A parametric design and optimization approach to enhance the fatigue life of a male pyramid socket adapter

Abstract: This research paper presents a parametric design approach to optimize a male pyramid socket adapter as used on a transtibial prosthetic limb for enhanced fatigue life. These adapters are prone to premature failure when used by individuals partaking in athletic sports. A parametric design and optimization approach is presented and applied. A current design was assessed for structural integrity by finite element analysis in combination with the load criteria as recommended by the ISO 10328:2016 code of practice. Highly-stressed regions where identified and improved using a parametric design approach to reduce the maximum 1st Principal stress while adhering to the industry code of practice as applicable to pyramid socket adapter design. The optimization was validated by experimentally comparing the current design and the optimised design for an appropriate load case by low cycle fatigue testing. The socket adapters were manufactured from Ti6Al4V and subjected to a simulated resultant knee bending moment. The fatigue validation indicated a significant improvement in fatigue life for the optimized socket geometry commensurate with a reduction in stress and comparison to an appropriate SN curve for Ti6Al4V. The parametric optimization process as utilized was found to be effective and should be applicable to many different applications in a more general sense

Development of a vehicle load control strategy for Malawi for the period 2016 to 2020

In an effort to improve the effectiveness of overload control the Malawi Directorate of Road Transport and Safety Services (DRTSS) appointed two Short Term Experts from the CSIR to assist with the updating of the DRTSS?s 2005 Axle Load Control Strategy and development of a five-year implementation plan for significantly improving the Directorate?s current capacity to effectively manage and enforce axle load control. Specific objectives were to: ? Assist the DRTSS to undertake an extensive nationwide survey to assess the extent of the overloading problem on the paved road network; ? Review and update the 2005 ?Vehicle Weights and Axle Load Control Strategy?, based on the outcome of this survey; ? Produce a Five-year Implementation (Business) Plan that will provide a ?roadmap? for the expansion of the current overload control system; ? Strengthen the overall management and monitoring of axle load control operations through the introduction of adequate monitoring and reporting; and ? Ensure that the underlying legislation adequately supports axle load control operations. The output of the project was a Vehicle Load Control (VLC) Strategy for Malawi for the period 2016 to 2020. The VLC strategy presents the strategic direction that the DRTSS will take for the next five years with regards its vehicle load control mandate. The VLC Strategy will form the basis for the planning and execution of vehicle load control infrastructure and operations. This paper covers the process followed in developing the strategy; the situational analysis undertaken prior to the development of the strategy; and the steps followed in the development of the strategy. The paper then presents the strategic outcomes, outcome targets and outputs that have to be implemented and achieved in terms of this strategy.Paper presented at the 35th Annual Southern African Transport Conference 4-7 July 2016 "Transport ? a catalyst for socio-economic growth and development opportunities to improve quality of life", CSIR International Convention Centre, Pretoria, South Africa.The Minister of Transport, South AfricaTransportation Research Board of the US

Baseline axle load survey in Malawi - 2014

As part of the project to update the Malawian Directorate of Road Transport and Safety Services? (DRTSS) 2005 Axle Load Control Strategy and to provide a five-year implementation plan, a country-wide axle load survey was undertaken to assess the incidence of overloading on the paved road network in Malawi. The baseline axle load survey was undertaken by staff members from the DRTSS after attending a two-day training course on overload control and the operation of the portable scales that were used for the survey. Heavy vehicles were weighed at 17 sites in two phases. 2 691 heavy vehicles were weighed on 68 weigh days at an average of 39 heavy vehicles per day. Of the 2 691 vehicles weighed, 1 356 were overloaded, which represents an extent of overloading of 50.4%. The average overloaded mass on the 1 356 overloaded vehicles was 4 264 kg, representing an average degree of overloading of 26.1%. Weigh data from 4 of the 5 permanent weighbridges in Malawi were also analysed to compare the extent and degree of overloading measured at the permanent weighbridges with what was measured during the axle load survey. This analysis showed that the average extent of overloading measured at the fixed weighbridges was 3.1% and the average degree of overloading 5%.Paper presented at the 34th Annual Southern African Transport Conference 6-9 July 2015 "Working Together to Deliver - Sakha Sonke", CSIR International Convention Centre, Pretoria, South Africa.The Minister of Transport, South AfricaTransportation Research Board of the US

A new rat model of creatine transporter deficiency reveals behavioral disorder and altered brain metabolism.

Creatine is an organic compound used as fast phosphate energy buffer to recycle ATP, important in tissues with high energy demand such as muscle or brain. Creatine is taken from the diet or endogenously synthetized by the enzymes AGAT and GAMT, and specifically taken up by the transporter SLC6A8. Deficit in the endogenous synthesis or in the transport leads to Cerebral Creatine Deficiency Syndromes (CCDS). CCDS are characterized by brain creatine deficiency, intellectual disability with severe speech delay, behavioral troubles such as attention deficits and/or autistic features, and epilepsy. Among CCDS, the X-linked creatine transporter deficiency (CTD) is the most prevalent with no efficient treatment so far. Different mouse models of CTD were generated by doing long deletions in the Slc6a8 gene showing reduced brain creatine and cognitive deficiencies or impaired motor function. We present a new knock-in (KI) rat model of CTD holding an identical point mutation found in patients with reported lack of transporter activity. KI males showed brain creatine deficiency, increased urinary creatine/creatinine ratio, cognitive deficits and autistic-like traits. The Slc6a8 <sup>Y389C</sup> KI rat fairly enriches the spectrum of CTD models and provides new data about the pathology, being the first animal model of CTD carrying a point mutation

Phase Separation of Rigid-Rod Suspensions in Shear Flow

We analyze the behavior of a suspension of rigid rod-like particles in shear flow using a modified version of the Doi model, and construct diagrams for phase coexistence under conditions of constant imposed stress and constant imposed strain rate, among paranematic, flow-aligning nematic, and log-rolling nematic states. We calculate the effective constitutive relations that would be measured through the regime of phase separation into shear bands. We calculate phase coexistence by examining the stability of interfacial steady states and find a wide range of possible ``phase'' behaviors.Comment: 23 pages 19 figures, revised version to be published in Physical Review

Avalanche Dynamics in Evolution, Growth, and Depinning Models

The dynamics of complex systems in nature often occurs in terms of punctuations, or avalanches, rather than following a smooth, gradual path. A comprehensive theory of avalanche dynamics in models of growth, interface depinning, and evolution is presented. Specifically, we include the Bak-Sneppen evolution model, the Sneppen interface depinning model, the Zaitsev flux creep model, invasion percolation, and several other depinning models into a unified treatment encompassing a large class of far from equilibrium processes. The formation of fractal structures, the appearance of $1/f$ noise, diffusion with anomalous Hurst exponents, Levy flights, and punctuated equilibria can all be related to the same underlying avalanche dynamics. This dynamics can be represented as a fractal in $d$ spatial plus one temporal dimension. We develop a scaling theory that relates many of the critical exponents in this broad category of extremal models, representing different universality classes, to two basic exponents characterizing the fractal attractor. The exact equations and the derived set of scaling relations are consistent with numerical simulations of the above mentioned models.Comment: 27 pages in revtex, no figures included. Figures or hard copy of the manuscript supplied on reques

In vivo comparison of the proangiogenic properties of chlordecone and three of its dechlorinated derivatives formed by in situ chemical reduction

In situ chemical reduction (ISCR) has been identified as a possible way for the remediation of soils contaminated by chlordecone (CLD). Evidences provided by the literature indicate an association between the development of prostate cancer and CLD exposure (Multigner et al. 2010). In a previous in vitro study, we demonstrated that the two main dechlorinated CLD derivatives formed by ISCR, CLD-1Cl, and CLD-3Cl have lower cytotoxicity and proangiogenic properties than CLD itself (Legeay et al. 2017). By contrast, nothing is known on the in vivo proangiogenic effect of these dechlorinated derivatives. Based on in vitro data, the aims of this study were therefore to evaluate the in vivo influence of CLD and three of its dechlorinated metabolites in the control of neovascularization in a mice model of prostate cancer. The proangiogenic effect of CLD and three of its dechlorinated derivatives, CLD-1Cl, CLD-3Cl, and CLD-4Cl, was evaluated on a murine model of human prostate tumor (PC-3) treated, at two exposure levels: 33 μg/kg and 1.7 μg/kg respectively reflecting acute and chronic toxic exposure in human. The results of serum measurements show that, for the same ingested dose, the three metabolite concentrations were significantly lower than that of CLD. Dechlorination of CLD lead therefore to molecules that are biologically absorbed or metabolized, or both, faster than the parent molecule. Prostate tumor growth was lower in the groups treated by the three metabolites compared to the one treated by CLD. The vascularization measured on the tumor sections was inversely proportional to the rate of dechlorination, the treatment with CLD-4Cl showing no difference with control animals treated with only the vehicle oil used for all substances tested. We can therefore conclude that the proangiogenic effect of CLD is significantly decreased following the ISCR-resulting dechlorination. Further investigations are needed to elucidate the molecular mechanisms by which dechlorination of CLD reduces proangiogenic effects in prostate tumor

Photosensitivity in South Africa. II. The experimental production of the ovine hepatogenous photosensitivity disease geeldikkop (Tribulosis ovis) by the simultaneous ingestion of Tribulus terrestris plants and cultures of Pithomyces chartarum containing the mycotoxin sporidesmin

The mycoflora of toxic pastures were surveyed during a number of outbreaks of ovine hepatogenous photosensitivity in South Africa. Pure cultures of several isolates were dosed to sheep, but only those of Pithomyces chartarum and Myrothecium verrucaria proved to be toxic. Photosensitization was induced in sheep by dosing them with cultures of a P. chartarum isolate (GAIO) obtained from Tribulus terrestris plants collected during an outbreak of geeldikkop in the Karoo. Thus for the first time a mechanism whereby T. terrestris plants can contribute to the causation of ovine hepatogenous photosensitivity was demonstrated. When cultures of GA10 equivalent to approximately 0, 75-4,0 mg/kg sporidesmin were dosed at Onderstepoort Veterinary Research Institute to Highveld and Karoo sheep on a diet of lucerne, facial eczema was produced. Dosing the same cultures at levels equivalent to c. 1,0 mg/kg of sporidesmin in the Karoo resulted in lesions characteristic of both facial eczema and geeldikkop. Typical hepatic lesions of geeldikkop could be elicited by dosing GAIO at levels equivalent to c. 0,25- 0,7 mg/kg of sporidesmin to Karoo sheep grazing on predominantly T. terrestris pastures in the Karoo. In the latter experiment geeldikkop was induced in the sheep on T. terrestris pastures, while those receiving identical doses on veld with little T. terrestris developed facial aczema. Geeldikkop, therefore, can be brought about by the ingestion of T. terrestris plants together with toxic cultures of P. chartarum. The plant appears not only to act as a vehicle for ingestion of spores, but also to interact with sporidesmin to induce lesions typical of geeldikkop, whereas sporidesmin alone results in facial eczema. Indications are that it can enhance the ability of sporidesmin to cause photosensitivity or, possibly, vice versa. The histopathological findings of these experiments are described in detail.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Measurement of W Polarisation at LEP

The three different helicity states of W bosons produced in the reaction e+ e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to measure the polarisation of W bosons, and its dependence on the W boson production angle. The fraction of longitudinally polarised W bosons is measured to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model expectation

Measurement of W Polarisation at LEP

The three different helicity states of W bosons produced in the reaction e+ e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to measure the polarisation of W bosons, and its dependence on the W boson production angle. The fraction of longitudinally polarised W bosons is measured to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model expectation