‘Work ability’ is a multidimensional concept with importance for both society and the individual. The overall aim of this thesis was to illuminate work ability from the perspective of individuals (Studies I, III), rehabilitation (Study II) and employers (Study IV). In Study I five focus-group interviews were conducted with a total of 16 former unemployed sickness absentee participants. The interviews focused on their experiences of the environmental impact on return to work. The participants expressed a changed self-image and life rhythm. A need for reorientation and support from professionals was stressed. Experiences of being stuck in a ‘time quarantine’, i.e. a long and destructive wait for support, were also revealed. Study II was a randomised controlled study evaluating the interventional capacity of problem-based method (PBM) groups regarding anxiety, depression and stress and work ability compared to cognitive behavioural therapy (CBT) as a method within the Rehabilitation Guarantee. Effects were measured with psychometric instruments. The participants, 22 in the PBM group and 28 in the CBT group, were persons on sick leave because of common mental disorders. Within-group analysis showed significant lower degree of symptoms regarding anxiety and depression for both interventions. Between-group analysis showed significant lower degree of symptoms for CBT regarding anxiety, depression and stress. Within-group analysis of work ability showed significant improvement in one (out of five) subscales for the PBM group and in four for the CBT group. No significant between-group differences were found regarding work ability. In Study III, 16 participants were interviewed after completed interventions in Study II, eight from each intervention group. The interviews focused on their experiences from the interventions and the impact on their ability to work and perform other everyday activities. The interventions were experienced as having a positive impact on their ability to work and perform other everyday activities in a more sustainable way. Reflecting on behaviour and achieving limiting strategies were perceived as helpful in both interventions, although varying abilities to incorporate strategies were described. The findings support the use of active coping-developing interventions rather than passive treatments. Study IV included interviews with 12 employers and investigated their conceptions of ‘work ability’. In the results three domains were identified: ‘employees’ contributions to work ability’, ‘employers’ contributions to work ability’ and ‘circumstances with limited work ability’. Work ability was regarded as a tool in production and its output, production, was the main issue. The employees’ commitment could bridge other shortcomings. In summary, in the work rehabilitation process, different perspectives on work ability need to be considered in order to improve not only individual performance but also rehabilitation interventions, work-places and everyday circumstances. Clearly pronounced perspectives can contribute to better illustrating the dynamic within the relational and multifaceted concept of ‘work ability’. The ability to work can thus be enhanced through improving individual abilities, discovered through reorientation and created through support and adaptation.

Demand-withdraw interaction is a pattern of communication in which one person demands change from another who withdraws. In the treatment domain, evidence of parallel demand-withdraw processes comes from a study of couple therapy for alcoholic men, where wife-demand/husband-withdraw interaction predicted poor response to a high-demand intervention (Shoham et al., 1998). The current study extends this parallelprocess idea to family therapy for substance-using adolescents by examining whether adolescents entrenched in parent-demand/adolescent-withdraw interaction are less likely to engage in treatment and more likely to use drugs post-treatment when counselors pressure them to change. Participants were 91 families who received ≥ 4 sessions of Brief Strategic Family Therapy (BSFT; Szapocznik et al., 2003) in a multi-site clinical trial on adolescent drug abuse and an additional non-engagement sample of 21 families who completed ≤ 2 sessions. Before randomization, families completed videotaped family interaction tasks from which trained observers coded parent-demand/adolescent-withdraw. Another team of raters coded therapists’ demands during an early and (for most cases) a later BSFT session, while a third team rated quality of BSFT. The main dependent variable was a composite index of adolescent substance use based on monthly self-reports and urine drug screens over 12 months. A matched-sample examination of sessions attended (≤ 2 vs. ≥ 4) revealed no effect of early-session therapist demand on engagement. However, multi-level models partially supported the main hypothesis: adolescents high in parent-demand/adolescent withdraw who received high-quality BSFT from relatively non-demanding therapists used fewer drugs during and after treatment than other adolescent participants. Furthermore, as therapist demand on high PD/AW adolescents increased, youth substance use also increased. Results suggest that attending to parallel demand-withdraw processes in parent/adolescent and therapist/adolescent dyads may be useful in family therapy for substance-using adolescents. Replicating ineffective parent behavior within the therapeutic system may undermine the prospect of decreased adolescent drug use outcomes.

In this thesis, we study the statistical issues in lost sales inventory systems, focusing on the complexity arising from the stochastic demand. We model the demand by the Zero Inflated Poisson (ZIP) distribution. The maximum likelihood estimator of the ZIP parameters taking censoring into account are derived separately for the newsvendor and the (s, S) inventory systems. We also investigate the effect of the estimation errors on the optimal policies and their costs. We observe from a simulation study that the MLE taking censoring into account performed the best in terms of cost as well as policy among various estimates. We then proceed to develop a Bayesian dynamic updating scheme of the ZIP parameters. It is applied to the newsvendor system. We perform a simulation study to investigate the advantage of the Bayesian updating approach over the traditional MLE approach. We conclude that the Bayesian pproach offers a better learning technique when one lacks of good understanding of the demand pattern in the first few periods. Since inventory policy affects the information acquisition and-the demand distribution updating process, how to determine the optimal inventory policy when the demand distribution is yet to be learned is the focus of the latter part of the thesis. We investigate the effect of demand censoring on the optimal policy in newsvendor inventory models with general parametric demand distribution and unknown parameter values. We provide theoretical proof of the conjecture that it is better off to adopt a higher than the myopic optimal policy in the initial periods when demand is learned in a censoring system. We show that the newsvendor problem with observable lost sales reduces to a sequence of single-period problems while the newsvendor problem with unobservable lost sales requires a dynamic analysis. We explore the economic rationality for this observation and illustrate it with numerical examples.

The three essays in this thesis address various problems in the general area of supply chain management. In general, supply chain management is concerned with management of the flow of goods, information, and funds among supply chain members, such as suppliers, manufacturers, distributors, retailers, and consumers. As such, its scope includes timing and quantity of material flow, logistics, improving efficiencies in problems with several decision makers, etc. The first essay in this thesis considers the problem of improving coordination in a decentralized system of retailers, while the second one addresses stability and profitability of Internet-based supply exchange alliances. The third essay analyzes a logistics problem, of finding an optimal route for a capacitated vehicle which travels on a graph and which can perform pickups and deliveries. In the first essay, we study a three-stage model of a decentralized distribution system with n retailers who each faces a stochastic demand for an identical product. In the first stage, before the demand is realized, each retailer independently orders her initial inventory. In the second stage, after the realization of the demand, each retailer decides what portion of her residual supply/demand she wants to share with the other retailers. In the third stage, residual inventories are transshipped in order to possibly meet residual demands, and an additional profit is allocated among the retailers. We study the effect of implementing various allocations rules in the third stage on the levels of the residual supply/demand the retailers are willing to share with others in the second stage, and the tradeoff involved in achieving a solution which is also optimal for the corresponding centralized system. The second essay is concerned with the formation of Internet-based supply exchange alliances among three or fewer retailers of possibly substitutable products. We provide some conditions, in terms of product substitutability and quality of suppliers, which would lead to the formation of a three member alliance, or a two member alliance, or no alliance at all. We also study the effect of alliance structure and quality of suppliers on the profit of a retailer. The third essay considers a vehicle routing problem with pickups and deliveries (VRPD problem) on some special graphs. Some vertices on the graph represent delivery customers, and other vertices represent pickup customers. The objective is to find a minimum length tour for a capacitated vehicle, which starts at a depot and travels on the graph while satisfying all the requests by the customers without violating the vehicle capacity constraint, and returns to a depot. We have developed linear time algorithms for the VRPD problem on a path and on tree graphs, linear and O (|V| log |V|) algorithm for a VRPD problem defined on a path with parametric initial capacity, and quadratic and O (|V|² log |V|) algorithms for a VRPD problem defined over a cycle graph.

This thesis seeks to advance our understanding of how quantitative models can be developed and applied to marketing in complex dynamic environments characterized by demand perishability. Specifically, it involves three essays on the dynamic shelf-space management of movies. The problem is particularly complex for exhibitors - the retailers in the motion picture supply chain - given the short life cycles of movies, their perishable and uncertain demand, and complicated contracts. Our objective is to understand, formalize, and develop optimal normative policies for such decision making situations. Essay 1 considers this problem from a theoretical standpoint by addressing the stochastic aspects of movie replacement, which is analogous to equipment replacement in maintenance theory. We formulate this problem as a Markov decision process model. A scenario analysis reveals that the exhibitor is better off when shelf-space becomes scarcer for the distributors. A smart exhibitor associates a cost with contract parameters and bears it if it makes economic sense. The results underscore the importance of precise information for making smart replacement decisions. The optimal policy under special conditions resembles a control limit policy, which is easy to implement and compute. Essay 2 applies the theoretical concepts developed in Essay 1 to a special case of the movie replacement problem. The output of this essay is SilverScreener, which is a decision support model for movie exhibitors. The model helps the exhibitors both select (which) and schedule (when, how long) the movies. The model is readily implementable and appears to lead to considerable improvement in profitability in different comparative cases. The general nature of optimal policy emerges as: choose fewer "right" movies and run them longer. The robustness of the results is shown through sensitivity analyses. Essay 3 proposes a two-tier application of the SilverScreener model to show its effectiveness as a managerial aid. The master plan helps the manager in bidding and planning for movies before a season. The rolling horizon approach is useful for weekly replacement decisions during the season. Our results show that SilverScreener can improve the manager's profitability and promises to be an effective scheduling and planning tool.

Kombinationen höga krav, låg kontroll och lågt socialt stöd leder, enligt krav-kontroll-stöd modellen, till de högsta stressnivåerna. Självledarskap ger individen möjligheten att, genom en inre kontroll, återta kontrollen och minska stressnivåerna. Genom att använda sig av självledarskapsstrategier kan individen förändra sina tankemönster och ageranden för att på så vis förhoppningsvis förbättra sin stresshantering. Studiens syfte var att studera relationen mellan självledarskap, stress och arbetets uppbyggnad. Med arbetets uppbyggnad menas här kombinationen av krav, kontroll, stöd samt tydlighet. Totalt besvarade 107 deltagare, varav 69 kvinnor, en enkät. Analyserna visade på samband mellan stress och samtliga 4 arbetsmiljövariabler (krav, kontroll, stöd samt tydlighet), vidare på positivt samband mellan självledarskapsvariabeln självbestraffning och stress samt positiva samband mellan strategigruppen naturliga belöningar och 2 av arbetsmiljövariablerna. Hypotesen, att goda självledarskapskunskaper medför bättre stresshantering, fick dock inte stöd. Det behövs ytterligare forskning för att tydliggöra sambanden mellan självledarskap, stress och arbetsmiljö, exempelvis genom experimentella studier.

In this thesis, a demand elasticity model is developed and tested for the dispatch of high voltage power systems and microgrids. The price obtained from dispatching a network in a base-case scenario is used as input to a price-elastic demand model. This demand model is then used to determine the price-responsive demand for the next iteration, assuming that the load schedule is defined a day-ahead. Using this scheme, trends for demand, hourly prices, and total operation costs for a system can be obtained to study the impact of demand response on unit commitment and dispatch of distributed energy resources. This way, the effect on the scheduling of dispatchable generators and energy storage systems can be analyzed with respect to price-elastic loads. The results for a test power system and a benchmark microgrid show that as the demand is more elastic, the longer it takes for the dispatch to converge to a final condition. The 24-hour model eventually converges to a steady state, with prices and costs at their lowest values for different scenarios, which is good for most system participants and desirable in a market environment, thus highlighting the importance of price-responsive loads in electricity markets.

Consistently researchers have demonstrated that marital interactions of couples with and without a depressed partner differ. Given the high comorbidity of depression and marital distress, it is unclear whether observed communication patterns are due to marital distress or depression. Recent investigations suggest that, after controlling for marital satisfaction, marital communication behaviours may not be specific to depression. However, depressed groups in these investigations may have consisted of individuals with a wide range of acute mood states, thus minimizing differences between depressed and non-depressed mood states. Consistent with cognitive vulnerability models of depression, depressed individuals’ dysfunctional behaviours may manifest only during negative mood states. The first purpose of the present study was to use a mood induction procedure (MIP) to examine whether any marital communication were specific to depression, after controlling for marital satisfaction. The second purpose of the study was to examine whether communication behaviours predicted depressive symptoms at 6-month follow-up. The hypotheses were tested in a sample of 69 couples characterized by a wide range of wife depressive symptoms and couple marital satisfaction. Results of the current study showed that women who endorsed higher depressive symptoms were more likely to use high-level negative demands (e.g., use of angry, belligerent tone) and indirect demands (e.g., use of flirting, whining, or nagging tone) after they received a sad MIP, but depressive symptoms were not related to these behaviours when there was no MIP. Interestingly, depressive symptoms were positively correlated with low-level negative demands (attempts to influence one’s partner in a frustrated, defensive manner) regardless of whether or not wives received a sad MIP. Results also showed that when wives were induced with a sad mood, husbands of wives who endorsed higher levels of depressive symptoms engaged in more positive demands (e.g., use of warmth and understanding). Additionally, preliminary longitudinal data suggest that, wives who engaged in higher levels of high-level negative demands report lower levels of subsequent depressive symptoms. These findings are discussed in light of interpersonal theories of depression. / Thesis (Master, Psychology) -- Queen's University, 2007-09-28 09:52:59.682

A stable money demand function and exogeneity of prices is at the core of planning and implementing a monetary policy of monetary targets. This thesis examines both the stability of M2 money demand and price exogeneity in Rwanda for the years 1980 to 2000. We estimate and test the elasticities of the determinants of Rwandan money demand function. We include in this demand function those variables which economic theory indicates must be part of any empirical investigation of money demand. All coefficients had the signs as required by economic theory. We estimate the money demand function for Rwanda using cointegration analysis and an error correction mechanism. The results show real income, prices and M2 to be cointegrated. We employ three tests to show that the estimated demand function for Rwanda is stable. We then test the second requirement for coherence in monetary aggregate targeting that money determines prices. The results show that prices are exogenous to money. But before we can definitely conclude that an inflation targeting regime is feasible from monetary policy perspective, we point out that future research on this important topic must account for exchange rate movements, measure permanent income and specify interest rate changes correctly. / Thesis (M.A.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

A stable money demand function is the essence of planning and implementing monetary policy. This thesis explores the stability of the M2 money demand function in Uganda for the period 1980-2002. We estimate and interpret the elasticities of the determinants of the money demand function. After analyzing the dynamics of money demand determinants, the variables crucial to money demand estimation in this thesis were established as being: real income, the nominal rate of interest on Treasury bills, the actual rate of inflation and the change in the exchange rate. All variables had the correct signs as required by economic theory, where real income was found to be positive whilst the nominal rates of interest on Treasury bills, the actual rate of inflation and the change in the exchange rate all have negative signs. We estimate the money demand function for Uganda, using cointegration analysis and an error correction mechanism (ECM) on quarterly data over the sample period 1980-2002. The results from the Johansen and Juselius (1990) cointegration test suggest that real income, the nominal interest rates on Treasury bills and real M2, are cointegrated. The results of the error correction mechanism suggest that in spite of major policy reforms in the years 1987 and 1993 such as the introduction of new financial instruments, and liberalization of the financial system, the estimated money demand function for Uganda is stable only in one time period 1994-2002 that is after major policy reforms. The results of the study show that M2 is a viable monetary policy tool that could be used as an intermediate target to stimulate economic activity in Uganda. We also conclude that the feasible approach for conducting monetary policy in Uganda is to adopt an inflationary targeting regime. However, monetary policy might continue to benefit from other economic indicators by monitoring the impacts of changes in interest rates and the change in exchange rates on real money demand in Uganda. / Thesis (M.A.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.