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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

Preference Elicitation in the Graph Model for Conflict Resolution

Ke, Yi January 2008 (has links)
Flexible approaches for eliciting preferences of decision makers involved in a conflict are developed along with applications to real-world disputes. More specifically, two multiple criteria decision making approaches are proposed for capturing the relative preferences of a decision maker participating in a conflict situation. A case study in logistics concerned with the conflict arising over the expansion of port facilities on the west coast of North America as well as a transportation negotiation dispute are used to illustrate how these approaches can be integrated with the Graph Model for Conflict Resolution, a practical conflict analysis methodology. Ascertaining the preferences of the decision makers taking part in a conflict constitutes a key element in the construction of a formal conflict model. In practice, the relative preferences, which reflect each decision maker’s objectives or goals in a given situation, are rather difficult to obtain. The first method for preference elicitation is to integrate an Analytic Hierarchy Process (AHP) preference ranking method with the Graph Model for Conflict Resolution. The AHP approach is used to elicit relative preferences of decision makers, and this preference information is then fed into a graph model for further stability analyses. The case study of the Canadian west coast port congestion conflict is investigated using this integrated model. Another approach is based on a fuzzy multiple criteria out-ranking technique called ELECTRE III. It is also employed for ranking states or possible scenarios in a conflict from most to least preferred, with ties allowed, by the decision maker according to his or her own value system. The model is applied to a transportation negotiation dispute between the two key parties consisting of shippers and carriers.
492

The HOT Solution: An examination of the desirability for High Occupancy/Toll (HOT) lanes in the Greater Toronto Area

Finkleman, Jeremy January 2010 (has links)
This study assessed the desirability for High-Occupancy/Toll (HOT) lanes in the Greater Toronto Area (GTA) through stated preference and revealed traffic volume data gathering and analysis techniques. 4,000 surveys, distributed in five sample areas, asked respondents how much they would be willing to pay to escape congestion in eight unique trip conditions. Stated preference results found considerable public support for HOT-lanes in the GTA. In six out of eight trip conditions, a majority of respondents preferred to pay to travel in express lanes rather than endure congestion. Respondent willingness to pay (WTP) mean values varied considerably by trip condition. Willingness to pay to escape congestion was influenced by trip characteristics and driver factors. Trip urgency, traffic speed, and freeway trip distance were found to be statistically significant trip characteristic indicators of WTP. Previous exposure to electronic tolling and annual household income were found to be significant driver factor indicators of WTP in most trip conditions. Respondent gender and freeway travel frequency were found to be statistically significant driver factor indicators of WTP in some trip conditions. The presence of Hwy 407-ETR, an electronically tolled by-pass to Hwy 401, allowed for an examination of the effects of Hwy 401 volume and trip urgency on driver choice to use the tolled alternative. Results indicated that trip urgency and Hwy 401 volume were correlated with Hwy 407 throughput share. During periods of high trip urgency and high Hwy 401 volume, a substantial proportion of Hwy 401/407 corridor drivers chose to pay approximately $0.20/km to escape congestion.
493

A Study in Preference Elicitation under Uncertainty

Hines, Greg January 2011 (has links)
In many areas of Artificial Intelligence (AI), we are interested in helping people make better decisions. This help can result in two advantages. First, computers can process large amounts of data and perform quick calculations, leading to better decisions. Second, if a user does not have to think about some decisions, they have more time to focus on other things they find important. Since users' preferences are private, in order to make intelligent decisions, we need to elicit an accurate model of the users' preferences for different outcomes. We are specifically interested in outcomes involving a degree of risk or uncertainty. A common goal in AI preference elicitation is minimizing regret, or loss of utility. We are often interested in minimax regret, or minimizing the worst-case regret. This thesis examines three important aspects of preference elicitation and minimax regret. First, the standard elicitation process in AI assumes users' preferences follow the axioms of Expected Utility Theory (EUT). However, there is strong evidence from psychology that people may systematically deviate from EUT. Cumulative prospect theory (CPT) is an alternative model to expected utility theory which has been shown empirically to better explain humans' decision-making in risky settings. We show that the standard elicitation process can be incompatible with CPT. We develop a new elicitation process that is compatible with both CPT and minimax regret. Second, since minimax regret focuses on the worst-case regret, minimax regret is often an overly cautious estimate of the actual regret. As a result, using minimax regret can often create an unnecessarily long elicitation process. We create a new measure of regret that can be a more accurate estimate of the actual regret. Our measurement of regret is especially well suited for eliciting preferences from multiple users. Finally, we examine issues of multiattribute preferences. Multiattribute preferences provide a natural way for people to reason about preferences. Unfortunately, in the worst-case, the complexity of a user's preferences grows exponentially with respect to the number of attributes. Several models have been proposed to help create compact representations of multiattribute preferences. We compare both the worst-case and average-case relative compactness.
494

Upper and lower visual field differences : an investigation of the gaze cascade effect

Burkitt Hiebert, Jennifer Ann 08 April 2010 (has links)
The purpose of the current thesis was to investigate the role of gaze direction, when making preference decisions. Previous research has reported a progressive gaze bias towards the preferred stimuli as participants near a decision, termed the gaze cascade effect (Shimojo, Simion, Shimojo & Scheir, 2003). The gaze cascade effect is strongest during the final 1500 msec prior to decision (Shimojo et al.). Previous eye-tracking research has displayed natural viewing biases towards the upper visual field. However, previous investigations have not investigated the impact of image placement on the gaze cascade effect. Study 1 investigated the impact of presenting stimuli vertically on the gaze cascade effect. Results indicated that natural scanning biases towards the upper visual field impacted the gaze cascade effect. The gaze cascade effect was reliably seen only when the preferred image was presented in the upper visual field. Using vertically paired stimuli study 2 investigated the impact of choice difficulty on the gaze cascade effect. Similar to study 1 the gaze cascade effect was only reliably seen when the preferred image was presented in the upper visual field. Additionally choice difficulty impacted the gaze cascade effect where easy decisions displayed a larger gaze cascade effect than hard decisions. Study 3 investigated if the gaze cascade effect is unique to preference decisions or present during all visual decisions. Judgments of concavity using perceptually ambiguous spheres were used and no gaze cascade effect was observed. Study 3 indicated that the gaze cascade effect is unique to preference decisions. Results of the current experiments indicate the gaze cascade effect is qualified by the spatial layout of the stimuli and choice difficulty. Results of the current experiments are consistent with previous eye-tracking research demonstrating biases towards the upper visual field and offering support for Prevics theory on how we interact in visual space.
495

iPrefer : A Qualtative Study of the Drivers of Brand Preference in the Swedish Smartphone Market

Djerv, Sara, Malla, Zeina January 2012 (has links)
Problem Discussion: The rapid development of the smartphone market led formerly well-established brands to subdue to new entrants. Understanding what drives brand preferences within the dynamic smartphone market is key to formulating marketing efforts that influence purchase intentions. Research Objective: To qualitatively explore how a brand's equity drives Uppsala University students brand preferences within the Swedish smartphone market. Furthermore, to suggest how to increase the level of brand preference that may lead to increased purchase intentions for smartphones. Research Question: a) What are the drivers of brand preferences for Uppsala University students within the Swedish smartphone market? b) How do these brand preferences influence purchase intentions? Method: A qualitative approach is adopted through conducting semi- structured interviews with Uppsala University students. The empirical findings are set against a theoretical framework in order to identify drivers of brand preferences and how they influence purchase intentions. Conclusion: The findings indicate that the Swedish smartphone market appears to be functionally oriented. Perceived quality emerges as the main driver of brand preferences.
496

Vilken preferens har tjockskalig målarmussla (Unio crassus) för bottensubstrat och vattenhastighet i Storån, Östergötland? / What preference does the thick shelled river mussel (Unio crassus) have regarding bottom substrate and water velocity in Storån, Östergötland?

Pettersson, Elin January 2012 (has links)
The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t>2.54, p<0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size <4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.
497

Vilken preferens har tjockskalig målarmussla (Unio crassus) för bottensubstrat och vattenhastighet i Storån, Östergötland? / What preference does the thick shelled river mussel (Unio crassus) have regarding bottom substrate and water velocity in Storån, Östergötland?

Pettersson, Elin January 2012 (has links)
The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t>2.54, p<0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size <4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.
498

Tre aspekter av arbetskraftsuthyrning

Herrera, Victor January 2010 (has links)
Sammanfattning *Denna uppsats betraktar begreppet arbetskraftsuthyrning ur olika synvinklar. Ur arbetstagarperspektivet görs detta genom att jämföra arbetsrättsliga villkor mellan inhyrd och traditionellt anställd personal samt redogöra för vad som händer med en arbetstagares olika förmåner när dennes anställning övergår från beställaren till uthyraren. Dessutom undersöks arbetstagares rättsliga möjligheter vid uppsägning som har sin grund i organisationsrelaterade skäl vilka resulterar i inhyrning. Ur beställarperspektivet undersöks vilka begränsningar som finns för inhyrning av arbetskraft i fall då egna anställda hävdar företrädesrätt till anställning. Slutligen undersöks uthyrarens möjligheter att säga upp personal på grund av arbetsbrist. Det framkommer att det är svårt att helt likställa inhyrd personal med traditionellt anställda. Detta grundar sig främst i att de två har olika motparter vilka de kan hävda sina rättigheter mot, något som främst visar sig vid en eventuell arbetsbristsituation hos beställaren. Trepartsrelationen får ytterligare konsekvenser i fall då arbetstagares anställning övergår från beställaren till uthyraren. De begränsningar som finns gällande beställares möjligheter att hyra in personal i fall då egna anställda har företrädesrätt består av skäl som motsvarande arbetstagarorganisation får svårt att bevisa. Uthyrningsföretags möjligheter att säga upp personal regleras på samma sätt som för företag i andra branscher. I de fall uthyrningsföretag vill framstå som seriösa bör de överväga vilken typ av anställning de ingår med respektive arbetstagare. Sökord: Anställningsskydd, Arbetsbrist, Arbetskraftsuthyrning, Företrädesrätt, Verksamhetsövergång * Tack till samtliga som gett råd och lämnat uppgifter. Ett särskilt tack riktas till Ann-Christine Hartzén, universitetsadjunkt på ekonomihögskolan vid Linnéuniversitetet, för hjälp och vägledning i uppsatsens internationella avsnitt.
499

Systematics of the Lichen Family Verrucariaceae and Evolution of the Rock-inhabiting Habit within a Group of Ecologically Diverse Fungi (Chaetothyriomycetidae, Ascomycota)

Gueidan, Cecile 04 December 2007 (has links)
Verrucariaceae are a family including mostly lichenized species (Verrucariales, Ascomycota). Its current generic classification, which mainly relies on three morphological characters (spore septation, thallus structure, and hymenial algae), has never been subjected to molecular data. Because these characters were suspected to be homoplastic, the monophyly of the genera as currently delimited based on morphology need to be assessed. A three-gene phylogenetic analysis was carried out using three methods (Maximum Parsimony, Maximum Likelihood, and a Bayesian approach) on 83 taxa, selected from 15 genera in Verrucariaceae. Ancestral state reconstructions were undertaken for four characters (spore septation, thallus structure, hymenial algae, and upper cortex structure). The results confirmed that most of the genera were not monophyletic, and that the most recent common ancestor of Verrucariaceae was most likely crustose, lacking hymenial algae, and with simple spores and a pseudocortex. The use of symplesiomorphic traits to define Verrucaria, the largest and type genus for the Verrucariaceae, as well as the non monophyly of the genera Polyblastia, Staurothele and Thelidium, explain most of the discrepancies between the current classification and a classification using monophyly as a grouping criterion. In order to accommodate newly inferred monophyletic groups, existing genera were re-delimited and three new genera were proposed. Recent broad-scale phylogenetic analyses have shown that Verrucariales was sister to Chaetothyriales, an order first known as including mostly saprophytes and opportunistic animal and human parasites. Investigations of fungal communities colonizing rocks in extreme environments have shown that some slow-growing melanized fungi inhabiting bare rock surfaces belonged to the Chaetothyriales. Multigene phylogenetic analyses were carried out using Maximum Likelihood and a Bayesian approach in order to confirm the affiliation of 25 of these rock isolates. Ancestral state reconstructions were then undertaken on two different datasets to look at the evolutionary history of lichenization within Pezizomycotina, and the rock-inhabiting habit within Eurotiomycetes. Results suggest that the ancestor of the lineage including Verrucariales and Chaetothyriales was likely to be an extremotolerant non-lichenized, rock-inhabiting fungus. Virulence factors of opportunistic parasites within Chaetothyriales, such as melanization and meristematic growth, might have primary been adaptations for life in extreme habitats. / Dissertation
500

Evolution of Floral Color Patterning in Chilean <em>Mimulus</Em>

Cooley, Arielle Marie 05 December 2008 (has links)
<p>Evolution can be studied at many levels, from phenotypic to molecular, and from a variety of disciplines. An integrative approach can help provide a more complete understanding of the complexities of evolutionary change. This dissertation examines the ecology, genetics, and molecular mechanisms of the evolution of floral anthocyanin pigmentation in four species of <em>Mimulus</em> native to central Chile. Anthocyanins, which create red and purple colors in many plants, are a valuable model for studying evolutionary processes. They are ecologically important and highly variable both within and between species, and the underlying biosynthetic pathway is well characterized. The focus of this dissertation is dramatic diversification in anthocyanin coloration, in four taxa that are closely related to the genomic model system <em>M. guttatus</em>. I posed three primary questions: (1) Is floral diversification associated with pollinator divergence? (2) What is the genetic basis of the floral diversification? (3) What is the molecular mechanism of the increased production of anthocyanin pigment? The first question was addressed by evaluating patterns of pollinator visitation in natural populations of all four study taxa. The second question was explored using segregation analysis for a series of inter- and intraspecific crosses. One trait, increased petal anthocyanins in <em>M. cupreus</em>, was further dissected at the molecular level, using candidate gene testing and quantitative gene expression analysis. Pollinator studies showed little effect of flower color on pollinator behavior, implying that pollinator preference probably did not drive pigment evolution in this group. However, segregation analyses revealed that petal anthocyanin pigmentation has evolved three times independently in the study taxa, suggesting an adaptive origin. In addition to pollinator attraction, anthocyanins and their biochemical precursors protect against a variety of environmental stressors, and selection may have acted on these additional functions. Molecular analysis of petal anthocyanins in <em>M. cupreus</em> revealed that this single-locus trait maps to a transcription factor, <em>McAn1</em>, which is differentially expressed in high- versus low-pigmented flowers. Expression of the anthocyanin structural genes is tightly correlated with <em>McAn1</em> expression. The results suggest that <em>M. cupreus</em> pigmentation evolved by a mutation cis to <em>McAn1</em> that alters the intensity of anthocyanin biosynthesis.</p> / Dissertation

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