9 resultados para Automobiles by Make, Model, Year.

em Helda - Digital Repository of University of Helsinki


Relevância:

100.00% 100.00%

Publicador:

Resumo:

The aim of this dissertation is to provide conceptual tools for the social scientist for clarifying, evaluating and comparing explanations of social phenomena based on formal mathematical models. The focus is on relatively simple theoretical models and simulations, not statistical models. These studies apply a theory of explanation according to which explanation is about tracing objective relations of dependence, knowledge of which enables answers to contrastive why and how-questions. This theory is developed further by delineating criteria for evaluating competing explanations and by applying the theory to social scientific modelling practices and to the key concepts of equilibrium and mechanism. The dissertation is comprised of an introductory essay and six published original research articles. The main theses about model-based explanations in the social sciences argued for in the articles are the following. 1) The concept of explanatory power, often used to argue for the superiority of one explanation over another, compasses five dimensions which are partially independent and involve some systematic trade-offs. 2) All equilibrium explanations do not causally explain the obtaining of the end equilibrium state with the multiple possible initial states. Instead, they often constitutively explain the macro property of the system with the micro properties of the parts (together with their organization). 3) There is an important ambivalence in the concept mechanism used in many model-based explanations and this difference corresponds to a difference between two alternative research heuristics. 4) Whether unrealistic assumptions in a model (such as a rational choice model) are detrimental to an explanation provided by the model depends on whether the representation of the explanatory dependency in the model is itself dependent on the particular unrealistic assumptions. Thus evaluating whether a literally false assumption in a model is problematic requires specifying exactly what is supposed to be explained and by what. 5) The question of whether an explanatory relationship depends on particular false assumptions can be explored with the process of derivational robustness analysis and the importance of robustness analysis accounts for some of the puzzling features of the tradition of model-building in economics. 6) The fact that economists have been relatively reluctant to use true agent-based simulations to formulate explanations can partially be explained by the specific ideal of scientific understanding implicit in the practise of orthodox economics.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The Thesis presents a state-space model for a basketball league and a Kalman filter algorithm for the estimation of the state of the league. In the state-space model, each of the basketball teams is associated with a rating that represents its strength compared to the other teams. The ratings are assumed to evolve in time following a stochastic process with independent Gaussian increments. The estimation of the team ratings is based on the observed game scores that are assumed to depend linearly on the true strengths of the teams and independent Gaussian noise. The team ratings are estimated using a recursive Kalman filter algorithm that produces least squares optimal estimates for the team strengths and predictions for the scores of the future games. Additionally, if the Gaussianity assumption holds, the predictions given by the Kalman filter maximize the likelihood of the observed scores. The team ratings allow probabilistic inference about the ranking of the teams and their relative strengths as well as about the teams’ winning probabilities in future games. The predictions about the winners of the games are correct 65-70% of the time. The team ratings explain 16% of the random variation observed in the game scores. Furthermore, the winning probabilities given by the model are concurrent with the observed scores. The state-space model includes four independent parameters that involve the variances of noise terms and the home court advantage observed in the scores. The Thesis presents the estimation of these parameters using the maximum likelihood method as well as using other techniques. The Thesis also gives various example analyses related to the American professional basketball league, i.e., National Basketball Association (NBA), and regular seasons played in year 2005 through 2010. Additionally, the season 2009-2010 is discussed in full detail, including the playoffs.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This study examines the narrative construction of consumerism in Finnish consumer culture in the early 21st century. The objects of the study are consumer life stories and essays on environmentally friendly consumption, written by 15-19-year-old high school students. Moreover, group discussions were used as additional research material. The data was gathered at five high schools in different areas of Finland. Young people's consumer narratives are interpreted through cultural stories and consumer ethos such as self-control, gratification and green consumerism. The narrative research approach is used to analyse what types of consumer positions these young people construct in stories on their own consumer history, and what kinds of ideas and thought patterns they construct on green consumerism. The study creates a multifaceted image of young people as agents in consumer society. They construct archetypical stories of wastrels and scrooges, as well as prudent and environmentally friendly consumers. Consumption and expenditure are however mostly a continuous battle between self-control and giving in to gratification. This reality is illustrated among other things by clever expressions invented by young people, such as Carefree Pennywise, Prudent Hedonist and Wasteful Scrooge. In their narratives, young people also analyse the usefulness - or uselessness - of their decisions on consumption, as well as develop themselves into controlling and sensible consumers. This kind of virtuous consumer allows him/herself the joy and the gratification of consumption, as long as these are "kept in check". One's view of expenditure and consumption is not permanent. Consumerism may alter with time. A wastrel may grow up to be a young person in control of their desires, or a thrifty child may awaken to the pleasures of consumption in their teens. Consumerism may also be polyphonic: it may simultaneously - and even uncomplicatedly - be constructed upon the discourses of wastefulness, prudence, gratification and green consumerism. Young people allow for gratification to form a part of green consumerism, too: it is not simply restrictive self-denial. They also see many hurdles in the way of green consumerism, such as the elevated price of ecological products, and the difficulties of green consumer practices. The stories also show the gender division in green consumerism. For young men, ecological considerations offer elements for the construction of consumerism only on the very rare occasion, whereas striving for day-to-day green practices is typical for young women.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Ongoing habitat loss and fragmentation threaten much of the biodiversity that we know today. As such, conservation efforts are required if we want to protect biodiversity. Conservation budgets are typically tight, making the cost-effective selection of protected areas difficult. Therefore, reserve design methods have been developed to identify sets of sites, that together represent the species of conservation interest in a cost-effective manner. To be able to select reserve networks, data on species distributions is needed. Such data is often incomplete, but species habitat distribution models (SHDMs) can be used to link the occurrence of the species at the surveyed sites to the environmental conditions at these locations (e.g. climatic, vegetation and soil conditions). The probability of the species occurring at unvisited location is next predicted by the model, based on the environmental conditions of those sites. The spatial configuration of reserve networks is important, because habitat loss around reserves can influence the persistence of species inside the network. Since species differ in their requirements for network configuration, the spatial cohesion of networks needs to be species-specific. A way to account for species-specific requirements is to use spatial variables in SHDMs. Spatial SHDMs allow the evaluation of the effect of reserve network configuration on the probability of occurrence of the species inside the network. Even though reserves are important for conservation, they are not the only option available to conservation planners. To enhance or maintain habitat quality, restoration or maintenance measures are sometimes required. As a result, the number of conservation options per site increases. Currently available reserve selection tools do however not offer the ability to handle multiple, alternative options per site. This thesis extends the existing methodology for reserve design, by offering methods to identify cost-effective conservation planning solutions when multiple, alternative conservation options are available per site. Although restoration and maintenance measures are beneficial to certain species, they can be harmful to other species with different requirements. This introduces trade-offs between species when identifying which conservation action is best applied to which site. The thesis describes how the strength of such trade-offs can be identified, which is useful for assessing consequences of conservation decisions regarding species priorities and budget. Furthermore, the results of the thesis indicate that spatial SHDMs can be successfully used to account for species-specific requirements for spatial cohesion - in the reserve selection (single-option) context as well as in the multi-option context. Accounting for the spatial requirements of multiple species and allowing for several conservation options is however complicated, due to trade-offs in species requirements. It is also shown that spatial SHDMs can be successfully used for gaining information on factors that drive a species spatial distribution. Such information is valuable to conservation planning, as better knowledge on species requirements facilitates the design of networks for species persistence. This methods and results described in this thesis aim to improve species probabilities of persistence, by taking better account of species habitat and spatial requirements. Many real-world conservation planning problems are characterised by a variety of conservation options related to protection, restoration and maintenance of habitat. Planning tools therefore need to be able to incorporate multiple conservation options per site, in order to continue the search for cost-effective conservation planning solutions. Simultaneously, the spatial requirements of species need to be considered. The methods described in this thesis offer a starting point for combining these two relevant aspects of conservation planning.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A total of 177 patients with primary dislocation of the patella (PDP) were admitted to two trauma centers in Helsinki, Finland during 1991 to 1992. The inclusion criteria were: 1. Acute (≤14 days old) first-time lateral dislocation of the patella. 2. No previous knee operations or major knee injuries. 3. No ligament injuries to be repaired. 4. No osteochondral fractures requiring fixation. 50 patients were excluded. 30 of these excluded patients would have met the inclusion criteria, 19 patients received treatment by consultants not involved in the study, 7 refused to participate and 4 had an erroneous randomization. 127 patients including, 82 females, were then randomized to have either tailor-made operative procedure (group O) or conservative treatment (group C). The aftercare was similar for both groups. The mean age of the patients was 20 (9-47) years. All patients were subjected to analysis of trauma history (starting position and knee movement during the dislocation), examination under anesthesia (EUA) and arthroscopy. 70 patients (52 females) were randomized by their odd year of birth to operative group O and 57 patients (30 females) by their even year of birth to conservative group C. The diagnosis of PDP was based on locked dislocation in 68 patients, on dislocatability in EUA in 47 patients, and on subluxation in EUA combined with typical intra-articular lesions in 12 patients. In group O, 63 patients had exploration of the injuries on the medial side of the knee and tailor made reconstruction added with lateral release in 54 cases. The medial injury was operated by suturing in 39 patients, by duplication in 18 patients and by additional augmentation of the medial patellofemoral ligament (MPFL) with adductor magnus tenodesis in 6 patients. 7 patients, without locking in trauma history and only subluxation in EUA had only lateral release for realignment. In adductor magnus tenodesis the proximal end of the distal tendinous part was rerouted to the upper medial border of the patella. In the conservative group C, the treatment was adjusted to the extent of patellar displacement in EUA. Patients with dislocation in EUA had 3 weeks’ immobilization with the knee in slight flexion. Mobilization was started with a soft patellar stabilizing orthosis (PSO) used for additional three weeks. The patients with subluxation in EUA wore an orthosis for six weeks. The aftercare was similar in group O. The outcome was similar in both groups. After an average of 25 (20-45) months´ follow-up, the subjective result was better in group C in respect of the mean Hughston VAS knee score (87 for group O and 90 for group C, p=0.04, visual analog scale), but similar in terms of the patient’s own overall opinion and the mean Lysholm II knee score. Recurrent instability episodes occurred in 18 patients in group O and in 20 patients in group C. After an average of 7 (6-9) years´ follow-up, the groups did not show statistical difference either in respect of the patient’s own overall opinion, or the mean Hughston VAS and Kujala knee scores. The proportions of stable patellae was 25/70 (36%) in group O and 17/57 (30%) in group O (p=0.5). In a multivariate risk analysis, there was a correlation between low Kujala score (<90) as dependent parameter and female gender (OR: 3.5; 95% CI: 1.4-9.0), and loose body on primary radiographs (OR: 4.1; 95% CI: 1.2-15). Recurrent instability correlated with young age at the time of PDP (OR: 0.9; 95% CI: 0.8-1.0/year). Girls with open tibial apophysis had the worst prognosis for instability (88%; 95% CI: 77-98). The most common mechanisms in trauma history of the patients were movement to flexion from a straight start (78%) and movement to extension from a well-bent start (8%). Spontaneous relocation of the patella had taken place in 13/39 of girls, in 11/21 of boys, in 26/42 of women and in 17/24 of men with skeletal maturity of the tibia. The dislocation in EUA was non-rotating in 96/126 patients followed by outward rotating dislocation in 14/126 patients. Operative treatment policy in PDP is not recommended. Locking tendency of the patella in PDP depended on the skeletal maturation. Recurrence rate after PDP was higher than expected.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this research I ask what is interpreted as sex-based harassment by 15-16-year old girls and boys. By sex-based harassment I refer to one-sided, unwanted attention that is based on gender and that makes the target feel embarrassed, frightened, hurt or angry. My focus is not on the most overt cases of harassment but rather on everyday encounters. While young people differentiate between harassing and non-harassing attention, at the same time they define, assign value to and construct differences and power relations on the basis of gender, age and ethnicity, for example. My main data consists of essays (N 104, 54 girls, 54 boys) and thematic interviews (N 14; 20 girls, 3 boys) of ninth graders of a secondary school in Helsinki. In the essays and interviews, students construe the border between pleasant and unpleasant, tolerable and intolerable attention as clear in principle, but, they suggest that in practice this border is ambivalent, negotiable and contextual. The interpretations of incidents are justified by referring to features of the target, the scene or the perpetrator. Targets of harassment are most often construed as being girls who are characterized as thin-skinned, but at the same time they are expected to be understanding toward any sex-based attention they may get, particularly when it is not physical. On the other hand, girls are regarded as equal and even active participants in incidents of harassment. Such statements include considerations of how girls either reject or invite particular kinds of attention by their actions and outward appearance. Forms of harassment, ways of understanding it as well as overcoming it vary according to spatial context. By situating incidents in different spaces and places, young people contrast their experiences with ordinary and predictable non-harassment that takes place e.g. in discos and unusual and unexpected harassment that takes place e.g. in the city streets in the daytime. The behaviour of boys harassing a girls is naturalized by appealing to young masculinity and the childishness but also strong sexual drive which is seen as characteristic of teenage boys. On the other hand, sex-based harassment is racialized and pathologized in ways that separate the phenomenon from young, Finnish, normal masculinity. Both the material experiences of the young people and the definitions of the parties involved in harassing incidents are gendered. Girls encounter and deal with sexualized commenting and unwanted approaches much more often and in a more intensive way than boys. Furthermore, there is a vast cultural repertoire of acceptable accounts that can be mobilised in order to excuse male harassers, to critically evaluate the appearance or action of the female targets and to divide the responsibility between the female target and the male perpetrator.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The goal of this study was to examine the role of organizational causal attribution in understanding the relation of work stressors (work-role overload, excessive role responsibility, and unpleasant physical environment) and personal resources (social support and cognitive coping) to such organizational-attitudinal outcomes as work engagement, turnover intention, and organizational identification. In some analyses, cognitive coping was also treated as an organizational outcome. Causal attribution was conceptualized in terms of four dimensions: internality-externality, attributing the cause of one’s successes and failures to oneself, as opposed to external factors, stability (thinking that the cause of one’s successes and failures is stable over time), globality (perceiving the cause to be operative on many areas of one’s life), and controllability (believing that one can control the causes of one’s successes and failures). Several hypotheses were derived from Karasek’s (1989) Job Demands–Control (JD-C) model and from the Job Demands–Resources (JD-R) model (Demerouti, Bakker, Nachreiner & Schaufeli, 2001). Based on the JD-C model, a number of moderation effects were predicted, stating that the strength of the association of work stressors with the outcome variables (e.g. turnover intentions) varies as a function of the causal attribution; for example, unpleasant work environment is more strongly associated with turnover intention among those with an external locus of causality than among those with an internal locuse of causality. From the JD-R model, a number of hypotheses on the mediation model were derived. They were based on two processes posited by the model: an energy-draining process in which work stressors along with a mediating effect of causal attribution for failures deplete the nurses’ energy, leading to turnover intention, and a motivational process in which personal resources along with a mediating effect of causal attribution for successes foster the nurses’ engagement in their work, leading to higher organizational identification and to decreased intention to leave the nursing job. For instance, it was expected that the relationship between work stressors and turnover intention could be explained (mediated) by a tendency to attribute one’s work failures to stable causes. The data were collected from among Finnish hospital nurses using e-questionnaires. Overall 934 nurses responded the questionnaires. Work stressors and personal resources were measured by five scales derived from the Occupational Stress Inventory-Revised (Osipow, 1998). Causal attribution was measured using the Occupational Attributional Style Questionnaire (Furnham, 2004). Work engagement was assessed through the Utrecht Work Engagement Scale (Schaufeli & al., 2002), turnover intention by the Van Veldhoven & Meijman (1994) scale, and organizational identification by the Mael & Ashforth (1992) measure. The results provided support for the function of causal attribution in the overall work stress process. Findings related to the moderation model can be divided into three main findings. First, external locus of causality along with job level moderated the relationship between work overload and cognitive coping. Hence, this interaction was evidenced only among nurses in non-supervisory positions. Second, external locus of causality and job level together moderated the relationship between physical environment and turnover intention. An opposite pattern of interaction was found for this interaction: among nurses, externality exacerbated the effect of perceived unpleasantness of the physical environment on turnover intention, whereas among supervisors internality produced the same effect. Third, job level also disclosed a moderation effect for controllability attribution over the relationship between physical environment and cognitive coping. Findings related to the mediation model for the energetic process indicated that the partial model in which work stressors have also a direct effect on turnover intention fitted the data better. In the mediation model for the motivational process, an intermediate mediation effect in which the effects of personal resources on turnover intention went through two mediators (e.g., causal dimensions and organizational identification) fitted the data better. All dimensions of causal attribution appeared to follow a somewhat unique pattern of mediation effect not only for energetic but also for motivational processes. Overall findings on mediation models partly supported the two simultaneous underlying processes proposed by the JD-R model. While in the energetic process the dimension of externality mediated the relationship between stressors and turnover partially, all the dimensions of causal attribution appeared to entail significant mediator effects in the motivational process. The general findings supported the moderation effect and the mediation effect of causal attribution in the work stress process. The study contributes to several research traditions, including the interaction approach, the JD-C, and the JD-R models. However, many potential functions of organizational causal attribution are yet to be evaluated by relevant academic and organizational research. Keywords: organizational causal attribution, optimistic / pessimistic attributional style, work stressors, organisational stress process, stressors in nursing profession, hospital nursing, JD-R model, personal resources, turnover intention, work engagement, organizational identification.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A functioning stock market is an essential component of a competitive economy, since it provides a mechanism for allocating the economy’s capital stock. In an ideal situation, the stock market will steer capital in a manner that maximizes the total utility of the economy. As prices of traded stocks depend on and vary with information available to investors, it is apparent that information plays a crucial role in a functioning stock market. However, even though information indisputably matters, several issues regarding how stock markets process and react to new information still remain unanswered. The purpose of this thesis is to explore the link between new information and stock market reactions. The first essay utilizes new methodological tools in order to investigate the average reaction of investors to new financial statement information. The second essay explores the behavior of different types of investors when new financial statement information is disclosed to the market. The third essay looks into the interrelation between investor size, behavior and overconfidence. The fourth essay approaches the puzzle of negative skewness in stock returns from an altogether different angle than previous studies. The first essay presents evidence of the second derivatives of some financial statement signals containing more information than the first derivatives. Further, empirical evidence also indicates that some of the investigated signals proxy risk while others contain information priced with a delay. The second essay documents different categories of investors demonstrating systematical differences in their behavior when new financial statement information arrives to the market. In addition, a theoretical model building on differences in investor overconfidence is put forward in order to explain the observed behavior. The third essay shows that investor size describes investor behavior very well. This finding is predicted by the model proposed in the second essay, and hence strengthens the model. The behavioral differences between investors of different size furthermore have significant economic implications. Finally, the fourth essay finds strong evidence of management news disclosure practices causing negative skewness in stock returns.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This thesis explores the link between South-South remittance and development. It attempts to establish improved understanding about the role of immigrants as agents of constituency growth and development. By doing so, it illuminates the dark corners of the policy implications that the unconventional development agency of immigrants might have for countries in the Organization ft Economic Cooperation and Development (OECD). The thesis problematises the existence of state-centric international cooperation as providing the recipe for failed Aid in the face of global poverty menace. In the last half a century, the relative shi' of focus to non-state actors brought about the proliferation of NGOs. That, intrun, helped improve international access to crisis situations; however, their long-term remedial impacts on poverty and development have been contested. Major misgivings for non-governmental organizations (NGOs) are, on one hand, low level goal-bound expenditures and lack of independence from influence of the state, on the other. Therefore, the thesis enterprises to empirically verify its fundamental question whether remitting immigrants constitute an alternative development agency to the traditional players: the State and NGOs. Its main arguments are: due to state's failures in bringing sustainable development in many countries of the South, the future of poverty reduction and development also rests in immigrants' remittances. Nonetheless, in the last decade, remittance security-nexus dominated its discourse. Because of that remittance was viewed as something requiring global regime and restrictions. These temptations to tightly regulate remittance flows carry the danger of overlooking its trans-boundary nature and its strong link with livelihood of the poor. Therefore, to avoid unintended consequences of interventions, there need to be clear policy that bases itself on a discursive knowledge on the issues of North-South and South-South remittances The study involved both literature based and empirical research. It employed Discourse Analysis (C as main method for the former and snow-balling as its approach for the latter. For the first part the thesis constructed three conceptual models, these are: metrological model, police model and ecological model on remittance development-nexus. Through this modeling, the thesis achieved better deconstruction on the concepts remittance, immigrants and development agency. The protagonists of each model, the values and interests they represent, and their main arguments along various lines of dichotomies have been discussed. For instance, the main treats of meteorological model include: it sees remittance as transitional economic variable which require constant speculations and global management; it acts as meteorological station for following up or predicting the level, direction, flow and movement of global remittance. It focuses on official lines and considers the state as legitimate recipient of advic and positive consequence of remittance. On the other hand, police model views remittance as beir at best, development neutral or as an illicit activity requiring global regulations and tight control. Both immigrants and remittance viewed as subversive to establishments. It gives primacy to state stable agent of development and a partner for international cooperation. The anti-thesis to the police model is supplied by ecological model, which this thesis is a part. Ecological model on remittance and immigrants argues that, tight global regulations alone cannot be a panacea for possible abuse of informal remittance system. Ecological model, not only links remittance to poverty reduction, the main trust of development, but also considers the development agency of immigrants as critical factor for 21st century north-south development intervention. It sees immigrants as development conscious and their remittance instrument as most stable flow of finance to the developing countries. Besides, it sees remittance as effective poverty solutions than Foreign Direct Investment and international AID. This thesis focuses on the significance of South-South remittance and investigates the South Africa - Ethiopia remittance corridor, as case study; and empirically verifies the role of Ethiopian (Kembata and Hadiya) immigrants in South Africa as agents of local development back home. The study involved techniques of interview, group discussions, observations and investigative study. It also looked into the determinants of their migration to South Africa, and their remittance to Ethiopia. The theoretical models in the first part of the thesis have been operationalised throughout the empirical part to verify if the Kembata and Hadiya immigrants played the crucial role in their household poverty and local development in comparison with the Ethiopian state and the NGOs involved in the system. As evidenced by the research the thesis has made three distinct contributions to the discourse of remittance development-nexus. Fist, it systematized the debate about linkages between remittance, immigrants, development agency and policy of international cooperation by creating three conceptual models (school of thoughts); second, it singled out remitting immigrants as new agents of development in the South; third, it deconstructed concept of remittance and established South¬South remittance as additional sphere of academic investigation. In addition to the above contributions, the thesis finds that Kembata and Hadiya immigrants have engaged in various developmental activities in their locality than usually anticipated. Hence, it concludes that Ethiopian immigrants constitute an alternative development agency to the state and other non-state actors in their country, and the lesson can be applied to poverty reduction strategies in most developing countries.