3,183 research outputs found

    Conceptual design study of advanced acoustic composite nacelle

    Get PDF
    Conceptual nacelle designs for wide-bodied and for advanced-technology transports were studied with the objective of achieving significant reductions in community noise with minimum penalties in airplane weight, cost, and in operating expense by the application of advanced composite materials to nacelle structure and sound suppression elements. Nacelle concepts using advanced liners, annular splitters, radial splitters, translating centerbody inlets, and mixed-flow nozzles were evaluated and a preferred concept selected. A preliminary design study of the selected concept, a mixed flow nacelle with extended inlet and no splitters, was conducted and the effects on noise, direct operating cost, and return on investment determined

    A case report: retigabine induced oral mucosal dyspigmentation of the hard palate

    Get PDF
    Background Dyspigmentation of the oral mucosa has a multitude of aetiological causes. Retigabine, a new antiepileptic drug, has the potential side effect of inducing a blue/purple pigmentation of the oral mucosa in addition to the skin, lips, nails and retina of the eyes. This article presents a unique case of dyspigmentation present in the oral mucosa of the hard palate which has previously been unreported in the dental literature. Case presentation A 70 year old white male presented to a secondary care oral surgery department with an unusual asymptomatic pigmented lesion present in the hard palate of the oral cavity. The pigmentation was remarkable for its distinct blue/purple colouration which was associated with a similar discolouration of the nail beds of the hands. This is believed to be a side effect of the anti-epileptic medication retigabine. Conclusion The dental profession and wider healthcare community should be made fully aware of the potential side effect of oral dyspigmentation associated with the novel anti-epileptic medication retigabine. Enhanced knowledge of the causative role of retigabine in dyspigementation of the oral mucosa will allow the practitioner to make an appropriate diagnosis. As far the authors are aware this is reaction is unreported in the dental literature and should be disseminated to the wider oral health professional’s community

    The Adiabatic Invariance of the Action Variable in Classical Dynamics

    Get PDF
    We consider one-dimensional classical time-dependent Hamiltonian systems with quasi-periodic orbits. It is well-known that such systems possess an adiabatic invariant which coincides with the action variable of the Hamiltonian formalism. We present a new proof of the adiabatic invariance of this quantity and illustrate our arguments by means of explicit calculations for the harmonic oscillator. The new proof makes essential use of the Hamiltonian formalism. The key step is the introduction of a slowly-varying quantity closely related to the action variable. This new quantity arises naturally within the Hamiltonian framework as follows: a canonical transformation is first performed to convert the system to action-angle coordinates; then the new quantity is constructed as an action integral (effectively a new action variable) using the new coordinates. The integration required for this construction provides, in a natural way, the averaging procedure introduced in other proofs, though here it is an average in phase space rather than over time.Comment: 8 page

    Violence brief interventions: a rapid review

    Get PDF
    Provision of a Violence Brief Intervention (VBI) to young men undergoing treatment for a violent injury may represent a teachable moment for the prevention of future interpersonal violence in Scotland. Prior to intervention design, a rapid review of the research literature was necessary to examine existing programmes. After title and abstract screening, eight distinct VBIs were identified from full texts. Whilst none of the programmes were a perfect match for our intervention goals, they did demonstrate the potential effectiveness of brief interventions for violence prevention at both cognitive and behavioural levels. Key themes of successful interventions included brief motivational interviewing as an effective method of engaging with at-risk participants and encouraging change, the utility of social norms approaches for correcting peer norm misperceptions, the usefulness of working with victims of violence in medical settings (particularly oral and maxillofacial surgeries), the importance of addressing the role of alcohol after violent injury, the advantages of a computer-therapist hybrid model of delivery, and the need for adequate follow-up evaluation as part of a randomised control trial. This information has been used to design a VBI which is currently under evaluation

    Role of configurational entropy in body-centred cubic or face-centred cubic phase formation in high entropy alloys

    Get PDF
    This study examines the comparative phase stability of transition and late transition element based high entropy alloys in body-centred cubic (BCC) or face-centred cubic (FCC) forms using a combined classical molecular dynamics and statistical mechanics based approach. Multi-configurational sampling was carried out using a hybrid genetic algorithm-molecular dynamics (GA-MD) based method. The calculations demonstrate that comparative BCC or FCC phase stability is influenced by configurational entropy. The present study also provides a theoretical explanation of the recently reported occurrence of BCC phase in CoCrFeNi HEA, where the high temperature structure may be retained

    Electron spin mediated distortion in metallic systems

    Get PDF
    The deviation of positions of atoms from their ideal lattice sites in crystalline solid state systems causes distortion and it causes variation in structural [1] and functional properties [2]. Severe lattice distortion has been proposed to be one of the core-effect in high-entropy alloys. But the fundamental mechanism of distortion at atomic scale is missing for real three-dimensional metallic systems. The present investigation aims to develop mechanistic understanding of atomic scale distortion in metallic systems in terms of the magneto-volume effects. The correlation between charge-disproportion, spin fluctuations, magneto-volume effects and Fermi surface nesting has been highlighted

    Selective Laser Melting processed Ti6Al4V lattices with graded porosities for dental applications

    Get PDF
    Dental implants need to support good osseointegration into the surrounding bone for full functionality. Interconnected porous structures have a lower stiffness and larger surface area compared with bulk structures, and therefore are likely to enable better bone-implant fixation. In addition, grading of the porosity may enable large pores for ingrowth on the periphery of an implant and a denser core to maintain mechanical properties. However, given the small diameter of dental implants it is very challenging to achieve gradations in porosity. This paper investigates the use of Selective Laser Melting (SLM) to produce a range of titanium structures with regular and graded porosity using various CAD models. This includes a novel 'Spider Web' design and lattices built on a diamond unit cell. Well-formed interconnecting porous structures were successfully developed in a one-step process. Mechanical testing indicated that the compression stiffness of the samples was within the range for cancellous bone tissue. Characterization by scanning electron microscopy (SEM) and X-ray micro-computed tomography (μCT) indicated the designed porosities were well-replicated. The structures supported bone cell growth and deposition of bone extracellular matrix

    Preliminary research informing policy on remote alcohol monitoring in criminal justice : the Scottish experience

    Get PDF
    This study was funded in part by a grant from the Scottish Violence Reduction Unit to Peter D Donnelly (no grant number) and partly by a grant from the Scottish School of Public Health to Fergus G Neville (no grant number).Objectives. To explore the views of Scottish offenders on the impact of alcohol on their experience of offending and their lives in general. Further, to explore their views on the concept of Remote Alcohol Monitoring (RAM) as a way to address alcohol misuse upon liberation from prison. Methods. A convenience sample of 12 serving offenders participated in one of three focus groups.Data were analysed using the principles of thematic analysis. Results. Analysis of the data revealed the significant impact of alcohol on the lives of the participants. Key themes included the amount and frequency of alcohol consumption; the association of alcohol with harm; the association of alcohol with offending; previous attempts to reduce alcohol consumption and possible reasons for failure; and the views of the participants on the utility of RAM in relation to crime prevention. Conclusions. This group of offenders had significant issues with alcohol misuse prior to incarceration that had impacted on their offending and resulted in a variety of health and social harms. Participants were generally positive but pragmatic about RAM, recognising that technology alone may not be enough to change deeply ingrained and addictive behaviours.PostprintPeer reviewe
    • …
    corecore