The identification of structural modal parameters, as an alternative in-vivo diagnosis for osteoporosis

Includes bibliographies.An alternative non-invasive diagnostic technique was sought for the diagnosis of osteoporosis in human subjects. The tibia vibration technique was proposed after reviewing the literature on detection techniques for osteoporosis. The basis of diagnosis of the tibia vibration technique is the measured resonant frequency of the patient's tibia. The patient's tibia is excited, generally by means of an impact hammer, while the response is captured and resonant frequencies extracted. This dissertation does not attempt to measure the resonant frequencies of a human tibia, but rather develop and validate the required experimental protocol and system identification procedures, on a simple test structure. A theoretical finite element model of the test structure was developed to ensure that both the experimental protocol and system identification procedures provided accurate results. The impulse response technique was adopted to excite the test structure

Effect of the surface temperature on surface morphology, deuterium retention and erosion of EUROFER steel exposed to low-energy, high-flux deuterium plasma

Samples of EUFROFER, a reduced activation ferritic martensitic steel, were exposed in the linear plasma device Pilot-PSI to a deuterium (D) plasma with incident ion energy of similar to 40 eV and incident D flux of 2-6 x10(23) D/m(2) s to fluences up to 10 27 D/m(2) at surface temperatures ranging from 400 K to 950 K. The main focus of the study lays on the surface morphology changes dependent on the surface temperature and the surface composition evolution, e.g., the enrichment in tungsten; but also the erosion and the D retention are studied. The created surface morphology varies strongly with surface temperature from needle-like to corral-like structures. The visible lateral length scale of the formed structures is in the range of tens of nanometres to above 1 mu m and exhibits two thermal activated regimes below and above similar to 770 K with activation energies of 0.2 eV and 1.3 eV, respectively. The lateral variation of the enrichment of heavy elements on the surface is correlated to this surface morphology at least in the high temperature regime, independent of the origin of the enrichment (intrinsic from the sample or deposited by the plasma). Also the erosion exhibits temperature dependence at least above similar to 770 K as well as a fluence dependence. The amount of deuterium retained in the top 500 nm is almost independent of the exposure temperature and is of the order of 10(18) D/m(2), which would correspond to a sub-monolayer D coverage on the surface. The retained D in the volume summing up over the complete samples exceeds the D retained close to the surface by one order of magnitude. (C) 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

Die sorgsaamheidsplig van trustees in die uitvoer van hulle beleggingsbevoegdhede: Kan ons by die Engelse trustreg leer?

It is settled law in South Africa that the trustee of a trust is unequivocally charged with the duty to invest the assets of the trust. However, in South Africa in the past, this duty has been qualified, with avoidance of risk seen as the trustee’s number one priority when investing. The legislature and the judiciary mainly focused on providing safeguards for beneficiaries, therefore trustees were to avoid all risk to the capital of the trust. Despite economic realities, such as the devaluation of currencies and progressive inflation, the courts have continued to favour investment in interest-bearing securities. Most of the time trustees erred on the side of caution, following the judiciary’s lead. Unfortunately, as it will be pointed out, this means that trustees are blind to their primary task, which is and always has been, to do the best for the beneficiaries.Trustees will have to expose the assets to at least some risk in order to outperform inflation, as the traditional investments are no longer sufficient. Change occured in English trust law with the introduction of the Trustee Act 2000. This Act removes the constraints that previous legislation imposed on trustees and imposes positive obligations on trustees which reflect the reality of modern investment practices. In this article, attention will be given to the legal position in South Africa regarding a trustee’s duty of care pertaining to trust investments. Subsequently, the legal position of a trustee in terms of English law will be discussed in order to advance recommendations for future developement in South Africa