Host-bacterial interactions underlying recurrent urinary tract infections

PhD ThesisAlthough most urinary tract infections (UTIs) are easily treated with antibiotics, many patients present with long-term bacterial colonisation of the urinary tract. Amongst these patients, some remain asymptomatic but others exhibit severe and frequent UTI symptoms. Currently, there is little understanding of the host-microbial interactions underpinning these clinical conditions. Hence further understanding of these interactions underlying the pathogenesis of asymptomatic bacteriuria (ASB) and recurrent UTIs is essential for effective clinical management. To explore these interactions further, genomic data from two clinical studies (AnTIC & BUTI) were mined and bacterial isolates exploited to determine the effects of antibiotic prophylaxis (AnTIC) and hostspecific factors (BUTI) on long-term bacterial colonisation. Using bioinformatic approaches, the AnTIC dataset was analysed to investigate the impact of antibiotic prophylaxis on bacterial colonisation of the urinary tract. The findings suggested that antibiotic prophylaxis reduced the frequency of symptomatic UTIs by not only clearing bacteria from the urinary tract, but also in a subset of patients through stabilising Escherichia coli colonisation. An association between stable colonisation and a reduction in UTI frequency was also observed in the BUTI study, but with a focus on Proteus mirabilis rather than E. coli. In these patients, host factors appeared important with patients characterised by a TLR1 1805T SNP associated with stable and clinically asymptomatic P. mirabilis colonisation. In vitro experiments using bladder RT4 cells and TLR agonists supported a role for TLR1 in modulating the immune response, which may play a role in ASB. Analysis of E. coli isolated from AnTIC patients supported a link between stable long-term bacterial colonisation and increased antibiotic resistance. In the UK, nitrofurantoin underpinned by the low incidence of resistance amongst uropathogens, is prescribed for managing UTIs. In vitro experiments using mutagenised clinical E. coli isolates were performed to investigate potential factors driving nitrofurantoin resistance. In the absence of nitrofurantoin, bacterial growth data demonstrated that nitrofurantoin resistant (NitR) strains grew as well as sensitive strains (NitS doubling time= 21.9 ± 0.9 min; NitR mutants= 25.7 ± 0.4 min; NitR natural= 25.7 ± 1.1 min). However, in the presence of nitrofurantoin (8 – 16 μg/ml), resistant strains showed a fitness advantage, with the average doubling time of these mutants reduced by 35% (p<0.001). These results in combination with clinical pharmacokinetics data suggest that urinary nitrofurantoin concentrations in prophylaxis therapy driving fitness via selective advantage, which potentially results in the selection of NitR isolates. Taken together, these studies show that investigating both host and microbial components and how they interact are essential to understanding the pathogenesis of UTI and will help improve the management of recurrent UTI sufferers

High Power Density Propulsion Motor for Hybrid Electric Aircraft

Ph. D. Thesis.The Civil Aerospace is looking ahead for new solutions that can offer further significant improvement in aircraft efficiencies and emissions. Hybrid Electric Distributed Propulsion (HEDP) aircraft’s configurations have been extensively modelled, and these results show it is possible to obtain notable benefits with some authors claiming that overall fuel savings of more than 70% are possible compared with today’s designs. However, these models depend critically on electrical power networks and machines being able to operate with significantly improved power densities and efficiencies in the aircraft electric plant. In general these multi-megawatt power systems have been used in applications where volume and weight have been secondary considerations and hence new techniques and approaches are now required. A further issue is designing machines to address other constraints required for aircraft installation, for example motors integrating with propulsive systems. Hence for these applications new and evermore performing electrical machine designs are now required. The work showcased in this thesis is meant as a beginning to address these new requirements. Chapter 1 presents the challenges identified and locates the motivation of this work in the more vast application sense of aerospace propulsion. Chapter 2 provides a literature review and initial considerations on the power density increase. Chapter 3 is a collection of methodologies developed for mainly mechanical and initial electromagnetic performance evaluation. Chapter 4 delivers the optimized result for different machines comparison as well as alternative choices of objectives and constraints dictated by the design envelope. Chapter 5 identifies and develops further the chosen candidate: high order effects in the mechanics/rotor-dynamics and rotor losses estimation are thoroughly investigated. Chapter 6 addresses the manufacture choices undertaken and initial tests conducted on the machine. The thesis ends with the conclusions in Chapter 7

Exploring the Effects of Bile Acid Inhibition in Cholestatic Pruritus

Ph. D. Thesis.Pruritus (itch) is an important symptom associated with cholestatic liver diseases. The aim of this work was to study cholestatic pruritus to further our understanding of the prevalence in primary biliary cholangitis (PBC) and explore the role of inhibiting circulating bile acids (BAs) in relieving cholestatic pruritus. The cross-sectional study of pruritus from over 2800 patients from the UK-PBC research cohort showed that prevalence of pruritus in PBC is high (74%) with a significant proportion of patients reporting severe itch during the course of their disease. This study also highlighted the undertreatment of itch with inadequate use of guideline recommended drugs in the UK. The impact of inhibiting circulating BAs on cholestatic pruritus was studied in two different ways- i) via nasobiliary drainage (NBD, i.e. external diversion of bile and BAs away from the ileum), and ii) via pharmacological inhibition of the ileal bile acid transporter (IBAT) that mediates enterohepatic circulation of BAs. The retrospective cohort study of NBD showed the intervention is a highly effective treatment, but only of short-term durability and associated with high complication rate. The phase 2 clinical trial of GSK2330672, a human IBAT inhibitor agent, showed that two-weeks of treatment significantly reduced pruritus severity compared to placebo. The metabonomic and microbiome studies explored the serum metabonome and gut microbiota profile of pruritus in PBC. In addition, the effects of GSK2330672 on metabonome and gut microbiome were investigated. The study demonstrated that pruritus in PBC is associated with elevated serum total and glyco-conjugated BAs but no gut bacterial dysbiosis. Also, GSK2330672 was shown to reduce all taurine and glyco- conjugated serum BAs, increase faecal BAs and alter the gut-microbial composition. Taken together, the research studies presented in this thesis suggest: i) high prevalence of pruritus and its under-treatment in PBC, ii) removal of BAs by NBD or inhibition by IBAT inhibitor drug improves cholestatic pruritus and, iii) serum BAs but not gut microbiome are altered in cholestatic pruritus and they can be modified by IBAT inhibitor treatmentNational Institute for Health Research (NIHR), Newcastle Biomedical Research Centre (BRC

Mitochondrial dysfunction as a driver of cellular senescence

Ph. D. ThesisCellular senescence is a stress response implicated in ageing and age-related diseases (Baker et al., 2016; von Zglinicki, 2002). Senescent cells are characterised by mitochondrial dysfunction (Dalle Pezze et al., 2014; Korolchuk et al., 2017; Passos et al., 2007). Importantly, mitochondria were shown to regulate the senescence-associated secretory phenotype (SASP) (Correia-Melo et al., 2016). However, the exact mechanisms via which mitochondria contribute to the SASP as well as its conservation between the main studied models of senescence, remains to be elucidated. In this thesis, I discovered that senescent cells are characterized by a sub-lethal mitochondrial apoptotic stress, consisting of the activation of pro-apoptotic factor, BAX and the release of cytochrome c and mtDNA into the cytosol. BAK and BAX are required for the SASP in damage-induced senescence (DIS), however, their genetic depletion in oncogeneinduced senescence (OIS), increases it. A pharmacological inhibition of BAX after the establishment of cell cycle arrest, ameliorates SASP in OIS. Cells in DIS secrete higher levels of mtDNA than proliferating cells. However, the level of circulating mtDNA is not a strong biomarker of senescence burden in mice and humans. Next, I demonstrate OIS and DIS are characterised by a different degree of mitochondrial apoptotic stress as well as oxidative phosphorylation (OXPHOS) dysfunction. Mitochondrial network was confirmed to be hyperfused in DIS (Dalle Pezze et al., 2014), however, it was found to be fragmented in OIS. Interfering with mitochondrial dynamics by inducing mitochondrial fusion exacerbates the SASP in both models of senescence. In contrast, a shift to mitochondrial fragmentation reduces the SASP in the model of DIS and exacerbates it in OIS. Finally, I found myxovirus resistance protein B (MxB) plays an important function in maintaining the integrity of mitochondrial network and mitochondrial bioenergetics, as MxB depletion induces mitochondrial apoptotic stress and activates mitochondrial biogenesis. In DIS, MxB is highly up-regulated and translocates from mitochondria to the nucleus. MxB was found to be a key factor required for the SASP development.Medical Research Council and Mayo Clini

The automatic classification of canine state

PhD ThesisOsteoarthritis is a prevalent disease among domestic dogs which, even when well managed, often causes bouts of chronic pain and a lesser quality of life. Despite a lack of training dog owners are relied upon to recognise the signs of pain or illness in their animals. This often leads to treatment being sought later than would be ideal, resulting in the unnecessary and avoidable suffering of their dogs. This can be further compounded by the qualitative nature of lameness assessment performed by veterin arians. The difficulty of which is further exacerbated when symptoms are subtle, and the disease is in its early stages. This thesis investigates the use of remote, animal borne, tri-axial accelerometers to supplement the welfare information available to both caregivers and veterinarians. Published acceleration-derived measures, of both the time and frequency domains, common within human and non-human animal acceler ometer research, are assessed for their potential as daily and weekly identifiers of os teoarthritic lameness. The suitability of identified measures was evaluated using both Principal Component Analysis based feature selection and logistic linear models. The results of this process highlighted a potential link between both the level and entropy of an animals overall weekly activity with the occurrence of osteoarthritis. It also provided insight into areas of further development and established the complexity of the task of recognising lameness from acceleration data. A behaviour-based methodology was established hybridising techniques used across wildlife ecology deployments, existing veterinary assessment of lameness and, the assessment of human gait impacted by both physical illness and neurodegeneration. This led to the development of a method ology focussing on the identification of behaviours, starting with canine postural state, to provide context as to the daily activities of the subject. Two distinct approaches to postural recognition were assessed both employing machine learning techniques with a focus on the interpretability of results. The first, examined the identification of 6 pos tural transitions, similar to methods established in human accelerometer assessments, using linear discriminant analyses at 3 different sliding window lengths. The inclusion of an empirical cumulative distribution function representation was also assessed. The results suggested that the isolation of transitional periods from among non-transitional periods was difficult and there was high confusion between the transitions themselves. The second examined the identification of the postures themselves alongside the oc currence of locomotion during the standing posture. Linear discrimination analyses were once again used due to the interpretability of the method and the simplicity of its implementation. The effects of pre-processing techniques and differing posture group ings were also explored. The findings suggested a binary decision tree approach was the most effective mechanism and that the application of pre-processing techniques to clean data caused a distinct negative impact that requires forethought as to the poten tial costs and benefits of their use. Standing was the most easily identified, perhaps due to its prominence, and the further classification of locomotion from among stand ing periods was ineffective. To further supplement the postural methods of identifying osteoarthritis an investigation of the remote monitoring of circadian rhythm was estab lished. This is of interest due to prior results highlighting the potential relationship of activity entropy and level with lameness and the reports of sleep disruption by human chronic pain sufferers. Features relating to the length and frequency of both resting and active bouts were used in logistic regression models to establish their relationship to the presence or absence of osteoarthritis. Minor disruption was observed to the amplitude of activity frequencies within osteoarthritic dogs consistent with prior find ings. However, further work is needed to disentangle this effect from that of advanced age, a possible confound. The potential of remote sensing technologies is shown but further development of methodologies is required. A combination of the described approaches, with the refinements highlighted within this thesis, could further improve their efficacy and should be investigated. A behaviour based, transparent and fully in terpretable monitor of lameness, pain, and/or welfare could prove valuable to the early and effective treatment of canine osteoarthritis and should be pursued furthe

Computational approaches for analysing and engineering micropollutant degradation in microbial communities

PhD ThesisThe presence of micropollutants in wastewater is problematic, as many micropollutants exert negative ecological and toxicological effects in their environment. A well-known effect of micropollutants is the feminisation of aquatic wildlife by environmental estrogens, a proportion of which enter water courses from municipal sources via wastewater treatment plants (WWTPs). While WWTPs remove some micropollutants, they are not designed to do so. Given that WWTPs already have high operating costs (both financially and energetically), there is a need for novel approaches to micropollutant removal that are both cost-effective and environmentally sustainable. One proposed approach is to use enzymes to degrade micropollutants, which requires an understanding of metabolic pathways for the desired micropollutant, and a strategy for deploying the enzymes in the environment. Although tools exist to assist with metabolic pathway prediction and enzyme discovery, there are currently no computational approaches that are able to identify enzymes from a user’s collection of proteins (given a query compound and expected change to that query compound). To address this research gap, we developed EnSeP, a data-driven, transformation-specific approach to enzyme discovery. Using EnSeP, we then identified candidate enzymes involved in estradiol degradation. Recent advances in synthetic biology mean that deploying a single synthetic construct in multiple microorganisms is feasible. In the context of micropollutant metabolism, this means that a biodegradative pathway could be introduced into multiple organisms in a community simultaneously, providing more opportunities for the construct (and its functionality) to persist in the population long-term. However, current design tools have not yet been adapted for multiple organism applications. To address this research gap, we developed an evolutionary algorithm (EA) that optimises a single coding sequence (CDS) for multiple hosts. Finally, based on insights from developing the EA, we developed an improved version of the single-organism CDS optimisation algorithm that the EA is based on

Biologically mediated abiotic degradation (BMAD) of chlorinated solvents using Fe-bearing clay minerals

Ph. D. Thesis.Chlorinated solvents, such as tetrachloroethene (PCE), trichloroethene (TCE), and trihalomethanes (THMs), are extremely persistent and widespread groundwater contaminants. Due to their ecotoxicological and physiochemical properties, chlorinated solvent contamination poses a major threat to the quality of safe potable groundwater. Bioremediation is often employed for sites requiring a low-cost long-term remediation scheme to transform these pollutants to lesser chlorinated products. Whilst many studies have shown successful removal of PCE and TCE to a certain extent, bioremediation often stalls at cis-DCE and vinyl chloride (VC), which are much more toxic than either PCE or TCE and requires specific bacterial assemblages to remove. Alternatively, the abiotic degradation pathway, for example in the presence of minerals, favours the conversion of PCE and TCE to benign C2 gases. Fe-bearing clay minerals are seen as a promising choice of mineral for abiotic degradation because of their resistance to dissolution and ubiquity in the subsurface, which make them a sustainable source of reduction. Furthermore, interactions between aqueous Fe(II) and aqueous S(-II), which is produced via microbial activity, and structural Fe(III) bound inside clay minerals leads to the formation of an electron-doped clay mineral which can be used to reduce contaminants. However, electron transfer from aqueous Fe(II) or S(-II) also leads to the formation of solid oxidation product(s), with their exact nature and identity causing some controversy, with recent work suggesting the formation of nanocrystalline mixed valent Fe phases such as green rust, which, in turn, could contribute to contaminant transformation as potential reactive mineral intermediates (RMIs). Here we evaluated the reactivity of Fe-bearing clay minerals toward the reductive degradation of PCE, TCE, and THMs. We compared the reactivity with dithionite-reduced clay minerals and for high and low Fe content clay minerals (nontronite, NAu-1; montmorillonite, SWy-2), to modulate the clay mineral Fe(II) concentration, and varied the concentrations of aqueous Fe(II) or aqueous S(-II) to investigate the effect the concentration of each aqueous species has on the identity and potential reactivity of any RMIs that may form. We also used a separate reactive probe, hexachloroethane (HCA), which follows the same reductive -elimination reaction mechanism as the abiotic degradation pathway PCE and TCE follows, to further investigate any differences in the Fe-bearing RMIs reactivity towards degrading recalcitrant contaminants. We complemented our reactivity studies with techniques to identify any RMIs and used a combination of 57Fe-Mössbauer spectroscopy and X-ray diffraction (XRD). Transformation of PCE and TCE was not observed when NAu-1 (20 wt% Fe) or dithionitereduced SWy-2 (2.5 wt% Fe) was present, suggesting that clay mineral structural Fe(II) alone was not capable of reducing PCE and TCE. Similarly, we found no detection of any PCE or TCE transformation products from any of our experimental conditions when Fe-bearing clay minerals were reduced using aqueous S(-II), and also found no detectable transformation products from our THMs degradation study. Interestingly, PCE and TCE transformation products (acetylene, ethene, and ethane) were detected only in reactors containing SWy-2 amended with 20 mM aqueous Fe(II). We found from our experiments using HCA that the reactivity of HCA is dependent on both the clay mineral Fe content, as well as the initial aqueous Fe(II) concentration used. We believe that the rate of HCA removal is affected by the precipitate that is formed, with the reactivity of the precipitate dependent on the Fe stoichiometry and the mineral phase that has formed. Mössbauer spectroscopy was used to identify the Fe stoichiometry of both the structural clay mineral Fe as well as any Fe-bearing precipitates that formed. In the case of Fe(II)-reduced clay minerals, Mössbauer shows that both precipitates that form in the presence of 20 mM Fe(II) have similar amounts of Fe(II) present (NAu-1: 80.9%; SWy-2: 82.9%), the ratio of Fe(II) bound in the precipitate relative to the clay mineral Fe total is far greater when SWy-2 is present compared with NAu-1 ( 4.3 vs 0.5 for 20 mM amended SWy-2 and NAu-1 respectively). XRD analysis has shown that the precipitate formed for 20 mM amended SWy-2 bears some resemblance to a 1:1 trioctahedral Fe-silicate, yet hyperfine parameters from Mössbauer spectroscopy show Fe(III) coordination for a 2:1 trioctahedral mineral. The reverse appears to be true in the case of S(-II)-reduced clay minerals, where on visual inspection precipitates only appeared to form when NAu-1 was present, but due to the limitations of Mössbauer spectroscopy and XRD on identifying RMIs, it was difficult to confirm the identity of these Fe-S precipitates. Overall, while we have evaluated that Fe-bearing clay minerals may not play a pivotal role in the reductive degradation of chlorinated solvents, we have highlighted the potential importance of RMIs in the subsurface as contributors to abiotic natural attenuation, with the composition and identity of RMIs that form due to interfacial electron transfer being strongly controlled by aqueous Fe(II) or S(-II) concentrations and clay mineral Fe content. The formation of these RMIs from interfacial electron transfer can also provide further insight into Fe-bearing mineral formation throughout geological history such as the formation of low-Fe(III) greenalite

The mid-Pleistocene climate transition in the Japan Sea: Insights of a combined palaeoceanographic and monsoon, multi-proxy study using marine sediments of IODP Site U1427 from the shallow, southern Japan Sea

Ph. D. Thesis.In this thesis marine sediments from the Japan Sea (IODP Expedition 346, “Asian monsoon”, Site U1427) are used to investigate the expression of the mid-Pleistocene transition (MPT) in this marginal basin. The thesis establishes a revised geochronology (age model) for the sediments of Site U1427 across the MPT using benthic foraminifera-based trace element and oxygen stable isotope analyses. A multi-proxy approach was applied to decipher the marine versus terrestrial sources of particles in a shallow marine setting with close proximity to land. Combined, these approaches enabled to build a new conceptual model of the palaeoceanography of the Japan Sea across the MPT. Establishing a geochronology for Site U1427 by comparing the benthic foraminiferal oxygen isotope record with a well-dated global reference stack of the same kind, is challenging because the Japan Sea, in contrast to the open ocean, is suggested to have been nearly isolated from the open ocean during glacial sea-level lowstands. This isolation restricted water mass exchange and led to widespread carbonate dissolution, which hampers the creation of continuous oxygen isotope records, and, counterintuitive, reduces glacial oxygen isotope ratios through the effect low saline (and low oxygen isotope ratio) waters accumulating in the basin. Instead, the geochronology is established by combining the benthic foraminiferal oxygen isotope record with trace element and shipboard colour reflectance data, and comparing those with age markers (biostratigraphic, palaeo-magnetic, tephrachronological) and a well-dated, global reference stack (LR04-stack). This approach resulted in identification of marine isotope stages (MIS) 39-17 in the analysed sediments. The Japan Sea sediments, including Site U1427, are influenced by the East Asian monsoons and glacio-eustatic sea-level variabilities, which both control marine productivity in the basin. The applied multi-proxy approach, combining bulk sediment organic matter parameters, i.e. total organic carbon (TOC), total nitrogen contents (TN) and carbon isotope ratios (13Corg), as well as carbonate content (CaCO3) and Rock-Eval pyrolysis, proved indispensable to decipher the signals, as the close proximity to land (35 km to shore) brought some proxies to the limitations of interpretability. In short, CaCO3 is used as a proxy for marine (carbonate) productivity, while TOC-TN (C/N) ratios, 13Corg and Rock-Eval pyrolysis parameters indicate the origin of organic matter (OM), although this is a summary and other processes additionally influence these proxies. The interpretation of C/N ratios is difficult as the proxy is likely influenced by an inorganic component to nitrogen, leading to low C/N ratios and an overestimation of marine-derived organic matter. Combining individual analyses to the above multi-proxy approach enables estimating variations in contributions of marine- and terrigenous-derived organic matter, hence providing clues on changes in monsoon precipitation and sea-level stands across the MPT. The sediments of Site U1427 record monsoon variations on sub-orbital timescales and indicate enhanced precipitation/freshwater input at times during certain glacials, such as MIS 36. A major outcome of this thesis is a revised palaeoceanographic model for the Japan Sea encompassing MPT. Previously, our understanding of the palaeoceanography of the Japan Sea was extrapolated from the most recent glacialinterglacial cycles. The palaeoceanographic model presented in this thesis proposes a better glacial connection between the open ocean and the shallow, southern Japan Sea during the early MPT, MIS 39-25, and a switch to the modern glacial nearisolation of the Japan Sea starting during the later stages of the MPT, MIS 24-17, caused by relatively higher glacial sea-levels, both globally and in the Japan Sea, during the early MPT compared to its later stage.NERC IAPETUS DTP, British Geological Survey (BGS),Integrated Ocean Drilling Program (IODP), European Consortium for Ocean Research Drilling (ECORD

Real-Time QoS Monitoring and Anomaly Detection on Microservice-based Applications in Cloud-Edge Infrastructure

Ph. D. Thesis.Microservices have emerged as a new approach for developing and deploying cloud applications that require higher levels of agility, scale, and reliability. A microservicebased cloud application architecture advocates decomposition of monolithic application components into independent software components called \microservices". As the independent microservices can be developed, deployed, and updated independently of each other, it leads to complex run-time performance monitoring and management challenges. The deployment environment for microservices in multi-cloud environments is very complex as there are numerous components running in heterogeneous environments (VM/container) and communicating frequently with each other using REST-based/REST-less APIs. In some cases, multiple components can also be executed inside a VM/container making any failure or anomaly detection very complicated. It is necessary to monitor the performance variation of all the service components to detect any reason for failure. Microservice and container architecture allows to design loose-coupled services and run them in a lightweight runtime environment for more e cient scaling. Thus, containerbased microservice deployment is now the standard model for hosting cloud applications across industries. Despite the strongest scalability characteristic of this model which opens the doors for further optimizations in both application structure and performance, such characteristic adds an additional level of complexity to monitoring application performance. Performance monitoring system can lead to severe application outages if it is not able to successfully and quickly detecting failures and localizing their causes. Machine learning-based techniques have been applied to detect anomalies in microservice-based cloud-based applications. The existing research works used di erent tracking algorithms to search the root cause if anomaly observed behaviour. However, linking the observed failures of an application with their root causes by the use of these techniques is still an open research problem. Osmotic computing is a new IoT application programming paradigm that's driven by the signi cant increase in resource capacity/capability at the network edge, along with support for data transfer protocols that enable such resources to interact more seamlessly with cloud-based services. Much of the di culty in Quality of Service (QoS) and performance monitoring of IoT applications in an osmotic computing environment is due to the massive scale and heterogeneity (IoT + edge + cloud) of computing environments. To handle monitoring and anomaly detection of microservices in cloud and edge datacenters, this thesis presents multilateral research towards monitoring and anomaly detection on microservice-based applications performance in cloud-edge infrastructure. The key contributions of this thesis are as following: • It introduces a novel system, Multi-microservices Multi-virtualization Multicloud monitoring (M3 ) that provides a holistic approach to monitor the performance of microservice-based application stacks deployed across multiple cloud data centers. • A framework forMonitoring, Anomaly Detection and Localization System (MADLS) which utilizes a simpli ed approach that depends on commonly available metrics o ering a simpli ed deployment environment for the developer. • Developing a uni ed monitoring model for cloud-edge that provides an IoT application administrator with detailed QoS information related to microservices deployed across cloud and edge datacenters.Royal Embassy of Saudi Arabia Cultural Bureau in London, government of Saudi Arabi

Landscape character and public perception: a participatory Historic Landscape Characterisation approach in Northumberland

Ph. D. Thesis.The public perception of landscape character has been recognised and legitimised as a fundamental aspect of landscape policy and research through the European Landscape Convention (ELC). However, the practice of integrating the way communities perceive and value landscape in management decisions remains limited. The aim of this research is to gain a better understanding of how landscape and its historic character is perceived by people and to map and operationalise public perception to inform participatory Historic Landscape Characterisation (HLC). This study uses two qualitative approaches: map-based interviews and walking and talking interviews with local people in two Northumbrian case study areas, Heddon-on-the-Wall and the Wallington Estate, to develop insights into the factors influencing landscape perception. Having gathered and analysed the qualitative data, the findings were incorporated within a GIS designed to inform the HLC project of Northumberland. Three main conclusions were reached as a result of the analysis and discussion of the research: (1) landscape perception must be understood as a dynamic synergy between four dimensions: personal, collective, space and time. (2) The unique combination of these dimensions mean that landscapes are interpreted differently by different people and mean that a landscape is perceived differently by the same individual at specific locations and at specific times. (3) To be included in characterisation processes and to include public perception in landscape management, people’s views cannot be focussed individually but must be generalised in line with the philosophy and principles of HLC. HLC databases form an ideal platform to integrate the multiplicity of views on landscapes and open them up for more focussed discussion during problem-oriented moments in the landscape management process.Arts and Humanities Research Council (AHRC