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Multi-Recycling of Transuranic Elements in a Modified PWR Fuel AssemblyChambers, Alex 2011 August 1900 (has links)
The nuclear waste currently generated in the United States is stored in spent fuel pools and dry casks throughout the country awaiting a permanent disposal solution. One efficient solution would be to remove the actinides from the waste and transmute these isotopes in a fast spectrum reactor. Currently this technology is unavailable on a commercial scale and a considerable amount of research and development is still required. An alternate solution is to reprocess and recycle the used fuel in thermal reactors, creating new fuel while reducing the amount of waste and its impact to the environment. This thesis examines the possibility of multi-recycling the transuranics (Pu, Np, Am, and Cm) in a standard pressurized water reactor (PWR). Two types of recycling strategies will be examined: one where Pu, Np, and Am are recycled (TRU-Cm) and a second where the previous isotopes as well as Cm are recycled (TRU+Cm). To offset the hardened neutron spectrum that results from the inclusion of the transuranics, a smaller fuel pin is employed to provide additional moderation.
Computer simulations are used to model the in-reactor physics and long-term isotopic decay. Each fuel type is assessed based on the required U-235 enrichment, void coefficient, transuranic production/destruction, and radiotoxicity reduction as compared to a UOX and MOX assembly.
It is found that the most beneficial recycling strategy is the one where all of the transuranics are recycled. The inclusion of Cm reduces the required U-235 enrichment, compared to the other multi-recycled fuel and, after a significant number of recycles, can result in the required enrichment to decrease. This fuel type also maintains a negative void coefficient for each recycle. The void coefficient of the fuel type without Cm becomes positive after the third cycle. The transmutation destruction of the two multi-recycled assemblies is less than that of a MOX assembly, but the transmutation efficiency of the multi-recycled assemblies exceeds the MOX assemblies. The radiotoxicity of both multi-recycled assemblies is significantly lower than the UOX and MOX with the TRU+Cm fuel being the lowest. When Curium is recycled only 28,000 years are required for the radiotoxicity of the waste to reach that of natural Uranium and when Cm is not recycled, the amount of time increases to 57,000 years.
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Neuroticism, daily hassles, and depressive symptoms an examination of moderating and mediating effects /Hutchinson, James, January 2004 (has links) (PDF)
Thesis (M.S. in psychology)--Washington State University. / Includes bibliographical references.
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Robustness of Latent Variable Interaction Methods to Nonnormal Exogenous IndicatorsJanuary 2010 (has links)
abstract: For this thesis a Monte Carlo simulation was conducted to investigate the robustness of three latent interaction modeling approaches (constrained product indicator, generalized appended product indicator (GAPI), and latent moderated structural equations (LMS)) under high degrees of nonnormality of the exogenous indicators, which have not been investigated in previous literature. Results showed that the constrained product indicator and LMS approaches yielded biased estimates of the interaction effect when the exogenous indicators were highly nonnormal. When the violation of nonnormality was not severe (symmetric with excess kurtosis < 1), the LMS approach with ML estimation yielded the most precise latent interaction effect estimates. The LMS approach with ML estimation also had the highest statistical power among the three approaches, given that the actual Type-I error rates of the Wald and likelihood ratio test of interaction effect were acceptable. In highly nonnormal conditions, only the GAPI approach with ML estimation yielded unbiased latent interaction effect estimates, with an acceptable actual Type-I error rate of both the Wald test and likelihood ratio test of interaction effect. No support for the use of the Satorra-Bentler or Yuan-Bentler ML corrections was found across all three methods. / Dissertation/Thesis / M.A. Psychology 2010
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Predicting Variation in Responsiveness to the Family Check-Up in Early Childhood: A Mixture Model ApproachJanuary 2016 (has links)
abstract: The present study applied latent class analysis to a family-centered prevention
trial in early childhood to identify subgroups of families with differential responsiveness to the Family Check-up (FCU) intervention. The sample included 731 families of 2-year- olds randomized to the FCU or control and followed through age five with yearly follow up assessments (Dishion et al., 2014; Shaw et al., 2015). A two-step mixture model was used to examine whether specific constellations of family characteristics at age 2 (baseline) were related to intervention response at age 3, 4, and 5. The first step empirically identified latent classes of families based on a variety of demographic and adjustment variables selected on the basis of previous research on predictors of response to the FCU and parent training in general, as well as on the clinical observations of FCU implementers. The second step modeled the effect of the FCU on longitudinal change in children's problem behavior in each of the empirically derived latent classes. Results suggested a five-class solution, where a significant intervention effect of moderate-to- large size was observed in one of the five classes. The families within the responsive class were characterized by child neglect, legal problems, and mental health issues. Pairwise comparisons revealed that the intervention effect was significantly greater in this class of families than in two other classes that were generally less at risk for the development of disruptive behavior problems, and post hoc analyses partially supported these results. Thus, results indicated that the FCU was most successful in reducing child problem behavior in the highly distressed group of families. We conclude by discussing the potential practical utility of these results and emphasizing the need for future research to evaluate this approach's predictive accuracy. / Dissertation/Thesis / Masters Thesis Psychology 2016
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Impact of early attachment experiences on adolescents' mental health and future thinkingWest, Holly January 2014 (has links)
Background: Attachment theory [Bowlby, J. 1969, 1973, 1980 Attachment & Loss, Volumes I-III, London: Hogarth Press] proposes that a person’s experiences of care in infancy and childhood lay the foundations for their internal working models of themselves and others. Inconsistent, unpredictable or hostile caregiving can lead individuals to hold negative internal working models which can impact on their mental health later in life. Many looked after and accommodated young people have experienced this type of neglectful or abusive parenting. These experiences of parenting may lead looked after young people to have internal working models of themselves as ineffective and of others as powerful, thus leading them to develop a learned helplessness and a more external locus of control. Objectives: A systematic review was carried out in order to explore the mechanisms by which the relationship between attachment and depression functions in adolescence. An empirical study aimed to investigate whether young people with negative attachment experiences, those who are looked after and accommodated, have higher levels of depression or a more external locus of control than other young people of the same age and the role these play in their future thinking. Method: Nineteen papers investigating mediators and moderators of the attachmentdepression relationship in adolescence were reviewed. In the empirical study, a group of looked after and a group of non-looked after young people aged 15-18 were asked about their approach and avoidance goals for the future and were asked to rate beliefs in their control over, and likelihood of, achieving these goals. Results: Evidence was found for a number of mediators of the relationship between attachment and adolescent depression. There were also found to be significant differences between the two groups with differing care histories with regards to levels of depression and locus of control, with looked after young people having higher levels of depression and a more external locus of control. A mediation analysis found that locus of control mediated the relationship between looked after status and future thinking. Conclusions: A person’s attachment history and experiences of care in early childhood can impact on their levels of depression and locus of control. There are a number of factors which mediate or moderate the attachment-depression relationship, most of which can be attributed to an individual’s internal working model of either themselves or others. Locus of control plays a critical role in young people’s future thinking and professionals working with accommodated adolescents should facilitate these young people to have experiences which will help to increase the internality of their locus of control. Objective: Attachment security has been found to be a significant predictor of depression in adolescence. This review aimed to examine the pathways by which this relationship functions by reviewing studies which have investigated potential mediating or moderating factors. Method: Studies were included if they investigated mediation and/or moderation of the relationship between attachment and adolescent depression. Results: A number of cognitive and social factors were found to mediate the attachmentdepression relationship. Age was found to be a significant moderator of the relationship but the findings on gender were inconsistent. The findings should be treated with caution, however, as many of the studies reviewed were potentially underpowered. Conclusions: A model is proposed in which mediating factors were linked to the internal working models of self and others. The need for future research to be carried out in clinical adolescent populations with sample sizes large enough to ensure adequate power was identified.
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Smluvní pokuta jako nástroj utvrzení dluhu v obchodních vztazích / Contractual penalty as a means of corroboration of a debt in business relationsPalan, Ondřej January 2015 (has links)
Contractual penalty as a means of corroboration of a debt in business relations The theme of this Masterʼs degree thesis is the contractual penalty as a means of corroboration of a debt in business relations. The author has chosen this topic because the contractual penalty is a traditional private institution, which enjoys great popularity for its function and relative simplicity of negotiation in current practice. The contractual penalty improves a creditorʼs status. It makes a borrowers fulfil their confirmed obligation since in case of its violation, they would have to provide the creditor with performance representing both generalized compensation of the damage and a penalty. In spite of a frequent use of the contractual penalty, its legislation is rather brief and does not cover all problematic aspects. The relevance of the topic increased with recodification of the private law. The main aim of the thesis is to explore legislative changes and their impact on selected problematic aspects of the contractual penalty using chosen methodology. The thesis explains whether legislative changes solve existing problems of the contractual penalty or not, what new questions in the context of the a contractual penalty arise and to what extent the conclusions of judicial decision-making practices are still...
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Disinhibition, Violence Exposure, and Delinquency: A Test of How Self-Control Affects the Impact of Exposure to ViolenceBrown, Wyatt 25 March 2016 (has links)
This dissertation examines the role of self-control in the relationship between exposure to violence and antisocial behavior. Specifically, this study proposes that the impact of exposure to violence changes depending on internalized factors such as self-control. Individuals with high exposure to violence but greater levels of self-control may be less influenced by the impact of exposure to violence. Conversely, individuals with low levels of exposure to violence and lower levels of self-control may be more influenced by the impact of violence. The findings from this study suggest that there is some buffering effect on the impact of exposure to violence which may be explained by levels of self-control. This finding is consistent with prior research which finds that the impact of environmental factors on crime and analogous behaviors can be influenced by other personal traits. The results of this study provide researchers and practitioners with important information regarding the impact of exposure to violence on antisocial behavior and the influence self-control has on this relationship. Due to the fickle nature of human behavior and the preciseness involved in developing treatment or diversion plans the relationship between environmental and internal factors should be addressed.
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Assessing home economics coursework in senior secondary schools in BotswanaLeepile, Gosetsemang 07 June 2011 (has links)
The aim of this research was to explore how examiners achieve and maintain high quality assessment during marking and moderation of the BGCSE (Botswana General Certificate of Secondary Education) Home Economics coursework in Botswana. In 2000, localization of the Cambridge Overseas School Certificate (COSC) to the Botswana General Certificate of Secondary Education (BGCSE) took place as per the recommendations of the Revised National Policy on Education (RNPE) document. This new certificate system, marked locally, allows for varied modes of assessment, with more emphasis being placed on continuous assessment. This also means that the assessment is school-based, with teachers centrally involved. As is procedure with this kind of assessment, it is subjected to moderation. However, implementation of this new assessment approach exposed, among other challenges, challenges in establishing dependability of teachers’ assessment, possible increase in teacher workload, teachers’ lack of expertise and confidence in undertaking the assessment scheme. This study, among other things, considers the forms of moderation used by the BGCSE to establish consistency in school-based assessment (SBA) and in so doing, it identifies that a dual form of moderation is used. The main research questions guiding this investigation were: <ul> <li>How are teachers and moderators trained so that they may be competent examiners?</li> <li>How is quality assured during marking of coursework?</li> <li>How does the examining body (BEC) Botswana Examination Council ensure that the examiners adhere to the quality control mechanisms?</li> </ul> This was a qualitative study and the sources of data were semi-structured interviews, document analysis and the research journal. The eight respondents who participated in this study were Home Economics teachers, moderators from senior secondary schools and subject experts from the examining body who were all non-randomly sampled from across the country. Purposive sampling was used based on the respondents’ characteristics relevant to the research problem. Data were analyzed using thematic content analysis to describe the phenomenon under inquiry and obtain detailed data. Major findings revealed inconsistencies between teachers and moderators’ marks, and that even though there are procedures that underpin a high quality assessment regime, there is little monitoring by the Botswana Examinations Council (BEC) to ensure adherence by the examiners. Other key concerns included examiners’ dissatisfaction about training and inadequate official support and guidance to equip them as competent examiners in general. / Dissertation (MEd)--University of Pretoria, 2009. / Science, Mathematics and Technology Education / unrestricted
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A Structural Equation Modeling Approach Combining Multitrait-Multimethod Designs with Moderated Mediation AnalysisLitson, Kaylee 01 August 2019 (has links)
Researchers who study clinical and developmental psychology are often interested in answering questions such as how interventions work, when treatment begins to improve health outcomes, or for whom treatment has the greatest impact. Answers to these and similar questions impact the general understanding of health and behavior, and can be imperative for effectively implementing intervention and prevention programs. To evaluate such complex relationships among variables, researchers have turned to moderated mediation analysis. Moderated mediation analysis is a statistical tool used to identify the conditional processes among observed or latent variables. However, in developmental and clinical psychology, variables are regularly measured using multiple sources or multiple methods. In fact, best practice recommendations in clinical psychology suggest measuring variables with multiple methods (Achenbach, 2006). The question arises how to use multimethod assessments in statistical analyses such as moderated mediation analysis. The objectives of the present study were to create a multimethod moderated mediation model, apply the model to an extant dataset of child developmental behaviors, and evaluate conditions under which the model performed well using a Monte Carlo simulation study. Results from the application showed that the indirect path from hyperactivity to academic impairment through oppositional defiant behavior was significant but not moderated by inattention. Results from the simulation study indicated that excluding true method effects from a moderated mediation model resulted in unacceptable parameter and standard error bias. These results point to the advantages of using the M4 model to evaluate moderated mediation in the presence of multimethod data.
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A Multilevel Investigation of the Relationships Between Personality and Team Role AdoptionMorrison, Chelsey Skipton 12 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / There is a plethora of team composition and personality research, but limited research
incorporating the influences of team context or teammate behaviors for a multilevel examination.
Using secondary data from a pre-existing study consisting of 86 teams and 430 total participants,
we investigated the multilevel relationships of personality and team role adoption. We predicted
hypotheses at three levels. At the individual-level, we predicted personality traits would predict
role adoption. At the team-level, we predicted team personality composition (measured as mean)
would predict role composition (measured as density). We also predicted cross-level interactions,
such that team personality composition would moderate relationships between individual
personality and role adoption. We utilized Density scores to calculate team role composition,
which captures mean ties per group member where a tie is being perceived as adopting a
leadership role. At the individual-level, we found support that extraversion levels predicted
adoption of all roles. At the team-level, mean conscientiousness predicted density of all team
roles. We found no support for any cross-level moderations that team personality composition
influenced individual-level personality to role predictions.
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