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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.
941

Incorporating external effects in economic evaluation : the case of smoking

Trapero-Bertram, Marta January 2011 (has links)
The aim of this thesis is to explore methods to incorporate external effects on decision making of public health programmes in a UK setting, using smoking cessation as an example. The National Institute for Health and Clinical Excellence (NICE) methodological guidance for evaluating public health programmes is missing the incorporation of external effects. Therefore there is a need for considering their incorporation in such evaluations and to assess what are the appropiate methods to do so. Smoking cessation is an example where epidemiological evidence of external effects exists but has not generally been incorporated into economic evaluation. This thesis therefore focused in measuring the impact, in terms of costs and QALYs lost, of the incorporation of passive smoking, smoking during pregnancy and transmission of smoking behavior into economic evaluation of smoking cessation programmes previously developed to inform policy. A static Markov model is used to incorporate passive smoking and smoking during pregnancy, whereas transmisison of smoking behaviour is incorporated through a dynamic model. The findings show that some external effects can be incorporated without a system dynamic model, when this does occur, a static Markov model may be used to account for external effects in economic evaluation. Sometimes, to incorporate external effects, the model needs a change of population. Because smoking cessation interventions are generally highly cost-effective, the incorporation of external effects does not appear to change policy decisions, but there is a clear impact on the magnitude of the ICER. Passive smoking and smoking during pregnancy have higher impact in terms of costs and QALYs lost than transmission of smoking behaviour. Our discussion considers the validity of the methods used; how much the decision making process would be affected considering or not external effects on economic evaluation of smoking cessation interventions; and other valuation approaches for external effects, such as contingent valuation.
942

Damaged reinforced concrete structures in fire

Ervine, Adam January 2012 (has links)
It is crucial for a building to maintain structural stability when subjected to multiple and sequential extreme loads. Safety and economic considerations dictate that structures are built to resist extreme events, such as a earthquakes, impacts, blasts or fires, without collapse and to provide adequate time for evacuation of the occupants. However, during such events, some structural damage may be permissible. Design codes do not account for the scenario where two extreme events occur consecutively on a structure nor do they address the situation of the structure having some initial damage prior to being subjected to a fire load. This work begins by detailing the major inconsistancies between designing reinforced concrete structures for extreme mechanical loads and designing for fire. The material behaviour and traits of the constitutive parts (i.e. the concrete and the steel), including post yielding behaviour, thermal relationships and their interaction with each other are all explored in detail. Comprehensive experimental and numerical investigations are undertaken to determine whether, and to what extent, phenomena such as tensile cracking and loss of the concrete cover affect the local and global fire resistance of a member or structure. The thermal propagation through tensile cracks in reinforced concrete beams is examined experimentally. A comparison is made between the rate of thermal propagation through beams that are undamaged and beams that have significant tensile cracking. The results show that, although small differences occur, there is no significant change in the rate of thermal propagation through the specimens. Consequently, it is concluded that the effects of tensile cracking on the thermal propagation through concrete can be ignored in structural analyses. Significantly this means that analyses of heated concrete structures which are cracked can be carried out with heat-transfer and mechanical analyses being conducted sequentially, as is currently normal and fully-coupled thermo-mechanical analyses are not required. The loss of concrete cover and the impact on the thermal performance is examined numerically. A comparison is made of the thermal propagation, beam deflections and column rotations between structures that are undamaged and structures that have partial cover loss in a variety of locations and magnitudes. Results show that any loss of cover can lead to unsymmetrical heating, causing larger deflections in both vertical and horizontal directions, which can result in a more critical scenario. It is concluded that the effect of cover loss on the thermal performance of the structure is extremely significant. A new approach to numerically simulating the loss of cover by mechanical means from a member is developed. This new approach provides the user with an extremely flexible yet robust method for simulating this loss of cover. The application of this method is then carried out to show its effectiveness. A large experimental study carried out at the Indian Institute of Technology, Roorkee and separately numerically modelled at the University of Edinburgh. Unfortunately, due to unforseen circumstances, the experimental data available is limited at this time and as a result the validation of the numerical simulation is limited. Through these investigations it is clear that it is necessary to develop a method in enhance the stability and integrity of the concrete when subjected to the scenario of a fire following another mechanically extreme event. Therefore, finally a method is proposed and experimentally investigated into the use of fibres to increase the post crushing cohesiveness of the concrete when subjected to thermal loads. Results show that the fibrous members display an increased thermal resistance by retaining their concrete cover through an enhanced post crushing cohesion. From this investigation, it is concluded that the use of fibrous concrete is extremely beneficial for the application of enhancing the performance under extreme sequential mechanical and thermal loading.
943

Logic and handling of algebraic effects

Pretnar, Matija January 2010 (has links)
In the thesis, we explore reasoning about and handling of algebraic effects. Those are computational effects, which admit a representation by an equational theory. Their examples include exceptions, nondeterminism, interactive input and output, state, and their combinations. In the first part of the thesis, we propose a logic for algebraic effects. We begin by introducing the a-calculus, which is a minimal equational logic with the purpose of exposing distinct features of algebraic effects. Next, we give a powerful logic, which builds on results of the a-calculus. The types and terms of the logic are the ones of Levy’s call-by-push-value framework, while the reasoning rules are the standard ones of a classical multi-sorted first-order logic with predicates, extended with predicate fixed points and two principles that describe the universality of free models of the theory representing the effects at hand. Afterwards, we show the use of the logic in reasoning about properties of effectful programs, and in the translation of Moggi’s computational ¸-calculus, Hennessy-Milner logic, and Moggi’s refinement of Pitts’s evaluation logic. In the second part of the thesis, we introduce handlers of algebraic effects. Those not only provide an algebraic treatment of exception handlers, but generalise them to arbitrary algebraic effects. Each such handler corresponds to a model of the theory representing the effects, while the handling construct is interpreted by the homomorphism induced by the universal property of the free model. We use handlers to describe many previously unrelated concepts from both theory and practice, for example CSS renaming and hiding, stream redirection, timeout, and rollback.
944

Spatio-temporal modelling of climate-sensitive disease risk : towards an early warning system for dengue in Brazil

Lowe, Rachel January 2011 (has links)
The transmission of many infectious diseases is affected by climate variations, particularly for diseases spread by arthropod vectors such as malaria and dengue. Previous epidemiological studies have demonstrated statistically significant associations between infectious disease incidence and climate variations. Such research has highlighted the potential for developing climate-based epidemic early warning systems. To establish how much variation in disease risk can be attributed to climatic conditions, non-climatic confounding factors should also be considered in the model parameterisation to avoid reporting misleading climate-disease associations. This issue is sometimes overlooked in climate related disease studies. Due to the lack of spatial resolution and/or the capability to predict future disease risk (e.g. several months ahead), some previous models are of limited value for public health decision making. This thesis proposes a framework to model spatio-temporal variation in disease risk using both climate and non-climate information. The framework is developed in the context of dengue fever in Brazil. Dengue is currently one of the most important emerging tropical diseases and dengue epidemics impact heavily on Brazilian public health services. A negative binomial generalised linear mixed model (GLMM) is adopted which makes allowances for unobserved confounding factors by including spatially structured and unstructured random effects. The model successfully accounts for the large amount of overdispersion found in disease counts. The parameters in this spatio-temporal Bayesian hierarchical model are estimated using Markov Chain Monte Carlo (MCMC). This allows posterior predictive distributions for disease risk to be derived for each spatial location and time period (month/season). Given decision and epidemic thresholds, probabilistic forecasts can be issued, which are useful for developing epidemic early warning systems. The potential to provide useful early warnings of future increased and geographically specific dengue risk is investigated. The predictive validity of the model is evaluated by fitting the GLMM to data from 2001-2007 and comparing probabilistic predictions to the most recent out-of-sample data in 2008-2009. For a probability decision threshold of 30% and the pre-defined epidemic threshold of 300 cases per 100,000 inhabitants, successful epidemic alerts would have been issued for 94% of the 54 microregions that experienced high dengue incidence rates in South East Brazil, during February - April 2008.
945

Immediate and subsequent effects of fixed-time food presentations on automatically maintained mouthing.

Simmons, Jason N. 12 1900 (has links)
Several studies have demonstrated that fixed-time (FT) schedules of stimulus delivery can function to reduce a variety of behaviors. The purpose of this study was to evaluate the immediate and subsequent effects of FT food deliveries on mouthing. In Phase 1, a preference assessment showed that caramel popcorn, chocolate cookies and pretzels were highly preferred food items. Thus, providing the basis for use of food items during treatment. In Phase 2, a functional analysis showed that mouthing was a nonsocially maintained problem behavior. Phase 3 demonstrated the use of FT schedules of food deliveries as treatment for nonsocially maintained mouthing. Results indicated that FT schedules of food significantly reduced mouthing. In addition, levels of mouthing observed during post-FT observations were reliably lower than pre-FT observations. Treatment effects, operative mechanisms responsible for the treatment effects and the experimental arrangement used to investigate varying FT schedules are discussed.
946

IT-baserade interventioner och dess hälsoeffekter vid egenvård hos personer med typ 2 diabetes : En litteraturöversikt / IT-based interventions and the health effects for self-care in people with type 2 diabetes : A literature review

Andersson, Rosalie, Sandh, Josefine January 2016 (has links)
No description available.
947

A global bifurcation theorem for Darwinian matrix models

Meissen, Emily P., Salau, Kehinde R., Cushing, Jim M. 09 May 2016 (has links)
Motivated by models from evolutionary population dynamics, we study a general class of nonlinear difference equations called matrix models. Under the assumption that the projection matrix is non-negative and irreducible, we prove a theorem that establishes the global existence of a continuum with positive equilibria that bifurcates from an extinction equilibrium at a value of a model parameter at which the extinction equilibrium destabilizes. We give criteria for the global shape of the continuum, including local direction of bifurcation and its relationship to the local stability of the bifurcating positive equilibria. We discuss a relationship between backward bifurcations and Allee effects. Illustrative examples are given
948

Optimized recovery of damaged electrical power grids

Ang, Chee Chien 03 1900 (has links)
Approved for public release; distribution is unlimited / This thesis formulates and solves a mixed-integer program to plan the recovery of an electrical power transmission grid that has been damaged by a natural disaster or terrorist attack. The damage can be extensive and recovery can take weeks or months. An efficient recovery plan that maximizes the utilization of repair resources can help ensure swift restoration of services. The network recovery-planning model is implemented in GAMS (General Algebraic Modeling System) and uses CPLEX as the solver. An electrical grid based on IEEE's 300-bus transmission network is used for testing. To simulate varying degrees of damage to the network, we choose up to 20% of the grid's lines, buses and transformers to be placed out of service. Based on the availability of repair resources, the repair-time horizon and penalties for unserved demand, the model produces a repair schedule that minimizes the cost of power shed. We demonstrate that for a network with up to 8% of its components damaged, the model can produce an optimal recovery plan within 20 minutes on a 2 GHz personal computer. For our largest test-case with 20% of network components damaged, the recovery plan is within 7% of optimal after 1 hour of solver time. / Outstanding Thesis
949

A prospective, epidemiological pilot study to investigate the level of knowledge of homoeopathy and its contextualization in pharmacy front shop assistants in the KwaZulu-Natal area

De Villiers, Lecia January 2006 (has links)
Mini-dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Homeopathy, Durban Institute of Technology, 2006. / It was my perception, after having worked in the Complementary and Alternative Medicines Industry, that the knowledge and understanding of homeopathy by retail providers, was poor. Considering that pharmacies also sold over-the- counter homeopathic medicine, I felt it would be of value to do an empirical study in order to obtain more accurate data on this topic. / M
950

Effect of vapor velocity during condensation on horizontal finned tubes

Hopkins, Charles Louis III 12 1900 (has links)
Approved for public release; distribution is unlimited / Heat-transfer measurements were made for condensation of R-113 and steam on a smooth tube and on three finned tubes with rectangular shape fins. These tubes had a fin height and width of 1.0 mm and spacings of 0.25, 1.5, and 4.0 mm (tubes A, B, and C respectively) . Data were taken by increasing the vapor velocity from 0.4 to 1.9 m/s for R-113 and 4.8 to 31.3 m/s for steam. For both fluids, the improvement of the condensing heat-transfer coefficient with vapor velocity was smaller for the finned tubes than for the smooth tube. For R-113, the smooth tube experienced a 32 percent improvement with vapor velocity, where the finned tubes (tubes A, B and C respectively) experienced improvements of only 0, 5 and 10 percent. For steam, the smooth tube experienced a 62 percent improvement, whereas the finned tubes (tubes A, B, and C respectively) experienced improvements of only 31, 11, and 9 percent. These test results show that, although finned tubes can provide significant heat transfer enhancement over smooth tubes at low vapor velocities, the degree of enhancement becomes smaller as vapor velocity increases. / CBT-8603582 (NSF) / http://archive.org/details/effectofvaporvel00hopk / National Science Foundation / Lieutenant Commander, United States Navy

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