772 resultados para Parallel factor analysis


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A functional polymorphism (Val-158-Met) at the Catechol-O-methyltransferase (COMT) locus has been identified as a potential etiological factor in schizophrenia. Yet the association has not been convincingly replicated across independent samples. We hypothesized that phenotypic heterogeneity might be diluting the COMT effect. To clarify the putative association, we performed an exploratory analysis to test for association between COMT and five psychosis symptom scales. These were derived through factor analysis of the Operational Criteria Checklist for Psychiatric Illness. Our sample was the Irish Study of High Density Schizophrenia Families, a large collection consisting of 268 multiplex families. This sample has previously shown a small but significant effect of the COMT Val allele in conferring risk for schizophrenia. We tested for preferential transmission of COMT alleles from parent to affected offspring (n = 749) for each of the five factor-derived scales (negative symptoms, delusions, hallucinations, mania, and depression). Significant overtransmission of the Val allele was found for mania (P <0.05) and depression (P = 0.01) scales. Examination of odds ratios (ORs) revealed a heterogeneous effect of COMT, whereby it had no effect on Negative Symptoms, but largest impact on Depression (OR = 1.4). These results suggest a modest affective vulnerability conferred by this allele in psychosis, but will require replication.

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This study investigated the relationship between consideration of future consequences and alcohol use among adolescents. A cross-sectional design was used and a large sample of 12-to 16-year-old schoolchildren (n = 806) in Northern Ireland were recruited for this study. Alcohol use was assessed using a composite measure of drinking behaviour, the Adolescent Alcohol Involvement Scale. Time perspective was measured using the Consideration of Future Consequences Scale (CFCS). Data were also gathered on self-esteem, three domains of self-efficacy and aggression, all of which have been found to be related to both drinking behaviour and time perspective. Factor analysis of the CFCS revealed support for a two-factor solution, with CFC-I representing present orientation and CFC-F representing future orientation. After controlling for year in school (proxy for age) and gender and for clustering at school level, scores on both subscales were significantly associated with alcohol use. Only CFC-F score remained significant with the addition of psychosocial variables. These results support recent findings of a significant relationship between CFCS score and alcohol use in UK adolescents and University undergraduates, and suggest that in more fully controlled analyses, future orientation, rather than present, is related to adolescent drinking. Results are discussed in relation to health promotion. © 2013 Informa UK Ltd.

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The purpose of this paper is to identify best practice construction dispute resolution in small-to-medium enterprises (SMEs) within Ireland during the recent economic recession. A sequential mixed methodology encompassing a detailed literature review, case studies, and questionnaire survey is adopted, with results analyzed using both exploratory (data reduction) and confirmatory (structural equation modelling) factor analysis. The results show that four core aspects should be adopted by SMEs to achieve best practice construction dispute resolution in recession: third-party intervention, adoption of a streamlined process, proactive party characteristics, and the use of legal professionals. Numerous studies of this subject have been conducted; however, no research has been done to date documenting best practice in construction dispute resolution within SMEs, particularly in light of the economic recession in Ireland. It is clear that dispute resolution in Ireland is currently undergoing fundamental changes, and time is necessary to see if the new Construction Contracts Act 2013 will help this practice. Therefore, it is a fundamental requirement for project management and legal professionals to acknowledge the changing environment attributable to the economic downturn and the resultant SME best practices in dispute resolution. This paper fulfills a gap in knowledge with the emergence of the economic recession and the evolution of best practice in dispute resolution within SMEs in the Irish construction sector.

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Aim: The aim of this paper is to identify best practice relating to the effective management of materials in an urban, confined construction site, using structural equation modelling.

Methodology: A literature review, case study analysis and questionnaire survey are employed, with the results scrutinised using confirmatory factor analysis in the form of structural equation modelling.

Results: The following are the leading strategies in the management of materials in a confined urban site environment; (1) Consult and review the project programme, (2) Effective communication and delivery, (3) Implement site safety management plans, and (4) Proactive spatial monitoring and control.

Implication for Practice: With the relentless expansion of urban centres and the increasing high cost of materials, any potential savings made on-site would translate into significant monetary concessions on completion of a development.

Originality/Value: As on-site project management professionals successfully identify and implement the various strategies in the management of plant and materials on a confined urban site, successful resource management in this restrictive environment is attainable.

Innovative Aspect of Paper: An empirical study of three different construction sites in three different countries (Ireland, England and USA) together with a questionnaire survey from the industry, investigating the managerial strategies in the management of plant and material in confined urban site environments

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Purpose - To identify the critical factors causing construction disputes in Small to Medium Enterprises (SMEs) in Ireland during the recent recession period of 2007 to 2013.
Design/Methodology/Approach - A mixed method approach incorporating a literature review, case studies and questionnaire survey, with results analysed using exploratory (data reduction) factor analysis.
Findings - The results indicate seven core critical factors which result in construction disputes in SMEs in Ireland during a recession: Payment and extras; Physical work conditions; Poor financial/legal practise; Changes to the agreed scope of works; Time overrun; Defects; and Requests for increase in speed of project and long-term defects.
Research Limitations/Implications - With Ireland emerging from the current economic recession and the prevalence of SMEs to the construction sector, it is essential to document the core critical factors of construction disputes which emerge within this particular segment of the built environment.
Practical Implications - To address the adversarial nature of the construction sector and the prevalence of SMEs, it is essential to identify and document the critical factors of construction disputes within this remit. It is envisaged that the results of this research will be acknowledged, and the recommendations adopted, by construction SMEs, particularly within Ireland, as they emerge from the economic recession.
Originality/Value - This paper fulfils a gap in knowledge with the emergence of the economic recession and the identification of critical factors of construction dispute within SMEs in the Irish construction industry.

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Across one longitudinal and two cross-sectional surveys in Northern Ireland, we tested a model of intergroup relations in which out-group attitudes and behavioral tendencies are predicted by cross-group friendship and positive intergroup appraisals, mediated by intergroup emotions and out-group trust. In study 1, out-group friendship at time 1 predicted out-group trust at time 2 (one year later), controlling for prior out-group trust. In study 2, positive and negative intergroup emotions mediated the effects of friendship on positive and negative behavioral tendencies and attitudes. In study 3, a confirmatory factor analysis indicated that trust and emotions are distinct constructs with unique predictive contributions. We then tested a model in which cross-group friendship predicted intergroup emotions and trust through intimate self-disclosure in out-group friendships. Our findings support an integration of an intergroup emotions framework with research highlighting the importance of cross-group friendship in fostering positive intergroup outcomes.

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A reliable and valid instrument is needed to screen for depression in palliative patients. The interRAI Depression Rating Scale (DRS) is based on seven items in the interRAI Palliative Care instrument. This study is the first to explore the dimensionality, reliability and validity of the DRS in a palliative population. Palliative home care patients (n = 5,175) residing in Ontario (Canada) were assessed with the interRAI Palliative Care instrument. Exploratory factor analysis and Mokken scale analysis were used to identify candidate conceptual models and evaluate scale homogeneity/performance. Confirmatory factor analysis compared models using standard goodness-of-fit indices. Convergent and divergent validity were investigated by examining polychoric correlations between the DRS and other items. The “known groups” test determined if the DRS meaningfully distinguished among client subgroups. The non-hierarchical two factor model showed acceptable fit with the data, and ordinal alpha coefficients of 0.83 and 0.82 were observed for the two DRS subscales. Omega hierarchical (ωh) was 0.78 for the bifactor model, with the general factor explaining three quarters of the common variance. Despite the multidimensionality evident in the factor analyses, bifactor modelling and the Mokken homogeneity coefficient (0.34) suggest that the DRS is a coherent scale that captures important information on sub-constructs of depression (e.g., somatic symptoms). Higher correlations were seen between the DRS and mood and psychosocial well-being items, and lower correlations with functional status and demographic variables. The DRS distinguished in the expected manner for known risk factors (e.g., social support, pain). The results suggest that the DRS is primarily unidimensional and reliable for use in screening for depression in palliative care patients.

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Title Evaluation of Video Presentation to Deliver Surgical Anatomy Teaching

Authors Walsh I.K., Boohan M., Dorman A.

Objectives To evaluate the efficacy of newly introduced video presentation to deliver Surgical Anatomy teaching to undergraduate medical students.

Design and Setting Qualitative and quantitative study using questionnaires and focus groups, employing students undertaking the perioperative medicine module of the phase 4 undergraduate medical curriculum at Queen’s University Belfast.

Outcome Measures To determine:
(1) if video presentation is effective in delivering surgical anatomy teaching,
(2) student’s learning preferences regarding this teaching method.
Results The questionnaire response rate was 89% (216 of 244 students; female: male ratio 1.25) and 42 students participated in 6 focus groups. Mean questionnaire responses indicated a favourable opinion on quality assurance items, with a mixed response to video presentation as a learning method. 71% of students preferred to receive a lecture in person, rather than via video presentation. There were no statistically significant differences between genders regarding learning preferences in general and regarding video versus live presentation in particular. Exploratory factor analysis demonstrated that favourable responses to video presentation were strongly associated with perceived audiovisual quality and learning preferences (Cronbach’s alpha coefficient 0.77), with 72% of students considering video presentation worthwhile. Positive perception of overall quality was strongly associated with learning preferences as well as more generic quality assurance issues (80% students; alpha coefficient 0.83).
The results were supported by triangulation of the above quantitative data with qualitative data generated by the focus groups. Students further articulated the view that video presentation may be more appropriate and effective in a mixed method setting.

Reference Basu Roy R, McMahon GT. Video-based cases disrupt deep critical thinking in problem-based learning. Med Educ 2012 Apr;46(4):426-435.

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Two important strands of research within the literature on Environmental Operations Management (EOM) relate to environmental approach and performance. Often in this research the links between environmental approach, environmental performance and EOM are considered separately with little consideration given to the interrelationships between them. This study develops and tests a theoretical framework that combines these two strands to explore how UK food manufacturers approach EOM. The framework considers the relationships between an environmentally pro-active strategic orientation, EOM and environmental and cost performance. A cross-sectional survey was developed to collect data from a sample of 1200 food manufacturing firms located within the UK. Responses were sought from production and operations managers who are knowledgeable about the environmental operations practices within their firms. A total of 149 complete and useable responses were obtained. The reliability and validity of the scales used in the survey were tested using exploratory factor analysis, prior to the testing of the hypotheses underpinning the theoretical framework using hierarchical regression analysis. Our results generate support for a link between environmental proactivity, environmental practices and performance, consistent with the natural resource-based view (NRBV) and a number of studies in the extant literature. In considering environmental proactivity as a standalone concept that influences the implementation of environmental practices outlined in the NRBV, our study generates some novel insights into these links. Further our results provide some interesting insights for managers within the food industry who can identify the potential benefits of certain practices for performance within this unique context.

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1. The population density and age structure of two species of heather psyllid Strophingia ericae and Strophingia cinereae, feeding on Calluna vulgaris and Erica cinerea, respectively, were sampled using standardized methods at locations throughout Britain. Locations were chosen to represent the full latitudinal and altitudinal range of the host plants.

2. The paper explains how spatial variation in thermal environment, insect life-history characteristics and physiology, and plant distribution, interact to provide the mechanisms that determine the range and abundance of Strophingia spp.

3. Strophingia ericae and S. cinereae, despite the similarity in the spatial distribution patterns of their host plants within Britain, display strongly contrasting geographical ranges and corresponding life-history strategies. Strophingia ericae is found on its host plant throughout Britain but S. cinereae is restricted to low elevation sites south of the Mersey-Humber line and occupies only part of the latitudinal and altitudinal range of its host plant. There is no evidence to suggest that S. ericae has reached its potential altitudinal or latitudinal limit in the UK, even though its host plant appears to reach its altitudinal limit.

4. There was little difference in the ability of the two Strophingia spp. to survive shortterm exposure to temperatures as low as - 15 degrees C and low winter temperatures probably do not limit distribution in S. cinereae.

5. Population density of S. ericae was not related to altitude but showed a weak correlation with latitude. The spread of larval instars present at a site, measured as an index of instar homogeneity, was significantly correlated with a range of temperature related variables, of which May mean temperature and length of growing season above 3 degrees C (calculated using the Lennon and Turner climatic model) were the most significant. Factor analysis did not improve the level of correlation significantly above those obtained for single climatic variables. The data confirmed that S. ericae has a I year life cycle at the lowest elevations and a 2 year life cycle at the higher elevations. However, there was no evidence, as previously suggested, for an abrupt change from a one to a 2 year life cycle in S. ericae with increasing altitudes or latitudes.

6. By contrast with S. ericae, S. cinereae had an obligatory 1 year life cycle, its population decreased with altitude and the index of instar homogeneity showed little correlation with single temperature variables. Moreover, it occupied only part of the range of its host plant and its spatial distribution in the UK could be predicted with 96% accuracy using selected variables in discriminant analysis.

7. The life histories of the congeneric heather psyllids reflect adaptations that allow them to exploit host plants with different distributions in climatic and thereby geographical space. Strophingia ericae has the flexible life history that enables it to exploit C. vulgaris throughout its European boreal temperate range. Strophingia cinereae has a less flexible life history and is adapted for living on an oceanic temperate host. While the geographic ranges of the two Strophingia spp. overlap within the UK, the psyllids appear to respond differently to variation in their thermal environment.

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This thesis investigates critical thinking with a particular focus on measurement in undergraduate students. A higher education context was chosen because many regard critical thinking development as a primary goal for third level education. Nine studies, both cross-sectional and longitudinal in design, were conducted with undergraduate psychology students (N=387), using the California Critical Thinking Disposition Inventory (CCTDI) and the California Critical Thinking Skills Test (CCTST). Studies 1-3 revealed psychometric weaknesses in the CCTDI and revised the scale with factor analysis and reliability analysis to form the CCTDI United Kingdom revision (CCTDI-UK). Study 4 investigated convergent validity and showed significant inter-correlation between the sub-scales of the CCTDI-UK, and significant correlations with the Openness scale of the NEO Personality Inventory (NEO PI-R). The study also provided evidence for improvement in scores on three of the six sub-scales in the CCTDI-UK (Truth-Seeking, Inquisitiveness, Open-Mindedness) during the course of an undergraduate degree. Study 5 explored a two factor structure for critical thinking dispositions. Study 6 used reliability analysis to revise the CCTST to produce the CCTST-UK. Study 7 showed that the CCTST-UK had a moderate correlation with degree attainment and a slightly higher correlation with a test of non-verbal intelligence (Raven’s Advanced Progressive Matrices short form); in addition, the study showed that scores on the CCTST-UK improved during the course of the degree. Studies 8 and 9 investigated the potential of critical thinking for predicting degree attainment. A-levels predicted approximately 10% of the variance of degree attainment while entry level scores on the CCTST-UK predicted an additional 5%. Exit level scores on the CCTST-UK and the Inquisitive sub-scale of the CCTDI-UK were found to be predictors of degree attainment The main conclusions of the thesis were that these tests had significant potential for predicting degree attainment and that they measured a substantial proportion of the theoretical constructs identified by the major authors in critical thinking.

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PURPOSE: The aim of this study was to determine whether combining potential biomarkers of fruit and vegetables is better at predicting FV intake within FV intervention studies than single biomarkers.

DESIGN: Data from a tightly controlled randomised FV intervention study (BIOFAV; all food provided and two meals/day on weekdays consumed under supervision) were used. A total of 30 participants were randomised to either 2, 5 or 8 portions FV/day for 4 weeks, and blood samples were collected at baseline and 4 weeks for plasma vitamin C and serum carotenoid analysis. The combined biomarker approach was also tested in three further FV intervention studies conducted by the same research team, with less strict dietary control (FV provided and no supervised meals).

RESULTS: The combined model containing all carotenoids and vitamin C was a better fit than either the vitamin C only (P < 0.001) model or the lutein only (P = 0.006) model in the BIOFAV study. The C-statistic was slightly lower in the lutein only model (0.85) and in the model based upon factor analysis (0.88), and much lower in the vitamin C model (0.68) compared with the full model (0.95). Results for the other studies were similar, although the differences between the models were less marked.

CONCLUSIONS: Although there was some variation between studies, which may relate to the level of dietary control or participant characteristics, a combined biomarker approach to assess overall FV consumption may more accurately predict FV intake within intervention studies than the use of a single biomarker. The generalisability of these findings to other populations and study designs remains to be tested. 

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The positive relationships between urban green space and health have been well documented. Little is known, however, about the role of residents’ emotional attachment to local green spaces in these relationships, and how attachment to green spaces and health may be promoted by the availability of accessible and usable green spaces. The present research aimed to examine the links between self-reported health, attachment to green space, and the availability of accessible and usable green spaces. Data were collected via paper-mailed surveys in two neighborhoods (n = 223) of a medium-sized Dutch city in the Netherlands. These neighborhoods differ in the perceived and objectively measured accessibility and usability of green spaces, but are matched in the physically available amount of urban green space, as well as in demographic and socio-economic status, and housing conditions. Four dimensions of green space attachment were identified through confirmatory factor analysis: place dependence, affective attachment, place identity and social bonding. The results show greater attachment to local green space and better self-reported mental health in the neighborhood with higher availability of accessible and usable green spaces. The two neighborhoods did not differ, however, in physical and general health. Structural Equation Modelling confirmed the neighborhood differences in green space attachment and mental health, and also revealed a positive path from green space attachment to mental health. These findings convey the message that we should make green places, instead of green spaces.

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The contemporary literature investigating the construct broadly known as time perspective is replete with methodological and conceptual concerns. These concerns focus on the reliability and factorial validity of measurement tools, and the sample-specific modification of scales. These issues continue to hamper the development of this potentially useful psychological construct. An emerging body of evidence has supported the six-factor structure of scores on the Adolescent Time Inventory-Time Attitudes Scale, as well as their reliability. The present study utilized data from the first wave of a longitudinal study in the United Kingdom to examine the reliability, validity, and cross-cultural invariance of the scale. Results showed that the hypothesized six-factor model provided the best fit for the data; all alpha and omega estimates were >. .70; scores on ATI-TA factors related meaningfully to self-efficacy scores; and the factor structure was invariant across both research sites. Results are discussed in the context of the extant temporal literature.

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O mercado imobiliário tem um papel importante nas economias modernas, tanto a nível macro como a nível micro. Ao nível macro, a construção de habitação representa um sector importante e influente na economia, com efeitos multiplicadores significativos sobre a produção e o emprego. Ao nível micro, uma residência representa o activo mais valioso da maioria dos indivíduos e uma parcela muito relevante da riqueza das famílias. Para estas, o custo e a qualidade das suas habitações influencia directa e indirectamente a sua qualidade de vida. A habitação é por isso mesmo um tema, que avaliado nas suas múltiplas dimensões, se caracteriza por ser bastante complexo, mas também ao mesmo tempo desafiante. De modo a delimitar o objecto de análise do trabalho de investigação, esta tese realça os aspectos de localização e distribuição espacial das habitações urbanas. Será desenvolvido um quadro conceptual e respectiva metodologia para a compreender a estrutura espacial da habitação urbana realçando os três aspectos fundamentais da análise espacial: heterogenidade espacial, dependência espacial e escala espacial. A metodologia, aplicada à área urbana de Aveiro e Ílhavo é baseada numa análise hedónica factorial de preços e na noção não geométrica do espaço. Primeiro, é fixada uma escala territorial e são definidos submercados habitacional. Posteriormente, quer a heterogeneidade quer a dependência espaciais são estudados utilizando métodos econométricos, sem considerar qualquer padrão fixo e conhecido de interações espaciais. Em vez disso, são desenvolvidos novos métodos,tendo como base o modelo hedónico factorial, para inferir sobre os potenciais drivers de difusão espacial no valor de uma habitação. Este modelo, foi aplicado a duas diferentes escalas espaciais, para compreender as preferências dos indivíduos em Aveiro ao escolher os seus locais de residencia, e como estas afectam os preços da habitação. O trabalho empírico, utilizando duas bases de dados de habitação distintas, aplicadas ao mercado de habitação de Aveiro mostram: i) em linha com a literatura, a dificuldade de definir submercados e compreender as inter-relações entre esses mercados; ii) a utilidade de uma abordagem híbrida, combinando análise factorial com regressão; iii) a importância fundamental que o efeito escala espacial desempenha no estudo da heterogeneidade e dos spillovers e, finalmente, iv) uma metodologia inovadora para analisar spillovers sem assumir aprioristicamente uma estrutura espacial específica de difusão espacial. Esta metodologia considera a matriz de pesos espaciais (W) desconhecida e estimatima as interações espaciais dentro e entre submercados habitação.