15,403 research outputs found

    The Catholic Doctor and the Church

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    When does ‘All Eggs in One Risky Basket’ Make Sense?

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    In an important paper comparing expected utility and mean-variance analysis, Feldstein (1969) examined a simple portfolio problem involving just two assets, one riskless and one risky. He concluded there could easily be ‘plunging’, that is, investment in the risky asset alone. His background assumptions were that the risky asset’s yield was log normally distributed and that the investor’s attitude to risk was expressible by a logarithmic utility. We look at how conclusions are affected by choice of distribution and utility function. While conclusions can depend on choice of distribution, they are remarkably robust to choice within the range of plausible positive distributions. In contrast, conclusions are sensitive to choice of utility function and we find the key determinant to be how much the investor’s relative risk aversion differs from unity and in what direction. Based on historical stock market returns, our analysis implies that the prevalence of diversification that is observed is consistent with a relative risk aversion coefficient of about 2.5.

    Simulation of the small punch creep test with consideration of variation of material properties

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    A new finite element model of the small punch creep test is described. The material constitutive relationship for creep considered is a simple Norton power law: in this study the exponent in the power law is varied for each element to simulate the random behaviour of creep. The influence of this random variation, and the effect of the friction factor between the punch and specimen, on the deformation and stress field has been investigated

    Hydrolysed formula and risk of allergic or autoimmune disease: a systematic review and meta-analysis

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    Objective To determine whether feeding infants with hydrolysed formula reduces their risk of allergic or autoimmune disease. Design Systematic review and meta-analysis, as part of a series of systematic reviews commissioned by the UK Food Standards Agency to inform guidelines on infant feeding. Two authors selected studies by consensus, independently extracted data, and assessed the quality of included studies using the Cochrane risk of bias tool. Data sources Medline, Embase, Web of Science, CENTRAL, and LILACS searched between January 1946 and April 2015. Eligibility criteria for selecting studies Prospective intervention trials of hydrolysed cows’ milk formula compared with another hydrolysed formula, human breast milk, or a standard cows’ milk formula, which reported on allergic or autoimmune disease or allergic sensitisation. Results 37 eligible intervention trials of hydrolysed formula were identified, including over 19 000 participants. There was evidence of conflict of interest and high or unclear risk of bias in most studies of allergic outcomes and evidence of publication bias for studies of eczema and wheeze. Overall there was no consistent evidence that partially or extensively hydrolysed formulas reduce risk of allergic or autoimmune outcomes in infants at high pre-existing risk of these outcomes. Odds ratios for eczema at age 0-4, compared with standard cows’ milk formula, were 0.84 (95% confidence interval 0.67 to 1.07; I2=30%) for partially hydrolysed formula; 0.55 (0.28 to 1.09; I2=74%) for extensively hydrolysed casein based formula; and 1.12 (0.88 to 1.42; I2=0%) for extensively hydrolysed whey based formula. There was no evidence to support the health claim approved by the US Food and Drug Administration that a partially hydrolysed formula could reduce the risk of eczema nor the conclusion of the Cochrane review that hydrolysed formula could allergy to cows’ milk. Conclusion These findings do not support current guidelines that recommend the use of hydrolysed formula to prevent allergic disease in high risk infants

    The Girl That You\u27ve Forgotten : Has Not Forgotten You

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    https://digitalcommons.library.umaine.edu/mmb-vp/4204/thumbnail.jp

    Acoustic energy transmission in cast iron pipelines

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    In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure
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