Anthropogenic structures fragment river connectivity, impeding the migration of diadromous fish between essential habitats. Tide gates are used worldwide primarily for flood protection and land reclamation by closing under hydraulic pressure during the flood tide and opening when head differential is sufficient during the ebb. Although tide gates are known to decrease fish species richness, abundance, and movement, their impacts on the migration of ecologically and socioeconomically important diadromous fish in terms of passage efficiency and delay have not been reported elsewhere. Acoustic and passive integrated transponder telemetry revealed that passage efficiencies of upstream migrating adult brown trout, Salmo trutta (92%), and downstream migrating juvenile sea trout smolts (96 - 100%) and adult European eel, Anguilla anguilla (98%), were high at top-hung tide gates in two small English streams. However, these fish experienced delay at the gates (adult brown trout, median = 6.0 h; sea trout smolts, mean = 6.5 and 23.7 h; eels, mean = 66.2 h) when compared to migration through unimpeded reaches. The percentage of time the gates were closed and mean angle of opening were positively related to delay in both species and life stages. Diel periodicity also influenced delay for smolts and eels, which were more active at night. For adult trout, water temperature was positively associated with delay. Upstream and downstream water temperature and salinity were influenced by the temporal operation of the gates. Orifices installed in the gates did not mitigate delay for adult or juvenile trout. For adult eels, delay was decreased when an orifice was operational, although this coincided with more eels first approaching the gates when open, higher tides and greater saline intrusion upstream of the gates. When gates were open, fish would not pass immediately through, indicating the potential influence of a behavioural avoidance component. To examine the effect of hydrodynamics created by top-hung tide gates with different aperture sizes, wild sea trout smolt behaviour was observed by video cameras in an experimental flume at night. Avoidance responses occurred within an average of 1.4 fish body lengths upstream of the gate. Fish were more likely to exhibit avoidance (switch in orientation from negative to positive rheotaxis, increased tail beat frequency and/or retreat upstream) in the vicinity of a model gate with a smaller angle of opening and passage aperture. Overall, top-hung tide gates delayed the migration of diadromous fish, potentially increasing energy expenditure and predation risk. Delay was not decreased by orifices. Modifying or replacing top-hung tide gates with designs that allow them to open wider and for longer could reduce migratory delay and improve the environmental conditions that cause behavioural avoidance.

A typical irrigation scheduling problem is one of preparing a schedule to service a group of outlets. These outlets may either be serviced sequentially or simultaneously. This problem has an analogy with the classical earliness/tardiness machine scheduling problems in operations research (OR). In previous published work integer programme were used to solve such problems; however, such scheduling problems belong to a class of combinatorial problems known to be computationally demanding (NP-hard). This is widely reported in OR. Hence integer programme can only be used to solve relatively small problems usually in a research environment where considerable computational resources and time can be allocated to solve a single schedule. For practical applications meta-heuristics such as genetic algorithms, simulated annealing or tabu search methods need to be used. However as reported in the literature, these need to be formulated carefully and tested thoroughly. This thesis demonstrates how arranged-demand irrigation scheduling problems can be correctly formulated and solved using genetic algorithms (GA). By interpreting arrangeddemand irrigation scheduling problems as single or multi-machine scheduling problems, the wealth of information accumulated over decades in OR is capitalized on. The objective is to schedule irrigation supplies as close as possible to the requested supply time of the farmers to provide a better level of service. This is in line with the concept of Service Oriented Management (SOM), described as the central goal of irrigation modernization in recent literature. This thesis also emphasizes the importance of rigorous evaluation of heuristics such as GA. First, a series of single machine models is presented that models the warabandi (rotation) type of irrigation distribution systems, where farmers are supplied water sequentially. Next, the multimachine models are presented which model the irrigation water distribution systems where several farmers may be supplied water simultaneously. Two types of multimachine models are defined. The simple multimachine models where all the farmers are supplied with identical discharges and the complex multimachine models where the farmers are allowed to demand different discharges. Two different approaches i.e. the stream tube approach and the time block approach are used to develop the multimachine models. These approaches are evaluated and compared to determine the suitability of either for the irrigation scheduling problems, which is one of the significant contributions of this thesis. The multimachine models are further enhanced by incorporating travel times which is an important part of the surface irrigation canal system and need to be taken into account when determining irrigation schedules. The models presented in this thesis are unique in many aspects. The potential of GA for a wide range of irrigation scheduling problems under arranged demand irrigation system is fully explored through a series of computational experiments.

Natural rubber has a good potential to be used as a material for the development of wave energy converters (WECs). Generally, rubber has the ability to withstand very large strains without permanent deformation or fracture and is not much affected by exposure to water. This makes it ideal for applications related to wave energy converter (WECs). However, there is a need to predict the efficiency of performance over the full lifetime of such an application given that WECs will represent large, expensive and novel products that must remain operational in an at-sea environment for 10-15 years. Pertaining to that criterion, fracture mechanics of rubber is an important aspect as well as strain-history and environmental effects. The objective of this study is to gain a fundamental understanding of several factors that contribute to service lifetime: the effect of ozone and oxidation, stress-strain behaviour including hysteresis, set, and cyclic stress relaxation, mechanical fatigue and the possible role of poorly dispersed filler agglomerates in nucleating failure. The work includes studies of the effect of protective coating layers and of naturally aged rubber artefacts using a mathematical model for diffusion limited oxidation. A literature review has been performed to address rubber science and associated technology, including, the durability of rubber. Experiments encompassing the effect of ozone, cyclic stress-strain behaviour and crack growth & fatigue of rubber were performed to interpret the relevant properties for the consideration of the development of wave energy converters. New parameters for characterizing macro dispersion in rubber are introduced in an attempt to seek a correlation with the life span of rubbers. All these observations and outcomes give an opportunity to enhance our understanding of the factors that determine long-term mechanical properties of rubber, to the general benefit of rubber science and technology.

No description available.

The erosion of mixed sediment deposits is described, under the action of unidirectional steady currents and (simulated) waves, separately, and in combination. The experiments were undertaken using a rectangular recirculating flume, incorporating an oscillating tray. The mixtures consisted of angular fine-grained quartz sands (D50=152.5 m and 215 m) combined with a very cohesive estuarine mud. Time-averaged erosion threshold current speeds, during the unidirectional and combined flow experiments, were measured. In addition, pore (water) pressure measurements, during the oscillatory and combined flow experiments, have been monitored. The results obtained under the action of currents show that there is an incremental increase, with clay content, in critical erosion shear stress. This increase is small for clay percentages lower than 11% (dry weight); it is larger for clay contents in excess of 11-14%. The quantity and cohesive nature of the clay fraction are suggested as the mechanisms to explain the bi-modal pattern of sediment erodibility. When the mixtures were subjected to different pre-threshold current speeds, together with various time-periods of flow, the critical erosion shear stress was higher than the original. In this process, current velocity is more important than flow duration. Data obtained under the influence of simulated wave action show that, for clay contents 11%, sediment erodibility is unaffected by the increasing clay concentrations. However, with clay contents in excess of 11-14%, a positive linear function may describe the variation in erosion threshold with clay content. Results obtained under the co-linear combined action of waves and currents demonstrate a significant and positive linear relation between erosion threshold and the cohesive additive. Furthermore, waves protect the sediment/water interface from the eroding competence of the steady currents. The resistance to erosion increases with a decrease in wave period (from 10 s to 6 s).

No description available.

Flood risk management is increasingly seeking to involve local stakeholders in decision-making, both to harness and benefit from their tacit knowledge and to devolve responsibility for delivering local-scale, individual and community responses. Current techniques used in flood risk management centre on a techno-scientific approach, which is well-suited to appraising and modelling hazard, but often inaccessible to those without specialist, technical expertise. This leads to participation that is often limited to infrequent consultation periods, keeping local stakeholders at the periphery of the decision-making process. Their absence from the more technical elements of the process can leave local stakeholders struggling to understand how different options have been identified, appraised and/or prioritised. This can in turn lead to dissatisfaction with process outcomes, lack of support for selected options, and foster distrust in expert practitioners. This thesis explores how participatory modelling techniques could complement current approaches, facilitating the co-production of models with local stakeholders that explore social constructions of risk, and the vulnerability of different receptors. It identifies the qualities that are sought from participation, including the need to remain highly accessible, yet sufficiently robust to capture the complexities encountered when working at the interface of social and physical systems. Reporting on two UK case studies, it exemplifies the benefits that two popular techniques, Bayesian networks and system dynamics, can deliver at different stages in the flood risk decision-making process. In each case, the effectiveness of the participatory approach is assessed using an evaluative framework that advances current approaches by including an early assessment of context, as well as a detailed exploration of substantive (user-defined goals), and social change outcomes. The holistic nature of the evaluation framework, and its population with practical criteria bespoke to flood risk management, enhance its transferability between different contexts. The thesis finds that participatory modelling techniques support the collating of diffuse tacit knowledge, building of consensus, strengthening of social networks, and the empowerment of local citizens to become volunteer risk managers; provided that process managers are willing to simplify the techniques to maintain accessibility, and be open to different metrics of success.

Introdução: A incidência do melanoma cutâneo (MC) está crescendo mais rapidamente que a de qualquer outro câncer. Devido ao seu potencial para metástases e à falta de terapias efetivas para a maioria dos pacientes em estágio avançado, o diagnóstico precoce do MC é crucial. Alguns dos fatores prognósticos mais importantes no MC são a espessura de Breslow e a presença de metástase linfonodal. O Tecnécio-99m-sestamibi (MIBI) é um radiofármaco usado rotineiramente em cintilografias miocárdicas e tem conhecidas propriedades para detecção de tumores malignos, incluindo câncer de mama, tumores cerebrais e melanomas primários e metastáticos. Objetivo: Avaliar a correlação entre a espessura de Breslow e a intensidade da captação de MIBI (IC-MIBI) em lesões primárias de MC. Métodos: Foram selecionados pacientes com lesões clinica e dermatoscopicamente suspeitas de MC. Os pacientes receberam uma injeção intravenosa de 740 – 1110 MBq (20 mCi) de MIBI. Após 10 minutos, o equipamento gamma-probe foi usado para detectar a IC-MIBI na lesão cutânea e em 2 pontos equidistantes na pele normal. A razão entre as contagens radioativas na lesão e a média da pele normal foi considerada a IC-MIBI. A seguir, pacientes realizaram SPECT (Single Photon Emission Computed Tomography) do local da lesão e da região linfonodal correspondente. Exérese da lesão cutânea e exame anatomopatológico foram então realizados. Pacientes portadores de lesões com Breslow > 1 mm ou < 1mm com ulceração/regressão espontânea realizaram biópsia do linfonodo sentinela. Resultados: Dezesseis pacientes com 20 lesões foram estudados (8 homens, 8 mulheres, de 34 – 81 anos, média 61 anos). Quatorze lesões eram melanomas e 6 eram nevos melanocíticos (NM). Cinco lesões eram melanomas in situ. A média da espessura de Breslow foi de 0,45 mm (variação: 0,30 – 14,90 mm). A média da IC-MIBI foi 1,54 (±0.58) contagens radioativas nos MC e 1,04 (±0.10) nos NM (P = 0.007). Houve forte correlação positiva entre a IC-MIBI e a espessura de Breslow (rs = 0.74, P= 0.003). Analisando as lesões em categorias de Breslow, houve diferença estatisticamente significativa (P < 0.001) entre as lesões com Breslow < 1mm (IC-MIBI = 1.23 ± 0.28 contagens radioativas) e Breslow > 1 mm (IC-MIBI = 2.32 ± 0.32 contagens radioativas). Nenhum dos NM apareceu nas imagens de SPECT. Dos MC, 4 lesões, que apresentavam Breslow > 1mm, apareceram nas imagens de SPECT. Conclusão: Neste estudo, embora tenha demonstrado uma diferença significativa entre melanomas finos (< 1mm) e espessos (> 1mm), a IC-MIBI no local da lesão não foi diferente entre NM e melanomas finos ou in situ. Por isso, MIBI parece ser útil principalmente em melanomas espessos, o que também foi confirmado pela positividade do SPECT apenas nestes casos. Entretanto, a possibilidade de correlacionar a IC-MIBI com categorias de Breslow pode facilitar os procedimentos cirúrgicos, permitindo a remoção de melanomas com margens cirúrgicas adequadas e a realização ou não de biópsia de linfonodo sentinela em um mesmo momento cirúrgico, reduzindo morbidade e custos. / Introduction: Given its propensity to metastasize, and lack of effective therapies for most patients with advanced disease, early detection of melanoma is a clinical imperative. The most important prognostic factors are Breslow thickness and nodal metastases. Technetium-99m-sestamibi (MIBI) is a radiopharmaceutical used routinely for cardiologic scintigraphy and has also well-known tumor-seeking properties. It has been used successfully to detect various tumors, including breast cancer, brain tumors, and primary and metastatic melanoma. Objetive: This study has been designed in order to evaluate the correlation between Breslow thickness and MIBI uptake by primary CM lesions. Methods: Patients were recruited by a dermatologist on the grounds of a clinically and dermoscopically suspicious melanocytic lesion. Patients received intravenous injection of 740 – 1110 MBq (20 mCi) of MIBI. After 10 minutes, gamma-probe was used to detect the intensity of MIBI uptake by the cutaneous lesion and at two equidistant points on normal skin. The ratio number of radioactive counts at cutaneous lesion / mean of radioactive counts at normal skin was considered to determinate the MIBI uptake intensity (MIBI-UI). Then, SPECT imaging of the lesion site and respective lymph node region was obtained. After scintigraphy, exeresis of the cutaneous lesion and histological analysis were performed. Lesions with Breslow thickness > 1 mm or < 1 mm with ulceration/spontaneous regression underwent sentinel lymph node biopsy. Results: Sixteen patients with 20 lesions were investigated (8 males, 8 females, age range 34 – 81 years, mean 61 years). Fourteen lesions were CM and 6 were melanocytic nevi (MN). Five lesions were melanoma in situ. Breslow thickness median was 0.45 mm (range 0.30 - 14,9 mm). The mean MIBI-UI was 1.54 (±0.58) radioactive counts in CM and 1.04 (±0.10) radioactive counts in MN (P = 0.007). There was strong positive correlation between MIBI-UI and Breslow thickness (rs = 0.74, P= 0.003). Grouping the lesions on Breslow categories, there was a statistically significant difference (P < 0.001) between lesions with Breslow thickness < 1 mm (MIBI-UI = 1.23 ± 0.28 radioactive counts) and Breslow thickness > 1 mm (MIBI-UI = 2.32 ± 0.32 radioactive counts). None of the MN appeared at SPECT images. Of melanomas, 4 (28,6%) were SPECT positive at cutaneous site. All those were Breslow thickness > 1 mm. Conclusion: On this study, although there is a significant difference between thin (< 1 mm) and thick (> 1 mm) melanomas, MIBI intensity at the lesion site is not different between benign nevus and in situ or thin melanomas. Then, MIBI seems to be useful mainly in thick melanomas, as also confirmed by the positivity of the SPECT image only in these cases. However, the possibility of correlating MIBI uptake intensity with Breslow categories may facilitate surgical procedures, allowing to remove melanomas with appropriated surgical margins and to perform or not sentinel lymph node biopsy in the same surgical time, reducing morbidity and cost.

The redevelopment of existing riverine barriers with modern hydropower turbines is becoming increasingly prevalent on main stem rivers with valuable stocks of migratory salmonids. This is a concern because these fish rely on longitudinal connectivity to complete their lifecycles, and modifications for hydropower could jeopardize that connectivity by obstructing or injuring migrating fish. In order to exploit very low head hydropower potential, novel turbine types are emerging. The Archimedean screw hydropower turbine is one such technology which is becoming increasingly popular for low-head applications. However the impact of these turbines on fish movements remains largely untested. This thesis aims to provide much needed evidence on the effects that these turbines and schemes may have on migrating salmonids. Fixed radio and passive integrated transponder receivers were used to track the downstream movements of wild migrating juvenile salmonids through a low-head Archimedean screw hydropower scheme. Atlantic salmon smolts were found to pass through the alternative routes of the turbine and main river channel in proportion to flow through these channels. Passage times were generally fast through both routes (median = 17.6, range = 5.1-905.6 minutes over the 350m scheme extent, for radio tagged fish), and longer passage times were associated with daytime presence in both routes. The majority of PIT tagged Atlantic salmon and sea trout smolts that passed through the 100 m long turbine channel, did so in under 27 minutes (median = 6.8 minutes), whilst a few fish had much longer passage times, associated with daytime presence. There were no differences in onward survival (measured as distance survived downstream) between turbine passed and non-turbine passed migrants. Atlantic salmon smolts were passed through an Archimedean screw turbine to test for harmful effects from the turbine, with comparison to equivalently handled non-turbine passed smolts. There was no evidence of visible damage aside from low to moderate scale loss, which was not significantly associated with turbine passage. Blood chemistry parameters were used to test for subtle turbine-induced damage. This novel application of these techniques did not yield conclusive results, but serves as a useful precedent for future studies. Radio and PIT telemetry equipment were used to investigate the movements of upstream migrating adult salmonids at three separate low-head hydropower schemes which may act as obstacles to migration. These schemes each had distinct configurations and flow management regimes. Movements within, and progression beyond these schemes varied substantially between sites, and in some cases were related to flow management parameters. Whilst not conclusive, the results suggest that scheme configuration and the management of flows influence the time that fish spend at such schemes, and the proportion of fish that ascend beyond them. With the global shift towards renewable energy generation, the exploitation of running water for hydropower is likely to become increasingly pervasive. The results of these studies provide valuable information for the informed and ecologically sustainable development of low-head hydropower schemes.

Ballast water has been identified as a major vector for the translocation of Non- Indigenous Invasive Species (NIS) and pathogens across zoogeographical regions and subsequent discharged into recipient port states/regions. This is bound to increase given factors like the globalization of trade and the economy of scale of the ship size. Established NIS has posed significant threat to the human health, economy, finances and marine bio-diversity of recipient regions and port states. The risks associated with the discharged NIS are uncertain and difficult to assess due to the stochastic nature of species assemblages and dispersal mechanism. The safest control measure advocated by the IMO is the conduct of ballast water exchange at sea while appropriate and effective proto-type treatment technologies are being developed and approved for future application. This study has been conducted while recognizing the inability of probabilistic approaches applied in ballast water risk management to addressing uncertainty and inadequacy of data. A qualitative approach using powerful multi-criteria decision making techniques and the safety principles of the Formal Safety Assessment framework have been utilized in this research to develop three generic models for ballast water hazard estimation, risk evaluation and decision-making analysis respectively. The models are capable of being modified and utilized in the industry to address the problems of uncertainty and inadequacy of data in ballast water management. This is particularly useful as an interim measure for port states in developing economies (with insufficient data and technology) to developed robust ballast water management plans. While recognising the huge impact of ballast water pollution in recipient regions this study recommends that ballast water management programmes be given due recognition as an important element of sustainable development programmes at national and international levels. The non-availability of a benchmark based on previous research on which to fully validate the research outcome was identified as a major limitation of this research study. The models developed will therefore be subject to modifications as new data become available.