Lattice Knots in a Slab

In this paper the number and lengths of minimal length lattice knots confined to slabs of width $L$, is determined. Our data on minimal length verify the results by Sharein et.al. (2011) for the similar problem, expect in a single case, where an improvement is found. From our data we construct two models of grafted knotted ring polymers squeezed between hard walls, or by an external force. In each model, we determine the entropic forces arising when the lattice polygon is squeezed by externally applied forces. The profile of forces and compressibility of several knot types are presented and compared, and in addition, the total work done on the lattice knots when it is squeezed to a minimal state is determined

Minimal knotted polygons in cubic lattices

An implementation of BFACF-style algorithms on knotted polygons in the simple cubic, face centered cubic and body centered cubic lattice is used to estimate the statistics and writhe of minimal length knotted polygons in each of the lattices. Data are collected and analysed on minimal length knotted polygons, their entropy, and their lattice curvature and writhe

The Compressibility of Minimal Lattice Knots

The (isothermic) compressibility of lattice knots can be examined as a model of the effects of topology and geometry on the compressibility of ring polymers. In this paper, the compressibility of minimal length lattice knots in the simple cubic, face centered cubic and body centered cubic lattices are determined. Our results show that the compressibility is generally not monotonic, but in some cases increases with pressure. Differences of the compressibility for different knot types show that topology is a factor determining the compressibility of a lattice knot, and differences between the three lattices show that compressibility is also a function of geometry.Comment: Submitted to J. Stat. Mec

Approach to and management of acute ankle ligamentous injuries

No Abstract

Acute psychiatric in-patients tested for HIV status: a clinical profile

No Abstract.South African Psychiatry Review Vol. 10 (2) 2007: pp.83-8

Corticosteroids in sports-related injuries: Friend or Foe

Corticosteroids act as potent anti-inflammatory drugs and have been used in various sport settings for the treatment of both acute and chronic injuries. Basic physiology and mechanisms of action for gluco- and mineralocorticoids are discussed. Methods of administration, the action on the inflammatory response, and potential short and long-term side effects of corticosteroid use are also deliberated. More specifically, corticosteroid use in the treatment and management of sport-related injuries are discussed, elucidating on the ethical boundaries and anti-doping regulations pertaining to corticosteroid use in sports, as well as putting forth suggestions for the use of local steroid injections and their contraindications. In conclusion, it was found that, despite some controversy in the use of corticosteroid treatment in the sports environment, little empirical evidence exists that could conclusively rule for or against its use. It is however clear that, if clinically justified, there is a significant role for corticosteroid treatment in the realm of sports injury and notably with a relatively low risk profile, if administered correctly.Keywords: Steroid hormones, athlete, sports, injury, inflammation

Partially directed paths in a wedge

The enumeration of lattice paths in wedges poses unique mathematical challenges. These models are not translationally invariant, and the absence of this symmetry complicates both the derivation of a functional recurrence for the generating function, and solving for it. In this paper we consider a model of partially directed walks from the origin in the square lattice confined to both a symmetric wedge defined by $Y = \pm pX$, and an asymmetric wedge defined by the lines $Y= pX$ and Y=0, where $p > 0$ is an integer. We prove that the growth constant for all these models is equal to $1+\sqrt{2}$, independent of the angle of the wedge. We derive functional recursions for both models, and obtain explicit expressions for the generating functions when $p=1$. From these we find asymptotic formulas for the number of partially directed paths of length $n$ in a wedge when $p=1$. The functional recurrences are solved by a variation of the kernel method, which we call the ``iterated kernel method''. This method appears to be similar to the obstinate kernel method used by Bousquet-Melou. This method requires us to consider iterated compositions of the roots of the kernel. These compositions turn out to be surprisingly tractable, and we are able to find simple explicit expressions for them. However, in spite of this, the generating functions turn out to be similar in form to Jacobi $\theta$-functions, and have natural boundaries on the unit circle.Comment: 26 pages, 5 figures. Submitted to JCT

Tuberculosis infection control practices in a high-burden metro in South Africa : a perpetual bane for efficient primary health care service delivery

Background: Tuberculosis (TB) prevention, including infection control, is a key element in the strategy to end the global TB epidemic. While effective infection control requires all health system components to function well, this is an area that has not received sufficient attention in South Africa despite the availability of policy and guidelines. Aim: To describe the state of implementation of TB infection control measures in a high-burden metro in South Africa. Setting: The research was undertaken in a high TB-and HIV-burdened metropolitan area of South Africa. More specifically, the study sites were primary health care facilities (PHC), that among other services also diagnosed TB. Methods: A cross-sectional survey, focusing on the World Health Organization levels of infection control, which included structured interviews with nurses providing TB diagnosis and treatment services as well as observations, at all 41 PHC facilities in a high TB-burdened and HIV-burdened metro of South Africa. Results: Tuberculosis infection control was poorly implemented, with few facilities scoring 80% and above on compliance with infection control measures. Facility controls: 26 facilities (63.4%) had an infection control committee and 12 (29.3%) had a written infection control plan. Administrative controls: 26 facilities (63.4%) reported separating coughing and non-coughing patients, while observations revealed that only 11 facilities (26.8%) had separate waiting areas for (presumptive) TB patients. Environmental controls: most facilities used open windows for ventilation (n = 30; 73.2%); however, on the day of the visit, only 12 facilities (30.3%) had open windows in consulting rooms. Personal protective equipment: 9 facilities (22%) did not have any disposable respirators in stock and only 9 respondents (22%) had undergone fit testing. The most frequently reported barrier to implementing good TB infection control practices was lack of equipment (n = 22; 40%) such as masks and disposable respirators, as well as the structure or layout of the PHC facilities. The main recommendation to improve TB infection control was education for patients and health care workers (n = 18; 33.3%). Conclusion: All levels of the health care system should be engaged to address TB prevention and infection control in PHC facilities. Improved infection control will address the nosocomial spread of TB in health facilities and keep health care workers and patients safe from infection

An object oriented approach towards the specification of simulation models

To manage problems, is to try and cope with a flux of interacting events and ideas which unrolls through time - with the manager trying to improve situations seen as problematical, or at least as less than perfect. The ability of managing or solving these problems depends on the skills of the problem solver to analyse problems. This article introduces and discusses a proposed methodology for analysing real world problems in order to construct valid simulation models.Bestuurders probeer probleemsituasies bestuur, of verbeter deur 'n vloed van dinamiese interaktiewe gebeurtenisses te verstaan en te hanteer. Die sukses van die bestuur of oplos van die probleme hang af van die kundigheid van die probleemoplosser om die probleme te kan analiseer. Die artikel bespreek 'n voorgestelde benadering tot die analise van probleme om sodoende daaruit, simulasiemodelle te kan opstel.http://sajie.journals.ac.z

The design of a simulation generator

Successful simulation studies depend on a variety of expertise such as statistics, computer programming, systems analysis and design techniques. Unfortunately these requirements limit the availability of competent simulation analysts, while simulation applications are in demand. This paper presents a possible solution to the shortage of expert simulation knowledge through the design of a simulation generator, a software tool that translates conceptual simulation models into computer code. The design process for the expert system and simulation components of the simulation generator uses an adapted software lifecycle methodology.Suksesvolle simulasiestudies hang van verskeie kundigheidsonderwerpe af, soos byvoorbeeld statistiek, programmering, stelselanalise en ontwerptegnieke. Die vereistes beperk die beskikbaarheid van geskikte simulasiekundiges, ten spyte dat simulasietoepassings in aanvraag is. Die artikel bied ''n moontlike oplossing aan vir die tekort aan simulasiekundigheid, deur die ontwikkelling van simulasiegenerators te bespreek, wat rekenaarprogrammatuur is wat konseptuele simulasiemodelle in rekenaarkode omskryf. Die ontwerp van die simulasiegenerator se ekspertstelsel- en simulasiekomponent is gebaseer op 'n aangepaste rekenaarprogrammatuurlewenssiklus metodologie.http://sajie.journals.ac.z