• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 17
  • Tagged with
  • 517
  • 517
  • 517
  • 105
  • 92
  • 61
  • 59
  • 59
  • 41
  • 40
  • 34
  • 34
  • 32
  • 32
  • 31
  • 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.
131

Water resources in the State of Qatar : toward holistic management

Al-Mohannadi, Hassan I. January 2001 (has links)
No description available.
132

On the hydrology of peat

Rycroft, David William January 1972 (has links)
No description available.
133

Climate change as a knowledge controversy : investigating debates over science and policy

Sharman, Amelia January 2015 (has links)
Understanding climate change as a knowledge controversy, this thesis provides new insights into the form, value and impact of the climate change debate on science and policy processes. Based on 99 interviews in New Zealand and the United Kingdom as well as social network analysis, it provides an original contribution to knowledge by identifying previously unknown sites of knowledge contestation within the climate change debate, in addition to contributory factors, and potential solutions to, debate polarisation. It also addresses a fundamental gap in the literature regarding the impact of controversy on the production of scientific knowledge and policy decision-making. This thesis comprises five standalone papers (Chapters 2-6) which together explore climate change as a knowledge controversy using frameworks from science and technology studies, sociology and geography. Chapter 2 finds that the most central blogs within the climate sceptical blogosphere predominantly focus on the scientific element of the climate debate. It argues that by acting as an alternative public site of expertise, the blogosphere may be playing a central role in perpetuating doubt regarding the scientific basis for climate change policymaking. Chapter 3 suggests that the binary and dualistic format of labels used within the climate debate such as “denier” or “alarmist” contribute towards polarisation by reducing possibilities for constructive dialogue. Chapter 4 investigates rationales for debate participation and argues that identifying and emphasising commonalities between previously polarised individuals may serve to reduce antagonism within the climate change debate. Chapter 5 investigates the impact of controversy on the production of scientific knowledge and finds that climate scientists identify substantial impacts on their agency as scientists, but not on scientific practice. It argues that this distinction indicates that boundarymaking may be understood as a more active and explicit process under conditions of controversy. Finally, Chapter 6 introduces the concept of post-decisional logics of inaction, emphasising the role of place in determining the influence of controversial knowledge claims on climate change policymaking. These findings make explicit the underlying politics of knowledge inherent within the climate change debate, and emphasise the need for a more attentive consideration of the role of knowledge, place and performativity in contested science and policy environments.
134

The meteorology and climatology of air pollution in West Central Scotland

Sweeney, John C. January 1980 (has links)
No description available.
135

Assessing climatic and technological constraints to agricultural productivity in South Asia

Gorst, Ashley January 2017 (has links)
This thesis comprises of four essays that seek to advance understanding of the role that climatic constraints have on agricultural productivity in India and Pakistan. This work emphasises that the constraints posed to agricultural production must be understood within the context of an evolving set of environmental and technological conditions. The thesis employs empirical methods to understand these relationships, where particular emphasis is placed on methods suitable for learning about the challenges agriculture will face in the future. The first chapter studies the impact of climate change on rice yields in India by modelling the inter-annual distribution of yield conditional on projected temperature increases. The results suggest a decrease in average yield and a substantial increase in the probability of low yields. It is also shown that yields have become increasingly resilient to heat over time. The second chapter studies the e↵ect of drought on cereal production in India by estimating thresholds of drought impact. By examining thresholds over time, evidence is found of decreasing average impacts, but with evidence of an abrupt increase in average drought impacts in more recent years. Thresholds of precipitation are also estimated, indicating substantial heterogeneity in resilience to drought across crop types and regions of India. The third chapter examines how changes in agricultural technology brought about by the Green Revolution a↵ected the relative importance of agro-climatic factors in determining crop yields. Using a detailed measure of crop suitability it is found that yields increased relatively more in areas of higher suitability, indicating complementarity between agricultural technologies and favourable agro-climatic characteristics. The final chapter uses farm-level data from a specifically-designed survey to assess the impact and determinants of climate change adaptation strategies on crop productivity in Pakistan. Adaptation has a beneficial e↵ect on rice yields, but not on wheat yields. This chapter also finds that a number of household and institutional factors are strongly related to whether households have adapted to climate change.
136

Essays on the economic consequences of weather and climate change

Colmer, Jonathan January 2016 (has links)
This thesis seeks to advance our understanding of climatic influence on economic outcomes. The approach taken places emphasis on understanding the channels and mechanisms through which weather has an effect, and through which climate change could have an effect, on economic behaviour – rather than estimating the impact of future climate change – to better inform the design and implementation of policy. This thesis is composed of four papers that adopt this new paradigm, providing new insights into how weather affects economic outcomes today, how economic agents respond to and manage the economic consequences of changes in their natural environment, and providing explicit mechanisms through which the impacts of, and adaptation to, climate change could affect economic outcomes in the future.
137

Sustainable development in Libya : stakeholders' attitudes towards sustainable tourism development in Al-Jabal Al-Gharbi City, Libya

Amhemed, Mossa January 2014 (has links)
Tourism has become the most important source for stimulating the economies of countries of the world. It stimulates enormous investment in infrastructure and helps states to improve their balance of payments, which should help to create job opportunities and improve the living conditions of local people by helping to equalise economic opportunities and keep rural residents from moving to overcrowded cities (WTO, 2007). Libyan economy is still dependent on oil by a large margin, with the knowledge that there are other sectors which can participate in the diversification of the economy, but not given the opportunity by the Government (such as the tourism sector). But tourism development in order to be useful in the long term must be sustainable. Berlin Declaration of 1997 suggested that “achieving sustainable forms of tourism is the responsibility of all stakeholders involved, where it is critical that planners and decision-makers understand the attitudes of stakeholders towards sustainable actions in tourism development". The aim of the study is to explore the possibility of treating sustainable tourism development in the Al-Gabal Al-Gharbi City (GGC) in the future, by recognizing the extent of support that can be provided by key stakeholders for tourism, according to the study of their attitudes toward tourism development in this city. The GGC was selected as a case for the study because it is representative of other cities in Libya which are in urgent need of development projects in order to find solutions to many economic, social and environmental problems. Four key groups of stakeholders were selected to participate in this study (local residents, tourists, government sector, and the private sector). The researcher used "mixed method" to collect main data such as: The questionnaire which was used as a key method to discover the attitudes of residents and tourists, and the interviews used to explore the attitudes of the public and private sectors. Additionally, the researcher also used reports, studies, books, tables, images and maps published together with field visits to some tourist sites including close monitoring of the reality as a secondary source for data collection. The study led to some important findings, where it confirmed the existence of good tourist resources in the city in terms of quantity and quality of tourist products and identified the possibility of competition at the local and global levels. However many tourist sites would need more care and attention in terms of discovery, maintenance, advertising, and training. Thus there is a need for supportive policies such as legal, administrative and financial facilities. The study confirmed as well the existence of limitless support for tourism development by all stakeholders, which is an essential element for the sustainability of tourism development in the city. The study also identified the sustainable tourism development trends in the city by identifying tourism demand, its internal and external sources, and the key tourism projects that deserve priority for development and which have the support of stakeholders.
138

Exposure matters : effects of environmentally realistic exposure conditions on toxicity of model nanomaterials to Daphnia magna

Nasser, Fatima January 2018 (has links)
Nanomaterials (NMs) can be defined as having at least one external dimension between 1-100nm. Due to their small size, NMs have a large surface area giving them characteristics that differ from bulk material. NMs are incorporated into numerous applications making environmental exposure to NMs likely. Increased reliance on plastic results in accumulation of nano-plastics in fresh waters. Polystyrene (PS) acts as a representative of both nano-plastic and NMs. The deposition of gold (Au) NMs is also likely due to their use in medical applications so that both PS and Au have a potential to interact with environmental organisms. Daphnia manga (D. magna) is an ideal candidate in fresh water toxicity testing. Toxicity, uptake and retention of NMs by organisms is dependent on several factors such as NM charge, shape, chemical composition and the absorption of natural biomolecules binding to the surface of the NM creating an eco-corona, altering stability of the NMs thereby changing their toxicity. This work investigates the toxicity of PS and Au NMs and explores the effects of charge, shape, presence of a corona and the impact of realistic modes of presentation of NMs to D. magna and how these factors impact toxicity, uptake, retention and depuration.
139

Environmental influences on synthetic and biogenic calcium carbonate in aragonite-calcite sea conditions

Miller, Caroline E. January 2018 (has links)
Ocean chemistry has oscillated throughout Earth history to favour the dominant non-biogenic polymorph of calcium carbonate (CaCO3) to be either calcite or aragonite (Sandberg, 1983). Throughout the Phanerozoic these oscillations have occurred to facilitate aragonite-dominant conditions three times and calcite-dominant conditions twice. These aragonite-calcite seas conditions have previously been viewed as a global phenomenon where conditions fluctuate over time, but not in space, and represent the main environmental context in which the evolution of CaCO3 biomineralisation has occurred (Stanley and Hardie, 1998). CaCO3 is one of the most widely distributed minerals in the marine environment, occurring throughout geological history, both biogenically and non-biogenically (Lowenstam and Weiner, 1989). Marine non-biogenic precipitates are commonly found as carbonate ooids, sedimentary cements and muds (Nichols, 2009). Biogenic CaCO3 is formed via biomineralisation in calcifying organisms (Lowenstam and Weiner, 1989; Allemand et al., 2004), and is much more abundant than the non-biogenic forms. Although CaCO3 is abundant, it only accounts for a small proportion of the global carbon budget. Biogenic CaCO3 is representative of a larger proportion of the global carbon budget than non-biogenically formed CaCO3 (Berelson et al., 2007). The main driving force controlling the precipitation of CaCO3 polymorphs is the Mg:Ca molar ratio of seawater (Morse et al., 2007). However, other parameters such as temperature (Burton and Walter, 1984; Morse et al, 1997; Balthasar and Cusack, 2015), pCO2 (Lee and Morse, 2010), and SO4 (Morse et al., 2007) are also known to influence CaCO3 polymorph formation but are often overlooked in the context of aragonite-calcite seas. Fluctuations in these parameters of Mg:Ca ratio, SO42+ and pCO2 of seawater have been suggested to cause shifts in original composition of non-biogenic marine carbonates, and in turn viewed as the main driving mechanisms facilitating the switch between aragonite and calcite dominance (Morse et al., 1997; Lee and Morse, 2010; Bots et al., 2011). Specifically the influence of temperature is important because it is likely to result in aragonite-calcite sea conditions to vary spatially (Balthasar and Cusack, 2015). Today marine temperatures are changing across the latitudes due to environmental factors. Global CO2 levels have increased significantly since industrialisation (Doney et al., 2009), with 33% entering the oceans and reducing pH (Raven et al., 2005) accelerating climate change (IPCC, 2013) and influencing marine calcification (Fitzer et al., 2014a; 2015b; Bach, 2015; Zhao et al., 2017). Strong links between the carbon cycle and climate change observed in the rock record give evidence that environmental changes such as pCO2 and global warming have impacts on calcification and marine biota (Hönish et al., 2012). The first objective was to determine the influence of Mg:Ca ratio, temperature and water movement on the first-formed precipitates of non-biogenic CaCO3 precipitation yielded via a continuous addition technique experiments (Chapter 3). CaCO3 precipitation was induced by continuously adding bicarbonate to a bulk solution of known Mg:Ca ratio (1,2 or 3), and fixed salinity of 35 (practical salinity scale), at 20°C and 30ºC in still conditions, and then repeated with the solution being shaken at 80rpm mimicking more natural marine conditions. The mineralogy and crystal morphology of precipitates was determined using Raman Spectroscopy and Scanning Electron Microscopy. Results in Chapter 3 indicated that polymorphs co-precipitate, with the ratio of aragonite to calcite increasing with increased Mg:Ca ratio and elevated temperature. The main difference between still and shaken conditions was that overall, more crystals of aragonite compared to calcite precipitate in shaking conditions. The crystal size is less influenced in aragonite, but calcite crystals were smaller. These results contradict current views on aragonite-calcite seas as spatially homogenous ocean states need to be re-examined to include the effect of temperature on the spatial distribution of CaCO3 polymorphs. Examining polymorph growth under these experimental constraints allows us to gain a better understanding of how temperature and Mg:Ca together control non-biogenic aragonite and calcite precipitation providing a more realistic environmental framework in which to evaluate the evolution of biomineralisation. To further this work, the same continuous addition technique was used with the presence of sulphate in the mother solution (Chapter 4). Sulphate being the 4th most common marine ion (Halvey et al., 2012) and known to have an influence on mineralogy (Kontrec et al., 2004). The presence of sulphate increase the aragonite to calcite proportion formed compared to sulphate-free conditions (Chapter 4). Elevated temperature with sulphate further increased the proportion of aragonite to calcite facilitated (Chapter 4). In the presence of sulphate the main difference between sulphate-free environments and those with sulphate environments was: in still conditions the presence of sulphate increased the crystal number more than the crystal size at 20°C; at 30°C or in shaken conditions the presence of sulphate increased the crystal size of aragonite to calcite much more than it had influence on the crystal number. Non-biogenically the influence of sulphate lowered the threshold of Mg:Ca ratio that the switch between calcite and aragonite would be facilitated at (Bots et al., 2011). This would have implications for marine calcification as pure calcite seas would become very rare and imply that organisms would be forming calcified hard parts out with the supported mineralogies. Biogenic application of these results is complex however as organisms often have the ability to select aragonite as their main polymorph for their own functional requirements (Weiner and Dove, 2003). The growth parameters of non-biogenic polymorph formations grown from artificial seawater can be used to understand how organism control can influence the polymorph formation under similar conditions (Kawano et al., 2009). Assessing the elemental composition of mussel shells grown under know conditions of temperature and pCO2 allowed the environmental influences on mineralogy be assessed under possible the projected changes in climate forecast to occur by 2100 by IPCC (2013). Prior to this research, no study had used Mytilus edulis shell elemental composition to test the influence of aragonite-calcite sea conditions on mineralogy. This research compiles a detailed source of information on the constraints from environmental sources such as temperature and pCO2, on the elemental concentrations within shell formation and what potential changes could occur in response to a changing marine environment (Chapter 5). Here elevated temperature significantly increased the concentration of magnesium in calcite, but did not influence the magnesium concentration of aragonite unless combined with elevated pCO2. The concentrations of sulphur in calcite were significantly decreased at elevated pCO2 or combined increased temperature and pCO2 as concentrations of sodium were found to be increased under these conditions. In aragonite the concentrations of both sulphur and sodium were significantly different under all scenarios. Strontium did not yield any significant results in this research in either calcite or aragonite. Results observed indicate that the shell elemental concentrations are influenced differently in aragonite or calcite, and further influenced by environmental conditions based on the original mineralogy. This suggests that physiological mechanisms under the constraints of increased temperature and pCO2 can override the seawater chemistry influences of aragonite-calcite seas impacting on mineralogy. / This research allows comparison of how non-biogenic and biogenic CaCO3 formation is influenced by seawater chemistry and environmental parameters to determine the dominant mineralogy. Increased temperature in both formations has shown to increase the impact of magnesium on calcite enabling the facilitation of aragonite. However, magnesium has influence on biogenic aragonite in extreme combined conditions of elevated temperature and pCO2. This work indicates that CaCO3 formation is complex and requires a multi-variable approach to understanding the mechanisms that facilitate the dominant mineralogy. By including variables such as temperature, this research suggests that aragonite-calcite seas conditions do not facilitate globally homogeneous switches in mineralogy, but the mineralogy is indeed influenced on latitudinal scales by other factors that influence the mechanisms involved.
140

Urban scale modelling of traffic and cycling flow using spatial analysis and an assessment of factors that influence cyclist behaviour

Patterson, Joanne Louise January 2014 (has links)
To understand and facilitate modal shift to more sustainable modes of transport there is a need to model accessibility and connectivity at an urban scale using data collection and modelling procedures that require less data and specialist input than traditional transport models. This research has used spatial analysis modelling procedures based on space syntax to investigate the potential to model aggregate traffic flows at an urban scale, and to investigate the potential to apply the same methodology to model both aggregate and individual cycle flows. Cyclist behaviour has been investigated through a questionnaire to support modelling work. The research has demonstrated that spatial analysis modelling is an effective means of representing urban scale motor traffic network, however, modifications to the model were required to achieve a correlation between modelled and measured motor traffic flow comparable to other modelling procedures. Boundary weighting was found to be effective at representing traffic crossing the boundary of an isolated urban sub-area, but was not so effective at an urban scale. Road weighting was found to be effective in improving model performance by representing traffic flows along routes according to a national classification scheme. It was demonstrated that these modelling principles could be used to represent an urban bicycle network and that the impact of the modification of infrastructure on relative flows of both cyclists and motor traffic could be accommodated. The modelling approach has the potential to be extremely useful at an early planning stage to represent changes to flows across the network. A survey of behaviour identified that cyclists modify their journey to use cycling facilities such as on-road lanes and off-road paths, or to avoid particular areas perceived to be less favourable for cyclists and that analysis indicates that it is difficult to predict (25% from survey) individual route choice. Results indicate that there were more opportunities related to route characteristics that could be influenced by infrastructure changes for occasional cyclists than for frequent/everyday cyclists.

Page generated in 0.1046 seconds