• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 213
  • 66
  • 53
  • 7
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 391
  • 150
  • 105
  • 76
  • 56
  • 56
  • 53
  • 49
  • 49
  • 48
  • 46
  • 44
  • 43
  • 36
  • 36
  • 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.
91

The evolution of residential property price premia in a metropolis: Reconstitution or contamination?

Huston, Simon Unknown Date (has links)
Residential property price premia (‘premia’) have long fascinated investors, particularly in times of euphoria, but their social, climatic and urban ramifications are much wider. A proper understanding of premia is hindered by the variety of exogenous influences determining them. They occur within idiosyncratic, complex, and continuously reconfiguring metropoli, conditioned by topography, history, regime, commerce, and culture. Given imperfectly competitive housing markets, conventional explanations for premia are either restricted to their financial dissection, trawl though metrics or cast around for hedonic coefficients. However, premia illuminate affordability and other problems in the broader planning and social debate. With the general significance of premia clarified, the research question of the project becomes: ‘What drives residential property price premium evolution in a metropolis?’ A complete answer involves dissecting the nature and establishing the location of putative premia and disentangling the influence and interactions of their various price drivers. To provide it, the project conducts a property and urban literature review. Based on theory’s insight that higher order contains lower order systems, it develops and investigates a general systems model of residential premia with two modes. The system is conditioned by ideology but forced by population and capital inflows. Within it, premia mutate, influenced by a nested hierarchy of more or less contaminated information. To investigate the model and its different modes, the project employs tests across system pointers, at the macro, meso (all urban) and micro spatial resolutions. First, the turbulence and permeability of residential property markets to exogenous influences is assessed. The project then looks at the urban mosaic in the growing Sunbelt migration city of Brisbane, Australia, over the boom period from 1998-2004. Locally, it conducts a case study and survey in one micro-location, seeking clues in transaction patterns (output), property system agents (components) and the information they use (feedback mechanisms). Finally, the project draws some relevant policy implications. Its key findings are that urban housing markets are open, complex and polarised. In an exuberant economic climate, migration and debt fuel metropolitan price escalation. Public urban initiatives reinforce central incumbent affluence or spark fresh bouts of speculation. Individual premia are heterogeneous but often feed off local construction projects or iconic refurbishment. Reflecting their demographics and motives, agent risk appetites are diverse although investors are usually less averse to renewal. System feedback involves a congruence of media and local activity signals. Neither local conviviality nor Bohemian influences are, by themselves, significant. Rather, buyer rationality is validated by post-purchase infrastructure completions. The thesis of this project is, hence, that in euphoric capital markets, migration and debt accelerates the endogenous mutation of property from homes within a community towards speculative paper assets. The implication is that the excessive proliferation of premia indicates economic imbalance and urban malaise which requires recognition and treatment. While premia are paid for perceived privilege or prospects, cognitive risk representations and expectations evolve. Sometimes judgment is contaminated by media fantasy but often validated by accommodating government policy and central revitalisation projects. Yet, within a wider social and ecological remit, rampant premia suggest flaws in urban strategy, governance and planning practice. In terms of windfall events or unearned rent, the cumulative effects of ill-considered projects and price distortions can be ugly and wasteful. They alienate and accentuate spatial privilege without generating sustainable jobs. The project has procedural and substantive policy implications. The dynamics of residential premia cannot be disentangled from capital market volatility, urban fragmentation and reconstitution. Enlightened property development requires visionary urban planning beyond electoral cycles. Rather than unregulated markets or disjointed incrementalism, the project points to the advantages of cohesive projects and inclusive hubs. It impels ecological and people-focused development to nurture capable, connected and considerate edge communities. Its first steps are theoretical recognition, policy clarification, government reform, market constraints, price and tax rationalisation and spatial transparency.
92

Inférences sur l'histoire des populations à partir de leur diversité génétique : étude de séquences démographiques de type fondation-explosion

Calmet, Claire 16 December 2002 (has links) (PDF)
L'étude de la démographie dans une perspective historique participe à la compréhension des processus évolutifs. Les données de diversité génétique sont potentiellement informatives quant au passé démographique des populations: en effet, ce passé est enregistré avec perte d'information par les marqueurs moléculaires, par l'intermédiaire de leur histoire généalogique et mutationnelle. L'acquisition de données de diversité génétique est de plus en plus rapide et aisée, et concerne potentiellement n'importe quel organisme d'intérêt. D'où un effort dans la dernière décennie pour développer les outils statistiques permettant d'extraire l'information démographique des données de typage génétique.<br />La présente thèse propose une extension de la méthode d'inférence bayésienne développée en 1999 par M. Beaumont. Comme la méthode originale, (i) elle est basée sur le coalescent de Kingman avec variations d'effectif, (ii) elle utilise l'algorithme de Metropolis-Hastings pour échantillonner selon la loi a posteriori des paramètres d'intérêt et (iii) elle permet de traiter des données de typage à un ou plusieurs microsatellites indépendants. La version étendue généralise les modèles démographique et mutationnel supposés dans la méthode initiale: elle permet d'inférer les paramètres d'un modèle de fondation-explosion pour la population échantillonnée et d'un modèle mutationnel à deux phases, pour les marqueurs microsatellites typés. C'est la première fois qu'une méthode probabiliste exacte incorpore pour les microsatellites un modèle mutationnel autorisant des sauts.<br />Le modèle démographique et mutationnel est exploré. L'analyse de jeux de données simulés permet d'illustrer et de comparer la loi a posteriori des paramètres pour des scénarios historiques: par exemple une stabilité démographique, une croissance exponentielle et une fondation-explosion. Une typologie des lois a posteriori est proposée. Des recommandations sur l'effort de typage dans les études empiriques sont données: un unique marqueur microsatellite peut conduire à une loi a posteriori très structurée. Toutefois, les zones de forte densité a posteriori représentent des scénarios de différents types. 50 génomes haploides typés à 5 marqueurs microsatellites suffisent en revanche à détecter avec certitude (99% de la probabilité a posteriori) une histoire de fondation-explosion tranchée. Les conséquences de la violation des hypothèses du modèle démographique sont discutées, ainsi que les interactions entre processus et modèle mutationnel. En particulier, il est établi que le fait de supposer un processus mutationnel conforme au modèle SMM, alors que ce processus est de type TPM, peut générer un faux signal de déséquilibre génétique. La modélisation des sauts mutationnels permet de supprimer ce faux signal.<br />La méthode est succinctement appliquée à l'étude de deux histoires de fondation-explosion: l'introduction du chat Felis catus sur les îles Kerguelen et celle du surmulot Rattus norvegicus sur les îles du large de la Bretagne. Il est d'abord montré que la méthode fréquentiste développée par Cornuet et Luikart (1996) ne permet pas de détecter les fondations récentes et drastiques qu'ont connu ces populations. Cela est vraisemblablement dû à des effets contraires de la fondation et de l'explosion, sur les statistiques utilisées dans cette méthode.<br />La méthode bayésienne ne détecte pas non plus la fondation si l'on force une histoire démographique en marche d'escalier, pour la même raison. La fondation et l'explosion deviennent détectables si le modèle démographique les autorise. Toutefois, les dépendances entre les paramètres du modèle empêchent de les inférer marginalement avec précision. Toute information a priori sur un paramètre contraint fortement les valeurs des autres paramètres. Ce constat confirme le potentiel de populations d'histoire documentée pour l'estimation indirecte des paramètres d'un modèle de mutation des marqueurs.
93

An examination of the implementation of an ecological sanitation project as an instrument of the Environmental Sanitation Policy of Ghana: the case of Kumasi Metropolis

Ekuful, Joyce January 2010 (has links)
<p>The generation of large volumes of solid and liquid wastes in urban and periurban areas of Ghana is a big problem for the people and government of Ghana. It contributes to the outbreak of many diseases in the country such as malaria, diarrhoea and typhoid fever. In managing the situation, a new concept called ecological sanitation (ecosan), which focuses on reuse of waste, has been introduced in the country. The objectives of the thesis were to criticise the environmental sanitation policy&nbsp / by analysing its content in relation to policy implementation arrangements, to discuss programmes and projects identified under the policy, to critically examine the implementation of an ecosan project as a way of achieving the goal and objectives by outlining its implementation processes, prospects and challenges, and to make appropriate recommendations. The analysis and discussion of the thesis were based on both primary and secondary data. The primary data, on one hand, were collected on the prospects and challenges that exist in the implementation of ecosan projects from Kumasi metropolis. The secondary data, on the other hand, were from&nbsp / books, journals and websites. From the research analysis, it emerged that the policy allows the implementation of many sanitation projects including ecosan. Secondly, stakeholders see ecosanto be a good approach to reduce waste generation in the country. However, the main challenges that exist in promoting the concept are inadequate financial support, unavailability of implementation guidelines and lack of knowledge about concept details. It is therefore argued that financial support, implementation guidelines and awareness-creation activities should be available in the implementation of ecosan in the metropolis. Government, private organisations, companies and individuals should each contribute their quota in the support and processes.</p>
94

Conditions for Rapid and Torpid Mixing of Parallel and Simulated Tempering on Multimodal Distributions

Woodard, Dawn Banister 14 September 2007 (has links)
Stochastic sampling methods are ubiquitous in statistical mechanics, Bayesian statistics, and theoretical computer science. However, when the distribution that is being sampled is multimodal, many of these techniques converge slowly, so that a great deal of computing time is necessary to obtain reliable answers. Parallel and simulated tempering are sampling methods that are designed to converge quickly even for multimodal distributions. In this thesis, we assess the extent to which this goal is acheived.We give conditions under which a Markov chain constructed via parallel or simulated tempering is guaranteed to be rapidly mixing, meaning that it converges quickly. These conditions are applicable to a wide range of multimodal distributions arising in Bayesian statistical inference and statistical mechanics. We provide lower bounds on the spectral gaps of parallel and simulated tempering. These bounds imply a single set of sufficient conditions for rapid mixing of both techniques. A direct consequence of our results is rapid mixing of parallel and simulated tempering for several normal mixture models in R^M as M increases, and for the mean-field Ising model.We also obtain upper bounds on the convergence rates of parallel and simulated tempering, yielding a single set of sufficient conditions for torpid mixing of both techniques. These conditions imply torpid mixing of parallel and simulated tempering on a normal mixture model with unequal covariances in $\R^M$ as $M$ increases and on the mean-field Potts model with $q \geq 3$, regardless of the number and choice of temperatures, as well as on the mean-field Ising model if an insufficient (fixed) set of temperatures is used. The latter result is in contrast to the rapid mixing of parallel and simulated tempering on the mean-field Ising model with a linearly increasing set of temperatures. / Dissertation
95

The effects of three different priors for variance parameters in the normal-mean hierarchical model

Chen, Zhu, 1985- 01 December 2010 (has links)
Many prior distributions are suggested for variance parameters in the hierarchical model. The “Non-informative” interval of the conjugate inverse-gamma prior might cause problems. I consider three priors – conjugate inverse-gamma, log-normal and truncated normal for the variance parameters and do the numerical analysis on Gelman’s 8-schools data. Then with the posterior draws, I compare the Bayesian credible intervals of parameters using the three priors. I use predictive distributions to do predictions and then discuss the differences of the three priors suggested. / text
96

An examination of the implementation of an ecological sanitation project as an instrument of the Environmental Sanitation Policy of Ghana: the case of Kumasi Metropolis

Ekuful, Joyce January 2010 (has links)
<p>The generation of large volumes of solid and liquid wastes in urban and periurban areas of Ghana is a big problem for the people and government of Ghana. It contributes to the outbreak of many diseases in the country such as malaria, diarrhoea and typhoid fever. In managing the situation, a new concept called ecological sanitation (ecosan), which focuses on reuse of waste, has been introduced in the country. The objectives of the thesis were to criticise the environmental sanitation policy&nbsp / by analysing its content in relation to policy implementation arrangements, to discuss programmes and projects identified under the policy, to critically examine the implementation of an ecosan project as a way of achieving the goal and objectives by outlining its implementation processes, prospects and challenges, and to make appropriate recommendations. The analysis and discussion of the thesis were based on both primary and secondary data. The primary data, on one hand, were collected on the prospects and challenges that exist in the implementation of ecosan projects from Kumasi metropolis. The secondary data, on the other hand, were from&nbsp / books, journals and websites. From the research analysis, it emerged that the policy allows the implementation of many sanitation projects including ecosan. Secondly, stakeholders see ecosanto be a good approach to reduce waste generation in the country. However, the main challenges that exist in promoting the concept are inadequate financial support, unavailability of implementation guidelines and lack of knowledge about concept details. It is therefore argued that financial support, implementation guidelines and awareness-creation activities should be available in the implementation of ecosan in the metropolis. Government, private organisations, companies and individuals should each contribute their quota in the support and processes.</p>
97

LITHOLOGIC AND STRATIGRAPHIC COMPILATION OF NEAR-SURFACE SEDIMENTS FOR THE PADUCAH GASEOUS DIFFUSION PLANT, MCCRACKEN COUNTY, KY

Sexton, Joshua L. 01 January 2006 (has links)
The Jackson Purchase region of western Kentucky consists of Coastal Plain sediments near the northern margin of the Mississippi Embayment. Within this region is the Paducah Gaseous Diffusion Plant (PGDP), a uranium enrichment facility operated by the US Department of Energy. At PGDP, a Superfund site, soil and groundwater studies have provided subsurface lithologic data from hundreds of monitoring wells and borings. Despite preliminary efforts by various contractors, these data have not been utilized to develop detailed stratigraphic correlations of sedimentary units across the study area. In addition, sedimentary exposures along streams in the vicinity of PGDP have not been systematically described beyond the relatively simple geologic quadrangle maps published by the US Geological Survey in 196667. This study integrates lithologic logs, other previous site-investigation data, and outcrop mapping to provide a compilation of near-surface lithologic and stratigraphic data for the PGDP area. A database of borehole data compiled during this study has been provided to PGDP for future research and archival. Developments in understanding near-surface geology include the adoption of nomenclature used by the Illinois State Geological Survey (ISGS), which separates the Continental Deposits into two distinct units, the Mounds Gravel and Metropolis Formation, based on their unique depositional histories. Additionally, faulting presented on the preliminary Joppa (IL) 7.5-minute quadrangle map, but not mapped on the Joppa (KY) 7.5-minute quadrangle map, appears to have impacted deposition of post-Eocene sediments at the site. These faults are co-linear to zones of irregularity noted in the Cretaceous McNairy Formation structure elevation map created during this study, thick zones of the Mounds Gravel noted in an isopach map from this study, and contaminant plume maps created previously by contractors.
98

Study of Magnetic Nanostructures using Micromagnetic Simulations and Monte Carlo Methods

Bäckström, Nils, Löfgren, Jonathan, Rydén, Vilhelm January 2014 (has links)
We perform micromagnetic simulations in MuMax3 on various magneticnanostructures to study their magnetic state and response to external fields. Theinteraction and ordering of nanomagnetic arrays is investigated by calculating themagnetostatic energies for various configurations. These energies are then used inMonte Carlo simulation to study the thermal behaviour of systems of nanomagneticarrays. We find that the magnetic state of the nanostructures are related to theirshape and size and furthermore affect the emergent properties of the system, givingrise to temperature dependent ordering among the individual structures. Results fromboth micromagnetic and statistical mechanic simulations agree well with availableexperimental data, although the Monte Carlo algorithm encounter problems at lowsimulation temperatures.
99

Kernel Selection for Convergence and Efficiency in Markov Chain Monte Carol

Potter, Christopher C. J. 24 April 2013 (has links)
Markov Chain Monte Carlo (MCMC) is a technique for sampling from a target probability distribution, and has risen in importance as faster computing hardware has made possible the exploration of hitherto difficult distributions. Unfortunately, this powerful technique is often misapplied by poor selection of transition kernel for the Markov chain that is generated by the simulation. Some kernels are used without being checked against the convergence requirements for MCMC (total balance and ergodicity), but in this work we prove the existence of a simple proxy for total balance that is not as demanding as detailed balance, the most widely used standard. We show that, for discrete-state MCMC, that if a transition kernel is equivalent when it is “reversed” and applied to data which is also “reversed”, then it satisfies total balance. We go on to prove that the sequential single-variable update Metropolis kernel, where variables are simply updated in order, does indeed satisfy total balance for many discrete target distributions, such as the Ising model with uniform exchange constant. Also, two well-known papers by Gelman, Roberts, and Gilks (GRG)[1, 2] have proposed the application of the results of an interesting mathematical proof to the realistic optimization of Markov Chain Monte Carlo computer simulations. In particular, they advocated tuning the simulation parameters to select an acceptance ratio of 0.234 . In this paper, we point out that although the proof is valid, its result’s application to practical computations is not advisable, as the simulation algorithm considered in the proof is so inefficient that it produces very poor results under all circumstances. The algorithm used by Gelman, Roberts, and Gilks is also shown to introduce subtle time-dependent correlations into the simulation of intrinsically independent variables. These correlations are of particular interest since they will be present in all simulations that use multi-dimensional MCMC moves.
100

Metropolis, Techno-culture, Digitilized Musical Genres And Clubbing In Turkey

Arican, Tunca 01 September 2003 (has links) (PDF)
This thesis will analyze the social life in metropolises in terms of technological changes and social transformations with their effects on everyday practices especially musical genres. This thesis also aims to understand the relationships between techno-culture, contemporary musical genres and clubbing as a subculture that reflects the aspects of techno-culture with its life style especially musical tendencies. The thesis will also make some illustrations of the features and life style of clubbers in Turkey. So, this study is composed of both theoretical and empirical structures. In order to make a comparative study, clubbing will be compared with the other subcultures appeared after the Second World War like Jazz, Punk or Acid House. The aspects of everyday life like drug use, consumption or appearance of those subcultures will be the base of this comparison.

Page generated in 0.0282 seconds