Swedish education needs to change in order to reverse the negative trend in PISA and TIMSS. At the same time digital artifacts are increasingly present in the classroom and commercial applications more available. It is difficult to determine which technical tool that provide real results and it is not yet clear what role technology should have in the classroom. This study examines how visualisation and technology can be used to promote deeper understanding of algebra by addressing the misconception that frequently occurs among students. Observation and interviews were held with students from two schools, one in Norrköping and one in Östersund. Theory regarding algebraic misconceptions have been studied and compiled into two categories. In addition, three prototypes were developed with and later evaluated by a focus group. This work has resulted in suggestions on what technical and interactive activities could be used in algebraic education. The study shows that more research is needed to determine how technology best can be implemented and used effectively in teaching. The work also shows that such research and development needs to be implemented with a user-centered approach with the involvement of relevant target groups. / Svensk undervisning är i behov att förändras för att vända den negativa trenden i PISA och TIMSS. Samtidigt är digitala artefakter alltmer närvarande i klassrummet och kommersiella applikationer alltmer tillgängliga. Det är svårt att avgöra vilka tekniska verktyg som ger faktiska resultat och det är ännu inte klarlagt vilken roll tekniken bör spela i en klassrumssituation. I detta arbete undersöks hur visualiseringar och teknik kan användas för att främja djupare förståelse inom algebra genom att adressera missuppfattningar som ofta förekommer hos elever. Observation och intervjuer genomfördes med elever på två skolor, en i Norrköping och en i Östersund. Teori om algebraiska missuppfattningar har studerats och sammanställts i två kategorier. Dessutom har tre prototyper utvecklats tillsammans med, och utvärderats av, en fokusgrupp. Arbetet har resulterat i förslag på vad tekniska och interaktiva aktiviteter skulle kunna innebära i algebraisk matematikundervisning. Det visar att mer forskning behövs för att avgöra hur teknik på bästa sätt kan implementeras och utnyttjas effektivt inom undervisning. Arbetet visar också att sådan forskning och utveckling behöver genomföras med en användarcentrerad ansats med delaktighet från berörda målgrupper.

The changing working environment and ageing workforce suggest that many workers will inevitably reach a career plateau, a stage where people regard future promotions as unlikely, or no longer feel challenged at work. Experiencing career plateau is found to be associated with negative job attitudes and performance in the workplace. However, existing studies have been mainly cross-sectional in design and few of them investigate the mechanisms and the conditions that influence the negative relationship. This study follows a quantitative longitudinal research design to further enhance the understanding of the relationships between career plateau and job outcomes. The job outcomes in this research include work attitudes such as job satisfaction, organisational commitment, turnover intentions and three aspects of job performance. Specifically, the three research aims of this thesis are: (1) to understand the causal directions between career plateau and job outcomes, (2) to examine whether employees’ unmet expectations may explain these relations and (3) to investigate whether employees’ age may modify the mediation effects of career plateau on job outcomes via unmet expectations. Three waves of data were collected from working individuals in various industries over an eight-month period. The majority of the participants were working in the UK or in Taiwan. Results showed that unmet expectations partially explain the negative relationship between career plateau and job attitudes over time but not for job performance. Furthermore, age did not affect the strength of the mediation effect of career plateau on the job outcomes through unmet expectations. The significance of this research is three-fold. First, it provides a new explanation for the unfavourable work attitudes of plateaued individuals. The findings that career plateaued employees have lower job satisfaction, lower organisational commitment and higher turnover intentions can partly be explained by unfulfilled expectations in receiving promotions or challenging tasks. Second, the study signals the danger of career plateau at any age, as younger and older workers were found to be equally influenced by career plateau. Finally, this is the first study in the area that seeks to resolve the debate over the directional relationship between career plateau and job outcomes. The implications in theory and in practice, limitations and suggestions for future research directions are discussed.

The purpose of this study was to explore the following relationships: (a) how moderating factors (gender, age, ethnicity, social support, marital status, reason for role assumption and number of grandchildren in the home) can influence the mediating role of resiliency, and (b) how resiliency may mediate the negative effects of raising grandchildren (role demands, life disruptions, and difficulties with grandchildren) on grandparent adjustment over time. Resiliency was hypothesized to have the greatest effect on custodial grandparents who experienced the most stress (i.e., older, single, Caucasian males lacking social support and raising more than one grandchild). Mediation was assessed using structural equation modeling. Results indicated resilience mediated the relationship between role assumptions (i.e., role demands and life disruptions) and grandparent adjustment; however, resilience did not mediate the relationship between grandchild characteristics and grandparent adjustment. Due to the small number of custodial grandfathers (n = 14), non-married grandparents (n = 29), non-Caucasian grandparents (n = 10), the small number of grandparents who assumed the custodial role for less ambiguous reasons (n = 24), and the number of custodial grandparents with more than one grandchild residing in the home (n = 29) participating within the study, hierarchical multiple regressions were only conducted to test for moderated mediation for perceived social support and the age of the grandparent. Results indicated resilience mediates the relationship between life disruption and grandparent well-being for younger custodial grandparents and for custodial grandparents with perceived high social support.

The Pebble Bed Modular Reactor (PBMR) is a high temperature graphite-moderated nuclear reactor that uses helium as a coolant. The triple coated (TRISO) particles contain enriched uranium oxide fuel which is coated with layers of various forms of pyrolytic carbon and silicon carbide. The TRISO particles are further embedded in the matrix of spherical graphite pebbles. The graphite matrix is a composite moulded from a compound containing natural flake graphite (64 wt.%), synthetic graphite (16 wt.%) and a phenolic resin binder (20 wt.%) heated to 1800 °C in inert atmosphere. The graphitic composite provides structural integrity, encasement and act as a moderator material. In this work, low density model graphite composites similar to those used in nuclear applications as encasement material in fuel pebbles were made by uniaxial cold compression moulding. The graphitic composites contained various ratios of natural flake graphite and synthetic graphite at fixed phenolic novolac resin binder content of 20 wt.% (green state). The fabrication process employed entails mixing the graphite powders, followed by addition of methanol phenolic resin solution to the graphite powder mix, drying, grinding, milling and sieving; and finally compression moulding in a stainless steel die at 13 MPa using a hydraulic press. The green moulded disc specimens were then carbonized at 900 °C in nitrogen atmosphere to remove volatiles followed by annealing at 1800 °C in helium atmosphere. The annealing step diminishes structural defects and result in densification of the composites. The microstructure of fabricated graphitic composites was characterized using various techniques. Particle Size Distributions determined using Laser diffraction showed that the inclusion of the binder leads to agglomeration. The composite powders had larger mean particle sizes than the raw graphite powders showing the binding effect of the novolac phenolic resin. X-ray diffraction studies showed that the graphitic composites had a hexagonal crystal structure after annealing. Raman spectroscopy revealed the presence of the structurally disordered phase derived from the resin carbon (indicated by the pronounced D-band in the Raman spectra). XRD and Raman observations were consistent with literature and gave results supporting existing knowledge base. Optical microscopy revealed a flake-like microstructure for composites containing natural graphite and needle-coke like particles for composites containing mainly synthetic graphite. Optical microscopy confirmed that the effect of the manufacturing route employed here was to align the particles in the direction perpendicular to the compression moulding direction. As a result, the graphitic composites exhibited anisotropic property behavior. The bulk density of the composites increased with the increase in the natural graphite content due to compactability of natural flakes in the manufacturing route. Thermogravimetric analysis studies on the composites showed that they were stable in air to 650 °C. Composites containing mainly synthetic graphite were thermally more stable in air compared to their natural graphite counterparts. The linear coefficients of thermal expansion of the composites were measured using thermomechanical analysis (20-600 °C). In the moulding direction, the average CTE (αP) values were in the range (5-9) × 10-6 K-1 and increased with increment in the natural graphite content in the composite. In the direction perpendicular to moulding direction, the average CTE (αN) values were in the range (1.7-2.1) × 10-6 K-1 showing that the expansion was similar or constant in this direction. Therefore an anisotropic expansion ratio, i.e. αP:αN, of about 3 was observed in the composites. This anisotropy is attributable to the alignment of the filler particles in the manufacturing route. The thermal conductivity of the annealed composites were measured in the pressing direction from 100 to 1000 °C and the values ranged from 19 to 30 W m-1 K-1. Anisotropy was also observed as far as strength was concerned. A composite containing 64:16:20 wt.% ratio had the best mechanical properties, high thermal conductivity and slightly high expansion coefficient. This work demonstrates the complimentary properties of the graphite fillers in the composites. It also reports for the first time, data on the effect of variation of the filler graphites on microstructure and properties of model low density compression moulded graphitic composites. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Chemistry / unrestricted

In today’s connected world, there exists a large amount of tools that did not exist during the inception of computing and user interfaces. Many of these have seen their natural advent due to the Internet’s global accessibility. Ever since the initial simple user interfaces of text-based terminals, user testing has been researched and developed thoroughly as it provides a rigid set of feedback to the system architect which can help to more quickly and easily construct a system suited for its purpose. Through various methods of remote usability testing, a teacher-student interface is tested with a set of real users. The results of which are qualitatively compared between themselves and previous results using similar tools and evaluated for their usability. The results indicate that the system that was tested was generally perceived as well-performing but indicated several issues with how the tasks were created, underlining the necessity for a well-documented and thought through approach to the creation of usability testing tasks.

Suicide is a national public health concern, and unmet interpersonal needs (i.e., perceived burdensomeness, thwarted belongingness) may contribute to enhanced risk. However, mechanisms of action and certain protective variables are not well understood. The present study examined simple mediation models, with internal hostility as a mechanism of action between interpersonal needs and suicide risk. Additionally, our study examined the moderating role of various aspects of receiving forgiveness on the association between interpersonal needs and internal hostility in these simple mediation models. A community-based convenience sample was surveyed (N=712). Our findings indicated that internal hostility partially mediated the association between perceived burdensomeness/thwarted belongingness and suicide risk, such that higher levels of interpersonal needs variables were associated with higher levels of internal hostility, and in turn, higher levels of suicide risk. No evidence was found for a buffering effect of feeling forgiven on these statistical models. Our findings suggest that negative, internalized self-perception contributes to suicide risk above and beyond that of interpersonal needs alone. Implications are discussed for both theory and practice.

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The present study examines the joint roles of leadership and stressors for presenteeism of scientific staff. Leaders may have an impact on employees’ health, both directly through interpersonal interactions and by shaping their working conditions. In the field of science, this impact could be special because of the mentoring relationships between the employees (e.g., PhD students) and their supervisors (e.g., professors). Based on the job demands-resources framework (JD-R), we hypothesized that the pressure to be present at the workplace induced by supervisors (supervisorial pressure) is directly related to employees’ presenteeism as well as indirectly via perceptions of time pressure. The conservation of resources theory (COR) states that resource loss resulting from having to deal with job demands weakens the resource pool and therefore the capacity to deal with other job demands. Thus, we hypothesized that accumulation of work moderates the relationship between supervisorial pressure and time pressure, such that the relationship is stronger when accumulation of work is high compared to if accumulation of work is low. Cross-sectional data were obtained from 212 PhD students and postdocs of 30 scientific institutions in Germany. Analysis was performed using the SPSS macro PROCESS (Hayes, 2013). Supervisorial pressure was directly associated with higher presenteeism of employees and indirectly through increased time pressure. Moreover, supervisorial pressure and accumulation of work interacted to predict time pressure, but in an unexpected way. The positive relationship between supervisorial pressure and time pressure is stronger when accumulation is low compared to if accumulation of work is high. It seems possible that job stressors do not accumulate but substitute each other. Threshold models might explain the findings. Moreover, specific patterns of interacting job demands for scientific staff should be considered in absence management.

Prior research has established significant associations between regular physical activity and enhancements in well-being, quality of life, and self-regulation. Given that these benefits may extend to influence the quality of romantic relationships, the present study was the first to evaluate the relationship between exercise and romantic relationship satisfaction through the role of body image, drawing upon the Self-Determination Theory as the theoretical framework. Specifically, the current study aimed to achieve three objectives: (a) to investigate the impact of exercise on romantic relationship satisfaction, (b) to examine the effects of body image as a mediator in the exercise-relationship connection, and (c) to determine whether exercise motives moderate the mediating effect of body image. Data were gathered from an online survey completed by 392 cisgender women in heterosexual relationships and analyzed using PROCESS Macro for SPSS Model 4 and Model 7, respectively. The results showed that exercise frequency was not directly related to romantic relationship satisfaction. However, body image fully mediated this association, indicating that increased exercise predicted body satisfaction and subsequently contributed to individuals' perceived relationship quality. While exercise motivation did not emerge as a moderator of the mediation of body image, health/fitness and enjoyment/mood motives significantly predicted positive body evaluation and relationship quality. In contrast, concerns related to appearance were linked to higher levels of social comparison and negative affect. Therefore, these findings highlight the value of fostering a positive body image and reducing body-focused motivation, as well as prioritizing autonomous exercise for the quality of romantic relationships and overall well-being.

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