8,763 research outputs found

    Lubrication handbook

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    Information on lubricants from government reports, military specifications, qualified parts lists, and suppliers of commercial lubricants has been consolidated in one source. Handbook includes data on chemical and physical properties of solid, bonded solid, and liquid lubricants; dispersions and composites; and greases, oils, and hydraulic fluids

    The credibility of health economic models for health policy decision-making: the case of population screening for abdominal aortic aneurysm

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    <i>Objectives</i>: To review health economic models of population screening for abdominal aortic aneurysm (AAA) among elderly males and assess their credibility for informing decision-making. <i>Methods</i>: A literature review identified health economic models of ultrasound screening for AAA. For each model focussing on population screening in elderly males, model structure and input parameter values were critically appraised using published good practice guidelines for decision analytic models. <i>Results</i>: Twelve models published between 1989 and 2003 were identified. Converting costs to a common currency and base year, substantial variability in cost-effectiveness results were revealed. Appraisals carried out for the nine models focusing on population screening showed differences in their complexity, with the simpler models generating results most favourable to screening. Eight of the nine models incorporated two or more simplifying structural assumptions favouring screening; uncertainty surrounding these assumptions was not investigated by any model. Quality assessments on a small number of parameters revealed input values varied between models, methods used to identify and incorporate input data were often not described, and few sensitivity analyses were reported. <i>Conclusions</i>: Large variation exists in the cost-effectiveness results generated by AAA screening models. The substantial number of factors potentially contributing to such disparities means that reconciliation of model results is impossible. In addition, poor reporting of methods makes it difficult to identify the most plausible and thus most useful model of those developed

    Introduction to MINISIS

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    Text also presented by W.S. Page at a meeting on "Minicomputers in Information and Documentation" held in Frankfurt am Main, 30 June-4 July, 198

    Changes to DPPC domain structure in the presence of carbon nanoparticles

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    DPPC (dipalmitoylphosphatidylcholine) is a disaturated lipid capable of forming closely packed monolayers at the air–liquid interface of the lung and allows the surface tension within the alveoli to reduce to almost zero and thus prevent alveolar collapse. Carbon nanoparticles are formed in natural and man-made combustion events, including diesel engines, and are capable of reaching the alveolar epithelium during breathing. In this work, we have used Brewster angle microscopy and neutron reflectivity to study the effect of differing concentrations of carbon nanoparticles on the structure of DPPC monolayer as the monolayer is subject to compression and expansion. The results show that the inclusion of carbon nanoparticles within a DPPC monolayer affects the formation and structure of the lipid domains. The domains lose their circular structure and show a crenated structure as well as a reduction in overall size of the domains. This change in structure is also evident following expansion of the lipid monolayer, suggesting that some carbon nanoparticles may remain associated with the monolayer. This observation could have an important implication regarding the removal of nanosized airborne pollutants from the human lung

    Insulin and insulin-like growth factor-I responsiveness and signalling mechanisms in C2C12 satellite cells: effect of differentiation and fusion

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    AbstractIn proliferating C2C12 myoblasts, serum and physiological concentrations of insulin and IGF-I stimulated protein synthesis and RNA accretion. After fusion, the multinucleated myotubes remained responsive to serum but not to insulin or IGF-I, even though both insulin and type-1 IGF receptor mRNAs increased in abundance. Protein synthetic responses to insulin and IGF-I in myoblasts were not inhibited by dexamethasone, ibuprofen or Ro-31-8220, thus phospholipase A2, cyclo-oxygenase and protein kinase C did not appear to be involved in the signalling mechanisms. Neither apparently were polyphosphoinositide-specific phospholipase C or phospholipase D since neither hormone increased inositol phosphate, phosphatidic acid, choline or phosphatidylbutanol production. Only the phosphatidylinositol-3-kinase inhibitor, wortmannin, and the 70 kDa S6-kinase inhibitor, rapamycin, wholly or partially blocked the effects of insulin and IGF-I on protein synthesis. 2-deoxyglucose uptake remained responsive to insulin and IGF-I after fusion and was also inhibited by wortmannin. The results suggest that the loss of responsiveness after fusion is not due to loss of receptors, but to the uncoupling of a post-receptor pathway, occurring after the divergence of the glucose transport and protein synthesis signalling systems, and that, if wortmannin acts at a single site, this is prior to that point of divergence

    The Structural Basis of Actin Organization by Vinculin and Metavinculin

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    Vinculin is an essential adhesion protein that links membrane-bound integrin and cadherin receptors through their intracellular binding partners to filamentous actin, facilitating mechanotransduction. Here we present an 8.5-Å-resolution cryo-electron microscopy reconstruction and pseudo-atomic model of the vinculin tail (Vt) domain bound to F-actin. Upon actin engagement, the N-terminal "strap" and helix 1 are displaced from the Vt helical bundle to mediate actin bundling. We find that an analogous conformational change also occurs in the H1' helix of the tail domain of metavinculin (MVt) upon actin binding, a muscle-specific splice isoform that suppresses actin bundling by Vt. These data support a model in which metavinculin tunes the actin bundling activity of vinculin in a tissue-specific manner, providing a mechanistic framework for understanding metavinculin mutations associated with hereditary cardiomyopathies

    Instabilities in the Flux Line Lattice of Anisotropic Superconductors

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    The stability of the flux line lattice has been investigated within anisotropic London theory. This is the first full-scale investigation of instabilities in the `chain' state. It has been found that the lattice is stable at large fields, but that instabilities occur as the field is reduced. The field at which these instabilities first arise, b(ϵ,θ)b^*(\epsilon,\theta), depends on the anisotropy ϵ\epsilon and the angle θ\theta at which the lattice is tilted away from the cc-axis. These instabilities initially occur at wavevector k(ϵ,θ)k^*(\epsilon,\theta), and the component of kk^* along the average direction of the flux lines, kzk_z, is always finite. As the instability occurs at finite kzk_z the dependence of the cutoff on kzk_z is important, and we have used a cutoff suggested by Sudb\ospace and Brandt. The instabilities only occur for values of the anisotropy ϵ\epsilon appropriate to a material like BSCCO, and not for anisotropies more appropriate to YBCO. The lower critical field Hc1(ϕ)H_{c_1}(\phi) is calculated as a function of the angle ϕ\phi at which the applied field is tilted away from the crystal axis. The presence of kinks in Hc1(ϕ)H_{c_1}(\phi) is seen to be related to instabilities in the equilibrium flux line structure.Comment: Extensively revised paper, with modified analysis of elastic instabilities. Calculation of the lower critical field is included, and the presence of kinks in Hc1H_{c_1} is seen to be related to the elastic instabilities. 29 pages including 16 figures, LaTeX with epsf styl

    Poultry producer\u27s willingness to invest in on-farm carcass disposal

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    Foreign animal diseases (FAD) can cause substantial economic losses in production, consumption, and the supply chain. These diseases are typically highly pathogenic and lead to disruptions in normal business practices and to demands for higher investment in biosecurity practices. For poultry producers this can lead to changes in bird pick-ups, chick placements, and length of out time on farms as well as changes in day-to-day operations. When an FAD is reported, poultry producers that rely on off-premises carcass disposal (e.g., renderers or landfills) may be required to develop on-farm disposal capacity (e.g., incinerators or burial) rapidly if their operation falls within movement restriction zones. While preemptive planning is suggested, not all producers have an environmentally approved plan given disruptions in business continuity. This study estimated poultry producers’ willingness to pay (WTP) for on-farm carcass disposal methods for routine, non-catastrophic mortality during an FAD outbreak to understand what factors contribute to the investment decision. Poultry producers were surveyed about their operations’ characteristics, their disease perceptions, and were presented with a hypothetical disease scenario. The estimated mean WTP for additional disposal capacity was $15,651. Besides indicating that a market for on-farm carcass disposal exists, our findings also provide information that can be used when creating policy to simultaneously incentivize farm-level biosecurity and carcass disposal protocols while continuing to encourage disease reporting, which together, improves overall livestock disease management in the United States
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