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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.
261

Essays in networks and behaviour

Carpenter, William John Wakefield January 2019 (has links)
This dissertation, submitted for the degree of Doctor of Philosophy, is comprised of three essays on networks and human behaviour. The first studies the capacity for some agent in a network, who we term the 'principal', to ensure the robustness of their network to potentially disruptive external shocks. Agents susceptible to shocks may invest in contingencies but have insufficient incentive to do so from the perspective of the principal. We derive results on the cost to the principal of overcoming the resulting moral hazard problem. We focus first on the case where agents can only write contracts with their immediate neighbors, finding that costs are strictly increasing in the longest path in the network away from the principal when the probability of shocks is low. However, we also find that for a fixed longest path away from the principal, a secondary 'responsibility' effect can cause costs to be lower when the average distance away from the principal is higher. We extend our model to allow the principal to contract directly with all agents but with additional information processing costs. We consider applications to supply chain robustness to natural disasters and employee adherence to safety regulations in a firm. The second essay develops a model of demand led innovation in supply chains and studies the general equilibrium effects of demand shocks on R&D expenditure. It is found that when no final good producers share suppliers, a positive demand shock will weakly increase innovation in all firms. However, with common suppliers, negative pecuniary externalities may reduce R&D expenditure in some firms. The final essay was produced in collaboration with Dr. Matthew Elliott. It proposes a new model of individual choice as a Markovian decision process over emotional states. This approach allows for economic decisions to depend upon both an individual's current emotional state as well as introspection about how choices will affect their future emotional state. The generality of this framework is shown formally before demonstrating its efficacy in dealing with specific applications drawn from empirical findings in psychology and neuroscience. Specifically, the role of frustration in gambling is explored, along with the role of angry emotional responses in generating inefficiency and delay in negotiation and bargaining.
262

Analysing crowd behaviours using mobile sensing

Katevas, Kleomenis January 2018 (has links)
Researchers have examined crowd behaviour in the past by employing a variety of methods including ethnographic studies, computer vision techniques and manual annotation-based data analysis. However, because of the resources to collect, process and analyse data, it remains difficult to obtain large data sets for study. Mobile phones offer easier means for data collection that is easy to analyse and can preserve the user's privacy. The aim of this thesis is to identify and model different qualities of social interactions inside crowds using mobile sensing technology. This Ph.D. research makes three main contributions centred around the mobile sensing and crowd sensing area. Firstly, an open-source licensed mobile sensing framework is developed, named SensingKit, that is capable of collecting mobile sensor data from iOS and Android devices, supporting most sensors available in modern smartphones. The framework has been evaluated in a case study that investigates the pedestrian gait synchronisation phenomenon. Secondly, a novel algorithm based on graph theory is proposed capable of detecting stationary social interactions within crowds. It uses sensor data available in a modern smartphone device, such as the Bluetooth Smart (BLE) sensor, as an indication of user proximity, and accelerometer sensor, as an indication of each user's motion state. Finally, a machine learning model is introduced that uses multi-modal mobile sensor data extracted from Bluetooth Smart, accelerometer and gyroscope sensors. The validation was performed using a relatively large dataset with 24 participants, where they were asked to socialise with each other for 45 minutes. By using supervised machine learning based on gradient-boosted trees, a performance increase of 26.7% was achieved over a proximity-based approach. Such model can be beneficial to the design and implementation of in-the-wild crowd behavioural analysis, design of influence strategies, and algorithms for crowd reconfiguration.
263

Testing shopping experience and behavior for distant shopping by focus on communication between web shops and consumer

RIZWAN RAFIQUE, MUHAMMAD, USMAN SAEED ARIAN, MUHAMMAD January 2010 (has links)
Planet earth is shrinking due to the virtual world. Internet applications all over the world have now made it necessary for the people to make internet a part of daily life. This advent is leaving its impression on all industries and especially the clothing industry. E-commerce is a business application of internet all over the world. The companies which are operating in apparel business are developing their web shops. In order to create loyal customers and meeting the consumer demand it is important to do necessary communication of the products with the consumers. Otherwise the products might be a surprise at the time of delivery to the consumers. Every consumer has his/ her own way of evaluating a product. So it is important for a web shop to address to every kind of consumer in order to meet the consumer demand and create more customers. The virtual world has its own complications and deviation from the usual world. So the thesis is focused on testing of shopping experience for an online purchase and to do the analysis of the communication between the web shop and the consumer. The studies are done on the basis of evaluation of feedback collection from consumers and information search of the various products online. The focus was more on the customers who do careful information search before doing a purchase and also some random customers who purchase a product without deep evaluation of the products. Traditional consumer behavior and the consumer behavior for online shopping were compared analytically and the results have been discussed in the end. Need for improvement in existing systems is the base for this thesis. Studies showed that the e-commerce systems are still unable to understand the new customer segment for online shopping and there is a great need of improvement in this area to get more customers. The results from this study are significant for the web shops which are operating the Scandinavian countries.
264

Why aggregate?

Gillmeister, Andrea Brigitta January 1999 (has links)
No description available.
265

The geometry of colour

Wilkins, Lucas January 2013 (has links)
This thesis explores the geometric description of animal colour vision. It examines the relationship of colour spaces to behavior and to physiology. I provide a derivation of, and explore the limits of, geometric spaces derived from the notion of risk and uncertainty aversion as well as the geometric objects that enumerate the variety of achievable colours. Using these principles I go on to explore evolutionary questions concerning colourfulness, such as aposematism, mimicry and the idea of aesthetic preference.
266

Synthèse électrochimique de films d'hydroxydes doubles lamellaires : applications aux biocapteurs / Electrochemical synthesis of layered doubles hydroxides films : applications to biosensors

Ben Assaker, Ibtissem 01 July 2009 (has links)
Ce travail de thèse est consacré à la synthèse électrochimique de films minces d’hydroxydes doubles lamellaires (HDL) et à l’élaboration de biocapteurs enzymatiques à détection ampérométriques, utilisant ces films comme matrices d’immobilisation des enzymes. Des études préalables de synthèse de suspensions de HDLs à partir de la neutralisation de mélange de cations métalliques divalents et trivalents par la soude ont été effectuées. Les solides formés ont été caractérisés par spectroscopie FTIR et par diffraction des rayons X ; leurs compositions ont été déterminées par dosages chimiques et par ICP-OES. Les conditions permettant de former exclusivement un HDL ont été précisées pour plusieurs couples cations divalents / cations trivalents, en présence d’ions bicarbonate ou du complexant EDTA. Les suivis pHmétriques ont permis de définir les compositions d’électrolytes les plus adaptées pour les synthèses électrochimiques des films de HDLs. Des films minces d’Hydrotalcite ou de Pyroaurite ont été obtenus sur substrat conducteur (Pt, Au) par augmentation du pH local résultant de la réduction de l’oxygène dissous ou de l’eau. Les paramètres potentiel, courant et temps de réduction ont été étudiés. Des comportements électrochimiques linéaires de ces électrodes modifiées vis-à-vis de l’ion ferricyanure ou des produits de catalyse enzymatique, H2O2 et NADH, ont été mis en évidence. Deux types de biocapteurs, à glucose ou à lactate, ont été fabriqués par co-déposition électrochimique du film HDL et de l’enzyme, glucose oxydase ou lactate déshydrogénase. Leurs sensibilités ampérométriques pour leur substrat, glucose ou lactate, ont été étudiées en fonction de différents paramètres de préparation ou de fonctionnement. / This work is devoted to the electrochemical synthesis of layered double hydroxides (LDH) thin films and to the development of enzymatic biosensors with amperometric detection, using these films as immobilization matrices of enzymes. Preliminary studies of LDH suspensions synthesis by neutralization of mixed divalent and trivalent metallic cations with sodium hydroxide were performed. The powders were characterized by FTIR spectroscopy and X-ray diffraction, and their compositions were determined by chemical titration and ICP-OES. Conditions for the formation of pure LDH were specified for several couples of divalent / trivalent cations, in the presence of bicarbonate ions or EDTA. The pH titration curves allow the determination of the best suited electrolyte compositions for the electrodeposition of LDHs films. Hydrotalcite or Pyroaurite thin films were obtained on conductive substrates (Pt, Au) from the increase of local pH induced by dissolved oxygen or water electrochemical reduction. The following parameters were studied, potential, current and reduction time. The linear electrochemical behaviour of these LDH-modified electrodes was verified for the oxidation of ferricyanide ions or H2O2 and NADH, the products resulting from bio-catalysed reactions. Two types of biosensors, for glucose or lactate determination, were elaborated by electrochemical co-deposition of LDH film and enzyme, glucose oxidase or lactate dehydrogenase. Amperometric sensitivities for glucose or lactate were studied as a function of preparation and operation parameters.
267

The systematics and biology of the genus Poltys (Araneae: Araneidae) in Australasia

Smith, Helen Motum January 2006 (has links)
Doctor of Philosophy / The genus Poltys C.L. Koch is revised for Australia and partly examined for the wider Australasian region. Five of the ten species originally described from Australia are found to be synonymous with South East Asian species, a further three are synonymous with an Australian species and four which were previously overlooked are newly described, resulting in a total of eight current species recorded from Australia. Poltys coronatus Keyserling, P. keyserlingi Keyserling, P. multituberculatus Rainbow and P. penicillatus Rainbow are synonymised with P. illepidus C.L. Koch; P. microtuberculatus Rainbow is synonymised with P. stygius Thorell; P. bimaculatus Keyserling, P. mammeatus Keyserling and P. salebrosus Rainbow are synonymised with P. laciniosus Keyserling; P. sigillatus Chrysanthus from New Guinea is synonymised with P. frenchi Hogg. Five new species are described, four from Australia, P. grayi sp.nov., P. jujorum sp.nov., P. milledgei sp.nov. and P. noblei sp.nov., and P. timmeh sp.nov. from New Caledonia. A checklist of all Poltys types described from the region, including illustrations, is included. The delimitation of the Australian species is aided and confirmed by DNA sequencing. Sequences from two genes and morphological characters are used to reconstruct a phylogeny of the Australian species. The generic relationships of Poltys are examined in the context of the putative tribe Poltyini (Simon, 1895). No firm conclusions about the relationships of Poltys can be made, however the results indicate that the Poltyini is polyphyletic. The results of field studies are presented; these indicate that P. noblei is less likely to move between web sites than diurnal taxa referenced from other studies. Specimens were shown to sometimes occupy the same, or a closely adjacent web site, for over eight months. Spiders most often move during spring and summer but often remain in the same site throughout winter. Specimens of Poltys noblei are also shown to be unevenly distributed on trees and bushes in respect to aspect and position. It is suggested that these observations indicate the importance of camouflage to deter wasp and bird predators. Specimens of several Poltys species were reared from egg sacs, confirming male–female identification and showing the variation in abdominal shape between siblings. Growth data indicate that sibling males and females cannot normally interbreed; males mature after 2–4 moults, females after 8–11 moults. Field and cage observations of general aspects of Poltys biology are presented including preferred habitat, prey capture and handling, courtship and mating, competition and web construction.
268

Adult attachment syle and vulnerability to depression

Murphy, Barbara, barbara.murphy@heartresearchcentre.org January 2000 (has links)
This thesis explores the utility of Attachment Theory (Bowlby, 1969; 1973; 1980) as a framework for understanding both the personality and cognitive processing styles associated with depression and vulnerability to depression. In two separate but related studies, the present investigation identified depressive personality characteristics and depressive cognitive processing styles associated with each of the styles of adult attachment defined by Bartholomew and Horowitz's (1991) four-category attachment model. Using self-report data from a sample of 305 respondents (225 female; 80 male), Study 1 explored associations among each of the adult attachment styles and sociotropic and autonomous personality-based vulnerabilities to depression (Beck, 1983). Extending the work of Zuroff and Fitzpatrick (1995; Study 2), associations among the attachment styles and the specific components of the two depressive personality styles, as defined by Robins et al. (1994), were examined. Using cued recall of autobiographical memories for a subsample of 44 of the same respondents (35 female; 9 male), Study 2 explored attachment style group differences in autobiographical memory retrieval, thereby identifying specific depressive cognitive processing biases associated with each adult attachment style. Past research has focused on the assessment of memory accessibility, using either recall latency (Mikulincer & Orbach, 1995; Mikulincer, 1998a) or memory generality (Tasker, MacLeod & Maynard, 1996) to indicate accessibility. In the present study, both latency and generality were used as indicators of memory accessibility, and the content of memories was also examined. In addition, use of a four-category rather than a three-category measure of attachment style permitted distinction of cognitive biases for the fearful-avoidant and dismissive-avoidant styles. The present findings support a notion that the two adult attachment styles understood to be characterised by a negative self-view, namely fearful and preoccupied attachment, are associated with depressive vulnerability. Replicating previous findings (Carnelley, Pietromonaco & Jaffe, 1994), both the fearful and preoccupied styles were associated with state depression and with perceptions of negative parental bonding. The fearful style in particular was associated with perceptions of 'affectionless control' in childhood. As the major focus of this thesis, the fearful and preoccupied attachment styles were each associated with both personality styles and cognitive processing deficits which have previously been linked with depression and depressive vulnerability. In terms of personality styles (Study I), the fearful attachment style was broadly associated with the autonomous personality style, whereas the preoccupied attachment style was broadly associated with the sociotropic personality style, as previously demonstrated by Zuroff and Fitzpatrick (1995; Study 2). By focusing on associations with the individual components of the autonomous and sociotropic vulnerabilities, as defined by Robins et al. (1994), the more specific 'depressive' personality characteristics were identified for both these insecure attachment styles. In particular, the findings suggest that a fearful attachment style involves both avoidant and self-critical characteristics, whereas a preoccupied attachment style involves both dependent and self-critical characteristics. In terms of cognitive processing deficits (Study 2), fearful individuals had difficulty accessing autobiographical memories, indicated by delayed memory recall and reduced memory specificity across a range of memory cues. Indeed, these individuals demonstrated a globalised 'mnemonic interlock' typical of depressed individuals (Williams, 1996) and their memories were predominantly negative in content. In contrast, preoccupied individuals demonstrated a ruminative cognitive processing style, indicated by relatively fast recall of predominantly specific and negative memories across a range of memory cues. However, these individuals had difficulty accessing personally-relevant memories of abandonment, arguably due to both encoding and retrieval deficits emanating from their hypersensitivity to abandonment experiences. Dismissive attachment was associated with the avoidant but not the self-critical aspect of the autonomous personality style and involved a repressive cognitive processing style. This repressive style was indicated by delayed recall of specific negative memories. Nonetheless, unlike the fearful and preoccupied styles, dismissive attachment was not shown to be associated with state depression, suggesting that an avoidant attachment style does not necessarily contribute to depressive vulnerability. Instead, dismissive individuals' use of defensive repression of negative affects and memories appears to be an effective coping mechanism in the maintenance of a positive self-concept and a non-self-critical approach. Furthermore, in light of self-narrative models of personality (e.g., McAdams, 1993; Bruhn, 1990; 1992; 1995; Singer & Salovey, 1993), dismissive individuals' easy access to positive memories, particularly personally-relevant memories of independence, can be viewed as maintaining their positive self-concept. Overall, the findings of the present thesis support the proposition that Attachment Theory provides a framework for understanding both the personality and cognitive processing styles associated with depression. Indeed, the findings suggest that the fearful and preoccupied adult attachment styles can both be regarded as constituting vulnerability factors for depression. As expected, the fearful attachment style was highlighted as conferring greater depressive vulnerability. Thus, the findings provide further insight into the factors involved in the onset and maintenance of depression and highlight the importance of assessing adult attachment style during therapy for depression. Other clinical implications, as well as directions for future research, are outlined.
269

An experimental study of human reasoning and conceptual behaviour

Taplin, John Eaton. January 1971 (has links) (PDF)
No description available.
270

Consumer Behaviour

Martínez, Bárbara, Pérez, Sara January 2008 (has links)
<p>The aim of this work is to understand the consumer behaviour. The research is going to be focus on the factors that influence the consumers behaviour. The purpose of this paper is to know the different aspects that the consumers have into account when they decide to use a certain product.</p>

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