896 research outputs found

    New similarity solutions of the thermocline equations with vertical variations of diffusion

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    Three new classes of exact solution of the thermocline equations are obtained through use of an ansatz based method (Clarkson and Kruskal, 1989), which is related to the older Classical Lie Group Method used by Salmon and Hollerbach (1991) to obtain exact solutions. The newer method has not previously been applied to oceanographic problems. Our results are more general than those of Salmon and Hollerbach in two distinct ways: we obtain new classes of solution not obtainable by the older method and, in addition, we determine solutions in which the vertical temperature diffusion profile is an arbitrary function of depth. Application of the solutions to understand the control of the main thermocline is considered in a companion paper

    Evaluation of the Type I child car restraints fitting service in WA

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    Child passenger injury remains a major road safety issue despite advances in biomechanical understanding and child restraint design. In Australia, one intervention with parents to encourage universal and consistent use of the most appropriate restraint as well as draw their attention to critical aspects of installation is the RoadWise Type 1 Child Car Restraints Fitting Service, WA. A mixed methods evaluation of this service was conducted in early 2010. Evaluation results suggest that it has been effective in ensuring good quality training of child restraint fitters. In addition, stakeholder and user satisfaction with the Service is high, with participants agreeing that the Service is valuable to the community, and fitters regarding the training course, materials and post-training support as effective. However, a continuing issue for interventions of this type is whether the parents who need them perceive this need. Evidence from the evaluation suggests that only about 25% of parents who could benefit from the Service actually use it. This may be partly due to parental perceptions that such services are not necessary or relevant to them, or to overconfidence about the ease of installing restraints correctly. Thus there is scope for improving awareness of the Service amongst groups most likely to benefit from it (e.g. new parents) and for alerting parents to the importance of correct installation and getting their self-installed restraints checked. Efforts to inform and influence parents should begin when their children are very young, preferably at or prior to birth and/or before the parent installs the first restraint

    On frontal and ventilated models of the main thermocline

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    A new similarity approach is applied to the thermocline equations in order to examine contrasting frontal and ventilated models of the main thermocline. The method of solution involves reducing the number of independent variables of the controlling partial differential equation, leading to a particular form for the solutions which satisfy appropriate boundary conditions. A frontal model of the thermocline is obtained following the study of Salmon and Hollerbach (1991). When the vertical diffusivity becomes vanishingly small, an interior front in the subtropical gyre appears at the depth where the vertical velocity changes sign. The front separates downwelling warm water in the subtropical gyre from the underlying upwelling of cold, deep water. These solutions appear to be robust to changes in the vertical diffusivity profile, as long as there is a small, nonzero value in the interior. However, when there is uniform diffusivity, there is no implied surface heat flux and surface isotherms are coincident with streamlines. As the diffusivity increases toward the surface, the surface heat input increases in magnitude and the temperature field becomes more plausible. A ventilated model of the thermocline is formed using the similarity approach with a diffusive surface boundary-layer overlying an adiabatic interior. In this case, the temperature and velocity fields are solved for in the limit of uniform potential vorticity. There is now a more plausible cross-isothermal flow in the surface layer with a polewards decrease in temperature, and the implied surface heat input increases equatorwards. Fluid is subducted from the surface boundary layer into the adiabatic interior and forms a continuous thermocline. In conclusion, the contrasting frontal and ventilated solutions arise from modeling different aspects of the circulation, rather than depending on the type of model employed. The ventilated solutions form a thermocline by advecting the surface temperature field into the interior of a subtropical gyre, whereas the frontal solutions create a thermocline from the interaction of the wind-driven gyre and the underlying thermohaline circulation. These thermocline solutions might occur separately or together in the real ocean, although both solutions might be modified by higher-order processes or more complicated forcing

    All-Wales licensed premises intervention (AWLPI): a randomised controlled trial to reduce alcohol-related violence

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    Background: Alcohol-related violence in and in the vicinity of licensed premises continues to place a considerable burden on the United Kingdom’s (UK) health services. Robust interventions targeted at licensed premises are therefore required to reduce the costs of alcohol-related harm. Previous evaluations of interventions in licensed premises have a number of methodological limitations and none have been conducted in the UK. The aim of the trial was to determine the effectiveness of the Safety Management in Licensed Environments intervention designed to reduce alcohol-related violence in licensed premises, delivered by Environmental Health Officers, under their statutory authority to intervene in cases of violence in the workplace.<p></p> Methods/Design: A national randomised controlled trial, with licensed premises as the unit of allocation. Premises were identified from all 22 Local Authorities in Wales. Eligible premises were those with identifiable violent incidents on premises, using police recorded violence data. Premises were allocated to intervention or control by optimally balancing by Environmental Health Officer capacity in each Local Authority, number of violent incidents in the 12 months leading up to the start of the project and opening hours. The primary outcome measure is the difference in frequency of violence between intervention and control premises over a 12 month follow-up period, based on a recurrent event model. The trial incorporates an embedded process evaluation to assess intervention implementation, fidelity, reach and reception, and to interpret outcome effects, as well as investigate its economic impact.<p></p> Discussion: The results of the trial will be applicable to all statutory authorities directly involved with managing violence in the night time economy and will provide the first formal test of Health and Safety policy in this environment. If successful, opportunities for replication and generalisation will be considered.<p></p&gt

    Measurement in sports biomechanics

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    One of the major roles of a sports biomechanist or coach is to assess the movement patterns within sports performances. Movements can be analysed to enhance an individual's technique in terms of efficiency or to provide technical advantage. This paper aims to highlight the different measurement techniques available for the biomechanist to assess the movement characteristics of the technical and mechanical aspects of athletic performance. </jats:p

    Haemophilus Influenzae Microarrays: Virulence and Vaccines

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    In 1995 the genome sequence of the Haemophilus influenzae KW20 (Rd) strain was published, the first available for a free-living organism. The genome has been invaluable in global strategies to identify certain virulence-related genes, e.g. those involved in LPS synthesis, and also essential genes, but there is a paucity of wholegenome transcriptome studies. We have now constructed a whole-genome array consisting of genes from Rd, additional genes identified in other strains of H. influenzae and controls (from eukaryotic sources and other bacteria). We intend to use this array in studies aimed at understanding the bacterium’s basic metabolism and its response to changing environments; deciphering global regulatory networks (by comparison of wild-type and mutant strains); and identifying genes expressed in vivo. The use of H. influenzae DNA arrays combined with proteomic approaches will enhance our understanding of the metabolism and virulence of the organism. Additionally, the genome sequence of a non-typable H. influenzae strain is in progress. The sequence from this isolate will be invaluable not only in identifying potential novel antibiotic targets and putative vaccine candidates but also in the design of a microarray for genome-typing purposes

    Idiopathic Hemochromotosis and Alpha‐1‐Antitrypsin Deficiency: Coexistence in a Family with Progressive Liver Disease in the Proband

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    A patient with coexistent hemochromatosis and alpha‐1‐antitrypsin deficiency which led to cirrhosis and death despite adequate therapy for hemochromatosis is reported. Evaluation of the family revealed first degree relatives with iron overload and others with alpha‐1‐antitrypsin deficiency but none with both conditions. The role of family studies in the early recognition and possible prevention of overt clinical disease in individuals with either of these two genetic diseases is discussed. Copyright © 1983 American Association for the Study of Liver Disease

    Squeezed-light-enhanced atom interferometry below the standard quantum limit

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    We investigate the prospect of enhancing the phase sensitivity of atom interferometers in the Mach-Zehnder configuration with squeezed light. Ultimately, this enhancement is achieved by transferring the quantum state of squeezed light to one or more of the atomic input beams, thereby allowing operation below the standard quantum limit. We analyze in detail three specific schemes that utilize (1) single-mode squeezed optical vacuum (i.e., low-frequency squeezing), (2) two-mode squeezed optical vacuum (i.e., high-frequency squeezing) transferred to both atomic inputs, and (3) two-mode squeezed optical vacuum transferred to a single atomic input. Crucially, our analysis considers incomplete quantum state transfer (QST) between the optical and atomic modes, and the effects of depleting the initially prepared atomic source. Unsurprisingly, incomplete QST degrades the sensitivity in all three schemes. We show that by measuring the transmitted photons and using information recycling [Phys. Rev. Lett. 110, 053002 (2013)], the degrading effects of incomplete QST on the sensitivity can be substantially reduced. In particular, information recycling allows scheme (2) to operate at the Heisenberg limit irrespective of the QST efficiency, even when depletion is significant. Although we concentrate on Bose- condensed atomic systems, our scheme is equally applicable to ultracold thermal vapors
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