1,775 research outputs found

    RESPOND – A patient-centred programme to prevent secondary falls in older people presenting to the emergency department with a fall: Protocol for a mixed methods programme evaluation.

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    Background Programme evaluations conducted alongside randomised controlled trials (RCTs) have potential to enhance understanding of trial outcomes. This paper describes a multi-level programme evaluation to be conducted alongside an RCT of a falls prevention programme (RESPOND). Objectives 1) To conduct a process evaluation in order to identify the degree of implementation fidelity and associated barriers and facilitators. 2) To evaluate the primary intended impact of the programme: participation in fall prevention strategies, and the factors influencing participation. 3) To identify the factors influencing RESPOND RCT outcomes: falls, fall injuries and ED re-presentations. Methods/ Design Five hundred and twenty eight community-dwelling adults aged 60–90 years presenting to two EDs with a fall will be recruited and randomly assigned to the intervention or standard care group. All RESPOND participants and RESPOND clinicians will be included in the evaluation. A mixed methods design will be used and a programme logic model will frame the evaluation. Data will be sourced from interviews, focus groups, questionnaires, clinician case notes, recruitment records, participant-completed calendars, hospital administrative datasets, and audio-recordings of intervention contacts. Quantitative data will be analysed via descriptive and inferential statistics and qualitative data will be interpreted using thematic analysis. Discussion The RESPOND programme evaluation will provide information about contextual and influencing factors related to the RCT outcomes. The results will assist researchers, clinicians, and policy makers to make decisions about future falls prevention interventions. Insights gained are likely to be transferable to preventive health programmes for a range of chronic conditions

    The influence of fear of falling on the control of upright stance across the lifespan

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    Background Standing at height, and subsequent changes in emotional state (e.g., fear of falling), lead to robust alterations in balance in adults. However, little is known about how height-induced postural threat affects balance performance in children. Children may lack the cognitive capability necessary to inhibit the processing of threatand fear-related stimuli, and as a result, may show more marked (and perhaps detrimental) changes in postural control compared to adults. This work explored the emotional and balance responses to standing at height in children and compared responses to young and older adults. Methods Children (age: 9.7 ± 0.8 years, n=38), young adults (age: 21.8 ± 4.0 years, n=45) and older adults (age: 73.3 ± 5.0 years, n=15) stood in bipedal stance in two conditions: on the floor and 80cm above ground. Centre of pressure (COP) amplitude (RMS), frequency (MPF) and complexity (sample entropy) were calculated to infer postural performance and strategy. Emotional responses were quantified by assessing balance confidence, fear of falling and perceived instability. Results Young and older adults demonstrated a postural adaptation characterised by increased frequency and decreased amplitude of the COP, in conjunction with increased COP complexity (sample entropy). In contrast, children demonstrated opposite patterns of changes: they exhibited an increase in COP amplitude and decrease in both frequency and complexity when standing in a hazardous situation. Significance Children and adults adopted different postural control strategies when standing at height. Whilst young and older adults exhibited a (potentially protective) “stiffening” response to a height-induced threat, children demonstrated a (potentially maladaptive) ineffective postural adaptation strategy. These observations expand upon existing postural threat related research in adults, providing important new insight into understanding how children respond to standing in a hazardous situation

    Hydrogen-methane blend fuelling of a heavy-duty, direct-injection engine

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    Combining hydrogen with natural gas as a fuel for internal combustion engines provides an early opportunity to introduce hydrogen into transportation applications. This study investigates the effects of fuelling a heavy-duty engine with a mixture of hydrogen and natural gas injected directly into the combustion chamber. The combustion system, developed for natural gas fuelling, is not modified for blended hydrogen operation. The results demonstrate that hydrogen can have a significant beneficial effect in reducing emissions without affecting efficiency or requiring significant engine modifications. Combustion stability is enhanced through the higher reactivity of the hydrogen, resulting in reduced emissions of unburned methane. The fuel’s lower carbon:energy ratio also reduces CO2 emissions. These results combine to significantly reduce tailpipe greenhouse gas (GHG) emissions. However, the effect on net GHG’s, including both tailpipe and fuelproduction emissions, depends on the source of the hydrogen. Cleaner sources, such as electrolysis based on renewables and hydro-electric power, generate a significant net reduction in GHG emissions. Hydrogen generated by steam-methane reforming is essentially GHG neutral, while electrolysis using electricity from fossil-fuel power plants significantly increases net GHG emissions compared to conventional natural gas fuelling

    The influence of fuel composition on a heavy-duty, natural-gas direct-injection engine

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    This work investigates the implications of natural gas composition on the combustion in a heavy-duty natural gas engine and on the associated pollutant emissions. In this engine system, natural gas is injected into the combustion chamber shortly before the end of the compression stroke; a diesel pilot that precedes the natural gas injection provides the ignition source. The effects of adding ethane, propane, hydrogen, and nitrogen to the fuel are reported here. The results indicate that these additives had no significant effect on the engine’s power or fuel consumption. Emissions of unburned fuel are reduced for all additives through either enhanced ignition or combustion processes. Black carbon particulate matter emissions are increased by ethane and propane, but are virtually eliminated by including nitrogen or hydrogen in the fuel

    The effects of fuel dilution in a natural-gas direct-injection engine

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    This study reports the effects of fuelling a heavy-duty single-cylinder research engine with pilot-ignited late-cycle direct-injected natural gas diluted with 0, 20, and 40 per cent nitrogen. The combustion duration is unaffected while its intensity is reduced and its stability is increased. Emissions of nitrogen oxides, particulate matter, hydrocarbons, and carbon monoxide are all reduced, with no effect on the engine’s performance and efficiency. The results indicate the benefits of increased in-cylinder turbulence and are of particular relevance when considering fuel composition variations with non-conventional sources of gaseous fuels

    Combustion in a heavy-duty direct-injection engine using hydrogen–methane blend fuels

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    Adding hydrogen to the fuel in a direct injection natural gas engine offers the potential significantly to reduce local and global air pollutant emissions. This work reports on the effects of fuelling a heavy-duty engine with late-cycle direct injection of blended hydrogen– methane fuels and diesel pilot ignition over a range of engine operating conditions. The effect of hydrogen on the combustion event varies with operating condition, providing insight into the fundamental factors limiting the combustion process. Combustion stability is enhanced at all conditions studied; this leads directly to a significant reduction in emissions of combustion byproducts, including carbon monoxide, particulate matter, and unburned fuel. Carbon dioxide emissions are also significantly reduced by the lower carbon–energy ratio of the fuel. The results suggest that this technique can significantly reduce both local and global pollutant emissions associated with heavy-duty transport applications while requiring minimal changes to the fuelling system

    Drum vortons in high density QCD

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    Recently it was shown that high density QCD supports of number of topological defects. In particular, there are U(1)_Y strings that arise due to K^0 condensation that occurs when the strange quark mass is relatively large. The unique feature of these strings is that they possess a nonzero K^+ condensate that is trapped on the core. In the following we will show that these strings (with nontrivial core structure) can form closed loops with conserved charge and currents trapped on the string worldsheet. The presence of conserved charges allows these topological defects, called vortons, to carry angular momentum, which makes them classically stable objects. We also give arguments demonstrating that vortons carry angular momentum very efficiently (in terms of energy per unit angular momentum) such that they might be the important degrees of freedom in the cores of neutron stars.Comment: 11 pages, accepted for publication in Physical Review

    Isolation, identification and genetic characterisation of a microsporidium isolated from carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae)

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    'Microsporidia' is a term used for organisms belonging to the phylum Microspora, which contains approximately 187 genera and 1500 species (Corradi 2015). They are obligate intracellular parasites with no active metabolic stages of the life cycle occurring outside of the host cells (Franzen & Muller 1999; Garcia 2002; Tsai et al. 2003; Huang et al. 2004). They exhibit eukaryotic characteristics such as a membrane-bound nucleus, an intracytoplasmic membrane system, and chromosome separation occurs on mitotic spindles. However, they also exhibit prokaryotic characteristics such as possession of a 70S ribosome, lack of true mitochondria and peroxisomes, a simple version of the Golgi apparatus, and a small genome which is much less complex than those of most eukaryotes (Franzen & Muller 1999; Garcia 2002). Microspo- ridia are parasitic in all major groups of animals, both vertebrates and invertebrates (Sprague 1977; Franzen & Muller 1999). Microsporidia were first recognised as pathogens in silkworms by Nageli (1857), and now have been found to infect many hosts such as humans, insects, fish and mammals (Stentiford et al. 2016)

    Probing Heavy Higgs Boson Models with a TeV Linear Collider

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    The last years have seen a great development in our understanding of particle physics at the weak scale. Precision electroweak observables have played a key role in this process and their values are consistent, within the Standard Model interpretation, with a light Higgs boson with mass lower than about 200 GeV. If new physics were responsible for the mechanism of electroweak symmetry breaking, there would, quite generally, be modifications to this prediction induced by the non-standard contributions to the precision electroweak observables. In this article, we analyze the experimental signatures of a heavy Higgs boson at linear colliders. We show that a linear collider, with center of mass energy \sqrt{s} <= 1 TeV, would be very useful to probe the basic ingredients of well motivated heavy Higgs boson models: a relatively heavy SM-like Higgs, together with either extra scalar or fermionic degrees of freedom, or with the mixing of the third generation quarks with non-standard heavy quark modes.Comment: 21 page

    A Taylor Model Based Description of the proof stress of magnesium AZ31 during hot working

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    A series of hot-compression tests and Taylor-model simulations were carried out with the intention of developing a simple expression for the proof stress of magnesium alloy AZ31 during hot working. A crude approximation of wrought textures as a mixture of a single ideal texture component and a random background was employed. The shears carried by each deformation system were calculated using a full-constraint Taylor model for a selection of ideal orientations as well as for random textures. These shears, in combination with the measured proof stresses, were employed to estimate the critical resolved shear stresses for basal slip, prismatic slip, ⟨c+a⟩ second-order pyramidal slip, and { } twinning. The model thus established provides a semianalytical estimation of the proof stress (a one-off Taylor simulation is required) and also indicates whether or not twinning is expected. The approach is valid for temperatures between &sim;150 &deg;C and &sim;450 &deg;C, depending on the texture, strain rate, and strain path
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