16,027 research outputs found
In the wake of the erbium-doped fiber amplifier - functional fibers and their impact
There have been a number of laser developments in recent years that are quite staggering in their simplicity, that are so powerful in their operation that engineers and scientist have to rethink the laser future. One such is the high power fibre laser, born out of the optical telecoms revolution. It challenges currently held views on how to make things, how to repair things, and how to destroy things. With small size, maintenance-free operation, high thermal and electrical efficiency and outstanding beam quality, it has the potential to change every industry and discipline it encounters
Fibre lasers: the new wave in material processing
In the last few years, fibre lasers have established themselves as the preferred laser source in many applications. The combination of small size, maintenance-free operation, thermal and electrical efficiency combined with outstanding (diffraction-limited) beam quality have made the fibre laser an attractive alternative to more established technologies. In fact, in some processes the fiber laser is the enabling technology. Unique among high power lasers, the fiber laser is monolithic, the light being entirely confined to the fiber core. This gives immunity to thermal distortion of the beam, almost instant startup, very high stability and protection from the environment. Maintenance is minimal, since no realignment or cleaning of components is necessary
Flexible Service Provisioning with Advance Agreements
In this paper, we develop a novel algorithm that allows service consumer agents to automatically select and provision service provider agents for their workflows in highly dynamic and uncertain computational service economies. In contrast to existing work, our algorithm reasons explicitly about the impact of failures on the overall feasibility of a workflow, and it mitigates them by proactively provisioning multiple providers in parallel for particularly critical tasks and by explicitly planning for contingencies. Furthermore, our algorithm provisions only part of its workflow at any given time, in order to retain flexibility and to decrease the potential for missing negotiated service time slots. We show empirically that current approaches are unable to achieve a high utility in such uncertain and dynamic environments; whereas our algorithm consistently outperforms them over a range of environments. Specifically, our approach can achieve up to a 27-fold increase in utility and successfully completes most workflows within a strict deadline, even when the majority of providers do not honour their contracts
Sensitivity Analysis of Flexible Provisioning
This technical report contains a sensitivity analysis to extend our previous work. We show that our flexible service provisioning strategy is robust to inaccurate performance information (when the available information is within 10% of the true value), and that it degrades gracefully as the information becomes less accurate. We also identify and discuss one particular case where inaccurate information may lead to undesirable losses in highly unreliable environments
An Effective Strategy for the Flexible Provisioning of Service Workflows
Recent advances in service-oriented frameworks and semantic Web technologies have enabled software agents to discover and invoke resources over large distributed systems, in order to meet their high-level objectives. However, most work has failed to acknowledge that such systems are complex and dynamic multi-agent systems, where service providers act autonomously and follow their own decision-making procedures. Hence, the behaviour of these providers is inherently uncertain - services may fail or take uncertain amounts of time to complete. In this work, we address this uncertainty and take an agent-oriented approach to the problem of provisioning service providers for the constituent tasks of abstract workflows. Specifically, we describe an algorithm that uses redundancy to deal with unreliable providers, and we demonstrate that it achieves an 8-14% improvement in average utility over previous work, while performing up to 6 times as well as approaches that do not consider service uncertainty. We also show that our algorithm performs well in the presence of inaccurate service performance information
Job demands, resources and work-related well-being in UK firefighters
Background There is evidence that firefighters are at risk of work-related stress and mental health problems, but little is known about the organizational hazards they experience. Insight is needed into the work-related factors that are most likely to threaten or protect their work-related well-being.
Aims To identify levels of job demands and resources (including demands relating to workload, work patterns and the working environment, relationship conflicts, control, support, role clarity and change management) among firefighters, and to use a job demands-resources framework to examine their impacts on work-related well-being. The role played by recovery strategies in predicting work-related well-being was also considered.
Methods Job demands and resources were assessed by the Health and Safety Executive (HSE) Management Standards Indicator Tool. Validated scales measured recovery strategies (detachment, affective rumination and problem-solving pondering)Â and work-related well-being (anxiety-contentment and depression-enthusiasm). The impact of job demands, resources and recovery strategies was tested by multiple linear regression.
Results The sample comprised 909 firefighters across seven Fire and Rescue Services in the UK (85% male). Levels of job demands and resources did not meet HSE benchmarks. The main risk factors for poor work-related well-being were relationship conflicts and affective rumination, but resources such as role clarity and job control and the use of problem-solving pondering and detachment were beneficial.
Conclusions Interventions that aim to reduce relationship conflicts at work and promote problem-solving rather than affective rumination, and detachment from work when off-duty, are likely to improve work-related well-being. Attention to enhancing job resources may also be beneficial
People's perceptions and classifications of sounds heard in urban parks : semantics, affect and restoration
Sounds have been broadly categorized by researchers into âhumanâ, ânatureâ and
âmechanicalâ. It is less clear if the general public define and classify sounds in the same
way and which factors influence their classification process. Establishing peopleâs
classification and impression of urban park sounds helps identify their perception and
experience of urban parks. This in turn aides the process of defining parks with reference to
soundscapes, to produce an appreciated and potentially restorative place. This study
involved urban park sounds, identified by park users, being presented in card sorts and
survey items. Participants sorted the sounds into similar groups, in reference to a visited
park. The terminology, factors involved and classification of the sounds was assessed using
multidimensional scaling. Triangulation of the results suggests affect is a key factor in
peopleâs classification process. Participantsâ grouped sounds were labelled by affective
terms more often than their perceived physical properties. Affective evaluations of each
sound produced a similar classification structure as the card sort results. Peopleâs
classification structure also varied depending on how restorative they found their urban
park. Furthermore schematic recollections played a part with many sounds being
âexpectedâ. Overall similarities and differences with âhumanâ, ânatureâ and âmechanicalâ
classifications were observed
Resilience, stress and burnout in student midwives
Background: There is a lack of research on resilience in midwifery, yet this may be a factor that can help prevent burnout and intention to leave the profession.
Objectives: To explore the relationship between perceived stress, resilience and burnout and the intention to leave midwifery within Midwifery students.
Design: A Quantitative study with a cross-sectional survey design
Setting: A London University in the UK.
Participants: 150 BSc student midwives, aged between 18 and 44, studying at University participated in this study. This included 72 students in year one, 26 in year two and 52 in year three.
Methods: Participants completed the Perceived Stress Scale, the Oldenburg burnout Inventory and the Resilience scale-14 to examine their self-reported stress levels, burnout (emotional exhaustion and disengagement) and level of resilience. Intentions to quit the profession were also measured.
Results: All variables were significantly correlated but in multiple regression analyses only stress predicted disengagement, and stress and year of study predicted emotional exhaustion. High stress and reduced resilience predicted intentions to quit midwifery. Resilience did not act as a moderator. Thus the findings suggest that resilience did not protect students from high levels of stress leading to burnout or wanting to quit, although resilience did help to reduce intentions to quit.
Conclusion: Student stress levels are not moderated by resilience and resilience played no role in reducing burnout. However, resilience may help students to persevere in the profession rather than leaving their studies. In order to minimise burnout and stress we need to consider alternative ways of enhancing the current workforce to reduce the decline in midwives entering the profession
Reiki practitionersâ perceptions of the impact of the COVID-19 pandemic on the experience, practice and future of Reiki
Objectives: This study examined the impact of the COVID-19 pandemic on the experience, practice and future of Reiki in the UK, including the personal impact of the pandemic on practitioners and their work, practitioner perceptions of the future of the profession and Reiki delivery, and practitioner experiences and views of distant Reiki in comparison to hands on or near the body treatments.
Method: A qualitative study using semi-structured interviews was carried out with 10 Reiki practitioners. Interviews were recorded, transcribed verbatim and analysed using thematic analysis.
Results: Three themes were identified: adapting and growing with the challenges of COVID-19, Reiki for individual and community resilience, and moving from the mainstream hands on to lesser known distant Reiki.
Conclusion: While the COVID-19 pandemic personally impacted Reiki practitioners, they focused on turning adversity into opportunity to overcome a sense of disconnectedness and social isolation by providing social support and promoting individual and community resilience. Practitioners focused on self-care, personal development and reaching out to the community. Personal Protective Equipment was perceived as necessary for infection control but a potential barrier to the clientâs experience of Reiki. They saw value in adapting their practice as part of the future of the profession by utilising new technology and distant Reiki healing, but were clear this could not replace in person contact
Healthy eating beliefs and intentions of mothers and their adult children: an intergenerational transmission perspective
This study examined possible intergenerational transmission of eating beliefs and intentions between 60 mothers and their adult children. Maternal restrictive feeding practices were correlated with mothers' own healthy eating attitudes and subjective norms and with their adult children's subjective norms. Mothersâ beliefs and intentions were correlated with their adult childrenâs. Adult children's intentions to eat healthily were predicted by their attitudes and PBC, and also by their mothers' intentions and PBC. Mothersâ own beliefs and intentions may be involved in shaping their childrenâs beliefs and intentions into adulthood but their child feeding practices may have less of an influence
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