914 resultados para Three Factor Model
Resumo:
'Brain drain' is a phenomenon in which people of a high level of skills, qualifications, and competence, leave their countries and emigrate. One major case of the brain drain happens when students from developing countries studying in the developed countries decide not to return home after their studies. We examined the reasons for international students' inclination to stay in their host countries in a sample of 949 management students who came to study in the United Kingdom and the United States. The results support a three-fold model of factors that influenced this inclination. Students' perceptions of ethnic differences and labor markets, their adjustment process to the host country, and their family ties in host and home countries all affect their intention to stay. © 2006 Elsevier Inc. All rights reserved.
Resumo:
We use regulatory focus theory to derive specific predictions regarding the differential relationships between regulatory focus and commitment. We estimated a structural equation model using a sample of 520 private and public sector employees and found in line with our hypotheses that (a) promotion focus related more strongly to affective commitment than prevention focus, (b) prevention focus related more strongly to continuance commitment than promotion focus, (c) promotion and prevention focus had equally strong effects on normative commitment. Implications of these findings for the three-component model of commitment, especially the ‘dual nature’ of normative commitment, as well as implications for human resources management and leadership are discussed.
Resumo:
This thesis describes an experimental and analytic study of the effects of magnetic non-linearity and finite length on the loss and field distribution in solid iron due to a travelling mmf wave. In the first half of the thesis, a two-dimensional solution is developed which accounts for the effects of both magnetic non-linearity and eddy-current reaction; this solution is extended, in the second half, to a three-dimensional model. In the two-dimensional solution, new equations for loss and flux/pole are given; these equations contain the primary excitation, the machine parameters and factors describing the shape of the normal B-H curve. The solution applies to machines of any air-gap length. The conditions for maximum loss are defined, and generalised torque/frequency curves are obtained. A relationship between the peripheral component of magnetic field on the surface of the iron and the primary excitation is given. The effects of magnetic non-linearity and finite length are combined analytically by introducing an equivalent constant permeability into a linear three-dimensional analysis. The equivalent constant permeability is defined from the non-linear solution for the two-dimensional magnetic field at the axial centre of the machine to avoid iterative solutions. In the linear three-dimensional analysis, the primary excitation in the passive end-regions of the machine is set equal to zero and the secondary end faces are developed onto the air-gap surface. The analyses, and the assumptions on which they are based, were verified on an experimental machine which consists of a three-phase rotor and alternative solid iron stators, one with copper end rings, and one without copper end rings j the main dimensions of the two stators are identical. Measurements of torque, flux /pole, surface current density and radial power flow were obtained for both stators over a range of frequencies and excitations. Comparison of the measurements on the two stators enabled the individual effects of finite length and saturation to be identified, and the definition of constant equivalent permeability to be verified. The penetration of the peripheral flux into the stator with copper end rings was measured and compared with theoretical penetration curves. Agreement between measured and theoretical results was generally good.
Resumo:
Competition between four foliose lichen species which have distinct aspect distributions on slate rock in South Gwynedd, Wales, U.K. was studied in the field using a factorial experimental design. The lichens were grown as fragments glued to pieces of slate in monoculture and in two-, three- and four-species mixtures. The pieces of slate were placed to face a northerly or southerly direction. Growth in area (mm2) was used as a measure of performance in the experiment. The growth in area of Parmelia conspersa in south facing plots was not reduced in the presence of any of its competitors but its growth was reduced in the presence of Parmelia saxatilis in north facing plots. The growth of Parmelia glabratula ssp. fuliginosa was reduced in the presence of P. conspersa and P. saxatilis in south and north facing plots. Physcia orbicularis was reduced by P. conspersa in south facing plots and by both P. glabratula ssp. fuliginosa and P. saxatilis in north facing plots. The growth of P. saxatilis was increased by P. glabratula ssp. fuliginosa in south facing plots but was not reduced by any of its competitors in north facing plots. Significant two and three factor interactions suggested that the results from the three- and four-species mixtures were not always predictable from the results of the two-species mixtures. The results of the experiment may help to explain the existing aspect distribution of the four species on slate rock in South Gwynedd.
Resumo:
This thesis presents an effective methodology for the generation of a simulation which can be used to increase the understanding of viscous fluid processing equipment and aid in their development, design and optimisation. The Hampden RAPRA Torque Rheometer internal batch twin rotor mixer has been simulated with a view to establishing model accuracies, limitations, practicalities and uses. As this research progressed, via the analyses several 'snap-shot' analysis of several rotor configurations using the commercial code Polyflow, it was evident that the model was of some worth and its predictions are in good agreement with the validation experiments, however, several major restrictions were identified. These included poor element form, high man-hour requirements for the construction of each geometry and the absence of the transient term in these models. All, or at least some, of these limitations apply to the numerous attempts to model internal mixes by other researchers and it was clear that there was no generally accepted methodology to provide a practical three-dimensional model which has been adequately validated. This research, unlike others, presents a full complex three-dimensional, transient, non-isothermal, generalised non-Newtonian simulation with wall slip which overcomes these limitations using unmatched ridding and sliding mesh technology adapted from CFX codes. This method yields good element form and, since only one geometry has to be constructed to represent the entire rotor cycle, is extremely beneficial for detailed flow field analysis when used in conjunction with user defined programmes and automatic geometry parameterisation (AGP), and improves accuracy for investigating equipment design and operation conditions. Model validation has been identified as an area which has been neglected by other researchers in this field, especially for time dependent geometries, and has been rigorously pursued in terms of qualitative and quantitative velocity vector analysis of the isothermal, full fill mixing of generalised non-Newtonian fluids, as well as torque comparison, with a relatively high degree of success. This indicates that CFD models of this type can be accurate and perhaps have not been validated to this extent previously because of the inherent difficulties arising from most real processes.
Resumo:
A three-dimensional model of human ABCB1 nucleotide-binding domain (NBD) was developed by homology modelling using the high-resolution human TAP1 transporter structure as template. Interactions between NBD and flavonoids were investigated using in silico docking studies. Ring-A of unmodified flavonoid was located within the NBD P-loop with the 5-hydroxyl group involved in hydrogen bonding with Lys1076. Ring-B was stabilised by hydrophobic stacking interactions with Tyr1044. The 3-hydroxyl group and carbonyl oxygen were extensively involved in hydrogen bonding interactions with amino acids within the NBD. Addition of prenyl, benzyl or geranyl moieties to ring-A (position-6) and hydrocarbon substituents (O-n-butyl to O-n-decyl) to ring-B (position-4) resulted in a size-dependent decrease in predicted docking energy which reflected the increased binding affinities reported in vitro.
Resumo:
Secondary pyrolysis in fluidized bed fast pyrolysis of biomass is the focus of this work. A novel computational fluid dynamics (CFD) model coupled with a comprehensive chemistry scheme (134 species and 4169 reactions, in CHEMKIN format) has been developed to investigate this complex phenomenon. Previous results from a transient three-dimensional model of primary pyrolysis were used for the source terms of primary products in this model. A parametric study of reaction atmospheres (H2O, N2, H2, CO2, CO) has been performed. For the N2 and H2O atmosphere, results of the model compared favorably to experimentally obtained yields after the temperature was adjusted to a value higher than that used in experiments. One notable deviation versus experiments is pyrolytic water yield and yield of higher hydrocarbons. The model suggests a not overly strong impact of the reaction atmosphere. However, both chemical and physical effects were observed. Most notably, effects could be seen on the yield of various compounds, temperature profile throughout the reactor system, residence time, radical concentration, and turbulent intensity. At the investigated temperature (873 K), turbulent intensity appeared to have the strongest influence on liquid yield. With the aid of acceleration techniques, most importantly dimension reduction, chemistry agglomeration, and in-situ tabulation, a converged solution could be obtained within a reasonable time (∼30 h). As such, a new potentially useful method has been suggested for numerical analysis of fast pyrolysis.
Resumo:
Purpose: This paper aims to explore front line employee performance in retail banking and presents distinct components of employee performance, including extra-role and sabotage behaviours. Design/methodology/approach: Data was collected from Irish bank employees. Usable responses were received from 404 respondents and subjected to exploratory factor analysis. Structural Equation Modeling (SEM) was used to undertake a confirmatory factor analysis of the emergent five-factor model. Findings: Results indicate front line employee performance is multi-faceted and comprised of civility, assurance and reliability, customer orientation, as well as extra-role behaviour and anti-role behaviour, or sabotage. Research limitations/implications: This exploratory study focuses on the Irish banking sector. To explore the generalisabilty of results, replication studies among other samples of branch banking employees in other countries are in order. Moreover, our survey is limited to the views of branch employees. We advocate research among bank managers and customers to triangulate potentially divergent views about performance. Practical implications: Findings have implications for recruitment, training and rewards. To ensure new hires are service minded, managers must consider their potential for extra-role or sabotage behaviour. Employees who demonstrate extra-role behaviours must be rewarded to encourage the adoption of such behaviours. Managers must also seek to minimise job stress in order to curtail anti-role behaviours. Originality/value: This paper offers insights into employees' views about their own performance at the front line. It extends the conceptualisation of service quality, by considering extra-role behaviour and sabotage as components of employee performance. © Emerald Group Publishing Limited.
Resumo:
This case study investigated the decision-making process of high-achieving high school students and their parents in selecting a college or university. The conceptual framework that guided this study included theoretical and empirical research framed around a three-phase model of college choice. Parental influence dominated the first phase of this model. The search phase, which was the second and the most crucial one, included financial considerations related to this decision, admissions considerations during the search phase, the psychology of decision making, and advertising strategies for teenagers. Once students completed the search phase they developed expectations of the institutions they considered prior to making the final decision. The study employed qualitative methods using individual interviews with students and their parents. ^ Six high-achieving high school seniors from a South Florida high school and their parents were selected to participate in this study. Of these students, four were female and two were male. Participants were individually interviewed on two separate occasions over a three-month period. Students and their parents were interviewed separately, with one exception, during the first set of interviews and together during the second. The data obtained from these interviews were transcribed and these transcripts were coded, categorized, analyzed, and sorted into major themes and submitted to interpretive analysis. ^ In-depth descriptions of participants' experiences during the decision-making process are described in the study. Financial factors—which included the cost of college, the socio-economic status of the family, and scholarship possibilities—drove the selection process for these students and their parents, most of whom reported their family incomes between the lower-middle to upper-middle class range. All of these students took advantage of the Bright Futures Scholarship Program, other scholarship opportunities, and the lower tuition costs of in-state public institutions. The effectiveness of recruitment techniques, such as brochures, campus visits, the development of college Web sites, and the overall impact of Internet resources, was assessed by the researcher. ^ As these students had progressed through the search phase, they developed perceptions of potential institutions as they were assisted by those around them. The value of familiarity with institutions and the use of heuristics were quite evident in the final analysis of this study, based on what the students communicated about how their knowledge of and comfort in these institutions affected their decisions. Parental influence played an important role in the selection process for the students in this study as the parents clearly directed the process, by the constant advice they gave their children and by the financial limitations they communicated to them. ^
Resumo:
Context effects in a personality scale were examined by determining if conscientiousness scale (C) scores were significantly different when administered alone vs. part of a Five Factor Model inventory (Big5). The effectiveness of individual difference variables (IDVs) as predictors of the context effect was also examined. The experiment compared subjects who completed the full Big5 once and the C alone once (Big5/C or C/Big5) to subjects who complete either the Big5 inventory twice (Big5/Big5) or the C twice (C/C). No significant differences were found. When Big5/C and C/Big5 groups were combined, IDVs were tested, and only the field dependence variable (R2 = .06) was found to significantly predict the context effect. However, the small R2 minimized concerns of context effects in Big5 inventories. ^
Resumo:
Anxiety sensitivity is a multifaceted cognitive risk factor currently being examined in relation to anxiety and depression. The paucity of research on the relative contribution of the facets of anxiety sensitivity to anxiety and depression, coupled with variations in existing findings, indicate that the relations remain inadequately understood. In the present study, the relations between the facets of anxiety sensitivity, anxiety, and depression were examined in 730 Hispanic-Latino and European-American youth referred to an anxiety specialty clinic. Youth completed the Childhood Anxiety Sensitivity Index, the Revised Children’s Manifest Anxiety Scale, and the Children’s Depression Inventory. The factor structure of the Childhood Anxiety Sensitivity Index was examined using ordered-categorical confirmatory factor analytic techniques. Goodness-of-fit criteria indicated that a two-factor model fit the data best. The identified facets of anxiety sensitivity included Physical/Mental Concerns and Social Concerns. Support was also found for cross-ethnic equivalence of the two-factor model across Hispanic-Latino and European-American youth. Structural equation modeling was used to examine models involving anxiety sensitivity, anxiety, and depression. Results indicated that an overall measure of anxiety sensitivity was positively associated with both anxiety and depression, while the facets of anxiety sensitivity showed differential relations to anxiety and depression symptoms. Both facets of anxiety sensitivity were related to overall anxiety and its symptom dimensions, with the exception being that Social Concerns was not related to physiological anxiety symptoms. Physical/Mental Concerns were strongly associated with overall depression and with all depression symptom dimensions. Social Concerns was not significantly associated with depression or its symptom dimensions. These findings highlight that anxiety sensitivity’s relations to youth psychiatric symptoms are complex. Results suggest that focusing on anxiety sensitivity’s facets is important to fully understand its role in psychopathology. Clinicians may want to target all facets of anxiety sensitivity when treating anxious youth. However, in the context of depression, it might be sufficient for clinicians to target Physical/Mental Incapacitation Concerns.
Resumo:
The purpose of the present dissertation was to evaluate the internal validity of symptoms of four common anxiety disorders included in the Diagnostic and Statistical Manual of Mental Disorders fourth edition (text revision) (DSM-IV-TR; American Psychiatric Association, 2000), namely, separation anxiety disorder (SAD), social phobia (SOP), specific phobia (SP), and generalized anxiety disorder (GAD), in a sample of 625 youth (ages 6 to 17 years) referred to an anxiety disorders clinic and 479 parents. Confirmatory factor analyses (CFAs) were conducted on the dichotomous items of the SAD, SOP, SP, and GAD sections of the youth and parent versions of the Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV: C/P; Silverman & Albano, 1996) to test and compare a number of factor models including a factor model based on the DSM. Contrary to predictions, findings from CFAs showed that a correlated model with five factors of SAD, SOP, SP, GAD worry, and GAD somatic distress, provided the best fit of the youth data as well as the parent data. Multiple group CFAs supported the metric invariance of the correlated five factor model across boys and girls. Thus, the present study’s finding supports the internal validity of DSM-IV SAD, SOP, and SP, but raises doubt regarding the internal validity of GAD.^
Resumo:
The current study applies a two-state switching regression model to examine the behavior of a hypothetical portfolio of ten socially responsible (SRI) equity mutual funds during the expansion and contraction phases of US business cycles between April 1991 and June 2009, based on the Carhart four-factor model, using monthly data. The model identified a business cycle effect on the performance of SRI equity mutual funds. Fund returns were less volatile during expansion/peaks than during contraction/troughs, as indicated by the standard deviation of returns. During contraction/troughs, fund excess returns were explained by the differential in returns between small and large companies, the difference between the returns on stocks trading at high and low Book-to-Market Value, the market excess return over the risk-free rate, and fund objective. During contraction/troughs, smaller companies offered higher returns than larger companies (ci = 0.26, p = 0.01), undervalued stocks out-performed high growth stocks (h i = 0.39, p <0.0001), and funds with growth objectives out-performed funds with other objectives (oi = 0.01, p = 0.02). The hypothetical SRI portfolio was less risky than the market (bi = 0.74, p <0.0001). During expansion/peaks, fund excess returns were explained by the market excess return over the risk-free rate, and fund objective. Funds with other objectives, such as balanced funds and income funds out-performed funds with growth objectives (oi = −0.01, p = 0.03). The hypothetical SRI portfolio exhibited similar risk as the market (bi = 0.93, p <0.0001). The SRI investor adds a third criterion to the risk and return trade-off of traditional portfolio theory. This constraint is social performance. The research suggests that managers of SRI equity mutual funds may diminish value by using social and ethical criteria to select stocks, but add value by superior stock selection. The result is that the performance of SRI mutual funds is very similar to that of the market. There was no difference in the value added among secular SRI, religious SRI, and vice screens.
Resumo:
This paper explores the role of engagement in adult learning based on Illeris’ three dimensional model of learning and Yang’s holistic theory of knowledge and learning. Engagement and learning are integrated processes by which adult learners gain a deeper understanding and make meaning of the activities he or she is exposed to in a given learning environment.
Resumo:
This research was undertaken to explore dimensions of the risk construct, identify factors related to risk-taking in education, and study risk propensity among employees at a community college. Risk-taking propensity (RTP) was measured by the 12-item BCDQ, which consisted of personal and professional risk-related situations balanced for the money, reputation, and satisfaction dimensions of the risk construct. Scoring ranged from 1.00 (most cautious) to 6.00 (most risky).^ Surveys including the BCDQ and seven demographic questions relating to age, gender, professional status, length of service, academic discipline, highest degree, and campus location were sent to faculty, administrators, and academic department heads. A total of 325 surveys were returned, resulting in a 66.7% response rate. Subjects were relatively homogeneous for age, length of service, and highest degree.^ Subjects were also homogeneous for risk-taking propensity: no substantive differences in RTP scores were noted within and among demographic groups, with the possible exception of academic discipline. The mean RTP score for all subjects was 3.77, for faculty was 3.76, for administrators was 3.83, and for department heads was 3.64.^ The relationship between propensity to take personal risks and propensity to take professional risks was tested by computing Pearson r correlation coefficients. The relationships for the total sample, faculty, and administrator groups were statistically significant, but of limited practical significance. Subjects were placed into risk categories by dividing the response scale into thirds. A 3 x 3 factorial ANOVA revealed no interaction effects between professional status and risk category with regard to RTP score. A discriminant analysis showed that a seven-factor model was not effective in predicting risk category.^ The homogeneity of the study sample and the effect of a risk-encouraging environment were discussed in the context of the community college. Since very little data on risk-taking in education is available, risk propensity data from this study could serve as a basis for comparison to future research. Results could be used by institutions to plan professional development activities, designed to increase risk-taking and encourage active acceptance of change. ^