16,777 research outputs found

    Elastic Wave Scattering and Dynamic Stress Concentrations in Stretching Thick Plates with Two Cutouts by Using the Refined Dynamic Theory

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    Based on the refined dynamic equation of stretching plates, the elastic tension–compression wave scattering and dynamic stress concentrations in the thick plate with two cutouts are studied. In view of the problem that the shear stress is automatically satisfied under the free boundary condition, the generalized stress of the first-order vanishing moment of shear stress is considered. The numerical results indicate that, as the cutout is thick, the maximum value of the dynamic stress factor obtained using the refined dynamic theory is 19% higher than that from the solution of plane stress problems of elastic dynamics

    Sharpness of Wilker and Huygens type inequalities

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    We present an elementary proof of Wilker's inequality involving trigonometric functions, and establish sharp Wilker and Huygens type inequalities. Mathematics Subject Classification 2010: 26D05.published_or_final_versio

    Sharp Cusa and Becker-Stark inequalities

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    We determine the best possible constants θ,ϑ,α and β such that the inequalities ((2+cosx)/3)^θ < sinx/x < ((2+cosx)/3)^ϑ and ((π^2)/(π^2-4×^2))^α < tan×/× < ((π^2)/(π^2-4×^2))^β are valid for 0 < × < π/2. Our results sharpen inequalities presented by Cusa, Becker and Stark.published_or_final_versio

    Diastolic funciton correlates with the degree of iron overload in patients with haemoglobin H disease

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    The removal of thermally aged films of triacylglycerides by surfactant solutions

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    Thermal ageing of triacylglycerides (TAG) at high temperatures produces films which resist removal using aqueous surfactant solutions. We used a mass loss method to investigate the removal of thermally aged TAG films from hard surfaces using aqueous solutions of surfactants of different charge types. It was found that cationic surfactants are most effective at high pH, whereas anionics are most effective at low pH and a non-ionic surfactant is most effective at intermediate pH. We showed that the TAG film removal process occurs in several stages. In the first ‘‘lag phase’’ no TAG removal occurs; the surfactant first partitions into the thermally aged film. In the second stage, the TAG film containing surfactant was removed by solubilisation into micelles in the aqueous solution. The effects of pH and surfactant charge on the TAG removal process correlate with the effects of these variables on the extent of surfactant partitioning to the TAG film and on the maximum extent of TAG solubilisation within the micelles. Additionally, we showed how the TAG removal is enhanced by the addition of amphiphilic additives such as alcohols which act as co-surfactants. The study demonstrates that aqueous surfactant solutions provide a viable and more benign alternative to current methods for the removal of thermally aged TAG films

    Holographic Superconductors from Einstein-Maxwell-Dilaton Gravity

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    We construct holographic superconductors from Einstein-Maxwell-dilaton gravity in 3+1 dimensions with two adjustable couplings α\alpha and the charge qq carried by the scalar field. For the values of α\alpha and qq we consider, there is always a critical temperature at which a second order phase transition occurs between a hairy black hole and the AdS RN black hole in the canonical ensemble, which can be identified with the superconducting phase transition of the dual field theory. We calculate the electric conductivity of the dual superconductor and find that for the values of α\alpha and qq where α/q\alpha/q is small the dual superconductor has similar properties to the minimal model, while for the values of α\alpha and qq where α/q\alpha/q is large enough, the electric conductivity of the dual superconductor exhibits novel properties at low frequencies where it shows a "Drude Peak" in the real part of the conductivity.Comment: 25 pages, 13 figures; v2, typos corrected; v3, refs added, to appear in JHE

    In-hospital and long-term clinical outcome following percutaneous transluminal coronary angioplasty in octogenarians

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    Multiple Ca2+ signaling pathways regulate intracellular Ca 2+ activity in human cardiac fibroblasts

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    Ca2+ signaling pathways are well studied in cardiac myocytes, but not in cardiac fibroblasts. The aim of the present study is to characterize Ca2+ signaling pathways in cultured human cardiac fibroblasts using confocal scanning microscope and RT-PCR techniques. It was found that spontaneous intracellular Ca2+ (Cai 2+) oscillations were present in about 29% of human cardiac fibroblasts, and the number of cells with Cai 2+ oscillations was increased to 57.3% by application of 3% fetal bovine serum. Cai 2+ oscillations were dependent on Ca2+ entry. Cai2+ oscillations were abolished by the store-operated Ca2+ (SOC) entry channel blocker La3+, the phospholipase C inhibitor U-73122, and the inositol trisphosphate receptors (IP3Rs) inhibitor 2-aminoethoxydiphenyl borate, but not by ryanodine. The IP3R agonist thimerosal enhanced Ca2+ i oscillations. Inhibition of plasma membrane Ca2+ pump (PMCA) and Na+-Ca2+ exchanger (NCX) also suppressed Ca i 2+ oscillations. In addition, the frequency of Ca i 2+ oscillations was reduced by nifedipine, and increased by Bay K8644 in cells with spontaneous Cai 2+ oscillations. RT-PCR revealed that mRNAs for IP3R1-3, SERCA1-3, CaV1.2, NCX3, PMCA1,3,4, TRPC1,3,4,6, STIM1, and Orai1-3, were readily detectable, but not RyRs. Our results demonstrate for the first time that spontaneous Cai 2+ oscillations are present in cultured human cardiac fibroblasts and are regulated by multiple Ca2+ pathways, which are not identical to those of the well-studied contractile cardiomyocytes. This study provides a base for future investigations into how Ca2+ signals regulate biological activity in human cardiac fibroblasts and cardiac remodeling under pathological conditions. © 2009 Wiley-Liss, Inc.postprin

    In-hospital and long-term clinical outcome following percutaneous transluminal coronary angioplasty in octogenarians

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