We study the relations between algebraic properties of certain rings of functions and topological properties of the spaces on which the functions are defined. We begin by considering the relation between ideals of rings of functions and z-filters. Let [fomula omitted] be the ring of all m-times differentiable functions on a [formula omitted] differentiable n-manifold X , [formula omitted] the ring of all Lc-functions on a metric space X , and [formula omitted] the ring of all analytic functions on a subset X of the complex plane. It is proved that two m-(resp. Lc-) realcompact spaces X and Y are [formula omitted] diffeomorphic (resp. Lc-homeomorphic) iff [formula omitted] are ring isomorphic. Again if X and Y are m-(resp. Lc-) realcompact spaces, then X can be [formula omitted] (resp.Lc-) embedded as an open [resp. closed] subset in Y iff [formula omitted] homomorphic image of [formula omitted]. The subrings of [formula omitted] which determine the [formula omitted] diffeomorphism (resp. Lc-homeomorphism) of the spaces are studied. We also establish a representation for a transformation, more general than homomorphism, from a ring of [formula omitted] differentiable functions to another ring of [formula omitted] differentiable functions. Finally, we show that, for arbitrary subsets X and Y of the complex plane, if there is a ring isomorphism from [formula omitted] which is the identity on the constant functions, then X and Y are conformally equivalent. / Science, Faculty of / Mathematics, Department of / Graduate

Mold behavior, mold-related quality and the columnar-to-equiaxed transition influenced by in-mold EMS were examined by performing trials at two steel companies, metallurgical examination of the billet samples and mathematical modelling. The thermal fields in the walls of billet molds (102 X 102mm and 127 X 178mm) and in the cooling water were monitored by a system of thermocouples as the EMS was switched on and off during the continuous casting of several heats. The effect of electro-magnetic stirring on mold heat extraction was found to be negligible. The mold temperatures and cooling water temperatures are strongly dependent on the mold/billet gap which is affected by dynamic distortion of the mold tube. In the case of the square mold, the time-dependent mold distortion resulted from boiling adjacent to the cold face due to low water velocity and poor water quality. In the rectangular mold, differential expansion of the wide and narrow faces of the mold led to periodic wall movement at the midface causing cycling in the mold and water temperature. Both effects completely dominated any potential influence of EMS on mold heat extraction. Cooling water velocities measured in separate experiments and the mold temperature profiles were input to a two-dimensional heat-flow model to establish mold heat-flux profiles. A steep taper of 2.6 %/m in the upper regions of the mold increased heat extraction compared to previously published heat-flux data in 0.8 %/m tapered-molds. However, due to the periodic wall movement in the rectangular mold, the heat flux declines to lower values periodically. The calculated heat flux profiles were employed in a one-dimensional transient heat flow model to predict superheat removal from the liquid pool under a variety of assumed fluid flow conditions. The major heat flow effect of EMS was inferred to be one of increasing the convective heat flow at the solidification front leading to earlier superheat extraction from the liquid steel. Solidification structures in billet samples collected during the trials were examined. The columnar-to-equiaxed transition in continuous casting takes place provided all the superheat is removed from the melt and there is a sufficient density of nuclei present in the pool. At superheats of <20° C in the tundish, high heat extraction in the mold and remelting of the mold generated nuclei facilitate the removal of the superheat well within the mold and the columnar-equiaxed transition is triggered after 10-15 mm of shell growth on both the inside and outside radius faces. At higher superheat in the tundish, the liquid pool leaves the mold with residual superheat which takes longer to remove because of the declining fluid flow. Even though all the superheat is removed lower in the machine, the columnar-equiaxed transition occurs only if dendrite debris generated in the vicinity of the mold has survived in their descent through the superheated liquid. The effect of carbon on the columnar-to-equiaxed transition appears to stem from its influence on facilitating dendrite arm remelting and the survival of the dendrite fragments till the pool reaches sub-liquidus temperature. EMS extracts more superheat by maintaining a steep temperature gradient in the thermal boundary ahead of the solidification front and achieves an earlier columnar-equiaxed transition. Electro-magnetic stirring appears not to affect either the average depth or the variation of depth of oscillation marks across a given face. However, the electro-magnetically driven flow dominates the turbulance at the meniscus due to the input stream and stabilizes a meniscus shape with the result that the oscillation marks are also of a well-defined shape unlike the unstirred billets. No influence of EMS was found on the formation of "hooks" or the fine equiaxed crystal zone near the surface. The influence of EMS on inclining the growing dendrites appears to not come into effect until about 1 mm of shell has formed. It appears that the existence of the momentum boundary layer where the velocity of the rotating steel falls to zero at the surface is the reason for the absence of the influence of EMS on the subsurface solidification. Rhomboidity and off-corner crack formation were found to depend, as reported by previous researchers, on mold distortion and its dynamic nature. The absence of any effect of EMS on these defects is due to its lack of effect on mold heat transfer and thus mold distortion. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

A research report submitted in partial fulfilment of the requirements of the Master of Medicine at the University of Witwatersrand. Johannesburg, 16 April 2018. / Background: Chronic kidney disease and end stage kidney disease are becoming a huge health challenge. The optimal treatment is renal transplantation but due to low rates of transplantation most patients who are enrolled in the chronic renal replacement programme are on dialysis. This study aimed at investigating demographic and social factors that are associated with the outcomes of peritoneal dialysis (PD). The study also investigates how co-morbidity contributed to the outcomes of PD. Methods: The study makes use of retrospective analysis of demographic data (age, marital status, residential area, race) and socioeconomic status, level of education, family support, poor access to health care system as well as co-morbidities and underlying cause of ESKD, obtained from 167 patients who were enrolled on continuous ambulatory peritoneal dialysis (CAPD) over the period of 2008 - 2012 at the Charlotte Maxeke Academic Johannesburg Hospital (CMJAH). The data analysis for the present study was conducted using STATA version 14.0. To describe the demographic characteristics of the patients, frequency tables were computed for all categorical variables. For continuous variables, the Shapiro Wilk test for normality was used to assess the distribution of the data to report the appropriate central tendency measure i.e. mean±SD or median (IQR). To assess the contribution of demographic factors to the overall outcome of CAPD, a Fisher’s exact test of comparison was used to assess the difference between the proportions for each demographic factor and CAPD outcome. The Fisher exact test was used because the proportions for each frequency table included a proportion below five (<5). To assess how the relationship of demographic and co-morbid disease affects the outcome of the treatment, a multivariate logistic regression model was fitted adjusting for co-morbid disease for each of the demographic factors. Findings and interpretation: Of 167 patients enrolled, the majority were black with low levels of education, living in townships and 56% were on subsisting on disability grants. PD failure occurred in 53.3% of patients over the study period and 46.7% were successful on PD. Of the variables tested, age was statistically significant for CAPD outcomes [Fisher exact test (p= 0.004)], indicating a significant difference in the proportion of CAPD outcomes among different age categories). The univariate and multivariate logistic regression analysis did not show significant association with CAPD outcomes. Adherence also significantly impacted on outcomes in both univariate and multivariate analyses, showing that non-compliant patients were less likely to have successful outcomes on PD. In addition, the Fisher exact test showed no significant difference in the distribution of CAPD outcome with marital status while the multivariate analysis showed that single patients were three times more likely to succeed with PD compared to married patients. These could be due to chance, because of the small sample size, and require further investigation. Conclusions: Prospective studies are needed to fully understand the extent that demographic and socioeconomic factors impact on the outcomes of PD. This will assist in formulating comprehensive recommendations and ways to improve PD utilization and outcomes. / LG2018

An in vitro continuous culture rumen fermentation experiment was conducted to evaluate digestibility of annual ryegrass either fed alone or annual ryegrass supplemented with hay, corn, or soybean hulls. Nutrient disappearance of feedstuffs offered were not different (P > 0.05) as a percentage of the diet however there were differences (P < 0.05) in amounts of individual nutrients digested for each treatment. Ammonia-N concentrations of culture samples were less (P < 0.05) for vessels fed corn as a supplement however there was no difference (P > 0.05) among vessels fed either ryegrass alone or supplemented with hay or soybean hulls. This may indicate a more efficient use of available nutrients from annual ryegrass when corn was supplemented.

No description available.

In this thesis, we consider the problem of capturing finite-representability between Banach spaces using the tools of continuous model theory. We introduce predicates and additional sorts to capture finite-representability and show that these can be used to expand the language of Banach spaces. We then show that the class of infinite-dimensional Banach spaces expanded with this additional structure forms an elementary class K_G , and conclude that the theory T_G of K_G is interpretable in T^{eq} , where T is the theory of infinite-dimensional Banach spaces. Finally, we show that existential equivalence in a reduct of the language implies finite-representability. Relevant background on continuous model theory and Banach space theory is provided. / Thesis / Master of Science (MSc)

In traditional Software Development Life Cycle, medium and large organizations tend to divide the activities of Operations and Development into separate departments. These groups often have a troublesome relationship because of different incentives during the software delivery process. As a result, conflicts occur between development and operations personnel as they blame each other to be the cause of long lead times and inefficient software delivery processes. The concept of DevOps emerged trying to resolve the problem that arises when separating the work of Development and Operations into organizational silos. The term DevOps is a combination of the abbreviations of Development (Dev) and Operations (Ops). DevOps aim to create a coalition that spans between Development (software developers and quality assurance) and Operation (experts responsible to roll out software to production and managing the infrastructure, e.g. system, network and database administrators and technicians). The idea is to increase the speed of the software delivery process and to quickly solve critical issues, enable organizations to better serve their customers. DevOps means that development teams who previously were solely responsible for the development of their applications now have to manage and govern both development and operational responsibilities. Thus, the adoption of DevOps might introduce new type of challenges and implications for the traditional development teams. Current literature and research about DevOps focus mainly on the challenges that DevOps attempts to overcome. There is a lack of literature on the challenges that practitioners encounter during the adoption of DevOps. As more organizations and companies tend to adopt the concept of DevOps, it increases the need to understand potential challenges and effects of adopting DevOps. Therefore, the aim of this study is to investigate the challenges that development teams encounter during the adoption of DevOps. This research was conducted by an inductive research approach through a single qualitative case study, with the use of semi-structured interviews. In total, four main challenges and fourteen sub-challenges were identified in this study. The four main challenges identified was, lack of awareness, lack of support for DevOps, implementing DevOps technology and adapting organizational processes to DevOps. This study concludes that the adoption of DevOps has a profound impact on the role of a software developer, and that the traditional role of a software developer needs to be evolved. The research provides four recommendations and means to overcome the challenges identified in this research, establishing common ways of working and spreading the knowledge, building commitment and trust by smarter seating, allocate time and resources to transition and trying out with one team and one application. / I traditionell livscykel för mjukvaruutveckling tenderar medelstora och stora organisationer att dela upp verksamheten i drift och utveckling i separata avdelningar. Dessa grupper har ofta en besvärlig relation på grund av olika incitament under mjukvaruleveransprocessen. Som ett resultat uppstår konflikter mellan utvecklings- och driftpersonal eftersom de beskyller varandra för att vara orsaken till långa ledtider och ineffektiva mjukvaruleveransprocesser. Konceptet DevOps uppstod för att försöka lösa det problem som uppstår när man separerar utveckling och drift i organisationella silosar. Termen DevOps är en kombination av förkortningarna för utveckling (Dev) och drift (Ops). DevOps syftar till att skapa en koalition som sträcker sig mellan utveckling (mjukvaruutvecklare och kvalitetssäkring) och drift (system-, nätverks- och databasadministratörer och tekniker). Idén är att öka hastigheten av mjukvaruleveranser och att snabbt lösa kritiska problem för att förbättra organisationens förmåga att betjäna sina kunder. DevOps innebär att utvecklingsgrupper som tidigare enbart ansvarade för utvecklingen av sina applikationer nu även har driftansvar. Således kan antagandet av DevOps introducera nya typer av utmaningar och konsekvenser för de traditionella utvecklingsgrupperna. Aktuell litteratur och forskning kring DevOps fokuserar främst på de utmaningar som DevOps försöker övervinna. Därav finns det brist på litteratur kring de utmaningar som utövare stöter på under antagandet av DevOps. Eftersom fler organisationer och företag tenderar att adoptera begreppet DevOps ökar behovet av att förstå potentiella utmaningar och effekter av att anta DevOps. Därav är syftet med denna studie att undersöka de utmaningar som utvecklingsgrupper bemöter under antagandet av DevOps. Denna forskning utfördes genom en induktiv forskningsinriktning, en kvalitativ fallstudie och datainsamling genom halvstrukturerade intervjuer. Totalt identifierades fyra huvudutmaningar och fjorton sub utmaningar i denna studie. De fyra huvudsakliga utmaningar som identifierades var, brist på medvetenhet, brist på stöd för DevOps, implementering av DevOps-teknik och anpassning av organisationsprocesser till DevOps. Den här studien drar slutsatsen att antagandet av DevOps har en djupgående inverkan på rollen som en mjukvaruutvecklare och att den traditionella rollen som en mjukvaruutvecklare behöver utvecklas. Studien ger fyra rekommendationer och medel för att övervinna de utmaningar som identifierats, etablering av gemensamma sätt att arbeta och sprida kunskapen, bygga upp engagemang och förtroende genom smartare sittplatser, fördela tid och resurser till övergången samt prova med ett lag och en applikation.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on Oct. 6, 2006). PDF text:xxiii, 306 p. : ill. ; 15.42Mb. UMI publication number: AAT 3213328. Includes bibliographical references. Also available in microfilm, microfiche and paper format.

In this paper, we study continuous functions with no finite or infinite one-sided derivative anywhere. In 1925, A. S. Beskovitch published an example of such a function. Since then we call them Beskovitch functions. This construction is presented in chapter 2, The example was simple enough to clear the doubts about the existence of Besicovitch functions. In 1932, S. Saks showed that the set of Besicovitch functions is only a meager set in C[0,1]. Thus the Baire category method for showing the existence of Besicovitch functions cannot be directly applied. A. P. Morse in 1938 constructed Besicovitch functions. In 1984, Maly revived the Baire category method by finding a non-empty compact subspace of (C[0,1], || • ||) with respect to which the set of Morse-Besicovitch functions is comeager.

A problem encountered in the boundary element method is the difficulty caused by corners and/or discontinuous boundary conditions. An existing code using standard linear continuous elements is modified to overcome such problems using the multiple node method with an auxiliary boundary collocation approach. Another code is implemented applying the gradient approach as an alternative to handle such problems. Laplace problems posed on variety of domain shapes have been introduced to test the programs. For Poisson problems the programs have been developed using a transformation to a Laplace problem. This method cannot be applied to solve Poissontype equations. The dual reciprocity boundary element method (DRM) which is a generalised way to avoid domain integrals is introduced to solve such equations. The gradient approach to handle corner problems is co-opted in the program using DRM. The program is modified to solve non-linear problems using an iterative method. Newton's method is applied in the program to enhance the accuracy of the results and reduce the number of iterations. The program is further developed to solve coupled Poisson-type equations and such a formulation is considered for the biharmonic problems. A coupled pair of non-linear equations describing the ohmic heating problem is also investigated. Where appropriate results are compared with those from reference solutions or exact solutions. v