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Item Open Access 1-Methylcyclopropene (1-MCP) effects on natural disease resistance in stored sweetpotato(Wiley, 2018-03-06) Amoah, Robert S.; Terry, Leon ABACKGROUND The potential of 1-methylcyclopropene (1-MCP) to maintain postharvest storage of sweetpotato was studied. In two separate experiments, the orange-fleshed sweetpotato cv. Covington was fumigated with 1-MCP (1.0 μL L-1, 24 h) and roots stored at 15 oC. During storage, samples were evaluated for the respiration rate, sprout growth, weight loss, incidence of decay and changes in dry matter. The roots were further assayed for the temporal changes in individual non-structural carbohydrates and phenolic compounds in the skin and flesh tissues of the proximal (stem end), middle, and distal (root end) regions. RESULTS 1-MCP treatment reduced root weight loss and decay but respiration rate and non-structural carbohydrates were not affected. No sprouting was recorded irrespective of the treatment. 1-MCP transiently suppressed the accumulation of individual phenolic compounds, especially in the middle and distal segments. This accentuated the proximal dominance of phenolic compounds. Isochlorogenic acid A and chlorogenic acid were the dominant phenolics in the skin and flesh tissues, respectively. CONCLUSION 1-MCP treatment may have anti-decay effect and reduce weight loss. Therefore, storage trials which involve the use of continuous ethylene supplementation to inhibit sprout growth may be combined with 1-MCP to alleviate ethylene-induced weight loss and decay in sweetpotato.Item Open Access 1-Methylcyclopropene maintains postharvest quality in Norwegian apple fruit(Sage, 2019-12-26) Falagán Sama, Natalia; Terry, Leon ANorwegian fruit production is mostly destined for the local market and can suffer from poor-quality retention during storage. 1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene perception used to maintain the physical and functional quality of pome fruit. Extensive work has been carried out on the effect of 1-MCP on apples, but not on cultivars grown in Norway. In this work, the potential of 1-MCP application (0.625 ml l −1 for 24 h at 0 ± 1℃) for ripening control of the apple cultivars ‘Aroma’, ‘Red Gravenstein’, and ‘Summered’ was studied during 1 and 1.5 months of cold storage; both scenarios were followed by five days of shelf life. The application of 1-MCP reduced softening by an average of 12% in ‘Aroma’, ‘Red Gravenstein’, and ‘Summered’ apples when cold stored for both 1 and 1.5 months as compared to control. External colour remained similar to initial values in 1-MCP fruit when compared to control apples, which presented a significant skin darkening. This indicated a delay in the ripening process. 1-MCP treatment did not affect total soluble solids content. ‘Aroma’ samples treated with 1-MCP showed a low sucrose hydrolysis, indicating a slower ripening process. This work confirms that 1-MCP postharvest treatment shows great potential for maintenance of apple cvs. in Norway during cold storage and shelf life.Item Open Access A 2017 horizon scan of emerging issues for global conservation and biological diversity(Elsevier, 2016-12-10) Sutherland, William J.; Barnard, Phoebe; Broad, Steven; Clout, Mick; Connor, Ben; Côté, Isabelle M.; Dicks, Lynn V.; Doran, Helen; Entwistle, Abigail C.; Fleishman, Erica; Fox, Marie; Gaston, Kevin J.; Gibbons, David W.; Jiang, Zhigang; Keim, Brandon; Lickorish, Fiona A.; Markillie, Paul; Monk, Kathryn A.; Pearce-Higgins, James W.; Peck, Lloyd S.; Pretty, Jules; Spalding, Mark D.; Tonneijck, Femke H.; Wintle, Bonnie C.; Ockendon, NancyOpen Access We present the results of our eighth annual horizon scan of emerging issues likely to affect global biological diversity, the environment, and conservation efforts in the future. The potential effects of these novel issues might not yet be fully recognized or understood by the global conservation community, and the issues can be regarded as both opportunities and risks. A diverse international team with collective expertise in horizon scanning, science communication, and conservation research, practice, and policy reviewed 100 potential issues and identified 15 that qualified as emerging, with potential substantial global effects. These issues include new developments in energy storage and fuel production, sand extraction, potential solutions to combat coral bleaching and invasive marine species, and blockchain technology.Item Open Access The 28 November 2020 landslide, tsunami, and outburst flood – a hazard cascade associated with rapid deglaciation at Elliot Creek, British Columbia, Canada(American Geophysical Union, 2022-02-21) Geertsema, Marten; Menounos, Brian; Bullard, G.; Carrivick, Jonathan L.; Clague, J. J.; Dai, Chunli; Donati, Davide; Ekstrom, Goran; Jackson, Jennifer M.; Lynett, Patrick; Pichierri, M.; Pon, Andy; Shugar, Dan H.; Stead, D.; Del Bel Belluz, J.; Friele, P.; Giesbrecht, Ian J. W.; Heathfield, D.; Millard, Thomas H.; Nasonova, S.; Schaeffer, Andrew; Ward, B. C.; Blaney, D.; Blaney, Erik; Brillon, C.; Bunn, C.; Floyd, W.; Higman, B.; Hughes, Katie E.; McInnes, William; Mukherjee, Kriti; Sharp, Meghan A.We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m3 of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km2 glacier lake and producing >100-m high run-up. Water overtopped the lake outlet and scoured a 10-km long channel before depositing debris on a 2-km2 fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real-time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose.Item Open Access 3D computational fluid dynamics analysis of natural gas separation efficiency in multiphase pumping wells with heterogeneous flow regime(Taylor and Francis, 2024-12-31) Okafor, Charles C.; Verdin, Patrick G.This research uses 3D Computational Fluid Dynamics (CFD) simulations to investigate the downhole Natural Gas Separation Efficiency (NGSE) for multiphase pumping wells in the heterogeneous churn flow regime. Results explain the effects of key parameters such as liquid viscosity, intake port sizes/diameter, and casing diameter, on the NGSE. Methods are thus suggested to enhance the NGSE in oil field operations, and key improvements to the widely used mathematical formulations for viscous service are proposed. Transient numerical simulations were performed for a section of an experimental flow loop extracted from the literature, and the flow solution was obtained with the Volume of Fluid (VOF) model. For most simulations, turbulence effects were modelled with the k−ϵ turbulence model. The k−ω SST turbulence model was however considered for the sensitivity analysis on liquid viscosity. The final numerical results validated against the corresponding experimental data showed an average error of less than 6%. Combining past literature and current results confirms that (i), the NGSE is affected by the downhole geometry (i.e annulus space and pump intake port flow area geometry) and (ii), current analytical NGSE models are not ideal for multiphase viscous service (high viscosity Newtonian flow) in the heterogeneous flow regime. The widely used steady-state formulations might thus not be adequate for this flow regime.Item Open Access A comparative experimental study on the hydrodynamic performance of two floating solar structures with a breakwater in waves(Elsevier, 2024-12) Yang, Yifeng; Mi, Chenhao; Ou, Binjian; Wong, Anson; Duffy, John Gordon; Wood, Tim; Utama, IKAP; Chen, Wenchuang; Huang, LuofengFloating Photovoltaic (FPV) is considered as a highly promising clean energy solution. In recent years, FPV has been widely deployed in calm water around the world. However, to find available space for further expansion, FPV needs to be deployed in seas whilst the oceanic waves significantly influence the structural stability and energy performance. On one hand, wave loads may cause structural fatigue and damage. On the other hand, wave-induced rotations of a floating solar panel will vary its tilt angle to the sunlight and thus affect the power output. To explore the new research field of ocean-based FPV, this work first designed a novel catamaran FPV floater with a four-point mooring system. Comparative experiments were then conducted in a wave tank to compare its seakeeping ability with a conventional flat-plate floater. Besides, a breakwater structure was further introduced to enhance the stability of these two types of floaters. Detailed data on floater motions and mooring line forces were collected under monochromatic wave conditions. Extensive analysis was performed to evaluate the wave-mitigating performance of the breakwater, as well as the nonlinearity in the motion and force time histories. Overall, the work provides valuable experimental data and novel insights into the design of FPV floaters and breakwater protection, supporting long-term sustainability of FPV on the ocean.Item Open Access A data-driven approach to understanding online service access and technological energy injustice among minority ethnic communities(American Chemical Society, 2024-09-13) Guder, Mennan; Balta-Ozkan, NazmiyeIn the energy domain, various forms of injustice manifest, spanning distribution, production, access, environmental, economic, social, inter-generational, technological, cultural, and governance realms. This paper delves into the technological injustice regarding online service access by energy suppliers, specifically focusing on its impact on energy poverty among minority ethnic communities. The Ofgem Consumer Impacts of Market Conditions Survey Wave 3 Report highlights significant challenges within the energy market, particularly affecting minority ethnic communities. Despite initiatives to investigate legal services for minority ethnic communities, exploration of online service utilization remains inadequate, creating a significant gap in understanding. This paper proposes a comprehensive examination of online service usage and perceptions within minority ethnic communities to address this research gap. The proposed framework encompasses modules for survey construction, data analysis, Machine Learning (ML) integration, and Agent-Based Modelling (ABM) and simulation. Feature examination reveals correlations between accommodation type and online service satisfaction, influencing simulations. The ABM module simulates how changes in accommodation type affect online service satisfaction, with ML models predicting outcomes. Validation through empirical data and expert knowledge ensures model accuracy. This research contributes to understanding online service experiences, particularly for minority ethnic communities, aiming to empower researchers and service providers to address inequalities effectively. Future work involves expanding the ABM to incorporate threat modelling concepts, providing a tool for assessing and fortifying the security posture of online services for minority ethnic communities.Item Open Access A Moroccan soil spectral library use framework for improving soil property prediction: evaluating a geostatistical approach(Elsevier, 2024-12-01) Asrat, Tadesse Gashaw; Breure, Timo; Sakrabani, Ruben; Corstanje, Ron; Hassall, Kirsty L.; Hamma, Abdellah; Kebede, Fassil; Haefele, Stephan M.A soil spectrum generated by any spectrometer requires a calibration model to estimate soil properties from it. To achieve best results, the assumption is that locally calibrated models offer more accurate predictions. However, achieving this higher accuracy comes with associated costs, complexity, and resource requirements, thus limiting widespread adoption. Furthermore, there is a lack of comprehensive frameworks for developing and utilizing soil spectral libraries (SSLs) to make predictions for specific samples. While calibration samples are necessary, there is the need to optimize SSL development through strategically determining the quantity, location, and timing of these samples based on the quality of the information in the library. This research aimed to develop a spatially optimized SSL and propose a use-framework tailored for predicting soil properties for a specific farmland context. Consequently, the Moroccan SSL (MSSL) was established utilizing a stratified spatially balanced sampling design, using six environmental covariates and FAO soil units. Subsequently, various criteria for calibration sample selection were explored, including a spatial autocorrelation of spectra principal component (PC) scores (spatial calibration sample selection), spectra similarity memory-based learner (MBL), and selection based on environmental covariate clustering. Twelve soil properties were used to evaluate these calibration sample selections to predict soil properties using the near infrared (NIR) and mid infrared (MIR) ranges. Among the methods assessed, we observed distinct precision improvements resulting from spatial sample selection and MBL compared to the use of the entire MSSL. Notably, the Lin's Concordance Correlation Coefficient (CCC) values using the spatial calibration sample selection was improved for Olsen extractable phosphorus (OlsenP) by 41.3% and Mehlich III extractable phosphorus (P_M3) by 8.5% for the MIR spectra and for CEC by 25.6%, pH by 13.0% and total nitrogen (Tot_N) by 10.6% for the NIR spectra in reference to use of the entire MSSL. Utilizing the spatial autocorrelation of the spectra PC scores proved beneficial in identifying appropriate calibration samples for a new sample location, thereby enhancing prediction performance comparable to, or surpassing that of the use of the entire MSSL. This study signifies notable advancement in crafting targeted models tailored for specific samples within a vast and diverse SSL.Item Restricted A new framework for river restoration planning at catchment scale in the UK(Wiley, 2024-12-31) Robins, Joshua Edward; Naura, Marc; Austin, Sam; Bryden, Alexandra; Cullis, Jo; Prady, Jane; Shi, Fang; Treves, RichardThe main aim of catchment planning is to prioritise measures that will reverse the decline of biological communities. In recent decades, there has been an increase in methods, tools and the availability of data to aid this process. However, how we use data to make decisions is the crucial and often neglected part of catchment planning, and there is sometimes a tendency to revert to reach‐scale opportunism rather than planning at the catchment scale. Planning approaches in the UK have ranged from public sector–led plans in the 1990s to the present‐day partnership approach led by the third sector (non‐governmental charitable or not‐for‐profit organisations). We have reviewed 237 catchment plans from the UK to understand the approaches that have been taken. Our findings indicate that many plans do not clearly link evidence and data to decision‐making; problems are poorly defined using broad terms such as ‘issues’ instead of characterising pressures and impacts; catchment objectives tend to be broad and not specific; measures are often prioritised based on opportunity; and it is not always clear how measures are expected to contribute to the achievement of catchment targets. Altogether, we noted the absence of agreed, standardised frameworks for producing plans, describing how data should be analysed, problems identified and actions prioritised. We propose a new catchment planning framework that encourages evidence‐based decisions through the assessment of pressures and impacts, and ultimately the prioritisation of river restoration options (encompassing rehabilitation, renaturalisation, enhancement, re‐creation and mitigation of the hydrology, water quality and geomorphology of the river, floodplain and wider catchment) based on their contribution to the alleviation of catchment‐scale impacts, and which can be applied by nonspecialists using citizen science data.Item Open Access A reduced order model discretisation of the space-angle phase-space dimensions of the Boltzmann transport equation with application to nuclear reactor problems(Elsevier, 2024-07-30) Buchan, Andrew G.; Navon, Ionel M.; Yang, LiangThis article presents a new reduced order model (ROM) for fast solutions to neutron transport problems. The novelty lies in the construction of optimal basis functions spanning the space-angle phase-space dimensions of the Boltzmann transport equation (BTE). It uses Proper Orthogonal Decomposition and the method of snapshots to form the reduced basis, but here a 2-stage construction is proposed that compresses the angle, then space, dimensions sequentially. The approach alleviates the potentially limiting memory burden for BTE-based ROMs by not processing the full discretised solutions of BTE during the construction stage. The model is both accurate and efficient and is demonstrated here for eigenvalue and fixed source reactor physics problems with assumed uncertainties in material cross-section data. Reductions in problem size and solving times exceeds 5 orders of magnitude in comparison to high fidelity models, and which could potentially improve further for larger scale problems.Item Open Access A study into the correlation between single array-hull configurations and wave spectrum for floating solar photovoltaic systems(Elsevier BV, 2024-11-15) Jifaturrohman, Mohammad Izzuddin; Utama, I Ketut Aria Pria; Putranto, Teguh; Setyawan, Dony; Huang, LuofengFloating photovoltaic (FPV) systems offer a viable renewable energy solution due to easy installation and cost-effectiveness compared to other renewable energy generation methods. On the other hand, land-based solar photovoltaics face challenges such as space scarcity and environmental impacts. Shifting to nearshore locations unlocks vast ocean space potential, though waves expose significant challenges to FPV systems. Several novel FPV system designs are proposed, inspired by high-speed vessel multihulls, including catamaran, trimaran, quadrimaran, and pentamaran configurations, as floating supports for solar panels. Simulations were conducted to determine Response Amplitude Operators (RAOs) under various irregular wave spectrum conditions in a free-floating initial state. The FPV motion problem was solved using linear potential-flow theory with the Boundary Element Method (BEM) with Green-Function approach. Superposition of wave spectral energy and motion RAOs was used to obtain spectral structural responses. Motion in heave, roll, and pitch modes was evaluated across wave spectrum types. Results show that adding hulls reduces the significant amplitude response in all motion modes. In summary, valuable insights into floater designs and the hydrodynamic evaluation of FPV systems are presented.Item Open Access A study into the effect of Hull Configuration on the performance of floating solar PV structure(Akademia Baru Publishing, 2024-11-30) Jifaturrohman, Mohammad Izzuddin; Utama, I Ketut Aria Pria; Putranto, Teguh; Setyawan, Dony; Huang, LuofengAt present, energy transition is a reality in the journey towards achieving net zero emission. Among others, the development of floating solar photovoltaic (FPV) power plants is one of many possible renewable energy technologies that received considerable attention. One of the reasons for that is attributed to land acquisition which can lead to conflicts, whilst the use of sea is more flexible. Therefore, the development of floating solar PV situated at the near shore (later can be moved offshore) is promising particularly in order to withstand the harsh environment. The study aims to demonstrate such an innovative design of a floating structure and two types of hulls (monohull and twin-hull) are considered and focused on the seakeeping performance of the two bodies. BEM approach with Green-Function based on the 3-D diffraction panel method together with the use of the Joint North Sea Wave Project (JONSWAP) wave spectrum is carried out to accomplish the seakeeping characteristic. The final computational simulation results show that the twin-hull model has more advantages than the monohull design. The trend of the RAO pattern, response spectra, and significant response for heave and pitch motion represent only slight differences between the two proposed designs. However, substantial disparity emerges in roll motion, with the difference in response values in prevailing 0o -roll heading standing at 53%, 39%, 27%, and 18% for sea states 1 through 4, respectively. Moreover, in 45o wave heading (quartering sea) it demonstrates a slightly lower disparity compared to the 0o wave heading (following sea) through sea-state 1-4 standing for 50%, 37%, 24% and 16% respectively.Item Open Access A symmetric experimental study of the interaction between regular waves and a pontoon breakwater with novel fin attachments(MDPI, 2024-12-02) Lyu, Xiangcheng; Yang, Yifeng; Mi, Chenhao; Tang, Chi Man; Adeboye, Lukman; Farhan, Mohamed; Collins, Stan; Ou, Binjian; Wong, Anson; Duffy, John Gordon; Huang, LuofengFloating breakwaters are widely applied on the ocean water surface to protect human infrastructure from the destructive power of waves. This study designs and investigates the performance of a novel symmetric-pontoon floating breakwater with a symmetric pair of hydrofoils. Based at the Cranfield Ocean Systems Laboratory, the system was constructed and tested in various wave conditions using different fin configurations. The floating structure was anchored using a symmetric four-point mooring system. The tested waves were regular and symmetric perpendicular to the propagating direction. Key parameters, including the attenuated wave amplitude, motions of the breakwater, and the mooring forces, were measured. The wave parameters utilised for testing covered 1.61–5.42 relative wavelength to structural length, with wave heights of 3 cm and 5 cm. Results showed the 90° fin configuration can reduce wave transmission by up to 74%, with the lowest mooring forces at 3.05 relative wavelength, enhancing the performance of wave energy dissipation and structural seakeeping. At 90° setup, the mooring force was lowest at 2.41 relative wavelength. This research can inform novel designs of breakwaters to improve protection abilities for coastal cities and offshore infrastructures, especially renewable energy systems.Item Open Access A systematic review of socio-technical systems in the Water–Energy–Food Nexus: building a framework for infrastructure justice(MDPI, 2024-07-12) Shrimpton, Elisabeth A.; Balta-Ozkan, NazmiyeThis paper explores the place of technological interventions in the conceptualisation of the Water–Energy–Food Nexus (WEF Nexus). The focus is on the just infrastructure interventions required to decarbonise and adapt to the challenges of the climate crisis for sustainable livelihoods. We explore the overlap between two bodies of work, the WEF Nexus and Socio-Technical Systems, grown from different disciplinary perspectives, to scrutinise the extent to which there is a coherent synthesis of work that can examine infrastructure impacts and trade-offs in a WEF system. Following a systematic literature review and analysis, a framework is proposed for water and energy infrastructure interventions to both support sustainable development and recognise infrastructure’s role in a just and equitable society. This framework will support the creation of models that are less likely to miss vital components of a system or potential trade-offs and supports a multi-disciplinary approach to infrastructure interventions.Item Open Access A three-step weather data approach in solar energy prediction using machine learning(Elsevier, 2024-09) Falope, Tolulope Olumuyiwa; Lao, Liyun; Hanak, DawidSolar energy plays a critical part in lowering CO2 emissions and other greenhouse gases when integrated into the grid. Higher solar energy penetration is hindered by its intermittency leading to reliability issues. To forecast solar energy production, this study suggests a three-step forecasting method that selects weather variables with a moderate to strong positive correlation to solar radiation using Pearson correlation coefficient analysis. Low-level data fusion is used to combine weather inputs from a reliable local weather station and an on-site weather station, significantly improving the forecasting model's accuracy regardless of the machine learning method used. Weather data was obtained from the Kisanhub Weather Station located in Cranfield University, UK and the meteorological station in Bedford, UK. In addition, PV power supply data was obtained from four solar plants. Using the Regression Learner app in MATLAB, the proposed architecture is tested on a utility scale solar plant (1 MW), showing a 6% and 13% prediction accuracy improvement when compared to solely using data from the on-site and local weather station respectively. It is further validated using data from three residential rooftop solar systems (8 kW, 10.5 kW and 15 kW), achieving root-mean square values of 0.0984, 0.0885, and 0.1425 respectively. The data was pre-processed using both rescaling and list-wise deletion methods. Training and testing data from the 1 MW solar plant was divided into 75% and 25% respectively, while 100% of the residential rooftop solar plants was used for validation.Item Open Access A tiered assessment of human health risks associated with exposure to persistent, mobile and toxic chemicals via drinking water(Elsevier, 2025-01-01) Whelan, Mick J.; Pemberton, Emma; Hughes, Christopher B.; Swansborough, Chesney; Goslan, Emma Harriet; Gouin, Todd; Bell, Victoria A.; Bird, E.; Bull, S.; Segal, L.; Cook, S. H.; Jephcote, Calvin; Fane, SarahThere is increasing interest in chemicals which are persistent, mobile and toxic (PMT), primarily to protect drinking water. We present a tiered assessment of drinking water exposure and associated human health risks for 22 PMT substances. Worst-case exposure via drinking water is assumed to occur when wastewater is discharged to rivers which are then abstracted for water supply. Screening-level exposures assume daily per capita emissions based on REACH tonnage estimates, with removal in wastewater treatment calculated using SimpleTreat and no riverine dilution. Removal in water treatment was estimated for each substance assuming either conventional or advanced treatment processes. Higher tier spatially-resolved exposures used a gridded routing model which transfers chemical through the landscape based on flow directions derived from a 1 km digital elevation model. Emission was assumed to be proportional to population and no in-stream degradation was assumed. Exposures were calculated for 296 locations containing drinking water treatment works (WTWs) under mean discharge and Q95 (discharge exceeded 95% of the time). At low tiers, risk characterisation ratios (RCRs) were < 1 for all substances, assuming realistic tonnage and conventional treatment. If drinking water is assumed to represent only 20 % of total chemical intake, total RCRs (RCRT) were > 1 for three substances under conventional treatment but were < 1 for all substances under advanced treatment. Highest exposure and RCRs were predicted in highly populated areas with low dilution. RCRT values were > 1 for tetrachloroethylene (highest RCR) at up to 18 % of WTW locations under Q95 conditions assuming conventional treatment. However, RCRT was <1 for all locations assuming advanced treatment. Actual exposures will depend on catchment characteristics, but the model usefully allows prioritising higher risk chemicals and WTWs. Overall, the substances evaluated are unlikely to currently pose health risks, provided an appropriate level of water treatment is employed.Item Open Access A whole systems view to driving decentralised renewable energy investments in Sub-Saharan Africa.(Cranfield University, 2024-01) Abba, Yahajja Zara Ibrahim; Ozkan, Nazmiye; Drew, GillThe scaling-up of decentralised renewable energy (DRE), such as solar mini- grids, is vital to achieving climate goals and universal electricity access in sub- Saharan African (SSA) countries. However, high investor risk perception continues to impede DRE investment in SSA, highlighting the importance of understanding investors' risk perception and developing appropriate risk mitigation actions. Yet, the risk management (RM) literature offers a fragmented and singular approach, where the multidimensional nature of risk factors and their interactions are overlooked. In addition, current studies do not consider DRE site- specificity alongside investor heterogeneity in quantifying the implications of mitigation actions on the evolution of investment decisions. In this context, and to address these research gaps, this thesis aims to develop, validate, and implement a unified RM framework incorporating an investment decision model to assess the impacts of actions on investment and electricity access spatially, thus offering a more holistic outcome for decision-makers. This thesis focuses on solar mini-grids in Nigeria, which has one of the highest electricity deficits in SSA. The framework is implemented in two phases. In phase one, investment risks and potential mitigations were evaluated as perceived by four investor groups and various stakeholders through questionnaires, semi-structured interviews, focus groups, and an analytic hierarchy process methodology. In phase two, a novel DRE decision-support model was deployed to enhance existing methods by using a system dynamics-agent-based modelling (SD-ABM) approach. This approach incorporates complex interactions and feedback between heterogeneous investor and location attributes to establish investment outcomes for various case study mitigation scenarios. This thesis the following contributions. Phase one provides new empirical data comprising: identifying 13 additional risk factors compared to the literature, establishing importance of risk factors as perceived by diverse investor groups in Nigeria, and proposing mitigation strategies, some of which were tested in phase two as scenarios. The results indicated variations in risk importance among investors, with the most critical risk factors being revenue risks, limited access to low-cost capital, currency risks, insecurity, and inadequate policy implementation. Phase two contributes to the knowledge of how complex system modelling can be applied to evaluate the impact of mitigation actions on the spatial evolution of DRE investment in a liberalised market. The case study results revealed that the most impactful mitigation scenarios were increased funding availability and the implementation of renewable energy mandates for domestic finance institutions. Whilst our findings confirm the criticality of concessional investors as identified in the literature, we find that meeting electrification targets necessitates incentivising risk-averse non-concessional-type investors. The developed model can additionally enable policymakers to explore the potential implications of further policy actions and investors to identify potential projects that suit their investment profiles during the feasibility phase.Item Open Access Abscisic acid acts essentially on stomata, not on xylem, to improve drought resistance in tomato(Wiley, 2023-08-01) Haverroth, Eduardo J.; Oliveira, Leonardo A.; Andrade, Moab T.; Taggart, Matthew; McAdam, Scott A. M.; Zsögön, Agustin; Thompson, Andrew J.; Martins, Samuel C. V.; Cardoso, Amanda A.Drought resistance is essential for plant production under water-limiting environments. Abscisic acid (ABA) plays a critical role in stomata but its impact on hydraulic function beyond the stomata is far less studied. We selected genotypes differing in their ability to accumulate ABA to investigate its role in drought-induced dysfunction. All genotypes exhibited similar leaf and stem embolism resistance regardless of differences in ABA levels. Their leaf hydraulic resistance was also similar. Differences were only observed between the two extreme genotypes: sitiens (sit; a strong ABA-deficient mutant) and sp12 (a transgenic line that constitutively overaccumulates ABA), where the water potential inducing 50% embolism was 0.25 MPa lower in sp12 than in sit. Maximum stomatal and minimum leaf conductances were considerably lower in plants with higher ABA (wild type [WT] and sp12) than in ABA-deficient mutants. Variations in gas exchange across genotypes were associated with ABA levels and differences in stomatal density and size. The lower water loss in plants with higher ABA meant that lethal water potentials associated with embolism occurred later during drought in sp12 plants, followed by WT, and then by the ABA-deficient mutants. Therefore, the primary pathway by which ABA enhances drought resistance is via declines in water loss, which delays dehydration and hydraulic dysfunction.Item Open Access The absence or presence of a lytic coliphage affects the response of Escherichia coli to heat, chlorine, or UV exposure(Springer, 2018-03-15) Ameh, Ekwu M.; Tyrrel, Sean; Harris, Jim A.; Ignatiou, Athanasios; Orlova, Elena; Nocker, AndreasDisinfection aims at maximal inactivation of target organisms and the sustainable suppression of their regrowth. Whereas many disinfection efforts achieve efficient inactivation when the effect is measured directly after treatment, there are questions about the sustainability of this effect. One aspect is that the treated bacteria might recover and regain the ability to grow. In an environmental context, another question is how amenable surviving bacteria are to predation by omnipresent bacteriophages. Provisional data suggested that bacteria when subjected to sublethal heat stress might develop a phage-resistant phenotype. The result made us wonder about the susceptibility to phage-mediated lysis for bacteria exposed to a gradient of chlorine and UV-LED disinfection strengths. Whereas bacteria exposed to low sublethal chlorine doses still underwent phage-mediated lysis, the critical chlorine Ct of 0.5 mg min/L eliminated this susceptibility and induced phage resistance in the cells that survived treatment. In the case of UV, even the smallest tested dose of 2.8 mJ/cm2 abolished phage lysis leading to direct regrowth. Results suggest that bacteria surviving disinfection might have higher environmental survival chances directly after treatment compared to non-treated cells. A reason could possibly lie in their compromised metabolism that is essential for phage replication.Item Open Access Abundance and distribution of enteric bacteria and viruses in coastal and estuarine sediments - A review(Frontiers Media, 2016-11-01) Hassard, Francis; Gwyther, Ceri L.; Farkas, Kata; Andrews, Anthony; Jones, Vera; Cox, Brian; Howard, Brett; Jones, Davey L.; McDonald, James E.; Malham, Shelagh K.The long term survival of fecal indicator organisms (FIOs) and human pathogenic microorganisms in sediments is important from a water quality, human health and ecological perspective. Typically, both bacteria and viruses strongly associate with particulate matter present in freshwater, estuarine and marine environments. This association tends to be stronger in finer textured sediments and is strongly influenced by the type and quantity of clay minerals and organic matter present. Binding to particle surfaces promotes the persistence of bacteria in the environment by offering physical and chemical protection from biotic and abiotic stresses. How bacterial and viral viability and pathogenicity is influenced by surface attachment requires further study. Typically, long-term association with surfaces including sediments induces bacteria to enter a viable-but-non-culturable (VBNC) state. Inherent methodological challenges of quantifying VBNC bacteria may lead to the frequent under-reporting of their abundance in sediments. The implications of this in a quantitative risk assessment context remain unclear. Similarly, sediments can harbor significant amounts of enteric viruses, however, the factors regulating their persistence remains poorly understood. Quantification of viruses in sediment remains problematic due to our poor ability to recover intact viral particles from sediment surfaces (typically < 10%), our inability to distinguish between infective and damaged (non-infective) viral particles, aggregation of viral particles, and inhibition during qPCR. This suggests that the true viral titre in sediments may be being vastly underestimated. In turn, this is limiting our ability to understand the fate and transport of viruses in sediments. Model systems (e.g., human cell culture) are also lacking for some key viruses, preventing our ability to evaluate the infectivity of viruses recovered from sediments (e.g., norovirus). The release of particle-bound bacteria and viruses into the water column during sediment resuspension also represents a risk to water quality. In conclusion, our poor process level understanding of viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments.