20518 research outputs found
Sort by
Improving global accessibility to offshore wind power through decreased operations and maintenance costs: a hydrodynamic analysis
Get PDFImproved access to renewable energy in developing economies will be a major factor in future global efforts to reduce CO2 emissions, while simultaneously raising living conditions in areas presently without or with only limited access to electricity. Coastal populations stand to benefit greatly from reduced costs of offshore wind farms, which are one of the fastest growing and most economical sources of marine renewable energy. A considerable drawback of offshore wind power is the high cost of operations and maintenance (O&M), which can account for 25-50% of total energy production costs. Present-day maintenance procedures, using crew transfer vessels, rely on the significant wave height (HS) as the limiting factor by which to decide whether or not it is safe to access the offshore turbines. In practice, HS has to be applied conservatively, thus raising the costs through increased downtime. A method is proposed here with the objective of reducing overall costs through improved analysis of the motion of the crew transfer vessels (CTVs) used to transport repair technicians onto offshore wind turbine structures. CTV motion depends on the hydrodynamic forces incident on the vessel under operating conditions and the effect that the presence of the turbine has on the flow field. A change in the hydrodynamic field caused by the turbine monopile can cause a vessel abutted against the turbine support column to lose frictional contact and slip. Using the open-source computational fluid dynamics software, OpenFOAM, and in situ experimental results, the diffracted surface elevation and a wave kinematics model for the near-wake of a turbine monopile are presented. More accurate estimates of significant wave height and wave kinematics incident on a vessel close to a turbine monopile will facilitate much improved analysis of vessel motions under operational conditions
We Know their House, Family and Workplace:Trust in Entrepreneurs' Trade Credit Relationships in Weak Institutions
Get PDFThis study explores the processes of trade credit relationship development and enforcement by SME entrepreneurs and the role of trust in a developing economy context. Drawing on institutional, trade credit and trust theories data was collected and analysed from 16 SMEs owner/managers trading across cultures using qualitative interview approach and thematic analysis. The results show that SMEs develop and enforce trade credit relationships through their embeddedness in institutional contexts. Secondly, they use personal trust and specific social-cultural norms in the enforcement of trade credit agreements in absence of formal institutional trust. Conclusion, implications, limitations and further studies are delineated
SLICING-BASED RESOURCE ALLOCATION AND MOBILITY MANAGEMENT FOR EMERGING WIRELESS NETWORKS
Get PDFThe proliferation of smart mobile devices and user applications has continued to contribute to the tremendous volume of data traffic in cellular networks. Moreover, with the feature of heterogeneous connectivity interfaces of these smart devices, it becomes more complex for managing the traffic volume in the context of mobility. To surmount this challenge, service and resource providers are looking for alternative mechanisms that can successfully facilitate managing network resources and mobility in a more dynamic, predictive and distributed manner. New concepts of network architectures such as Software-Defined Network (SDN) and Network Function Virtualization (NFV) have paved the way to move from static to flexible networks. They make networks more flexible (i.e., network providers capable of on-demand provisioning), easily customizable and cost effective. In this regard, network slicing is emerging as a new technology built on the concepts of SDN and NFV. It splits a network infrastructure into isolated virtual networks and allows them to manage network resources based on their requirements and characteristics. Most of the existing solutions for network slicing are facing challenges in terms of resource and mobility management. Regarding resource management, it creates challenges in terms of provisioning network throughput, end-to-end delay, and fairness resources allocation for each slice, whereas, in the case of mobility management, due to the rapid change of user mobility the network slice operator would like to hold the mobility controlling over its clients across different access networks, rather than the network operator, to ensure better services and user experience. In this thesis, we propose two novel architectural solutions to solve the challenges identified above. The first proposed solution introduces a Network Slicing Resource Management (NSRM) mechanism that assigns the required resources for each slice, taking into consideration resource isolation between different slices. The second proposed v solution provides a Mobility Management architecture-based Network Slicing (MMNS) where each slice manages its users across heterogeneous radio access technologies such as WiFi, LTE and 5G networks. In MMNS architecture, each slice has different mobility demands (e.g,. latency, speed and interference) and these demands are governed by a network slice configuration and service characteristics. In addition, NSRM ensures isolating, customizing and fair sharing of distributed bandwidths between various network slices and users belonging to the same slice depending on different requirements of each one. Whereas, MMNS is a logical platform that unifies different Radio Access Technologies (RATs) and allows all slices to share them in order to satisfy different slice mobility demands. We considered two software simulations, namely OPNET Modeler and OMNET++, to validate the performance evaluation of the thesis contributions. The simulation results for both proposed architectures show that, in case of NSRM, the resource blocking is approximately 35% less compared to the legacy LTE network, which it allows to accommodate more users. The NSRM also successfully maintains the isolation for both the inter and intra network slices. Moreover, the results show that the NSRM is able to run different scheduling mechanisms where each network slice guarantee perform its own scheduling mechanism and simultaneously with other slices. Regarding the MMNS, the results show the advantages of the proposed architecture that are the reduction of the tunnelling overhead and the minimization of the handover latency. The MMNS results show the packets delivery cost is optimal by reducing the number of hops that the packets transit between a source node and destination. Additionally, seamless session continues of a user IP-flow between different access networks interfaces has been successfully achieved
Small room for compromise between oil palm cultivation and primate conservation in Africa
Get PDFDespite growing awareness about its detrimental effects on tropical biodiversity, land conversion to oil palm continues to increase rapidly as a consequence of global demand, profitability, and the income opportunity it offers to producing countries. Although most industrial oil palm plantations are located in Southeast Asia, it is argued that much of their future expansion will occur in Africa. We assessed how this could affect the continent’s primates by combining information on oil palm suitability and current land use with primate distribution, diversity, and vulnerability. We also quantified the potential impact of large-scale oil palm cultivation on primates in terms of range loss under different expansion scenarios taking into account future demand, oil palm suitability, human accessibility, carbon stock, and primate vulnerability. We found a high overlap between areas of high oil palm suitability and areas of high conservation priority for primates. Overall, we found only a few small areas where oil palm could be cultivated in Africa with a low impact on primates (3.3 Mha, including all areas suitable for oil palm). These results warn that, consistent with the dramatic effects of palm oil cultivation on biodiversity in Southeast Asia, reconciling a large-scale development of oil palm in Africa with primate conservation will be a great challenge
Locomotor exercise and circadian rhythms in mammals
Get PDFThe timing of locomotor activity is a major rhythmic output of the mammalian circadian system but both spontaneous and induced exercise can also themselves impact on circadian rhythms across levels of organisation and in multiple tissues, including both the brain and periphery. This review briefly summarises historical research on the influences of locomotor activity and its correlates on circadian function and then discusses recent advances in this area. Locomotor exercise can acutely alter circadian phase, both of overt behavioural rhythms and in peripheral tissues, and can stably entrain rhythms in behaviour driven by the hypothalamic master circadian pacemaker in the suprachiasmatic nucleus (SCN). Locomotor activity potently and acutely suppresses both electrical activity and clock gene expression in the master circadian pacemaker of the hypothalamus, though mechanistically how this is achieved is still unclear, as are the effects of locomotor activity in diurnal species, including humans. © 2018 Elsevier Lt
Synthetic Cannabinoids (SCs) in metaphors: A metaphorical analysis of user experiences of synthetic cannabinoids in two countries.
Get PDFNew psychoactive substances (NPS) remain a global public health and clinical challenge. Popular NPS include synthetic cannabinoids (SCs). A conceptual metaphorical analysis of user experiences of SCs was conducted in two European countries (Western and Central European). Metaphors are increasingly used to better understand drug user experiences and as medium to inform and guide clinical responses. Semi-structured interviews with 12 SC users were conducted in Hungary (n = 6) and Ireland (n = 6). Thematically segmented texts of SC usage (1) motivation, (2) effects, (3) consequences and (4) the setting were selected. A systematic analysis of conceptual metaphors was conducted on the selected texts. The conceptual target and source domains of the experiences of SC usage (motivation, effects, consequences) were analysed. Four conceptual source domains were found in all of the segmented and analysed narratives of psychological factors (motivations, effects, consequences): change in the vertical perception, perceiving that SC is everywhere, feeling disconnected, recognition of lack of control and identifying the SC as a destroying entity. The conceptual metaphors reflect how users perceive experiences of SC use, the discrepancy between the experience of embodiment and disembodiment. This study provides clinicians with an insight into the experiences of SC motivations, effects and consequences and can be used to inform and guide clinical and therapeutic responses in the support of those recovering from SC dependence
A Mechanistic Framework for Integrating Chemical Structure and High-Throughput Screening Results to Improve Toxicity Predictions
Get PDFAdverse Outcome Pathways (AOPs) establish a connection between a molecular initiating event (MIE) and an adverse outcome. Detailed understanding of the MIE provides the ideal data for determining chemical properties required to elicit the MIE. This study utilized high-throughput screening data from the ToxCast program, coupled with chemical structural information, to generate chemical clusters using three similarity methods pertaining to nine MIEs within an AOP network for hepatic steatosis. Three case studies demonstrate the utility of the mechanistic information held by the MIE for integrating biological and chemical data. Evaluation of the chemical clusters activating the glucocorticoid receptor identified activity differences in chemicals within a cluster. Comparison of the estrogen receptor results with previous work showed that bioactivity data and structural alerts can be combined to improve predictions in a customizable way where bioactivity data are limited. The aryl hydrocarbon receptor (AHR) highlighted that while structural data can be used to offset limited data for new screening efforts, not all ToxCast targets have sufficient data to define robust chemical clusters. In this context, an alternative to additional receptor assays is proposed where assays for proximal key events downstream of AHR activation could be used to enhance confidence in active calls. These case studies illustrate how the AOP framework can support an iterative process whereby in vitro toxicity testing and chemical structure can be combined to improve toxicity predictions. In vitro assays can inform the development of structural alerts linking chemical structure to toxicity. Consequently, structurally related chemical groups can facilitate identification of assays that would be informative for a specific MIE. Together, these activities form a virtuous cycle where the mechanistic basis for the in vitro results and the breadth of the structural alerts continually improve over time to better predict activity of chemicals for which limited toxicity data exist
Suggesting a Service Research Agenda in Sport Tourism: Working Experience(s) into Business Models
Get PDFPurpose: Business models describe how value is delivered to customers/consumers. When considering sport tourism, the focus on delivering value shifts to the sport experiences being offered in a destination. The purpose of this paper was to fulfil a void that links concept of business models to the area of sport tourism management by integrating notions of experience.
Approach: To merge these areas, a review of literature identifies key approaches and missing links. This paper determines research gaps to propose a new holistic research agenda for sport services—specifically relevant to sport tourism.
Findings/practical implications: This paper addresses types of sport experiences, economic dimensions of experiences, and business models to determine capabilities of delivering different types of experiences. These interrelated fields of analysis represent a platform for both academic and business stakeholders to shape the future of delivering sport tourism experiences–based on seeking a wider range of motivations in a specific spatial and activity context.
Originality/value: A series of research questions and proposals are identified to support the need for future research. Extending understandings of experience in relation to consumer demand has the potential to result in practical elements of sought after experiences being incorporated into business models—aimed at delivering service value
Gastropod parasitic nematodes (Phasmarhabditis sp.) are attracted to hyaluronic acid in snail mucus by cGMP signalling.
Get PDFPhasmarhabditis hermaphrodita is a parasitic nematode of terrestrial gastropods that has been formulated into a biological control agent for farmers and gardeners to kill slugs and snails. In order to locate slugs it is attracted to mucus, faeces and volatile cues; however, there is no information about whether these nematodes are attracted to snail cues. It is also unknown how wild isolates of P. hermaphrodita or different Phasmarhabditis species behave when exposed to gastropod cues. Therefore, we investigated whether P. hermaphrodita (commercial and wild isolated strains), P. neopapillosa and P. californica were attracted to mucus from several common snail species (Cepaea nemoralis, Cepaea hortensis, Arianta arbustorum and Cornu aspersum). We also examined whether snails (C. aspersum) collected from different locations around the UK differed in their attractiveness to wild isolates of P. hermaphrodita. Furthermore, we also investigated what properties of snail mucus the nematodes were attracted to, including hyaluronic acid and metal salts (FeSO4, ZnSO4, CuSO4 and MgSO4). We found that the commercial strain of P. hermaphrodita responded poorly to snail mucus compared to wild isolated strains, and C. aspersum collected from different parts of the UK differed in their attractiveness to the nematodes. We found that Phasmarhabditis nematodes were weakly attracted to all metals tested but were strongly attracted to hyaluronic acid. In a final experiment we also showed that pharmacological manipulation of cyclic guanosine monophosphate (cGMP) increased chemoattraction to snail mucus, suggesting that the protein kinase EGL-4 may be responsible for Phasmarhabditis sp. chemoattraction
Antimicrobial Photodynamic Therapy with Phenothiazinium Photosensitizers in non-vertebrate model Galleria mellonella infected with Fusarium keratoplasticum and Fusarium moniliforme.
Get PDFFusarium keratoplasticum and Fusarium moniliforme are filamentous fungi common in the environment and cause mycosis in both animals and plants. Human infections include mycetoma, keratitis and onychomycosis, while deeper mycosis occurs in immunocompromised patients. Most of the Fusarium spp. are frequently resistant to treatment with currently used antifungals. The frequent occurrence of antifungal resistance has motivated the study of antimicrobial photodynamic therapy as an alternative treatment for fungal infections. Many studies have investigated the in vitro use of antimicrobial photodynamic therapy to kill fungi, but rarely in animal models of infection. Thus, here we employed the invertebrate wax moth Galleria mellonella to study the in vivo effects of antimicrobial photodynamic therapy with three different phenothiazinium photosensitizers, methylene blue, new methylene blue N and the pentacyclic S137 against infection with microconidia of Fusarium keratoplasticum and Fusarium moniliforme. The effect of antimicrobial photodynamic therapy using these photosensitizers and light-emitting diodes with an emission peak at 635 nm and an integrated irradiance from 570 to 670 nm of 9.8 mW cm-2 was investigated regarding the toxicity, fungal burden, larval survival and cellular immune response. The results from this model indicate that antimicrobial photodynamic therapy with methylene blue, new methylene blue N and S137 is efficient for the treatment of infection with F. keratoplasticum and F. moniliforme. The efficiency can be attributed to the fungal cell damage caused by antimicrobial photodynamic therapy which facilitates the action of the host immune response
Data sources:
LJMU Research Online (Liverpool John Moo...PATT40 (LJMU)Biomolecular Research Reports (BRR) (LJM...Design and Technology Education (LJMU)BLResearchDay (LJMU)Journal of Living Labs (LJMU)Journal of Natural Products Discovery (L...Journal of Social Media for Learning (LJ...Student Law Journal (LJMU)PRISM (LJMU)Public Health Institute Journal (LJMU)SPARK (LJMU)Student Experience Proceedings (LJMU)Transformation in Education (LJMU)Innovations in Practice (LJMU)Links to Health and Social Care (LJMU)Access Repository Dashboard
Do you manage Liverpool John Moores University Research Archive? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!