and travel  

Microsoft Academic Search

A structural equations model system which represents the effects of transportation control measures on commuters’ daily activity patterns after work hours is presented. A commuter’s daily activity after work till going to sleep is defined in terms of variables that indicate time use and travel. These variables are the endogenous variables of the structural equations model system. The parameters of

Satoshi Fujii; Ryuichi Kitamura

2000-01-01

324

A special purpose symbolic manipulation program for the derivation of the equations of motion for large flexible structures  

NASA Technical Reports Server (NTRS)

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.

Hale, A. L.; Meirovitch, L.

1977-01-01

325

A Brief Guide to Questionnaire Development  

NSDL National Science Digital Library

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.

Frary, Robert

326

Emotional and behavioural difficulties in children referred for learning disabilities from two Arab countries: A cross-cultural examination of the Strengths and Difficulties Questionnaire.  

PubMed

The Strengths and Difficulties Questionnaire (SDQ) is a widely used child mental health questionnaire with five hypothesized subscales. There is theoretical and preliminary empirical support for combining the SDQ's hypothesized emotional and peer subscales into an 'internalizing' subscale and the hypothesized behavioural and hyperactivity subscales into an 'externalizing' subscale (alongside the fifth prosocial subscale). We examined both structures using the teacher informant version data from two Arab countries, namely Saudi Arabia (323) and Oman (439). Multigroup CFAs based on structural equation modelling revealed culture invariance for the SDQ. The three-factor model showed a better description of the SDQ structure. The analysis also revealed gender invariance for the SDQ three and five factor models in both the Omani and Saudi samples. There were gender differences in all the three and five factors between the Saudi and Omani samples. PMID:25462506

El-Keshky, Mogeda; Emam, Mahmoud

2014-11-11

327

Structural analysis of differential-algebraic equation systems—theory and applications  

Microsoft Academic Search

The choice of a feasible numerical method for the solution of a Differential-Algebraic Equation (DAE) model of general type F(z,z,u) = 0 requires knowledge about its solvability, index, number and type of dynamic degrees of freedom as well as the set of equations to be satisfied by consistent initial conditions. Furthermore, a set of design quantities has to be specified.

J. Unger; A. Kröner; W. Marquardt

1995-01-01

328

Factorial invariance of the Patient Health Questionnaire and Generalized Anxiety Disorder Questionnaire  

PubMed Central

Objectives The UK's Improving Access to Psychological Therapies (IAPT) programme uses the Patient Health Questionnaire Depression Scale (PHQ-9; Kroenke, Spitzer, & Williams, 2001, J. Gen. Intern. Med., 16, 606) and Generalized Anxiety Disorder Scale (GAD-7; Spitzer et al., 2006, Arch. Intern. Med., 166, 1092) to assess patients' symptoms of depression and anxiety respectively. Data are typically collected via telephone or face-to-face; however, no study has statistically investigated whether the questionnaires' items operate equivalently across these modes of data collection. This study aimed to address this omission. Methods & Results Questionnaire data from patients registered with an IAPT service in London (N = 23,672) were examined. Confirmatory factor analyses suggested that unidimensional factor structures adequately matched observed face-to-face and telephone data for the PHQ-9 and GAD-7. Invariance analyses revealed that while the PHQ-9 had equivalent factor loadings and latent means across data collection methods, the GAD-7 had equivalent factor loadings but unequal latent means. In support of the scales' convergent validity, positive associations between scores on the PHQ-9 and GAD-7 emerged. Conclusions With the exception of the GAD-7's latent means, the questionnaires' factor loadings and latent means were equivalent. This suggests that clinicians may meaningfully compare PHQ-9 data collected face-to-face and by telephone; however, such comparisons with the GAD-7 should be done with caution. Practitioner points The PHQ-9 and GAD-7's factor loadings were equivalent across data collection methods. Only the PHQ-9's latent means were equivalent across data collection methods. Clinicians may be confident collecting PHQ-9 data by telephone and face-to-face and, then, comparing such data. Caution is recommended when determining clinical effectiveness using telephone and face-to-face GAD-7 data. More psychometric research is warranted. PMID:24117915

Ryan, Travis A; Bailey, Alastair; Fearon, Pasco; King, John

2013-01-01

329

Ab initio Equation of State data for hydrogen, helium, and water and the internal structure of Jupiter  

E-print Network

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.

N. Nettelmann; B. Holst; A. Kietzmann; M. French; R. Redmer; D. Blaschke

2008-06-06

330

The ARSQ: the athletes' received support questionnaire.  

PubMed

To address calls for context-specific measurement of social support, this article reports the development of the Athletes' Received Support Questionnaire (ARSQ) and demonstrates initial evidence for its validity. Across four studies there was support for a four-dimensional structure reflecting emotional, esteem, informational, and tangible received support. There was also support for unidimensional and higher-order models. Further, Study 3 provided some support for convergent validity, with significant correlations between the corresponding dimensions of the ARSQ and the Inventory of Socially Supportive Behaviors. Study 4 provided evidence for the nomological validity of the ARSQ. Emotional and esteem support significantly predicted self-confidence and positive affect, and tangible support significantly moderated the relationship between stress and negative affect. Collectively, these results provide initial evidence for the validity of the ARSQ, and offer researchers flexibility to adopt either a multidimensional or aggregated approach to measuring received support. PMID:24686955

Freeman, Paul; Coffee, Pete; Moll, Tjerk; Rees, Tim; Sammy, Nadine

2014-04-01

331

The influence of locus of control on self-rated health in context of chronic disease: a structural equation modeling approach in a cross sectional study  

PubMed Central

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

2014-01-01

332

Bright and dark optical solitons in coupled higher-order nonlinear Schrodinger equations through singularity structure analysis  

Microsoft Academic Search

A fairly general form of coupled higher-order nonlinear Schrodinger (CHNLS) equations, which includes the effect of group velocity dispersion (GVD), third-order dispersion, Kerr-law nonlinearity and describing a large class of phenomena involving soliton interactions, has been investigated using Painleve (P) singularity structure analysis in order to identify the underlying integrable models. The identified integrable models agree well with those obtained

R. Radhakrishnan; M. Lakshmanan; M. Daniel

1995-01-01

333

Physical factors underlying the association between lower walking performance and falls in older people: A structural equation model  

Microsoft Academic Search

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

Hiroyuki Shimada; Anne Tiedemann; Stephen R. Lord; Megumi Suzukawa; Hyuma Makizako; Kumiko Kobayashi; Takao Suzuki

2011-01-01

334

Size and taxonomic plankton community structure and carbon flow at the equator, 175‡E during 1990–1994  

Microsoft Academic Search

Size and taxonomic structure of plankton community carbon biomass for the 0.2–2000 ?m equivalent spherical diameter range were determined at the equator at 175°E in September 1990–1993 and April 1994. Total biomass of the plankton community ranged from 1944 to 3448 mg C m?2. Phytoplankton, zooplankton and bacteria carbon biomasses were 604–1669 mg C m-2, 300–797 mg C m2, and

J. Ishizaka; K. Harada; K. Ishikawa; H. Kiyosawa; H. Furusawa; Y. Watanabe; H. Ishida; K. Suzuki; N. Handa; M. Takahashi

1997-01-01

335

The disenchantment of professionals in a new, implemented model of primary health care in Spain: A structural equations model  

Microsoft Academic Search

A new model of primary health care has been progressively implemented in Spain. Previous research (Peiró and González-Romá 1991) suggested that the implementation of this new model has produced a kind of disenchantment—that is, an experience of negative surprise—among health care professionals involved. In the present paper, a structural equations model about the antecedents and consequences of the experience of

J. M. Peiró; V. González-romá; P. Valcárcel; J. Ramos

1992-01-01

336

Impacts of Information and Communication Technologies (ICT) on time use and travel behavior: a structural equations analysis  

Microsoft Academic Search

The objective of this paper is to contribute an empirical study to the literature on transportation impacts of Information\\u000a and Communications Technologies (ICT). The structural equation model (SEM) is employed to analyze the impacts of ICT usage\\u000a on time use and travel behavior. The sample is derived from the travel characteristic survey conducted in Hong Kong in 2002.\\u000a The usage

Donggen Wang; Fion Yuk Ting Law

2007-01-01

337

“I Feel Present. Therefore, I Experience Flow:” A Structural Equation Modeling Approach to Flow and Presence in Video Games  

Microsoft Academic Search

Driven by theories of flow and presence, three studies examined the antecedents and consequences of flow across three different video game genres. Structural equation modeling analyses reveal the roles of (1) physical presence in medical simulation games; (2) spatial presence in driving games; and (3) self-presence in avatar-based narrative-driven games. A 3 (skill: low, medium, high) × 3 (challenge: low,

Seung-A Annie Jin

2011-01-01

338

Complex interactions among biocontrol agents, pollinators, and an invasive weed: a structural equation modeling approach.  

PubMed

Herbivores, seed predators, and pollinators can exert strong impacts on their host plants. They can also affect the strength of each other's impact by modifying traits in their shared host, producing super- or sub-additive outcomes. This phenomenon is especially relevant to biological control of invasive plants because most invaders are attacked by multiple agents. Unfortunately, complex interactions among agents are rarely studied. We used structural equation modeling (SEM) to quantify the effect of two biocontrol agents and generalist pollinators on the invasive weed Centaurea solstitialis, and to identify and quantify the direct and indirect interaction pathways among them. The weevil Eustenopus villosus is both a bud herbivore and a predispersal seed predator; the fly Chaetorellia succinea is also a predispersal seed predator; Apis mellifera is the primary pollinator. We conducted this work at three sites spanning the longitudinal range of C. solstitialis in California (USA) from the coast to the Sierra Nevada Mountains. SEM revealed that bud herbivory had the largest total effect on the weed's fecundity. The direct effect of bud herbivory on final seed set was 2-4 times larger in magnitude than the direct effect of seed predation by both agents combined. SEM also revealed important indirect interactions; by reducing the number of inflorescences plants produced, bud herbivory indirectly reduced the plant's attractiveness to ovipositing seed predators. This indirect, positive pathway reduced bud herbivory's direct negative effect by 11-25%. In the same way, bud herbivory also reduced pollinator visitation, although the magnitude of this pathway was relatively small. E. villosus oviposition deterred C. succinea oviposition, which is unfortunate because C. succinea is the more voracious of the seed predators. Finally, C. succinea oviposition indirectly deterred pollinator visitation, thereby enhancing its net effect on the plant. This study demonstrates the powerful insights that can be gained from the SEM approach in understanding the multiple direct and indirect interactions among agents and pollinators and their effects on an invasive weed. Such an approach may improve our ability to manage weeds with biocontrol agents by identifying pathways that could be exploited by future agents and minimizing the possibility of interference with established agents. PMID:23387114

Swope, Sarah M; Parker, Ingrid M

2012-12-01

339

The Heterogeneous Structure of Schizotypal Personality Disorder: Item-Level Factors of the Schizotypal Personality Questionnaire and Their Associations With Obsessive-Compulsive Disorder Symptoms, Dissociative Tendencies, and Normal Personality  

Microsoft Academic Search

A. Raine et al.'s (1994) 3-factor scheme is currently the most widely accepted model of schizotypal personality disorder (SPD). Factor analytic studies of the Schizotypal Personality Questionnaire (SPQ; A. Raine, 1991) subscales, which represent the 9 Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria for SPD, have provided the model's primary support. The use of only 9 modeled variables,

Michael Chmielewski; David Watson

2008-01-01

340

Development and Validation of the Uncivil Workplace Behavior Questionnaire  

Microsoft Academic Search

This article describes the development and validation of a new measure of workplace incivility, the Uncivil Workplace Behavior Questionnaire (UWBQ). Participants included 5 samples of Australian adult employees (total N = 368). Principal axis factoring of the UWBQ yielded 4 interpretable factors (Hostility, Privacy Invasion, Exclusionary Behavior, and Gossiping), all of which exhibited high internal consistency. The 4-factor structure received

Roberta J. Martin; Donald W. Hine

2005-01-01

341

Evaluation of questionnaires by means of formal concept analysis  

E-print Network

(International Physical Activity Questionnaire). The structured view on data provided by the method suggests, research plan MSM 6198959214, and by grant No. 6198959221 'Physical activity and inactivity of in of the Palacky University, Olomouc, who are involved in a world-wide project of monitoring physical activities

Belohlavek, Radim

342

The Development and Psychometric Properties of the Selective Mutism Questionnaire  

ERIC Educational Resources Information Center

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…

Bergman, R. Lindsey; Keller, Melody L.; Piacentini, John; Bergman, Andrea J.

2008-01-01

343

Thermodynamic structure of Lanczos-Lovelock field equations from near-horizon symmetries  

SciTech Connect

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.

Kothawala, Dawood; Padmanabhan, T. [IUCAA, Post Bag 4, Ganeshkhind, Pune - 411 007 (India)

2009-05-15

344

Implementation of the equation of radiative transfer on block-structured grids for modeling  

E-print Network

. Barbour, "Comparison of finite-difference transport and diffusion calculations for photon migration for solving the equation of radiative transfer (ERT) in the frequency domain (FD) on three-dimensional block, and refractive index. The solution on a 3-level BSG is obtained up to 4.2 times faster than the solution

Hielscher, Andreas

345

A modification of the likelihood equations for normal classes with field structure, preliminary report  

NASA Technical Reports Server (NTRS)

A statistical model on normal mixtures which takes into account the organization of LANDSAT agricultural data into fields which are homogeneous as to crop type is presented. Likelihood equations for the parameters of the model are derived which may be solved iteratively as in UHMLE.

Peters, C.

1979-01-01

346

The solution of linear systems of equations with a structural analysis code on the NAS CRAY-2  

NASA Technical Reports Server (NTRS)

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.

Poole, Eugene L.; Overman, Andrea L.

1988-01-01

347

Evaluation of a gastrointestinal symptoms questionnaire.  

PubMed

Questionnaires are widely used instruments to monitor gastrointestinal (GI) symptoms. However, few of these questionnaires have been formally evaluated. We sought to evaluate our GI symptoms questionnaire in terms of clarity and reproducibility. Primary care patients referred for open access Helicobacter pylori urea breath testing reported GI symptoms (type+severity) and demographic information by written questionnaire. In an interview, patients gave a personal description of the meaning of the GI symptoms on the questionnaire. Patients' descriptions of GI symptoms were compared with current definitions. Symptom severity scores were compared before and after, interview versus questionnaire. Of the 45 patients included, 19 (42%) described all symptoms correctly, whereas 17 (38%) described one symptom incorrectly. None of the patients made more than three mistakes. Regurgitation was the most common incorrectly described symptom (16 patients [36%]), whereas the other individual symptoms were well explained. Symptom severities before the interview, after the interview and reported by questionnaire (mean value+/-SEM) were 2.1 +/- 0.2, 2.1 +/- 0.2, and 1.5 +/- 0.2 points on a 7-point Likert scale (0-6), respectively. Mean severity reported by interview (95% CI) was 1.4 (1.3-1.5) times higher than reported by questionnaire (P < .05). In conclusion, the GI symptom questionnaire is understandable and has good reproducibility for measuring the presence of GI symptoms, although symptom severity is consistently rated higher when reported by interview. PMID:16927133

Bovenschen, H J; Janssen, M J R; van Oijen, M G H; Laheij, R J F; van Rossum, L G M; Jansen, J B M J

2006-09-01

348

Edge dislocation core structures in FCC metals determined from ab initio calculations combined with the improved Peierls-Nabarro equation  

NASA Astrophysics Data System (ADS)

We have employed the improved Peierls-Nabarro (P-N) equation to study the properties of 1/2lang110rang edge dislocation in the {111} plane in face-centered cubic (FCC) metals Al, Cu, Ir, Pd and Pt. The generalized-stacking-fault energy surface entering the equation is calculated by using first-principles density functional theory (DFT). The accuracy of the method has been tested by calculating the values for various stacking fault energies that favorably compare with previous theoretical and experimental results. The core structures, including the core widths of the edge and screw components, and dissociation behavior have been investigated. The dissociated distance between two partials for Al in our calculation agrees well with the values obtained from numerical simulation with DFT and molecular dynamics simulation, as well as experiment. Our calculations show that it is preferred to create partial dislocations in Cu, and easily observed full dislocations in Al, Ir, Pd and especially Pt.

Wang, Rui; Wang, Shaofeng; Wu, Xiaozhi

2011-04-01

349

Static aeroelastic analysis of wings using Euler/Navier-Stokes equations coupled with improved wing-box finite element structures  

NASA Technical Reports Server (NTRS)

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.

Guruswamy, Guru P.; MacMurdy, Dale E.; Kapania, Rakesh K.

1994-01-01

350

Code Development of Linearized Euler Equation on Block-Structured Cartesian Mesh Combined with Immersed Boundary Method  

NASA Astrophysics Data System (ADS)

Recently, acoustic analysis using the Linearized Euler Equation (LEE) on multi-block structured or unstructured mesh is focused. However, mesh generation around complicated geometries takes time on structured mesh and cost of high order calculation gets larger on unstructured mesh. In this research, a LEE code for aeroacoustic analysis is developed on block structured Cartesian mesh of Building-Cube Method. To make an accurate calculation, the Immersed Boundary Method is implemented for wall boundary treatment and high order Lagrange interpolation is implemented at the Cube boundary for data exchange. This code is validated through acoustics scattering problems around cylinders and the calculational errors are compared. The results show good agreement with analytical solutions and the usability of these methods.

Fukushima, Yuuma; Sasaki, Daisuke; Nakahashi, Kazuhiro

351

Force equation of the large-scale structure of the Universe  

E-print Network

This article presents a statistical-mechanical treatment of a relationship (the force equation) between the gravitational potential for two particles and the correlation functions in a relaxed distribution of particles with different masses. This relationship is used in the case of galaxies interacting through a Newtonian potential in an Universe in expansion, i.e. the large-scale distribution of galaxies. By applying this equation and from the observed two-point correlation function for galaxies as a $-1.8$ exponent power law, I derive the approximate dependence of a mass-mass correlation function as a $-2.8$ exponent power law, i.e. I infer that mass is more correlated than galaxies at short distances, when the distribution is considered as relaxed.

Martin Lopez Corredoira

1997-06-02

352

Causal structure of oscillations in gene regulatory networks: Boolean analysis of ordinary differential equation attractors  

NASA Astrophysics Data System (ADS)

A common approach to the modeling of gene regulatory networks is to represent activating or repressing interactions using ordinary differential equations for target gene concentrations that include Hill function dependences on regulator gene concentrations. An alternative formulation represents the same interactions using Boolean logic with time delays associated with each network link. We consider the attractors that emerge from the two types of models in the case of a simple but nontrivial network: a figure-8 network with one positive and one negative feedback loop. We show that the different modeling approaches give rise to the same qualitative set of attractors with the exception of a possible fixed point in the ordinary differential equation model in which concentrations sit at intermediate values. The properties of the attractors are most easily understood from the Boolean perspective, suggesting that time-delay Boolean modeling is a useful tool for understanding the logic of regulatory networks.

Sun, Mengyang; Cheng, Xianrui; Socolar, Joshua E. S.

2013-06-01

353

Analysis of the bulk and surface-induced structure of electrolyte solutions using integral equation theories  

SciTech Connect

We have developed robust and efficient numerical methods for solving integral equation theories for electrolyte solutions. These methods are hybrids of Newton-Raphson and Picard iterations and have been obtained as extended versions of the previous methods for pure solvents by solving nontrivial problems posed by the inclusion of ions. Bulk electrolytes and electrolytes near both inert and metallic surfaces are considered. The basic equations previously derived for a one-component fluid near a planar wall are extended to a multicomponent fluid. Analytical expressions for elements of the Jacobian matrices are arranged in compact form. A striking feature of the method for surface problems is that the Jacobian is determined only from bulk properties. A discussion of some special treatments that need to be considered for asymmetric anions and cations is included. These methods have been demonstrated using the full reference hypernetted-chain theory for various sizes of ions in a wide range of ionic concentrations. 19 refs., 3 tabs.

Kinoshita, M.; Berard, D.R. [Univ. of British Columbia, Vancouver (Canada)] [Univ. of British Columbia, Vancouver (Canada)

1996-03-01

354

Thermodynamic structure of field equations near apparent horizon for radiating black holes  

E-print Network

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 $TdS=dE+PdV$.

Uma Papnoi; Megan Govender; Sushant G Ghosh

2014-11-10

355

Nonequilibrium electrons in double quantum well structures: A Boltzmann equation approach  

NASA Astrophysics Data System (ADS)

A theoretical study of hot electrons in double quantum well is presented. We consider a system of coupled kinetic equations that describe nonequilibrium population in two lowest subbands, and find an analytical solution of these equations. All previous treatments of the electron distribution functions are based on the two extreme limits ?0/?ee<<1 or ?0/?ee>=1, where ?0 and ?ee refer to electron-LO-phonon (e-LO) and electron-electron (e-e) scattering times, respectively. In our approach, the distribution functions are investigated for the whole range of ?0/?ee ratios. The outcome of kinetic equation for subband distribution functions provides a comprehensive description of the lasing process in the intersubband lasers. Our calculations show that the lower subband distribution function above LO-phonon threshold is always strongly nonequilibrium and deviates far from thermal distributions while in the region below the LO-phonon threshold it could be close to a Maxwellian. Using these distribution functions we calculate spectral density of gain at various temperatures.

Khan-Ngern, S.; Larkin, I. A.

2001-09-01

356

The effects of indefinite nonlinear boundary conditions on the structure of the positive solutions set of a logistic equation  

NASA Astrophysics Data System (ADS)

We investigate a semilinear elliptic equation with a logistic nonlinearity and an indefinite nonlinear boundary condition, both depending on a parameter ?. Overall, we analyze the effect of the indefinite nonlinear boundary condition on the structure of the positive solutions set. Based on variational and bifurcation techniques, our main results establish the existence of three nontrivial non-negative solutions for some values of ?, as well as their asymptotic behavior. These results suggest that the positive solutions set contains an S-shaped component in some case, as well as a combination of a C-shaped and an S-shaped components in another case.

Ramos Quoirin, Humberto; Umezu, Kenichiro

2014-12-01

357

Asymptotic expansion of the solution of the steady Stokes equation with variable viscosity in a two-dimensional tube structure  

NASA Astrophysics Data System (ADS)

The Stokes equation with the varying viscosity is considered in a thin tube structure, i.e., in a connected union of thin rectangles with heights of order ? < < 1 and with bases of order 1 with smoothened boundary. An asymptotic expansion of the solution is constructed: it contains some Poiseuille type flows in the channels (rectangles) with some boundary layers correctors in the neighborhoods of the bifurcations of the channels. The estimates for the difference of the exact solution and its asymptotic approximation are proved.

Cardone, G.; Fares, R.; Panasenko, G. P.

2012-10-01

358

Developing a Questionnaire on Attitude towards School  

ERIC Educational Resources Information Center

The purpose of the present study was to develop a questionnaire to assess student attitudes towards school by describing the factors that affect these attitudes. For this purpose, a sample of 362 (11-13 years-old) elementary-school students was used. Both exploratory and confirmatory factor analyses were carried out. The questionnaire consists of…

Seker, Hasan

2011-01-01

359

Questionnaire Design: Asking Questions with a Purpose  

NSDL National Science Digital Library

This short document guides the user through the stages of creating and implementing an effective questionnaire. The types of questions and how they should be worded are addressed, and many good examples of the different types of questions that could go into a questionnaire are presented. This resource is intended for novice evaluators.

Taylor-Powell, Ellen

1998-05-01

360

A Nutritional Questionnaire for Older Adults.  

ERIC Educational Resources Information Center

Describes a questionnaire assessing nutritional knowledge and eating behaviors of older adults. The questionnaire consists of six sections: demographic and personal information, food resources, food consumption patterns, dietary practices related to health, activity patterns, and nutritional knowledge. Study results demonstrating the…

Fanelli, Marie T.; Abernethy, Marilyn M.

1986-01-01

361

PREDICTION OF RELIABILITY IN BIOGRAPHICAL QUESTIONNAIRES.  

ERIC Educational Resources Information Center

THE OBJECTIVES OF THIS STUDY WERE (1) TO DEVELOP A GENERAL CLASSIFICATION SYSTEM FOR LIFE HISTORY ITEMS, (2) TO DETERMINE TEST-RETEST RELIABILITY ESTIMATES, AND (3) TO ESTIMATE RESISTANCE TO EXAMINEE FAKING, FOR REPRESENTATIVE BIOGRAPHICAL QUESTIONNAIRES. TWO 100-ITEM QUESTIONNAIRES WERE CONSTRUCTED THROUGH RANDOM ASSIGNMENT BY CONTENT AREA OF 200…

STARRY, ALLAN R.

362

The Authority of the Student Evaluation Questionnaire.  

ERIC Educational Resources Information Center

Studied the use of the student evaluation questionnaire as a means of teacher evaluation through the views of two university lecturers. Findings suggest that the use of student evaluation questionnaires as a means of summative and comparative appraisal has several negative implications for lecturers' understandings of teaching and their…

Johnson, Rachel

2000-01-01

363

Development of the talent development environment questionnaire for sport.  

PubMed

As sporting challenge at the elite level becomes ever harder, maximizing effectiveness of the talent development pathway is crucial. Reflecting this need, this paper describes the development of the Talent Development Environment Questionnaire, which has been designed to facilitate the development of sporting potential to world-class standard. The questionnaire measures the experiences of developing athletes in relation to empirically identified "key features" of effective talent development environments. The first phase involved the generation of questionnaire items with clear content and face validity. The second phase explored the factor structure and reliability. This was carried out with 590 developing athletes through application of exploratory factor analysis with oblique rotation, principal axis factoring extraction and cronbach alpha tests. This yielded a 59-item, seven-factor structure with good internal consistency (0.616-0.978). The Talent Development Environment Questionnaire appears to be a promising psychometric instrument that can potentially be useful for education and formative review in applied settings, and as a measurement tool in talent development research. PMID:20694933

Martindale, Russell J J; Collins, Dave; Wang, John C K; McNeill, Michael; Lee, Kok Sonk; Sproule, John; Westbury, Tony

2010-09-01

364

Full equations utilities (FEQUTL) model for the approximation of hydraulic characteristics of open channels and control structures during unsteady flow  

USGS Publications Warehouse

The Full EQuations UTiLities (FEQUTL) model is a computer program for computation of tables that list the hydraulic characteristics of open channels and control structures as a function of upstream and downstream depths; these tables facilitate the simulation of unsteady flow in a stream system with the Full Equations (FEQ) model. Simulation of unsteady flow requires many iterations for each time period computed. Thus, computation of hydraulic characteristics during the simulations is impractical, and preparation of function tables and application of table look-up procedures facilitates simulation of unsteady flow. Three general types of function tables are computed: one-dimensional tables that relate hydraulic characteristics to upstream flow depth, two-dimensional tables that relate flow through control structures to upstream and downstream flow depth, and three-dimensional tables that relate flow through gated structures to upstream and downstream flow depth and gate setting. For open-channel reaches, six types of one-dimensional function tables contain different combinations of the top width of flow, area, first moment of area with respect to the water surface, conveyance, flux coefficients, and correction coefficients for channel curvilinearity. For hydraulic control structures, one type of one-dimensional function table contains relations between flow and upstream depth, and two types of two-dimensional function tables contain relations among flow and upstream and downstream flow depths. For hydraulic control structures with gates, a three-dimensional function table lists the system of two-dimensional tables that contain the relations among flow and upstream and downstream flow depths that correspond to different gate openings. Hydraulic control structures for which function tables containing flow relations are prepared in FEQUTL include expansions, contractions, bridges, culverts, embankments, weirs, closed conduits (circular, rectangular, and pipe-arch shapes), dam failures, floodways, and underflow gates (sluice and tainter gates). The theory for computation of the hydraulic characteristics is presented for open channels and for each hydraulic control structure. For the hydraulic control structures, the theory is developed from the results of experimental tests of flow through the structure for different upstream and downstream flow depths. These tests were done to describe flow hydraulics for a single, steady-flow design condition and, thus, do not provide complete information on flow transitions (for example, between free- and submerged-weir flow) that may result in simulation of unsteady flow. Therefore, new procedures are developed to approximate the hydraulics of flow transitions for culverts, embankments, weirs, and underflow gates.

Franz, Delbert D.; Melching, Charles S.

1997-01-01

365

On the Equation H=mv^2 and the Fine Structure of the Hydrogen Atom  

E-print Network

The recently introduced reconciliation of the theories of special relativity and wave mechanics implies that the mass-energy equivalence principle must be expressed mathematically as H = mv^2, where H is the total energy of a particle, m is its relativistic mass, and v is its velocity; not H = mc^2 as was widely believed. In this paper, the equation H = mv^2 will be used to calculate the energy levels in the spectrum of the hydrogen atom. It is demonstrated that the well-known Sommerfeld-Dirac formula is still obtained, but without the constant term m_0 c^2 that was originally present in the formula.

Ezzat G. Bakhoum

2002-12-26

366

Psychometric Properties of the Portuguese Version of the Quality of Life Questionnaire (QOL-Q)  

ERIC Educational Resources Information Center

Background: This study analyzes the psychometric properties of the Portuguese version of the Quality of Life Questionnaire (QOL-Q; Quality of Life Questionnaire Manual--1993 Manual and 2004 Revision. 2004, IDS Publishing Company, Worthington, OH; Schalock & Keith 2004). Method: The analysis of the factorial structure was carried out on a sample of…

Albuquerque, Cristina P.

2012-01-01

367

The Obsessive Beliefs Questionnaire (OBQ): Examination in Nonclinical Samples and Development of a Short Version  

ERIC Educational Resources Information Center

The study aimed to examine the factor structure of the Obsessive Beliefs Questionnaire (OBQ), the most widely used measure of dysfunctional beliefs in obsessive-compulsive disorder (OCD). Multiple exploratory methods (exploratory factor analysis, cluster analysis by variable, multidimensional scaling) were used to examine the questionnaire.…

Moulding, Richard; Anglim, Jeromy; Nedeljkovic, Maja; Doron, Guy; Kyrios, Michael; Ayalon, Ariel

2011-01-01

368

Validation of the Repetitive Behaviour Questionnaire for Use with Children with Autism Spectrum Disorder  

ERIC Educational Resources Information Center

The repetitive behaviour questionnaire (RBQ) (Turner, 1995) is one of the three most commonly used interview/questionnaire measures of repetitive behaviour (Honey et al., in preparation). Despite this there is a scarcity of information concerning its structure, reliability and validity. The psychometric properties of the RBQ were examined when…

Honey, Emma; McConachie, Helen; Turner, Michelle; Rodgers, Jacqui

2012-01-01

369

Algebraic structure of $tt^*$ equations for Calabi-Yau sigma models  

E-print Network

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...

Alim, Murad

2014-01-01

370

Thermodynamics and pair structures of liquid alkali and alkaline-earth metals from the perturbative hypernetted-chain equation  

NASA Astrophysics Data System (ADS)

We have theoretically studied liquid alkali and alkaline-earth metals by combining the second-order pseudopotential (PP) theory of ion-electron interaction and a statistical mechanical method for calculating ionic thermal motion. The latter is done by utilizing the perturbative hypernetted-chain equation recently proposed by the author. The PP is modelled through an ab initio method presented by Shaw, i.e., through the use of the optimized nonlocal model potential (OMP). Calculations are carried out with two different methods for extracting parameters in the OMP. They are due to Animalu and Heine (AH), and Ballentine and Gupta (BG). Results show that both of thermodynamic properties and pair structures are in good agreements with experimental data for alkali metals with the AH set of parameters. For alkaline-earth metals other than Ba, calculations with the BG set give the radial distributions and structure factors in good agreement with experimental data.

Seok Kang, Hong

1999-09-01

371

Analysis of causal relationships by structural equation modeling to determine the factors influencing cognitive function in elderly people in Japan.  

PubMed

The purpose of this study is to identify a potentiality factor that is a preventive factor for decline in cognitive function. Additionally, this study pursues to clarify the causal relationship between the each potential factor and its influence on cognitive function. Subjects were 366 elderly community residents (mean age 73.7 ± 6.4, male 51, female 315) who participated in the Taketoyo Project from 2007 to 2011. Factor analysis was conducted to identify groupings within mental, social, life, physical and cognitive functions. In order to detect clusters of 14 variables, the item scores were subjected to confirmatory factor analysis. We performed Structural Equation Modeling analysis to calculate the standardization coefficient and correlation coefficient for every factor. The cause and effect hypothesis model was used to gather two intervention theory hypotheses for dementia prevention (direct effect, indirect effect) in one system. Finally, we performed another Structural Equation Modeling analysis to calculate the standardization of the cause and effect hypothesis model. Social participation was found to be activated by the improvement of four factors, and in turn, activated "Social participation" acted on cognitive function. PMID:25658829

Kimura, Daisuke; Nakatani, Ken; Takeda, Tokunori; Fujita, Takashi; Sunahara, Nobuyuki; Inoue, Katsumi; Notoya, Masako

2015-01-01

372

Analysis of Causal Relationships by Structural Equation Modeling to Determine the Factors Influencing Cognitive Function in Elderly People in Japan  

PubMed Central

The purpose of this study is to identify a potentiality factor that is a preventive factor for decline in cognitive function. Additionally, this study pursues to clarify the causal relationship between the each potential factor and its influence on cognitive function. Subjects were 366 elderly community residents (mean age 73.7 ± 6.4, male 51, female 315) who participated in the Taketoyo Project from 2007 to 2011. Factor analysis was conducted to identify groupings within mental, social, life, physical and cognitive functions. In order to detect clusters of 14 variables, the item scores were subjected to confirmatory factor analysis. We performed Structural Equation Modeling analysis to calculate the standardization coefficient and correlation coefficient for every factor. The cause and effect hypothesis model was used to gather two intervention theory hypotheses for dementia prevention (direct effect, indirect effect) in one system. Finally, we performed another Structural Equation Modeling analysis to calculate the standardization of the cause and effect hypothesis model. Social participation was found to be activated by the improvement of four factors, and in turn, activated “Social participation” acted on cognitive function. PMID:25658829

Kimura, Daisuke; Nakatani, Ken; Takeda, Tokunori; Fujita, Takashi; Sunahara, Nobuyuki; Inoue, Katsumi; Notoya, Masako

2015-01-01

373

Psychometric properties of the Questionnaire for Secondary Traumatization  

PubMed Central

Background During the past several years, there has been a growing interest in the negative effects that providing therapy may have on therapists. Of special interest is a phenomenon called secondary traumatization, which can arise while working with traumatized clients. To develop a simple screening tool for secondary traumatization, a quantitative assessment instrument was constructed using a data-driven approach based on qualitative interviews with affected trauma therapists as well as experienced supervisors in trauma therapy. Objective The aim of the current study was to analyze the psychometric properties of the newly developed Questionnaire for Secondary Traumatization (FST) acute and lifetime version and to determine the most appropriate scoring procedure. Method To this end, three independent samples of psychotherapists (n=371), trauma therapists in training (n=80), and refugee counselors (n=197) filled out an online questionnaire battery. Data structure was analyzed using factor analyses, cluster analyses, and reliability analyses. Results Factor analyses yielded a six-factor structure for both the acute and the lifetime version with only a small number of items loading on differing factors. Cluster analyses suggested a single scale structure of the questionnaire. The FST total score showed good internal consistencies across all three samples, while internal consistency of the six extracted factors was mixed. Conclusion With the FST, a reliable screening instrument for acute and lifetime secondary traumatization is now available which is free of charge and yields a sum score for quick evaluation. The six-factor structure needs to be verified with confirmatory factor analyses. PMID:24427450

Weitkamp, Katharina; Daniels, Judith K.; Klasen, Fionna

2014-01-01

374

Screening Questionnaires for Parkinsonism: A Systematic Review  

PubMed Central

Parkinson’s disease (PD) is a common, treatable movement disorder that often remains undiagnosed despite clinically manifest symptoms. Screening for parkinsonism could lead to improved detection and earlier treatment, and facilitate research studies of PD prevalence. In order to determine the feasibility of screening, this study evaluated the validity of previously developed screening questionnaires. We systematically searched online databases PubMed and EMBASE for English-language studies published between 1980 and 2009. In each database a “Parkinson(s) disease” or “parkinsonism” term was combined with a screening term (“screening instrument,” screening questionnaire,” “screen” or “prevalence survey”) and a validity term (“validation,” “sensitivity” and “specificity”). Included studies reported the psychometric properties of at least one self-report questionnaire for parkinsonism. Twenty-seven studies met the inclusion criteria. From these studies, 9 screening questionnaires were identified. Sensitivity and specificity estimates varied widely. Sensitivity estimates were as high as 100% when questionnaires were tested among previously diagnosed PD patients and included a high number of parkinsonism-specific items, but were as low as 48% when tested among early cases in a community-based sample. Specificity estimates were lower, ranging from 22–100%. An older sample, presence of multiple co-morbid conditions and lower literacy led to lower specificity estimates. Higher specificity estimates were seen when the screening questionnaires were administered by a physician. Screening questionnaires can detect symptomatic parkinsonism. However, the performance of these questionnaires varied based on the individual items, study sample, and method of administration. The performance of screening questionnaires in the detection of early or mild parkinsonism was modest. PMID:21930414

Dahodwala, Nabila; Siderowf, Andrew; Baumgarten, Mona; Abrams, Aaron; Karlawish, Jason

2011-01-01

375

REGRES: A FORTRAN-77 program to calculate nonparametric and ``structural'' parametric solutions to bivariate regression equations  

NASA Astrophysics Data System (ADS)

REGRES allows a range of regression equations to be calculated for paired sets of data values in which both variables are subject to error (i.e. neither is the "independent" variable). Nonparametric regressions, based on medians of all possible pairwise slopes and intercepts, are treated in detail. Estimated slopes and intercepts are output, along with confidence limits, Spearman and Kendall rank correlation coefficients. Outliers can be rejected with user-determined stringency. Parametric regressions can be calculated for any value of ? (the ratio of the variances of the random errors for y and x)—including: (1) major axis ( ? = 1); (2) reduced major axis ( ? = variance of y/variance of x); (3) Y on X? = infinity; or (4) X on Y ( ? = 0) solutions. Pearson linear correlation coefficients also are output. REGRES provides an alternative to conventional isochron assessment techniques where bivariate normal errors cannot be assumed, or weighting methods are inappropriate.

Rock, N. M. S.; Duffy, T. R.

376

Schizotypal personality questionnaire: new sources of validity evidence in college students.  

PubMed

Schizotypal traits represent the behavioral expression of vulnerability to psychosis in general population. Among the most widely used measurement instruments, we could find the Schizotypal Personality Questionnaire (SPQ) (Raine, 1991). However, some aspects of its psychometric quality have yet to be analyzed. The main goal of the present study was to gather new sources of validity evidence of the SPQ scores in non-clinical young adults. The final sample was made up of 1123 college students (M=20.3 years; S.D.=2.6). The study of the internal structure using exploratory factor analysis revealed that SPQ items were grouped in a theoretical structure of seven second-order factors. Confirmatory factor analyses showed that the four-factor model (Paranoid) displayed better goodness-of-fit indices than the other hypothetical dimensional models tested. More complex measurement models, such as those tested using second-order confirmatory factor analyses and Exploratory Structural Equation Modeling, also showed adequate goodness-of-fit indices. The reliability of the SPQ scores ranged from 0.80 to 0.91. A total of 11 items showed differential functioning by gender. Advances in psychosis phenotype measurement open up new horizons to understand the structure and content of schizotypy. PMID:24889846

Fonseca-Pedrero, Eduardo; Fumero, Ascensión; Paino, Mercedes; de Miguel, Adelia; Ortuño-Sierra, Javier; Lemos-Giráldez, Serafín; Muñiz, José

2014-09-30

377

Quasiclassical limit of coupled KdV equations. Riemann invariants and multi-Hamiltonian structure  

Microsoft Academic Search

We consider the quasiclassical limit of the first nontrivial flow in coupled KdV hierarchy. Written down in Riemann invariants, it assumes the extremely simple form ?R+i= (?Sigmak=1nRk+ 2Ri)?Rxi, i=1...,n. Up to certain natural equivalence this turns out to be the only hydrodynamic system with n + 1 compatible purely local Hamiltonian structures.

E. V. Ferapontov; M. V. Pavlov

1991-01-01

378

What Influences Geography Teachers' Usage of Geographic Information Systems? A Structural Equation Analysis  

ERIC Educational Resources Information Center

Understanding the usage of the geographic information system (GIS) among geography teachers is a crucial step in evaluating the current dissemination of GIS knowledge and skills in Taiwan's educational system. The primary contribution of this research is to further our understanding of the factors that affect teachers' GIS usage. The structural

Lay, Jinn-Guey; Chi, Yu-Lin; Hsieh, Yeu-Sheng; Chen, Yu-Wen

2013-01-01

379

Structural Equation Model of the Consumer-Directed Theory of Empowerment in a Vocational Rehabilitation Context  

ERIC Educational Resources Information Center

One model that is potentially useful in the rehabilitation field is the Consumer-Directed Theory of Empowerment (CDTE; Kosciulek, 1999a). However, additional empirical data are needed to further develop and critically evaluate the CDTE. To accomplish this task, the purpose of this study was to test the hypothesized structural model CDTE in a…

Kosciulek, John F.

2005-01-01

380

EXIT INTERVIEW QUESTIONNAIRE FACULTY AND STAFF  

E-print Network

&T to a friend or colleague? Yes No Please explain. _____ 14. What most helped you achieve your goals at Missouri1 EXIT INTERVIEW QUESTIONNAIRE ­ FACULTY AND STAFF Missouri University of Science and Technology

Missouri-Rolla, University of

381

Physical Activity Questionnaires (PAQ) Validation Studies - References  

Cancer.gov

Wareham NJ, Jakes RW, Rennie KL et al. Validity and repeatability of a simple index derived from the short physical activity questionnaire used in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

382

Standardized Questionnaires of Walking & Bicycling Database  

Cancer.gov

This database contains questionnaire items and a list of validation studies for standardized items concerning walking and biking from multiple national and international physical activity questionnaires (PAQs). The purpose of this database is to provide easy access to a large number of items assessing duration and frequency of walking and bicycling in the non-disabled adult population. We also briefly review the results of validation studies identified for some of the PAQs.

383

Querying databases of trajectories of differential equations: Data structures for trajectories  

NASA Technical Reports Server (NTRS)

One approach to qualitative reasoning about dynamical systems is to extract qualitative information by searching or making queries on databases containing very large numbers of trajectories. The efficiency of such queries depends crucially upon finding an appropriate data structure for trajectories of dynamical systems. Suppose that a large number of parameterized trajectories gamma of a dynamical system evolving in R sup N are stored in a database. Let Eta is contained in set R sup N denote a parameterized path in Euclidean Space, and let the Euclidean Norm denote a norm on the space of paths. A data structure is defined to represent trajectories of dynamical systems, and an algorithm is sketched which answers queries.

Grossman, Robert

1989-01-01

384

Structure, equation of state and transport properties of molten calcium carbonate (CaCO3) by atomistic simulations  

NASA Astrophysics Data System (ADS)

First-principle molecular dynamics (FPMD) calculations have been performed to evaluate the physical properties of liquid calcium carbonate (CaCO3), which are up to now poorly known. The liquid structure, the density, the atomic vibration motions, the diffusion coefficients of calcium and carbonate ions and the electrical conductivity have been evaluated. As compared with silicate melts, molten CaCO3 is characterized by a low density (?2.25 g/cm3 at 1623 K and 0.5 GPa), a viscosity almost as low as that of water (?5 mPa s), and a high conductivity (?200 S/m). In using the FPMD calculations for benchmark, an empirical force field has been developed for predicting the properties of molten CaCO3 at any state point in the liquid stability field. This force field is implemented into a classical molecular dynamics (MD) code, much cheaper in computer time, and the equation of state and the phase diagram of the liquid phase have been obtained. The evolutions of the self diffusion coefficients, viscosity, and the electrical conductivity with pressure and temperature have been investigated and the results fitted with analytical forms. It is shown that the Stokes-Einstein equation, expressing the viscosity as a function of diffusion motion, is well followed, and that the Nernst-Einstein equation relating the electrical conductivity to the diffusion coefficients of charge carriers leads to an accurate prediction of the conductivity, provided that a constant correcting factor is applied. Consequently, viscosity and electrical conductivity of the liquid are found to be anticorrelated with each other and can be described by a simple law; ? = A/?0.9 (where A = 1.905, ? is in S/m, and ? in Pa s).

Vuilleumier, Rodolphe; Seitsonen, Ari; Sator, Nicolas; Guillot, Bertrand

2014-09-01

385

Multi-Center Electronic Structure Calculations for Plasma Equation of State  

SciTech Connect

We report on an approach for computing electronic structure utilizing solid-state multi-center scattering techniques, but generalized to finite temperatures to model plasmas. This approach has the advantage of handling mixtures at a fundamental level without the imposition of ad hoc continuum lowering models, and incorporates bonding and charge exchange, as well as multi-center effects in the calculation of the continuum density of states.

Wilson, B G; Johnson, D D; Alam, A

2010-12-14

386

Integrable Structure of Conformal Field Theory II.Q-operator and DDV equation  

Microsoft Academic Search

:  This paper is a direct continuation of [1] where we began the study of the integrable structures in Conformal Field Theory.\\u000a We show here how to construct the operators ${\\\\bf Q}_{\\\\pm}(\\\\lambda)$ which act in the highest weight Virasoro module and commute\\u000a for different values of the parameter ?. These operators appear to be the CFT analogs of the Q -

Vladimir V. Bazhanov; Sergei L. Lukyanov; Alexander B. Zamolodchikov

1997-01-01

387

Hamiltonian structure of an operator valued extension of Super KdV equations  

E-print Network

An extension of the super Korteweg-de Vries integrable system in terms of operator valued functions is obtained. In particular the extension contains the $N=1$ Super KdV and coupled systems with functions valued on a symplectic space. We introduce a Miura transformation for the extended system and obtain its hamiltonian structure. We also obtain an extended Gardner transformation which allows to find an infinite number of conserved quantities of the extended system.

Restuccia, A

2014-01-01

388

Structures, mechanical properties, equations of state, and electronic properties of ?-HMX under hydrostatic pressures: a DFT-D2 study.  

PubMed

We report the hydrostatic compression studies of the ?-polymorph of a cyclotetramethylene tetranitramine (HMX) energetic molecular crystal using DFT-D2, a first-principles calculation based on density functional theory (DFT) with van der Waals (vdW) corrections. The molecular structure, mechanical properties, electronic properties, and equations of state of ?-HMX are investigated. For the first time, we predict the elastic constants of ?-HMX using DFT-D2 studies. The equations of state under hydrostatic compression are studied for pressures up to 100 GPa. We found that the N-N bonds along the minor axis are responsible for the sensitivity of ?-HMX. The analysis of the charge distribution shows that the electronic charge is transferred from hydrogen atoms to nitro groups with the amount of 0.131 and 0.064e for the nitro groups along the minor axis and major axis, respectively, when pressure changes from 0 GPa to 100 GPa. The electronic energy band gap changes from direct at a pressure of 0 GPa to indirect at a pressure of 50 GPa and higher. The band gap decreases with respect to an increase in pressure, implying that the impact sensitivity increases with compression. Our study suggests that the van der Waals interactions are critically important in modeling the mechanical properties of this molecular crystal. PMID:25159551

Peng, Qing; Rahul; Wang, Guangyu; Liu, Gui-Rong; De, Suvranu

2014-10-01

389

Inverse Material Identification in Coupled Acoustic-Structure Interaction using a Modified Error in Constitutive Equation Functional  

PubMed Central

This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level. PMID:25339790

Warner, James E.; Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc

2014-01-01

390

Inverse Material Identification in Coupled Acoustic-Structure Interaction using a Modified Error in Constitutive Equation Functional.  

PubMed

This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level. PMID:25339790

Warner, James E; Diaz, Manuel I; Aquino, Wilkins; Bonnet, Marc

2014-09-01

391

Inverse material identification in coupled acoustic-structure interaction using a modified error in constitutive equation functional  

NASA Astrophysics Data System (ADS)

This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level.

Warner, James E.; Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc

2014-09-01

392

Dynamical equations for high-order structure functions, and a comparison of a mean-field theory with experiments in three-dimensional turbulence  

NASA Astrophysics Data System (ADS)

Two recent papers [V. Yakhot, Phys. Rev. E 63, 026307, (2001) and R. J. Hill, J. Fluid Mech. 434, 379, (2001)] derive, through two different approaches that have the Navier-Stokes equations as the common starting point, a set of dynamic equations for structure functions of arbitrary order in turbulence. These equations are not closed. Yakhot proposed a ``mean-field theory'' to close the equations for locally isotropic turbulence, and obtained scaling exponents of structure functions and expressions for the peak in the probability density function of transverse velocity increments, and for its behavior for intermediate amplitudes. At high Reynolds numbers, some relevant experimental data on pressure gradient and dissipation terms are presented that are needed to provide closure, as well as on other aspects predicted by the theory. Comparison between the theory and the data shows varying levels of agreement, and reveals gaps inherent to the implementation of the theory.

Kurien, Susan; Sreenivasan, Katepalli R.

2001-11-01

393

Dynamical equations for high-order structure functions, and a comparison of a mean-field theory with experiments in three-dimensional turbulence.  

PubMed

Two recent papers [V. Yakhot, Phys. Rev. E 63, 026307, (2001) and R. J. Hill, J. Fluid Mech. 434, 379, (2001)] derive, through two different approaches that have the Navier-Stokes equations as the common starting point, a set of dynamic equations for structure functions of arbitrary order in turbulence. These equations are not closed. Yakhot proposed a "mean-field theory" to close the equations for locally isotropic turbulence, and obtained scaling exponents of structure functions and expressions for the peak in the probability density function of transverse velocity increments, and for its behavior for intermediate amplitudes. At high Reynolds numbers, some relevant experimental data on pressure gradient and dissipation terms are presented that are needed to provide closure, as well as on other aspects predicted by the theory. Comparison between the theory and the data shows varying levels of agreement, and reveals gaps inherent to the implementation of the theory. PMID:11736089

Kurien, S; Sreenivasan, K R

2001-11-01

394

Body image during pregnancy: an evaluation of the suitability of the body attitudes questionnaire  

PubMed Central

Background Available data suggest that body dissatisfaction is common during pregnancy and may even be a precursor to post-natal depression. However, in order to accurately identify at-risk women, it is essential to first establish that body image measures function appropriately in pregnant populations. Our study examines the suitability of the Body Attitudes Questionnaire (BAQ) for measuring body dissatisfaction among pregnant women by comparing the psychometric functioning of the BAQ: (1) across key phases of pregnancy, and (2) between pregnant and non-pregnant women. Methods A total of 176 pregnant women from Melbourne, Victoria filled out a questionnaire battery containing demographic questions and the Body Attitudes Questionnaire at 16, 24, and 32 weeks during pregnancy. A comparison group of 148 non-pregnant women also completed the questionnaire battery at Time 1. Evaluations of the psychometric properties of the BAQ consisted of a series of measurement invariance tests conducted within a structural equation modelling framework. Results Although the internal consistency and factorial validity of the subscales of the BAQ were established across time and also in comparisons between pregnant and non-pregnant women, measurement invariance tests showed non-invariant item intercepts across pregnancy and also in comparison with the non-pregnant subgroup. Inspection of modification indices revealed a complex, non-uniform pattern of differences in item intercepts across groups. Conclusions Collectively, our findings suggest that comparisons of body dissatisfaction between pregnant and non-pregnant women (at least based on the BAQ) are likely to be conflated by differential measurement biases that serve to undermine attempts to accurately assess level of body dissatisfaction. Researchers should be cautious in assessments of body dissatisfaction among pregnant women until a suitable measure has been established for use in this population. Given the fact that body dissatisfaction is often associated with maladaptive behaviours, such as unhealthy eating and extreme weight loss behaviours, and with ante-and post-natal depression, that have serious negative implications for women’s health and well-being, and potentially also for the unborn foetus during pregnancy, developing a suitable body image screening tool, specific to the perinatal period is clearly warranted. PMID:22950761

2012-01-01

395

Periodic structures in the Franck-Hertz experiment with neon: Boltzmann equation and Monte-Carlo analysis  

NASA Astrophysics Data System (ADS)

The Franck-Hertz experiment with neon gas is modelled as an idealised steady-state Townsend experiment and analysed theoretically using (a) multi-term solution of Boltzmann equation and (b) Monte-Carlo simulation. Theoretical electron periodic electron structures, together with the `window' of reduced fields in which they occur, are compared with experiment, and it is explained why it is necessary to account for all competing scattering processes in order to explain the observed experimental `wavelength'. The study highlights the fundamental flaws in trying to explain the observations in terms of a single, assumed dominant electronic excitation process, as is the case in text books and the myriad of misleading web sites.

White, R. D.; Robson, R. E.; Nicoletopoulos, P.; Dujko, S.

2012-05-01

396

Three-Dimensional Structures of the Spatiotemporal Nonlinear Schrödinger Equation with Power-Law Nonlinearity in PT-Symmetric Potentials  

PubMed Central

The spatiotemporal nonlinear Schrödinger equation with power-law nonlinearity in -symmetric potentials is investigated, and two families of analytical three-dimensional spatiotemporal structure solutions are obtained. The stability of these solutions is tested by the linear stability analysis and the direct numerical simulation. Results indicate that solutions are stable below some thresholds for the imaginary part of -symmetric potentials in the self-focusing medium, while they are always unstable for all parameters in the self-defocusing medium. Moreover, some dynamical properties of these solutions are discussed, such as the phase switch, power and transverse power-flow density. The span of phase switch gradually enlarges with the decrease of the competing parameter k in -symmetric potentials. The power and power-flow density are all positive, which implies that the power flow and exchange from the gain toward the loss domains in the cell. PMID:24983624

Dai, Chao-Qing; Wang, Yan

2014-01-01

397

Electronic structure and equation of state of Sm2Co17 from first-principles DFT+U  

NASA Astrophysics Data System (ADS)

Rare-earth intermetallics have important applications as permanent magnet materials, and the rational optimization of their properties would benefit greatly from guidance from ab initio modeling. However, these systems are particularly challenging for current electronic structure methods. Here, we present an ab initio study of the prototype material Sm2Co17 and related compounds, using density functional theory with a Hubbard correction for the Sm 4f-electrons (DFT+U method) and ultrasoft pseudopotentials. The Hubbard U parameter is derived from first principles [Cococcioni and de Gironcoli, PRB 71, 035105 (2005)], not fit to experiment. Our calculations are in good agreement with recent photoemission measurements at ambient pressure and the equation of state up to 40 GPa, thus supporting the validity of our DFT+U model.

Huang, Patrick; Butch, Nicholas P.; Jeffries, Jason R.; McCall, Scott K.

2013-03-01

398

The consequences of ignoring measurement invariance for path coefficients in structural equation models  

PubMed Central

We report a Monte Carlo study examining the effects of two strategies for handling measurement non-invariance – modeling and ignoring non-invariant items – on structural regression coefficients between latent variables measured with item response theory models for categorical indicators. These strategies were examined across four levels and three types of non-invariance – non-invariant loadings, non-invariant thresholds, and combined non-invariance on loadings and thresholds – in simple, partial, mediated and moderated regression models where the non-invariant latent variable occupied predictor, mediator, and criterion positions in the structural regression models. When non-invariance is ignored in the latent predictor, the focal group regression parameters are biased in the opposite direction to the difference in loadings and thresholds relative to the referent group (i.e., lower loadings and thresholds for the focal group lead to overestimated regression parameters). With criterion non-invariance, the focal group regression parameters are biased in the same direction as the difference in loadings and thresholds relative to the referent group. While unacceptable levels of parameter bias were confined to the focal group, bias occurred at considerably lower levels of ignored non-invariance than was previously recognized in referent and focal groups. PMID:25278911

Guenole, Nigel; Brown, Anna

2014-01-01

399

Assessing perceptions about hazardous substances (PATHS): the PATHS questionnaire.  

PubMed

How people perceive the nature of a hazardous substance may determine how they respond when potentially exposed to it. We tested a new Perceptions AbouT Hazardous Substances (PATHS) questionnaire. In Study 1 (N = 21), we assessed the face validity of items concerning perceptions about eight properties of a hazardous substance. In Study 2 (N = 2030), we tested the factor structure, reliability and validity of the PATHS questionnaire across four qualitatively different substances. In Study 3 (N = 760), we tested the impact of information provision on Perceptions AbouT Hazardous Substances scores. Our results showed that our eight measures demonstrated good reliability and validity when used for non-contagious hazards. PMID:23104995

Rubin, G James; Amlôt, Richard; Page, Lisa; Pearce, Julia; Wessely, Simon

2013-08-01

400

Harvard University Respiratory Protection Program Medical Evaluation Questionnaire  

E-print Network

Harvard University Respiratory Protection Program Medical Evaluation Questionnaire Medical No Instructions: All employees must be medically evaluated prior to use of respiratory protection. Employees may University Respiratory Protection Program Medical Evaluation Questionnaire Medical Evaluation Questionnaire

Heller, Eric

401

7 CFR 550.31 - Questionnaires and survey plans.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Questionnaires and survey plans. 550.31 Section...Management § 550.31 Questionnaires and survey plans. The Cooperator...the REE Agency copies of questionnaires and other forms for...

2010-01-01

402

Non-Exercise Estimation of VO[subscript 2]max Using the International Physical Activity Questionnaire  

ERIC Educational Resources Information Center

Non-exercise equations developed from self-reported physical activity can estimate maximal oxygen uptake (VO[subscript 2]max) as well as sub-maximal exercise testing. The International Physical Activity Questionnaire is the most widely used and validated self-report measure of physical activity. This study aimed to develop and test a VO[subscript…

Schembre, Susan M.; Riebe, Deborah A.

2011-01-01

403

Development of the young spine questionnaire  

PubMed Central

Background Back pain in children is common and early onset of back pain has been shown to increase the risk of back pain significantly in adulthood. Consequently, preventive efforts must be targeted the young population but research relating to spinal problems in this age group is scarce. Focus has primarily been on the working age population, and therefore specific questionnaires to measure spinal pain and its consequences, specifically aimed at children and adolescents are absent. The purpose of this study was to develop a questionnaire for schoolchildren filling this gap. Methods The Young Spine Questionnaire (YSQ) was developed in three phases – a conceptualisation, development and testing phase. The conceptualisation phase followed the Wilson and Cleary model and included questions regarding spinal prevalence estimates, pain frequency and intensity, activity restrictions, care seeking behaviour and influence of parental back trouble. Items from existing questionnaires and the “Revised Faces Pain Scale” (rFPS) were included during the development phase. The testing phase consisted of a mixed quantitative and qualitative iterative method carried out in two pilot tests using 4th grade children and focusing on assessment of spinal area location and item validity. Results The testing phase resulted in omission of the pain drawings and the questions and answer categories were simplified in several questions. Agreement between the questionnaire prevalence estimates and the interviews ranged between 83.7% (cervical pain today) and 97.9% (thoracic pain today). To improve the understanding of the spinal boundaries we added bony landmarks to the spinal drawings after pilot test I. This resulted in an improved sense of spinal boundary location in pilot test II. Correlations between the rFPS and the interview pain score ranged between 0.67 (cervical spine) and 0.79 (lumbar spine). Conclusions The Young Spine Questionnaire contains questions that assess spinal pain and its consequences. The items have been tested for content understanding and agreement between questionnaire scores and interview findings among target respondents. These preliminary results suggest that the YSQ is feasible, has content validity and is a well understood questionnaire to be used in studies of children aged 9 to 11 years. PMID:23758965

2013-01-01

404

An investigation of the liquid to glass transition using integral equations for the pair structure of coupled replicae  

NASA Astrophysics Data System (ADS)

Extensive numerical solutions of the hypernetted-chain (HNC) and Rogers-Young (RY) integral equations are presented for the pair structure of a system of two coupled replicae (1 and 2) of a "soft-sphere" fluid of atoms interacting via an inverse-12 pair potential. In the limit of vanishing inter-replica coupling ?12, both integral equations predict the existence of three branches of solutions: (1) A high temperature liquid branch (L), which extends to a supercooled regime upon cooling when the two replicae are kept at ?12 = 0 throughout; upon separating the configurational and vibrational contributions to the free energy and entropy of the L branch, the Kauzmann temperature is located where the configurational entropy vanishes. (2) Starting with an initial finite coupling ?12, two "glass" branches G1 and G2 are found below some critical temperature, which are characterized by a strong remnant spatial inter-replica correlation upon taking the limit ?12 ? 0. Branch G2 is characterized by an increasing overlap order parameter upon cooling, and may hence be identified with the hypothetical "ideal glass" phase. Branch G1 exhibits the opposite trend of increasing order parameter upon heating; its free energy lies consistently below that of the L branch and above that of the G2 branch. The free energies of the L and G2 branches are found to intersect at an alleged "random first-order transition" (RFOT) characterized by weak discontinuities of the volume and entropy. The Kauzmann and RFOT temperatures predicted by RY differ significantly from their HNC counterparts.

Bomont, Jean-Marc; Hansen, Jean-Pierre; Pastore, Giorgio

2014-11-01

405

FRINQ End-of-year Questionnaire FRINQ End-of-year Questionnaire  

E-print Network

situations Inspired students to set and achieve goals which really challenged them. Asked students to share to real life situations. (M) Inspired students to set and achieve goals which really challenged them. (MFRINQ End-of-year Questionnaire FRINQ End-of-year Questionnaire Dear Student, In order to help us

406

Assessment of fear of fear in agoraphobics: The Body Sensations Questionnaire and the Agoraphobic Cognitions Questionnaire  

Microsoft Academic Search

Describes the development of the Agoraphobic Cognitions Questionnaire and the Body Sensations Questionnaire, companion measures for assessing aspects of fear of fear (panic attacks) in agoraphobics. The instruments were administered to 175 agoraphobics (mean age 37.64 yrs) and 43 controls (mean age 36.13 yrs) who were similar in sex and marital status to experimental Ss. Results show that the instruments

Dianne L. Chambless; G. Craig Caputo; Priscilla Bright; Richard Gallagher

1984-01-01

407

Reliability of the Conflict Resolution Questionnaire: Considerations for Using and Developing Internet-Based Questionnaires  

ERIC Educational Resources Information Center

In the current information age, there is a growing use of and reliance on the Internet. One area of concern for educators is the communication of information using an electronic questionnaire interface. Therefore, it seems pertinent to look at the issue of dissemination of Internet questionnaire information and the integrity of this process.…

Henning, Marcus

2004-01-01

408

[Internal statistical validation of a quality of life questionnaire].  

PubMed

In this paper we present two different statistical approaches to evaluate the psychometric properties of a quality of life questionnaire. First the study of the factorial structure is briefly exposed. Then we present the unidimensional classical models. They are based on the linear relationship between the observed score and the true score. The definition of the reliability was first addressed in this classical framework. Its estimation with the Cronbach alpha coefficient is one important feature of the evaluation of an instrument. More recently, modern response theory gives a better statistical framework to deal with unidimensional latent traits. These models describe the probability of positive answer to an item as a function of the actual value of the latent trait and an item parameter. We expose the principles of the Rasch model: hypothesis, estimations methods and fit tests. Finally practical applications to the validation process of a questionnaire are explored with data from a study of a short French version of the SIP questionnaire. PMID:10673591

Hamon, A; Mesbah, M

1999-12-01

409

Assessing vividness of mental imagery: The Plymouth Sensory Imagery Questionnaire.  

PubMed

Mental imagery may occur in any sensory modality, although visual imagery has been most studied. A sensitive measure of the vividness of imagery across a range of modalities is needed: the shorter version of Bett's Questionnaire upon Mental Imagery (Sheehan, , J. Clin. Psychology, 23, 386) uses outdated items and has an unreliable factor structure. We report the development and initial validation of the Plymouth Sensory Imagery Questionnaire (Psi-Q) comprising items for each of the following modalities: Vision, Sound, Smell, Taste, Touch, Bodily Sensation, and Emotional Feeling. An exploratory factor analysis on a 35-item form indicated that these modalities formed separate factors, rather than a single imagery factor, and this was replicated by confirmatory factor analysis. The Psi-Q was validated against the Spontaneous Use of Imagery Scale (Reisberg et al., , Appl. Cogn. Psychology, 17, 147) and Marks' (, J. Mental Imagery, 19, 153) Vividness of Visual Imagery Questionnaire-2 (VVIQ-2). A short 21-item form comprising the best three items from the seven factors correlated with the total score and subscales of the full form, and with the VVIQ-2. Inspection of the data shows that while visual and sound imagery is most often rated as vivid, individuals who rate one modality as strong and the other as weak are not uncommon. Findings are interpreted within a working memory framework and point to the need for further research to identify the specific cognitive processes underlying the vividness of imagery across sensory modalities. PMID:24117327

Andrade, Jackie; May, Jon; Deeprose, Catherine; Baugh, Sarah-Jane; Ganis, Giorgio

2014-11-01

410

TICS modelling : Conception of questionnaire Sylvie Damy  

E-print Network

TICS modelling : Conception of questionnaire Sylvie Damy Associate professor in Computer Science Techniques ­ 16 Route de Gray- F-25030 Besançon cedex Introduction Within the framework of the action "TICS. The modelling of the "Territorial Intelligence Community Systems", or TICS is useful to transcribe

Paris-Sud XI, Université de

411

University of Michigan Drug Education Questionnaire.  

ERIC Educational Resources Information Center

This questionnaire assesses attitudes toward potential drug education programs and drug use practices in college students. The 87 items (multiple choice or free response) pertain to the history and extent of usage of 27 different drugs, including two non-existent drugs which may be utilized as a validity check; attitude toward the content, format,…

Francis, John Bruce; Patch, David J.

412

Diagnosis of Twin Zygosity by Mailed Questionnaire  

Microsoft Academic Search

A deterministic questionnaire method for zygosity determination is developed for use in epidemiological studies of adult twins. It is based on the answers of both members of a twin pair to two questions on similarity and confusion in childhood. The algorithm of the method is used to determine the zygosity status of a twin pair at two different levels of

Seppo Sarna; Jaakko Kaprio; Pertti Sistonen; Markku Koskenvuo

1978-01-01

413

Assessing Caregiver Information Needs: A Brief Questionnaire.  

ERIC Educational Resources Information Center

A diagnostic evaluation for a person with suspected Alzheimer's disease is usually initiated by family members whose concerns go beyond strictly medical issues. To determine precisely what questions families want answered, a 15-point questionnaire was developed at a multi-disciplinary geriatric assessment clinic. Caregivers were asked to rate each…

Simonton, Linda J.; Haugland, S. M.

414

Print Name_______________________________________________________________________________ (Physical Activity Readiness Questionnaire)  

E-print Network

-Q (Physical Activity Readiness Questionnaire) YES NO 1. Has your doctor ever said that you have a heart condition and that you should only do physical activity recommended by a doctor? 2. Do you feel pain in your chest when you do physical activity? 3. In the past month, have you had chest pain when you were

415

Canadian Version of the Diet History Questionnaire  

Cancer.gov

The Diet History Questionnaire (DHQ) and the DHQ nutrient database were modified for use in Canada through the collaborative efforts of Dr. Amy Subar and staff at the Risk Factor Monitoring and Methods Branch, and Dr. Ilona Csizmadi and colleagues in the Division of Population Health and Information at the Alberta Cancer Board in Canada.

416

The pornography craving questionnaire: psychometric properties.  

PubMed

Despite the prevalence of pornography use, and recent conceptualization of problematic use as an addiction, we could find no published scale to measure craving for pornography. Therefore, we conducted three studies employing young male pornography users to develop and evaluate such a questionnaire. In Study 1, we had participants rate their agreement with 20 potential craving items after reading a control script or a script designed to induce craving to watch pornography. We dropped eight items because of low endorsement. In Study 2, we revised both the questionnaire and cue exposure stimuli and then evaluated several psychometric properties of the modified questionnaire. Item loadings from a principal components analysis, a high internal consistency reliability coefficient, and a moderate mean inter-item correlation supported interpreting the 12 revised items as a single scale. Correlations of craving scores with preoccupation with pornography, sexual history, compulsive internet use, and sensation seeking provided support for convergent validity, criterion validity, and discriminant validity, respectively. The enhanced imagery script did not impact reported craving; however, more frequent users of pornography reported higher craving than less frequent users regardless of script condition. In Study 3, craving scores demonstrated good one-week test-retest reliability and predicted the number of times participants used pornography during the following week. This questionnaire could be applied in clinical settings to plan and evaluate therapy for problematic users of pornography and as a research tool to assess the prevalence and contextual triggers of craving among different types of pornography users. PMID:24469338

Kraus, Shane; Rosenberg, Harold

2014-04-01

417

INSURANCE & CLAIMS MANAGEMENT SPECIAL EVENTS QUESTIONNAIRE  

E-print Network

INSURANCE & CLAIMS MANAGEMENT SPECIAL EVENTS QUESTIONNAIRE TODAY'S DATE: / / 1. TITLE OF EVENT: 2. IS THERE AN ADMISSION CHARGE? YES NO IF YES, AMOUNT OF ADMISSION? 17. SPONSOR INSURED BY: 18. ADDRESS OF INSURER: INSURANCE & CLAIMS MGT. WILL DETERMINE INSURANCE REQUIREMENTS AND MAY REQUIRE CERTIFICATES OF INSURANCE

418

A questionnaire measure of achievement motivation  

Microsoft Academic Search

Conducted 3 studies with 125, 67, and 118 male undergraduates to investigate the possibility of constructing a new questionnaire to measure the achievement motive. Study I started with an initial item pool whose content ranged over 10 aspects thought to be characteristic of an individual who is highly motivated to achieve. Items embodying all except 1 aspect were included in

Hubert J. Hermans

1970-01-01

419

ENERGY EXCEPTION REQUEST Energy Exception Request Questionnaire  

E-print Network

ENERGY EXCEPTION REQUEST Energy Exception Request Questionnaire rev AA.01 2013/04/02 GUIDELINES which exceed the normal schedule by completing this Energy Exception Request and submitting it to the Office of Energy Management. Energy Management will prepare a cost analysis and return

Rock, Chris

420

DRUG STUDY QUESTIONNAIRE PROGRAM DIRECTOR:______________________________________ DATE:_____________________________  

E-print Network

DRUG STUDY QUESTIONNAIRE PROGRAM DIRECTOR:______________________________________ DATE and/or efficacy of a drug? A. If yes, is the testing, study, evaluation or research primarily for use in pharmaceutical pre-market clearance applications to the Food and Drug Administration? 2. Is drug administered

Acton, Scott

421

Cardiff's TELEform: Scanning the Diet History Questionnaire  

Cancer.gov

Software, such as Cardiff's TELEform Information Capture System, is available to create and print a scannable version of the Diet History Questionnaire form. To create booklets, you may still need to hire a professional printer. Using TELEform, you will be able to scan the instrument with an imaging scanner (contact Cardiff for specifications).

422

Rasch Based Analysis of Reading Ability Questionnaire.  

ERIC Educational Resources Information Center

This paper examines the results of a questionnaire on reading ability in English by Japanese college students, which was formerly analyzed using raw scores, from the viewpoint of Rasch measured scores. In the Rasch analysis, the basic requirements for measuring are the following: (1) reduction of experience to one dimensional abstraction; (2)…

Nakamura, Yuji

2000-01-01

423

IRON AND STEEL EFFLUENT GUIDELINES ECONOMIC QUESTIONNAIRE  

EPA Science Inventory

Resource Purpose: This information acquired via the questionnaire is used to support development of the effluent guidelines for the Iron and Steel Point Source Category (40CFR Part 420). One of the statutory decision criteria for the adoption of a best available treatment t...

424

Psychometric Normalization of a Hyperacusis Questionnaire  

Microsoft Academic Search

Clinical hyperacusis consists of a marked intolerance to ordinary environmental sounds, while hearing thresholds are quite often normal. Hyperacusis appears to be a subjective phenomenon, which is not easily defined or quantified by objective measurements. In order to create a tool suitable to quantify and evaluate various hyperacusis symptoms, a questionnaire screening several aspects of auditory symptomatology has been constructed.

S. Khalfa; S. Dubal; E. Veuillet; F. Perez-Diaz; R. Jouvent; L. Collet

2002-01-01

425

Utah Drop-Out Drug Use Questionnaire.  

ERIC Educational Resources Information Center

This questionnaire assesses drug use practices in high school drop-outs. The 79 items (multiple choice or apply/not apply) are concerned with demographic data and use, use history, reasons for use/nonuse, attitudes toward drugs, availability of drugs, and drug information with respect to narcotics, amphetamines, LSD, Marijuana, and barbiturates.…

Governor's Citizen Advisory Committee on Drugs, Salt Lake City, UT.

426

PARENT QUESTIONNAIRE Has your child had  

E-print Network

PARENT QUESTIONNAIRE Has your child had swim lessons before? Yes No Is your child com- fortable in the water? Parent/child or level 1 class No Level 1 class Yes Does your child put their face in the water? No Level 2 class Yes Can your child swim underwater, swim Front crawl, and back crawl? No Level 3 class Yes

Saldin, Dilano

427

Effective Schools Questionnaires, 1981-82.  

ERIC Educational Resources Information Center

Five questionnaires based on Ronald Edmonds' work on "effective schools" were developed for elementary and secondary students, teachers, principals, and parents. They were designed to assess the perceptions of each group on the five areas identified by Edmonds as distinguishing effective and ineffective schools for students from low-income…

Austin Independent School District, TX. Office of Research and Evaluation.

428

Theoretical analysis of nonlinear pulse propagation in ferrite-dielectric-metal structures based on the nonlinear Schrödinger equation with higher order terms  

Microsoft Academic Search

An analysis of nonlinear magnetostatic surface wave pulse propagation in planar ferrite-dielectric-metal (FDM) structures has been performed. The analysis was based on numerical solutions to the higher-order nonlinear Schrödinger (HONLS) equation, with third-order (D3) and nonlinear (Q) dispersion terms taken into account. The analysis focuses on (1) the crossover dispersion region for FDM structures and the point in wave-number k

Alexander S. Kindyak; Mark M. Scott; Carl E. Patton

2003-01-01

429

Theoretical analysis of nonlinear pulse propagation in ferrite-dielectric-metal structures based on the nonlinear Schro¨dinger equation with higher order terms  

Microsoft Academic Search

An analysis of nonlinear magnetostatic surface wave pulse propagation in planar ferrite-dielectric-metal (FDM) structures has been performed. The analysis was based on numerical solutions to the higher-order nonlinear Schr&diaero;dinger (HONLS) equation, with third-order (D3) and nonlinear (Q) dispersion terms taken into account. The analysis focuses on (1) the crossover dispersion region for FDM structures and the point in wave-number k

Alexander S. Kindyak; Mark M. Scott; Carl E. Patton

2003-01-01

430

Modeling Latent Interactions at Level 2 in Multilevel Structural Equation Models: An Evaluation of Mean-Centered and Residual-Centered Unconstrained Approaches  

ERIC Educational Resources Information Center

Among the many methods currently available for estimating latent variable interactions, the unconstrained approach is attractive to applied researchers because of its relatively easy implementation with any structural equation modeling (SEM) software. Using a Monte Carlo simulation study, we extended and evaluated the unconstrained approach to…

Leite, Walter L.; Zuo, Youzhen

2011-01-01

431

Using an EM Covariance Matrix to Estimate Structural Equation Models with Missing Data: Choosing an Adjusted Sample Size to Improve the Accuracy of Inferences  

ERIC Educational Resources Information Center

Two methods, direct maximum likelihood (ML) and the expectation maximization (EM) algorithm, can be used to obtain ML parameter estimates for structural equation models with missing data (MD). Although the 2 methods frequently produce identical parameter estimates, it may be easier to satisfy missing at random assumptions using EM. However, no…

Enders, Craig K.; Peugh, James L.

2004-01-01

432

Sequential Temporal Dependencies in Associations between Symptoms of Depression and Posttraumatic Stress Disorder: An Application of Bivariate Latent Difference Score Structural Equation Modeling  

ERIC Educational Resources Information Center

Depression and posttraumatic stress disorder (PTSD) are highly comorbid conditions that may arise following exposure to psychological trauma. This study examined their temporal sequencing and mutual influence using bivariate latent difference score structural equation modeling. Longitudinal data from 182 emergency room patients revealed level of…

King, Daniel W.; King, Lynda A.; McArdle, John J.; Shalev, Arieh Y.; Doron-LaMarca, Susan

2009-01-01

433

Investigating Experimental Effects within the Framework of Structural Equation Modeling: An Example with Effects on Both Error Scores and Reaction Times  

ERIC Educational Resources Information Center

Structural equation modeling provides the framework for investigating experimental effects on the basis of variances and covariances in repeated measurements. A special type of confirmatory factor analysis as part of this framework enables the appropriate representation of the experimental effect and the separation of experimental and…

Schweizer, Karl

2008-01-01

434

A nitrogen model for European catchments: INCA, new model structure and equations Hydrology and Earth System Sciences, 6(3), 559582 (2002) EGS  

E-print Network

A nitrogen model for European catchments: INCA, new model structure and equations 559 Hydrology and Earth System Sciences, 6(3), 559­582 (2002) © EGS A nitrogen model for European catchments: INCA, new of the Integrated Nitrogen in Catchments model (INCA) was developed and tested using flow and streamwater nitrate

Boyer, Edmond

435

Nutrition, Balance and Fear of Falling as Predictors of Risk for Falls among Filipino Elderly in Nursing Homes: A Structural Equation Model (SEM)  

ERIC Educational Resources Information Center

While a number of empirical studies have been conducted regarding risk for falls among the elderly, there is still a paucity of similar studies in a developing country like the Philippines. This study purports to test through Structural Equation Modeling (SEM) a model that shows the interaction between and among nutrition, balance, fear of…

de Guzman, Allan B.; Ines, Joanna Louise C.; Inofinada, Nina Josefa A.; Ituralde, Nielson Louie J.; Janolo, John Robert E.; Jerezo, Jnyv L.; Jhun, Hyae Suk J.

2013-01-01

436

Do Teachers, Principals, and Superintendents Perceive Leadership the Same Way? A Structural Equation Modeling Test of the Equivalence of a Multi-Dimensional Construct across Groups  

ERIC Educational Resources Information Center

Structural Equation Modeling (SEM) was used in this study to determine the extent to which teachers, principals, and superintendents perceive the leadership construct in the same way. The researchers found that the two-factor model fits the principal group and particularly the superintendent group better than does the four-factor model. The…

Rodriguez-Campos, Liliana; Rincones-Gomez, Rigoberto; Shen, Jianping

2008-01-01

437

Are technical and soft skills required?: the use of structural equation modeling to examine factors leading to retention in the cs major  

Microsoft Academic Search

This research investigates the effects of technical (i.e. technical ability) and soft (i.e. emotional intelligence) skills on CS program retention. Structural equation modeling revealed that affinity (satisfaction with the major) was the most important factor in determining intention to leave the CS major. Unexpectedly, technical skills were the least important (compared to soft skills). Gender differences were also examined. Results

Tracy L. Lewis; Wanda J. Smith; France Bélanger; K. Vernard Harrington

2008-01-01

438

Quantified Choice of Root-Mean-Square Errors of Approximation for Evaluation and Power Analysis of Small Differences between Structural Equation Models  

ERIC Educational Resources Information Center

MacCallum, Browne, and Cai (2006) proposed a new framework for evaluation and power analysis of small differences between nested structural equation models (SEMs). In their framework, the null and alternative hypotheses for testing a small difference in fit and its related power analyses were defined by some chosen root-mean-square error of…

Li, Libo; Bentler, Peter M.

2011-01-01

439

Three Approaches to Using Lengthy Ordinal Scales in Structural Equation Models: Parceling, Latent Scoring, and Shortening Scales  

PubMed Central

Lengthy scales or testlets pose certain challenges for structural equation modeling (SEM) if all the items are included as indicators of a latent construct. Three general approaches (parceling, latent scoring, and shortening) to modeling lengthy scales in SEM were reviewed and evaluated. A hypothetical population model was simulated containing two exogenous constructs with 14 indicators each and an endogenous construct with four indicators. The simulation generated data sets with varying numbers of response options, two types of distributions, factor loadings ranging from low to high, and sample sizes ranging from small to moderate. The population model was varied to incorporate one of the following: (1) single parcels, (2) various parcels as indicators of two exogenous constructs, (3) latent scores as observed exogenous variables, and (4) four and six of individual items as indicators of two exogenous constructs. The dependent variables evaluated were biases in the covariance and partial covariance population parameters. Biases in these parameters were found to be minimal under the following conditions: (1) when parcels of indicators of five response options were used as indicators of two latent exogenous constructs; (2) when latent scores were used as observed variables at sample sizes above 100 and with indicators that were relatively less skewed in the case of dichotomous indicators; and (3) when four or six individual items with high or diverse factor loadings were used as indicators of two exogenous constructs. These findings provided guidelines for resolving the inconsistency of findings from applying various approaches to empirical data. PMID:20514149

Yang, Chongming; Nay, Sandra; Hoyle, Rick H.

2009-01-01

440

Predicting Changes in PM Exposure Over Time at U.S. Trucking Terminals Using Structural Equation Modeling Techniques  

PubMed Central

This study analyzes the temporal variability of occupational and environmental exposures to fine particulate matter in the U.S. trucking industry and tests the predictive ability of a novel multilayer statistical approach to occupational exposure modeling using structural equation modeling (SEM) techniques. For these purposes, elemental carbon mass in PM<1 µm at six U.S. trucking terminals were measured twice during the same season up to 2 years apart, observing concentrations in the indoor loading dock (median EC: period 1 = 0.65 µg/m3; period 2 = 0.94 µg/m3 ) and outdoor background location (median EC: period 1 = 0.46 µg/m3 ; period 2 = 0.67 µg/m3 ), as well as in the truck cabs of local drivers while on the road (median EC: period 1=1.09 µg/m3 ; period 2 = 1.07 µg/m3 ). There was a general trend toward higher exposures during the second sampling trips; however, these differences were statistically significant in only a few cases and were largely attributable to changes in weather patterns (wind speed, precipitation, etc.). Once accounting for systematic prediction errors in background concentrations, the SEM approach provided a strong fit for work-related exposures in this occupational setting. PMID:19367483

Davis, Mary E.; Laden, Francine; Hart, Jaime E.; Garshick, Eric; Blicharz, Andrew; Smith, Thomas J.

2009-01-01

441

A structural equation modeling approach for the adoption of cloud computing to enhance the Malaysian healthcare sector.  

PubMed

The investments and costs of infrastructure, communication, medical-related equipments, and software within the global healthcare ecosystem portray a rather significant increase. The emergence of this proliferation is then expected to grow. As a result, information and cross-system communication became challenging due to the detached independent systems and subsystems which are not connected. The overall model fit expending over a sample size of 320 were tested with structural equation modelling (SEM) using AMOS 20.0 as the modelling tool. SPSS 20.0 is used to analyse the descriptive statistics and dimension reliability. Results of the study show that system utilisation and system impact dimension influences the overall level of services of the healthcare providers. In addition to that, the findings also suggest that systems integration and security plays a pivotal role for IT resources in healthcare organisations. Through this study, a basis for investigation on the need to improvise the Malaysian healthcare ecosystem and the introduction of a cloud computing platform to host the national healthcare information exchange has been successfully established. PMID:24957398

Ratnam, Kalai Anand; Dominic, P D D; Ramayah, T

2014-08-01

442

Solar Resource and Forecasting QuestionnaireSolar Resource and Forecasting QuestionnaireSolar Resource and Forecasting QuestionnaireSolar Resource and Forecasting Questionnaire As someone who is familiar with solar energy issues, we hope that you will tak  

E-print Network

Page 1 Solar Resource and Forecasting QuestionnaireSolar Resource and Forecasting QuestionnaireSolar Resource and Forecasting QuestionnaireSolar Resource and Forecasting Questionnaire As someone who is familiar with solar energy issues, we hope that you will take a few moments to answer this short survey

Islam, M. Saif

443

Validation of a maternal questionnaire on correlates of physical activity in preschool children  

Microsoft Academic Search

BACKGROUND: Valid measures of physical activity correlates in preschool children are lacking. This study aimed to assess the validity, factor structure and internal consistency of a maternal questionnaire on potential correlates of four-year-old children's physical activity. METHODS: The questionnaire was designed to measure the following constructs: child personal factors; parental support and self-efficacy for providing support; parental rules and restrictions;

Alison M McMinn; Esther MF van Sluijs; Nicholas C Harvey; Cyrus Cooper; Hazel M Inskip; Keith M Godfrey; Simon J Griffin

2009-01-01

444

World War I History Commission Questionnaires  

NSDL National Science Digital Library

In 1928, the Library of Virginia inherited a mass of materials from the Virginia War History Commission, which had spent the previous eight years gathering information on Virginia's participation in World War I. Included in this material were over 14,900 four-page questionnaires from a survey of WWI veterans in Virginia. The Library of Virginia has digitized these survey forms and created a free, fully-searchable database. Users have three search options: by word or phrase, combination, and expert/boolean. Search returns offer basic information on each individual, and users must follow the link at the bottom of the page to download the digitized images (in .tif format) of the questionnaire forms. In some cases, respondents submitted photos or additional pages with their forms and these are included in the database.

445

The Pain Coping Questionnaire: preliminary validation  

Microsoft Academic Search

A new measure of coping, the Pain Coping Questionnaire (PCQ), is presented and validated in two studies of children and adolescents. Factor analyses of data from healthy children and adolescents supported eight hypothesized subscales (information seeking, problem solving, seeking social support, positive self-statements, behavioral distraction, cognitive distraction, externalizing, internalizing\\/catastrophizing) and three higher-order scales (approach, problem-focused avoidance, emotion-focused avoidance). The subscales

Graham J Reid; Cheryl A Gilbert; Patrick J McGrath

1998-01-01

446

Building and mining web-based questionnaires and surveys with SySQ.  

PubMed

A questionnaire is a method for collecting data that can come from many sources such as observations, telephone interviews or documentary sources. Whatever the source of data is, the questionnaire provides a framework of questions that facilitate researcher's work. A manual approach for collecting data using questionnaire presents some limitations and introduces several sources of errors. A second issue regards the statistical and data mining of data that often is conducted using different tools than the questionnaire system, which may introduce errors in the analysis pipeline. For instance, common methods applied to data set concern the normality test, the association and correlation discovery, linear regression, classification and clustering. Usually this analysis is performed using external tools, often not free, such as SPSS, SAS, STATA, Weka, or Clementine.We present a web-based software system, to automatize the analysis pipeline and to support researchers involved in the collection of questionnaire data, such as in epidemiology, aiming to reduce the errors listed above and including some basic functions to conduct statistical analysis on collected data. Our system allows researchers to create questionnaires, adding sections and structured questions. It provides a preview of the questionnaire, the exportation of saved data into statistical software compatible formats, or it permits to analyze them directly applying statistical methods and common data mining techniques from the main interface. PMID:24307414

Sarica, Alessia; Guzzi, Pietro Hiram; Cannataro, Mario

2013-09-01

447

Measurement Properties of a Park Use Questionnaire  

PubMed Central

We determined the criterion validity and test-retest reliability of a brief park use questionnaire. From five US locations, 232 adults completed a brief survey four times and wore a global positioning system (GPS) monitor for three weeks. We assessed validity for park visits during the past week and during a usual week by examining agreement between frequency and duration of park visits reported in the questionnaire to the GPS monitor results. Spearman correlation coefficients (SCC) were used to measure agreement. For past week park visit frequency and duration, the SCC were 0.62–0.65 and 0.62–0.67, respectively. For usual week park visit frequency and duration, the SCC were 0.40–0.50 and 0.50–0.53, respectively. Usual park visit frequency reliability was 0.78–0.88 (percent agreement 69%–82%) and usual park visit duration was 0.75–0.84 (percent agreement 64%–73%). These results suggest that the questionnaire to assess usual and past week park use had acceptable validity and reliability. PMID:23853386

Evenson, Kelly R.; Wen, Fang; Golinelli, Daniela; Rodríguez, Daniel A.; Cohen, Deborah A.

2012-01-01

448

The Sexual and Physical Abuse Questionnaire (SPAQ): A Screening Instrument for Adults To Assess Past and Current Experiences of Abuse.  

ERIC Educational Resources Information Center

Criterion validity of the Sexual and Physical Abuse Questionnaire was investigated in 134 psychiatric patients using the Structured Trauma Interview. The measures of agreement and the predictive measures of the questionnaire were satisfactory, particularly with sexual abuse. Positive answering increased odds for sexual abuse by a factor of…

Kooiman, C. G.; Ouwehand, A. W.; ter Kuile, M. M.

2002-01-01

449

Convergence of Scores on the Interview and Questionnaire Versions of the Eating Disorder Examination: A Meta-Analytic Review  

ERIC Educational Resources Information Center

Significant discrepancies have been found between interview- and questionnaire-based assessments of psychopathology; however, these studies have typically compared instruments with unmatched item content. The Eating Disorder Examination (EDE), a structured interview, and the questionnaire version of the EDE (EDE-Q) are considered the preeminent…

Berg, Kelly C.; Peterson, Carol B.; Frazier, Patricia; Crow, Scott J.

2011-01-01

450

Altered effective connectivity during working memory performance in schizophrenia: a study with fMRI and structural equation modeling.  

PubMed

The present study aimed to explore altered effective connectivity in schizophrenic patients while performing a 2-back working memory task. Twelve right-handed, schizophrenic patients treated with typical or atypical antipsychotics and 6 healthy control subjects were studied with fMRI while performing a "2-back" working memory task. Effective connectivity within a cortical-subcortical-cerebellar network for mnemonic information processing was assessed and compared between both groups. The path model included cortico-cortical connections comprising the parietal association cortex, ventrolateral prefrontal cortex (VLPFC), and the dorsolateral prefrontal cortex (DLPFC) as well as a cortico-cerebellar feedback loop comprising prefrontal cortex, contralateral cerebellum, and thalamus. Group differences were analyzed with a stacked models approach. Relative to normal controls, both patient groups revealed a pattern of reduced connectivity within the prefrontal-cerebellar and the cerebellar-thalamic limbs but enhanced connectivity in the thalamo-cortical limb of the cortical-cerebellar circuit. Moreover, a direct comparison of both treatment groups revealed enhanced connectivity in the interhemispheric connections between the cortical association areas in patients treated with atypical antipsychotics. However, right prefrontal and left parieto-frontal path coefficients were lower in the patient group receiving atypical antispychotic drugs. The findings suggest that the relationship between pathology in cortical-subcortical cerebellar networks and associated functional connectivity is complex and may include aspects of increased and decreased levels of connectivity consistent with the notion of "cognitive dysmetria" in schizophrenia. The observed pronounced connectivity within thalamo-cortical projections could be attributed to a compensatory increase of thalamic input in the presence of disrupted effective connectivity within the preceding limb of the cortical-cerebellar circuitry. The study demonstrated the feasibility of structural equation modeling for the investigation of group and treatment-related differences in effective connectivity and provides a promising approach to further disentangle the relationship between altered functional capacity and associated fMRI signal changes. PMID:12880804

Schlösser, Ralf; Gesierich, Thomas; Kaufmann, Bettina; Vucurevic, Goran; Hunsche, Stefan; Gawehn, Joachim; Stoeter, Peter

2003-07-01

451

Validation of the Finnish Autism Spectrum Screening Questionnaire (ASSQ) for Clinical Settings and Total Population Screening  

ERIC Educational Resources Information Center

We assessed the validity and determined cut-off scores for the Finnish Autism Spectrum Screening Questionnaire (ASSQ). A population sample of 8-year-old children (n = 4,408) was rated via the ASSQ by parents and/or teachers, and a subgroup of 104 children was examined via structured interview, semi-structured observation, IQ measurement, school…

Mattila, Marja-Leena; Jussila, Katja; Linna, Sirkka-Liisa; Kielinen, Marko; Bloigu, Risto; Kuusikko-Gauffin, Sanna; Joskitt, Leena; Ebeling, Hanna; Hurtig, Tuula; Moilanen, Irma

2012-01-01

452

Measuring determinants of implementation behavior: psychometric properties of a questionnaire based on the theoretical domains framework  

PubMed Central

Background To be able to design effective strategies to improve healthcare professionals’ implementation behaviors, a valid and reliable questionnaire is needed to assess potential implementation determinants. The present study describes the development of the Determinants of Implementation Behavior Questionnaire (DIBQ) and investigates the reliability and validity of this Theoretical Domains Framework (TDF)-based questionnaire. Methods The DIBQ was developed to measure the potential behavioral determinants of the 12-domain version of the TDF (Michie et al., 2005). We identified existing questionnaires including items assessing constructs within TDF domains and developed new items where needed. Confirmatory factor analysis was used to examine whether the predefined structure of the TDF-based questionnaire was supported by the data. Cronbach’s alpha was calculated to assess internal consistency reliability of the questionnaire, and domains’ discriminant validity was investigated. Results We developed an initial questionnaire containing 100 items assessing 12 domains. Results obtained from confirmatory factor analysis and Cronbach’s alpha resulted in the final questionnaire consisting of 93 items assessing 18 domains, explaining 63.3% of the variance, and internal consistency reliability values ranging from .68 to .93. Domains demonstrated good discriminant validity, although the domains ‘Knowledge’ and ‘Skills’ and the domains ‘Skills’ and ‘Social/professional role and identity’ were highly correlated. Conclusions We have developed a valid and reliable questionnaire that can be used to assess potential determinants of healthcare professional implementation behavior following the theoretical domains of the TDF. The DIBQ can be used by researchers and practitioners who are interested in identifying determinants of implementation behaviors in order to be able to develop effective strategies to improve healthcare professionals’ implementation behaviors. Furthermore, the findings provide a novel validation of the TDF and indicate that the domain ‘Environmental context and resources’ might be divided into several environment-related domains. PMID:24641907

2014-01-01

453

A Permutation Test for Correlated Errors in Adjacent Questionnaire Items  

ERIC Educational Resources Information Center

Response patterns are of importance to survey researchers because of the insight they provide into the thought processes respondents use to answer survey questions. In this article we propose the use of structural equation modeling to examine response patterns and develop a permutation test to quantify the likelihood of observing a specific…

Hildreth, Laura A.; Genschel, Ulrike; Lorenz, Frederick O.; Lesser, Virginia M.

2013-01-01

454

APPLICATIONS OF LASERS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Three-dimensional optical structures described by the nonlinear Helmholtz equation  

NASA Astrophysics Data System (ADS)

New distributions of the optical field described by the three-dimensional nonlinear Helmholtz equation correspond both to periodic (in the space of standing waves realized in a nonlinear resonator) and spherical self-localized optical bunches.

Alfimov, G. L.; Eleonski?, V. M.; Kulagin, N. E.; Lerman, L. M.; Silin, Viktor P.

1990-07-01

455

The development and psychometric properties of the selective mutism questionnaire.  

PubMed

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 Internet sample of parents of children ages 3 to 11 to demonstrate that the SMQ has a theoretically and clinically meaningful factor structure accounting for a significant portion of variance in responses with good internal consistency. Study 2 (N = 66) supported the validity of the SMQ in that scores discriminated clinic-referred children with SM from children with other anxiety disorders. Scores on the SMQ were correlated with measures of several theoretically and clinically important dimensions. PMID:18470781

Bergman, R Lindsey; Keller, Melody L; Piacentini, John; Bergman, Andrea J

2008-04-01

456

Generalized Moyal structures in phase space, kinetic equations and their classical limit: II. Applications to harmonic oscillator models  

E-print Network

The formalism of generalized Wigner transformations developped in a previous paper, is applied to kinetic equations of the Lindblad type for quantum harmonic oscillator models. It is first applied to an oscillator coupled to an equilibrium chain of other oscillators having nearest-neighbour interactions. The kinetic equation is derived without using the so called rotating-wave approximation. Then it is shown that the classical limit of the corresponding phase-space equation is independent of the ordering of operators corresponding to the inverse of the generalized Wigner transformation, provided the latter is involutive. Moreover, this limit equation, which conserves the probabilistic nature of the distribution function and obeys an H-theorem, coincides with the kinetic equation for the corresponding classical system, which is derived independently and is distinct from that usually obtained in the litterature and not sharing the above properties. Finally the same formalism is applied to more general model equations used in quantum optics and it is shown that the above results remain unaltered.

C. Tzanakis; A. P. Grecos; P. Hatjimanolaki

1996-05-14

457

Psychometric properties of the Achievement Goal Questionnaire-Revised administered to Greek university students.  

PubMed

This study examined the generalizability of the Achievement Goal Questionnaire-Revised (AGQ-R) in a different cultural and ethnic context than other published studies and across different levels of specificity in the academic domain. The study assessed the structural validity and reliability of the questionnaire as administered to 105 Greek University students in both a course-specific context and in a more general academic context. Six plausible alternative models with three- and two-factor structures were compared to the four-factor structure of the questionnaire. In the course-specific context administration, the four-factor structure of the AGQ-R was supported, but a three-factor structure model did not provide a worse fit. None of the remaining models provided a good fit. At the more general academic context, the four-factor structure of the questionnaire did not show adequate fit to the data. The same was true for each one of the six alternative models. The internal consistency reliabilities for the factors depicted in the four- and three-factor structure models were very good, ranging from .90 to .98. PMID:24597436

Apostolou, Mary

2013-10-01

458

Sexual behavioral abstine HIV/AIDS questionnaire: Validation study of an Iranian questionnaire  

PubMed Central

Background: This study was designed to assess the validity and reliability of the designed sexual, behavioral abstinence, and avoidance of high-risk situation questionnaire (SBAHAQ), with an aim to construct an appropriate development tool in the Iranian population. Materials and Methods: A descriptive–analytic study was conducted among female undergraduate students of Tehran University, who were selected through cluster random sampling. After reviewing the questionnaires and investigating face and content validity, internal consistency of the questionnaire was assessed by Cronbach's alpha. Explanatory and confirmatory factor analysis was conducted using SPSS and AMOS 16 Software, respectively. Results: The sample consisted of 348 female university students with a mean age of 20.69 ± 1.63 years. The content validity ratio (CVR) coefficient was 0.85 and the reliability of each section of the questionnaire was as follows: Perceived benefit (PB; 0.87), behavioral intention (BI; 0.77), and self-efficacy (SE; 0.85) (Cronbach's alpha totally was 0.83). Explanatory factor analysis showed three factors, including SE, PB, and BI, with the total variance of 61% and Kaiser–Meyer–Olkin (KMO) index of 88%. These factors were also confirmed by confirmatory factor analysis [adjusted goodness of fitness index (AGFI) = 0.939, root mean square error of approximation (RMSEA) = 0.039]. Conclusion: This study showed the designed questionnaire provided adequate construct validity and reliability, and could be adequately used to measure sexual abstinence and avoidance of high-risk situations among female students. PMID:24741650

Najarkolaei, Fatemeh Rahmati; Niknami, Shamsaddin; Shokravi, Farkhondeh Amin; Tavafian, Sedigheh Sadat; Fesharaki, Mohammad Gholami; Jafari, Mohammad Reza

2014-01-01

459

Mediational Effects of Self-Efficacy Dimensions in the Relationship between Knowledge of Dengue and Dengue Preventive Behaviour with Respect to Control of Dengue Outbreaks: A Structural Equation Model of a Cross-Sectional Survey  

PubMed Central

Background Dengue fever is endemic in Malaysia, with frequent major outbreaks in urban areas. The major control strategy relies on health promotional campaigns aimed at encouraging people to reduce mosquito breeding sites close to people's homes. However, such campaigns have not always been 100% effective. The concept of self-efficacy is an area of increasing research interest in understanding how health promotion can be most effective. This paper reports on a study of the impact of self-efficacy on dengue knowledge and dengue preventive behaviour. Methods and Findings We recruited 280 adults from 27 post-outbreak villages in the state of Terengganu, east coast of Malaysia. Measures of health promotion and educational intervention activities and types of communication during outbreak, level of dengue knowledge, level and strength of self-efficacy and dengue preventive behaviour were obtained via face-to-face interviews and questionnaires. A structural equation model was tested and fitted the data well (?2?=?71.659, df?=?40, p?=?0.002, RMSEA?=?0.053, CFI?=?0.973, TLI?=?0.963). Mass media, local contact and direct information-giving sessions significantly predicted level of knowledge of dengue. Level and strength of self-efficacy fully mediated the relationship between knowledge of dengue and dengue preventive behaviours. Strength of self-efficacy acted as partial mediator in the relationship between knowledge of dengue and dengue preventive behaviours. Conclusions To control and prevent dengue outbreaks by behavioural measures, health promotion and educational interventions during outbreaks should now focus on those approaches that are most likely to increase the level and strength of self-efficacy. PMID:24086777

Isa, Affendi; Loke, Yoon K.; Smith, Jane R.; Papageorgiou, Alexia; Hunter, Paul R.

2013-01-01

460

Singularities of the boundary layer equations and the structure of the flow in the vicinity of the convergence plane on conical bodies  

Microsoft Academic Search

The singularities of the boundary layer equations and the laminar viscous gas flow structure in the vicinity of the convergence\\u000a plane on sharp conical bodies at incidence are analyzed. In the outer part of the boundary layer the singularities are obtained\\u000a in explicit form. It is shown that in the vicinity of a singularity a boundary domain, in which the

V. I. Shalaev

2007-01-01

461

Psychometric Evaluation of the Persian Version of the ‘Aging Male Scales’ Questionnaire  

PubMed Central

Background: Men, much like women, are faced with age-related menopause-like symptoms as they age. In recent years, increasing attention has been drawn to clinical research into elderly men and their health-related quality of life. The Aging Male Scales (AMS) questionnaire is an international tool for assessing the health-related quality of life in elderly men. Hence far this questionnaire has not been subjected to psychometric assessment in Iran. This study aims to evaluate the validity and reliability of the Persian version of the AMS questionnaire specific to the health of elderly men in Iran. Methods: To validate this instrument, a cross-sectional study was conducted on 521 healthy Iranian men aged 40-65 years old, who attended the blood transfusion center clinic between February 2011 and June 2012. The English version of the AMS questionnaire was translated to Persian and then back-translated. To determine the reliability of the AMS questionnaire, internal consistency was evaluated and test-retest was done. The questionnaire was validated using convergent and structural validity methods. To assess the factor structure of the questionnaire, a correlation matrix of questions and domains was used. Results: Cronbach's alpha was higher than 0.7 (0.73-0.88) in all domains. A Pearson's correlation coefficient of 0.87 between pretest and posttest indicated a high correlation and an acceptable reliability. The convergent validity of the questionnaire was found acceptable by calculating the correlation between the domains and items-total correlation ranging 0.40-0.85, except for question 14 that had a 0.28 correlation with the whole test. The criterion-related validity of the questionnaire in the psychological domain was confirmed with the “two-item Patient Health Questionnaire” (r = 0.63, P < 0.001). Conclusions: According to the results, the Persian version of the AMS questionnaire has high validity and reliability and may be used to assess the health-related quality of life of men between 40 and 65 years old. PMID:25317302

Ardebili, Hasan Eftekhar; Khosravi, Shahla; Larijani, Bagher; Nedjat, Saharnaze; Nasrabadi, Alireza Nikbakht

2014-01-01

462

Impact of organisational characteristics on turnover intention among care workers in nursing homes in Korea: a structural equation model.  

PubMed

Objective The aim of the present study was to analyse the impact of organisational characteristics on the turnover intention of care workers working at nursing homes in Korea. Methods Study participants included 504 care workers working at 14 nursing homes in Korea. The variables measured were: high-performance work practices, consisting of five subfactors (official training, employment stability, autonomy, employee participation and group-based payment); organisational commitment, consisting of three subfactors (affective, normative and continuance commitment); organisational support; and turnover intention. The inter-relationship between high-performance work practices, organisational support, organisational commitment and turnover intention and the fit of the hypothetical model were analysed using structural equation modelling. Results According to our analysis, high-performance work practices not only had a direct effect on turnover intention, but also an indirect effect by mediating organisational support and commitment. The factor having the largest direct influence on turnover intention was organisational commitment. Conclusions The results of the present study suggest that to improve health conditions for frail elderly patients at nursing homes, as well as the efficiency of nursing homes through the continuance of nursing service and enhancement of quality of service, long-term care facilities should reduce the turnover intention of care workers by increasing their organisational commitment by actively implementing high-performance work practices. What is known about the topic? Considerable studies have shown that the adoption of high-performance work practices is related to an organisation's performance and job satisfaction. In addition, previous studies found that job satisfaction is inversely related to the turnover intention of employees. What does this paper add? This paper identified that high-performance work practices are closely related to the turnover intention of care workers in nursing homes. These findings could improve our understanding of the factors that impact on labour management in nursing homes. What are the implications for practitioners? The turnover of care workers is one of the major managerial challenges for nursing home managers. The findings of this study suggest that managers should be focused on high-performance work practices to improve the efficiency of their organisations. PMID:24870928

Ha, Jong Goon; Man Kim, Ji; Hwang, Won Ju; Lee, Sang Gyu

2014-09-01

463

The contribution of spatial analysis to understanding HIV/TB mortality in children: a structural equation modelling approach  

PubMed Central

Background South Africa accounts for more than a sixth of the global population of people infected with HIV and TB, ranking her highest in HIV/TB co-infection worldwide. Remote areas often bear the greatest burden of morbidity and mortality, yet there are spatial differences within rural settings. Objectives The primary aim was to investigate HIV/TB mortality determinants and their spatial distribution in the rural Agincourt sub-district for children aged 1–5 years in 2004. Our secondary aim was to model how the associated factors were interrelated as either underlying or proximate factors of child mortality using pathway analysis based on a Mosley-Chen conceptual framework. Methods We conducted a secondary data analysis based on cross-sectional data collected in 2004 from the Agincourt sub-district in rural northeast South Africa. Child HIV/TB death was the outcome measure derived from physician assessed verbal autopsy. Modelling used multiple logit regression models with and without spatial household random effects. Structural equation models were used in modelling the complex relationships between multiple exposures and the outcome (child HIV/TB mortality) as relayed on a conceptual framework. Results Fifty-four of 6,692 children aged 1–5 years died of HIV/TB, from a total of 5,084 households. Maternal death had the greatest effect on child HIV/TB mortality (adjusted odds ratio=4.00; 95% confidence interval=1.01–15.80). A protective effect was found in households with better socio-economic status and when the child was older. Spatial models disclosed that the areas which experienced the greatest child HIV/TB mortality were those without any health facility. Conclusion Low socio-economic status and maternal deaths impacted indirectly and directly on child mortality, respectively. These factors are major concerns locally and should be used in formulating interventions to reduce child mortality. Spatial prediction maps can guide policy makers to target interventions where they are most needed. PMID:23364095

Musenge, Eustasius; Vounatsou, Penelope; Collinson, Mark; Tollman, Stephen; Kahn, Kathleen

2013-01-01

464

Burn Sexuality Questionnaire: Brazilian translation, validation and cultural adaptation.  

PubMed

In measuring the quality of life of burn victims, it is essential that we find reliable and valid means. The Burn Sexuality Questionnaire (BSQ) is a specific instrument that assesses sexuality in the context of quality of life of burn victims. We set out to translate, validate and culturally adapt the BSQ into Brazilian Portuguese. The Portuguese version was applied to 80 patients. After translation, cultural adaptation was performed with 30 patients. We also tested the final version for reliability in 20 patients, and for face, content and construct validities in 30 patients, according to standard procedures. Total Cronbach's alpha was 0.87. Pearson's correlation was significant between scores for different time points. Construct validity was demonstrated with the correlation of the BSQ with the Burn Specific Health Scale-Revised (BSHS-R) questionnaire. It showed significant correlation between the BSQ social comfort domain and the BSHS-R affect and body image (p=0.025), simple function ability (p=0.008), work (p=0.016) and treatment (p=0.037) domains. This cultural adaptation of the BSQ suggests that it is a reliable tool and has construct validity for the social comfort domain. There is still need for a better-structured tool that could possibly evaluate functional and psychological aspects of sexuality, because one could easily overlook the psychosocial aspects of patients with major, complex burns. PMID:23199826

Piccolo, Monica Sarto; Gragnani, Alfredo; Daher, Ricardo Piccolo; de Tubino Scanavino, Marco; de Brito, Maria José; Ferreira, Lydia Masako

2013-08-01

465

Questionnaire Design for Student Measurement of Teaching Effectiveness.  

ERIC Educational Resources Information Center

The design and use of questionnaires in course and faculty evaluation are discussed and the literature reviewed. Problems of questionnaire construction and interpretation of results are described and a questionnaire developed at the Faculty of Engineering at the University of Waterloo is given as an example. (Author/MSE)

McBean, Edward A.; Al-Nassri, Sabah

1982-01-01

466

Increasing response rates to postal questionnaires: systematic review  

Microsoft Academic Search

Objective To identify methods to increase response to postal questionnaires. Design Systematic review of randomised controlled trials of any method to influence response to postal questionnaires. Studies reviewed 292 randomised controlled trials including 258 315 participants Intervention reviewed 75 strategies for influencing response to postal questionnaires.

Phil Edwards; Ian Roberts; Mike Clarke; Carolyn DiGuiseppi; Sarah Pratap; Reinhard Wentz; Irene Kwan

2002-01-01

467

Construction of a questionnaire for readiness to reconcile in victims of human rights violations  

PubMed Central

Background Post-conflict reconciliation is supposed to have a positive impact on survivors of war and conflict. However, knowledge is limited as validated questionnaires to assess individual readiness to reconcile in the context of human rights violations are still missing. Objectives This study aimed to develop and pilot-test a questionnaire to assess individual readiness to reconcile in victims of human rights violations. Methods The questionnaire was developed and pilot-tested in a sample of 60 adult Kurdish refugees from Turkey. In addition to the questionnaire, trauma exposure, Posttraumatic Stress Disorder (PTSD), depression, anxiety, perceived emotional closeness to the Kurdish people as well as the participants’ ability to differentiate between perpetrators and the people in general were assessed in structured interviews, and their associations with readiness to reconcile were analyzed. Results Factor and item analysis resulted in an 18-item questionnaire with three subscales (openness to interactions; absence of feelings of revenge; openness to conflict resolution). Cronbach's ? for the subscales ranged from 0.74 to 0.90, explaining 61% of the total variance. The ability to differentiate between perpetrators and people in general and perceived emotional closeness were the best predictors for readiness to reconcile. The level of trauma exposure was not linked to readiness to reconcile. Although readiness to reconcile was negatively related to PTSD, depression and anxiety, none of these associations reached statistical significance. Conclusions The questionnaire appears to be a reliable measure with good psychometric properties. Further validations in different samples are needed. PMID:22893837

Stammel, Nadine; Neuner, Frank; Böttche, Maria; Knaevelsrud, Christine

2012-01-01

468

Assessment of Questionnaires Measuring Quality of Life in Infertile Couples: A Systematic Review  

PubMed Central

Background Infertility has potentially inappropriate effects on quality of life in infertile couples. Various general and specific questionnaires have been structured for assessing different aspects of quality of life in infertile men, women, or couples. The present systematic review was designed to assess these questionnaires and also identify different factors affecting infertile couples based on the aforesaid questionnaires. Methods The research strategy involved general and specific terms in relation to couples's infertility and their quality of life. A review was done for studies published from 1982 to 2012 that were indexed in Medline, ISI Web of Science and Scopus as well as abstract books on this subject. We also corresponded with the authors of the references in related studies for introducing more resources and references. Results In all reviewed studies, different aspects of the quality of life in couples were evaluated including sexual, psychological, social, communicational, environmental, occupational, medical, as well as economical ones. In total, after initial screening of all studies, 10 general and 2 specific questionnaires were retrieved. Although no meta-analysis was found in the review, infertility had a negative effect on quality of life in couples. Conclusion This study revealed that some general questionnaires such as SF-36 and WHO-QOL were mostly used for assessing quality of life in infertile couples and some specific questionnaires such as FERTI-QoL and Fertility Problem Inventory were rarely used. Thus, it seems that the evaluation of quality of life in infertile couples needs valid instruments for measurement. PMID:24163794

Mousavi, Seyyed Abbas; Masoumi, Seyyedeh Zahra; Keramat, Afsaneh; Pooralajal, Jalal; Shobeiri, Fatemeh

2013-01-01

469

The Heritability of Cluster B Personality Disorders Assessed both by Personal Interview and Questionnaire  

PubMed Central

Whereas the heritability of common personality traits has been firmly established, the results of the few published studies on personality disorders (PDs) are highly divergent, with some studies finding high heredity and others very low. A problem with assessing personality disorders by means of interview is errors connected with interviewer bias. A way to overcome the problem is to use self-report questionnaires in addition to interviews. This study used both interview and questionnaire for assessing DSM-IV Cluster B personality disorders: antisocial personality disorder (APD), borderline (BPD), narcissistic (NPD), and histrionic (HPD). We assessed close to 2,800 twins from the Norwegian Institute of Public Health Twin Panel using a self-report questionnaire and, a few years later, the Structured Interview for DSM-IV Personality (SIDP-IV). Items from the self-report questionnaire that best predicted the PDs captured by the interview were then selected. Measurement models combining questionnaire and interview information were applied and were fitted using Mx. Whereas the heritability of Cluster B PDs assessed by interview was around .30, and around .40–.50 when assessed by self-report questionnaire, the heritability of the convergent latent factor, including information from both interview and self-report questionnaire was .69 for APD, .67 for BPD, .71 for NPD, and .63 for HPD. As is usually found for personality, the effect of shared-in families (familial) environment was zero. In conclusion, when both interview and self-report questionnaire are taken into account, the heritability of Cluster B PD appears to be in the upper range of previous findings for mental disorders. PMID:23281671

Torgersen, Svenn; Myers, John; Reichborn-Kjennerud, Ted; Røysamb, Espen; Kubarych, Thomas S.; Kendler, Kenneth S.

2013-01-01

470

PACHIQ-R: the Parent-Child Interaction Questionnaire--revised.  

PubMed

The PACHIQ (Parent-Child Interaction Questionnaire) is designed to help clinicians and researchers assess how parents view relationship with their children (PACHIQ-Parent version), and how children evaluate their relationship with their parents (PACHIQ-Child version). The items in this questionnaire refer to both interpersonal behavior and feelings. Conceptually, the PACHIQ is based on learning theory and structural systems theory. The development of the PACHIQ was described by Lange, Blonk and Wiers (1998). The present article reports additional psychometric data obtained in the development and validation of a revised, shorter version of the questionnaire (PACHIQ-R). We present norm tables for families with children who are referred for psychological treatment, and norm tables for families in the normal Dutch population. The PACHIQ-R displays a two-factor structure with factors interpreted as Conflict Resolution and Acceptance. The parent version of the PACHIQ-R contains 21 items, the child version 25 items. PMID:12613126

Lange, Alfred; Evers, Anouk; Jansen, Hedi; Dolan, Conor

2002-01-01

471

Liouville's equation as a Schrödinger equation  

NASA Astrophysics Data System (ADS)

We show that every non-negative solution of Liouville's equation for an arbitrary (possibly non-Hamiltonian) dynamical system admits a factorization \\psi\\psi^*, where \\psi satisfies a Schrödinger equation of special form. The corresponding quantum system is obtained by Weyl quantization of a Hamiltonian system whose Hamiltonian is linear in the momenta. We discuss the structure of the spectrum of the special Schrödinger equation on a multidimensional torus and show that the eigenfunctions may have finite smoothness in the analytic case. Our generalized solutions of the Schrödinger equation are natural examples of non-selfadjoint extensions of Hermitian differential operators. We give conditions for the existence of a smooth invariant measure of a dynamical system. They are expressed in terms of stability conditions for the conjugate equations of variations.

Kozlov, V. V.

2014-08-01

472

Berkeley Expressivity Questionnaire The Berkeley Expressivity Questionnaire assesses three facets of emotional expressivity: negative  

E-print Network

: Gross, J.J., & John, O.P. (1997). Revealing feelings: Facets of emotional expressivity in self include: Gross, J.J. (2000). The Berkeley Expressivity Questionnaire. In J. Maltby, C.A. Lewis, & A Mellen Press. Gross, J.J., & John, O.P. (1998). Mapping the domain of expressivity: Multi-method evidence

Gross, James J.

473

Body Dissatisfaction and Eating Disturbances in Early Adolescence: A Structural Modeling Investigation Examining Negative Affect and Peer Factors  

ERIC Educational Resources Information Center

This study tested five proposed models of the relationship of negative affect and peer factors in early adolescent body dissatisfaction, die