Organisational strategic drivers and core competencies applied in the South African mining sector

This paper compares the organisational strategic drivers of a South African mining house with those of industries abroad. It furthermore compares the key competencies or capabilities of the mining house with those of the overseas industries. A Delphi panel participants comprising of nine experts - with a combined experience base of over 130 years - provided the data. The strategic drivers as well as the key competencies of the South African mining house showed marked similarities to industries such as petrochemical, engineering and construction industries abroad. While safety enjoys higher priority in the South African mining environment than in comparable industries abroad, there is room for improvement in the level of prioritisation of projects that takes place within project portfolios. The degree of authorisation given to project teams within the South African mining house to execute the project strategy is lower than that in comparable industries abroad while the level of business focus and business awareness within the South African mining project teams is relatively high. The correlation between strategic drivers and core competencies was weaker than would be expected.http://www.journals.co.za/ej/ejour_jcman.htmlam2013ai201

A stepwise transformation:description and outcome of perioperative procedures in patients receiving a total knee arthroplasty

Aims To investigate the impact of consecutive perioperative care transitions on in-hospital recovery of patients who had primary total knee arthroplasty (TKA) over an 11-year period. Methods This observational cohort study used electronic health record data from all patients undergoing preoperative screening for primary TKA at a northern netherlands hospital between 2009 and 2020. In this timeframe, three perioperative care transitions were divided into four periods: Baseline care (Joint Care, n = 171; May 2009 to August 2010), Function-tailored (n = 404; September 2010 to October 2013), Fast-track (n = 721; november 2013 to May 2018), and Prehabilitation (n = 601; June 2018 to December 2020). In-hospital recovery was measured using inpatient recovery of activities (IROA), length of stay (LOS), and discharge to preoperative living situation (PLS). Multivariable regression models were used to analyze the impact of each perioperative care transition on in-hospital recovery. Results The four periods analyzed involved 1,853 patients (65.9% female (1,221/1,853); mean age 70.1 years (SD 9.0)). IROA improved significantly with each transition: Function-tailored (0.9 days; p &lt; 0.001 (95% confidence interval (CI) -0.32 to -0.15)), Fast-track (0.6 days; p &lt; 0.001 (95% CI -0.25 to -0.16)), and Prehabilitation (0.4 days; p &lt; 0.001 (95% CI -0.18 to -0.10)). LOS decreased significantly in Function-tailored (1.1 days; p = 0.001 (95% CI -0.30 to -0.06)), Fast-track (0.6 days; p &lt; 0.001 (95% CI -0.21 to -0.05)), and Prehabilitation (0.6 days; p &lt; 0.001 (95%CI -0.27 to -0.11)). Discharge to PLS increased in Function-tailored (77%), Fast-track (91.6%), and Prehabilitation (92.6%). Post-hoc analysis indicated a significant increase after the transition to the Fast-track period (p &lt; 0.001 (95% CI 3.19 to 8.00)). Conclusion This study highlights the positive impact of different perioperative care procedures on in-hospital recovery of patients undergoing primary TKA. Assessing functional recovery, LOS, and discharge towards PLS consistently, provides hospitals with valuable insights into postoperative recovery. This can potentially aid planning and identifying areas for targeted improvements to optimize patient outcomes.</p

Multidimensional relativistic MHD simulations of Pulsar Wind Nebulae: dynamics and emission

Pulsar Wind Nebulae, and the Crab nebula in particular, are the best cosmic laboratories to investigate the dynamics of magnetized relativistic outflows and particle acceleration up to PeV energies. Multidimensional MHD modeling by means of numerical simulations has been very successful at reproducing, to the very finest details, the innermost structure of these synchrotron emitting nebulae, as observed in the X-rays. Therefore, the comparison between the simulated source and observations can be used as a powerful diagnostic tool to probe the physical conditions in pulsar winds, like their composition, magnetization, and degree of anisotropy. However, in spite of the wealth of observations and of the accuracy of current MHD models, the precise mechanisms for magnetic field dissipation and for the acceleration of the non-thermal emitting particles are mysteries still puzzling theorists to date. Here we review the methodologies of the computational approach to the modeling of Pulsar Wind Nebulae, discussing the most relevant results and the recent progresses achieved in this fascinating field of high-energy astrophysics.Comment: 29 pages review, preliminary version. To appear in the book "Modelling Nebulae" edited by D. Torres for Springer, based on the invited contributions to the workshop held in Sant Cugat (Barcelona), June 14-17, 201

High Energy Processes in Pulsar Wind Nebulae

Young pulsars produce relativistic winds which interact with matter ejected during the supernova explosion and the surrounding interstellar gas. Particles are accelerated to very high energies somewhere in the pulsar winds or at the shocks produced in collisions of the winds with the surrounding medium. As a result of interactions of relativistic leptons with the magnetic field and low energy radiation (of synchrotron origin, thermal, or microwave background), the non-thermal radiation is produced with the lowest possible energies up to $\sim$100 TeV. The high energy (TeV) gamma-ray emission has been originally observed from the Crab Nebula and recently from several other objects. Recent observations by the HESS Cherenkov telescopes allow to study for the first time morphology of the sources of high energy emission, showing unexpected spectral features. They might be also interpreted as due to acceleration of hadrons. However, theory of particle acceleration in the PWNe and models for production of radiation are still at their early stage of development since it becomes clear that realistic modeling of these objects should include their time evolution and three-dimensional geometry. In this paper we concentrate on the attempts to create a model for the high energy processes inside the PWNe which includes existence not only relativistic leptons but also hadrons inside the nebula. Such model should also take into account evolution of the nebula in time. Possible high energy expectations based on such a model are discussed in the context of new observations.Comment: 9 pages, 1 figure, Proc. Multimessenger approach to high energy gamma-ray source

Modelling Jets, Tori and Flares in Pulsar Wind Nebulae

In this contribution we review the recent progress in the modelling of Pulsar Wind Nebulae (PWN). We start with a brief overview of the relevant physical processes in the magnetosphere, the wind-zone and the inflated nebula bubble. Radiative signatures and particle transport processes obtained from 3D simulations of PWN are discussed in the context of optical and X-ray observations. We then proceed to consider particle acceleration in PWN and elaborate on what can be learned about the particle acceleration from the dynamical structures called GwispsG observed in the Crab nebula. We also discuss recent observational and theoretical results of gamma-ray flares and the inner knot of the Crab nebula, which had been proposed as the emission site of the flares. We extend the discussion to GeV flares from binary systems in which the pulsar wind interacts with the stellar wind from a companion star. The chapter concludes with a discussion of solved and unsolved problems posed by PWN

A case-only study to identify genetic modifiers of breast cancer risk for BRCA1/BRCA2 mutation carriers

Breast cancer (BC) risk for BRCA1 and BRCA2 mutation carriers varies by genetic and familial factors. About 50 common variants have been shown to modify BC risk for mutation carriers. All but three, were identified in general population studies. Other mutation carrier-specific susceptibility variants may exist but studies of mutation carriers have so far been underpowered. We conduct a novel case-only genome-wide association study comparing genotype frequencies between 60,212 general population BC cases and 13,007 cases with BRCA1 or BRCA2 mutations. We identify robust novel associations for 2 variants with BC for BRCA1 and 3 for BRCA2 mutation carriers, P < 10−8, at 5 loci, which are not associated with risk in the general population. They include rs60882887 at 11p11.2 where MADD, SP11 and EIF1, genes previously implicated in BC biology, are predicted as potential targets. These findings will contribute towards customising BC polygenic risk scores for BRCA1 and BRCA2 mutation carriers

Linoleic acid intake and vitamin E requirement

In experiments with rats and Peking ducklings it has been investigated to what extent the linoleic acid content of the diet is of influence on the requirement of vitamin E. This requirement was determined by adding D-α-tocopheryl acetate in increasing doses to vitamin E-free diets and to determine how much vitamin E was necessary to prevent deficiency symptoms, such as invitro haemolysis in the rat and myopathy in the duckling. For these symptoms methods were developed with with the deficiency grade could be expressed by a number.The erythrocytes of rats with a vitamin E deficiency haemolyse spontaneously in vitro. Use was made of this phenomenon todetermine the requirement of vitamin E. For this purpose, newly weaned male rats were placed on diets with increasing doses of vitamin E. After 2 weeks the haemolysis test was positive. The test was repeated weekly. Good results were obtained when a 0.01% erythrocyte suspension was incubated for 4 hours in a solution of physiological saline buffered with phosphate, at pH 7.4 and 38°C. It was found that there was a negatively linear relation between the logarithm of the vitamin E content of the food and the percentage invitro haemolysis. By linear extrapolation it could be calculated how much vitamin E was necessary to prevent haemolysis. This is invitro haemolysis, which cannot in itself be regarded as a deficiency symptom, was found, after prolonged vitamin E deficiency in rats, to show a clear relation with the degree of myopathy of the leg muscles.The experiment with Peking ducklings was started with one-day-old chickens which were kept for 4 weeks on diets with increasing doses of vitamin E. In contrast with rats, in these ducklings the erythrocytes showed invitro only a very slight spontaneous haemolysis. On the other hand, strong myopathy occurred. The strongest was the hyaline-degeneration of theskeletal muscles, Moreover, necrocalcinosis was found in the smooth muscles of stomach and intestines and in the heart muscle. In the duckling, besides the degree of myopathy in the various organs, certain other criteria were investigated for their suitability for determining the requirement of vitamin E: weight increase, differential counting of leucocytes, activity of the serum enzymes creatine-phosphokinase, aspartate-aminotransferase and lactic acid dehydrogenase, differential determination of the serum proteins and the serum tocopherol level, All these criteria showed a clear connection with the vitamin E content of the food. The histologically determined degree of myopathy of the skeletal muscles was found to be the most suitable for the determination of the requirement of vitamin E. The degree of myopathy of a duckling was expressed as a score (0-24) which was determined by a microscopic assessment of the cross-sections of three pairs of leg muscles (score 0-4 per muscle). A linear relation was found between the myopathy score and the logaritm of the vitamin E content of the food. The amount of vitamin E needed to prevent myopathy could be calculated by linear extrapolation.Myopathy in ducklings was found to occur only if the food contained little vitamin E at the same time as very little selenium. As little as 0.1 mg Se (as Na 2 SeO 3 ) per kg food was sufficient to prevent myopathy completely, This amount has an anti-myopathic effect that is equal to at least 20 mg D-α-tocopheryl acetate,All diets, of the rats as well as of the ducklings, contained 35 cal% fat. The linoleic acid content of the diet was varied by the use of fats with a low (lard and coconut fat) or with a high linoleic acid content (maize oil and safflower oil). Lard and coconut fat contain very little vitamin E; in the case of maize oil and safflower oil, the tocopherols were removed. Increasing doses of linoleic acid were obtained by the use of mixtures of coconut fat and safflower oil, Study of the effect of an increasing linoleic acid content of the food led to the following conclusions:- Up to 10 cal% the linoleic acid content of the food has no influence on the requirement of vitamin E. This requirement is roughly 3.0 mg D-α-tocopherol per 1000 Kcal food.- At a linoleic acid uptake of more than 10 cal% the requirement of vitamin E can increase to 6 mg D-α-tocopherol per 1000 Kcal food, This is probably the result of an increased breakdown of vitamin E in the gastro-intestinal tract.- From the ratio between the content of vitamin E and linoleic acid it is not possible to deduce whether or not a diet contains sufficient vitamin E.- Many investigators have observed an increase in the requirement of vitamin E after only very small doses of linoleic acid. However, they were working with diets which contained insufficient essential fatty acids (EFA). With these diets (0-2 cal% linoleic acid) linoleic acid uptake causes a proportional increase in the requirement of vitamin E, which no longer increases once the EFA-deficiency has been corrected. It seems probable that in biomembranes a critical ratio exists between vitamin E and polyunsaturated fatty acids.- At a fat consumption of 30-40 cal% a dietary fat will need to contain 100 mg D-α-tocopherol (or an equivalent amount of other tocopherols) per kg fat to meet the requirement of vitamin E, This requirement can rise to 200 mg, if the fat contains more than 25% linoleic acid.- In general, vegetable oils with a high linoleic acid content contain ample vitamin E. Strongly saturated fats often contain too little vitamin E

Diffusion processes in demographic transitions: a prospect on using multi agent simulation to explore the role of cognitive strategies and social interactions

Multi agent simulation (MAS) is a tool that can be used to explore the dynamics of different systems. Considering that many demographic phenomena have roots in individual choice behaviour and social interactions it is important that this behaviour is being translated in agent rules. Several behaviour theories are relevant in this context, and hence there is a necessity of using a meta-theory of behaviour as a framework for the development of agent rules. The consumat approach provides a basis for such a framework, as is demonstrated with a discussion of modelling the diffusion of contraceptives. These diffusion processes are strongly influenced by social processes and cognitive strategies. Different possible research lines are discussed which might be addressed with a multi-agent approach like the consumats

Relative risk versus absolute risk: one cannot be interpreted without the other (vol 32, pg ii13, 2017)

Clinical epidemiolog