Determining if an athlete, who has had Anterior Cruciate Ligament (ACL) surgery, is ready to return to sport is a difficult clinical decision, partially due to the lack of standardized evaluation protocols. Since there is a risk of re-injury post-surgery, medical teams need to be cautious. However, athletes who are perceived to be ready to return to sport do not necessarily do so. Some leave sport altogether while others return to a lower competition level. As psychological thoughts and emotions are relevant to athletes’ injury experiences, a psychological component, such as sport confidence, needs to be thoughtfully considered during the return to sport process. Our objectives were to develop the relationship between drop vertical jump (DVJ) performance and physical attributes in young healthy adults and to then apply this relationship to ACL participants. Another objective was to see if the relationship is improved by including confidence (determined from a survey). It was hypothesized that including confidence will predict the ACL participants’ DVJ performance more precisely. Thirty-five participants were in the control group with thirteen participants in the ACL group. All were recreationally active and all had the following anthropometric and performance measurements recorded: height, weight, calf and thigh girth, knee angle, leg dominance, percent body fat, skeletal muscle mass, anaerobic power, balance, and drop vertical jump height. The ACL group also completed a confidence survey. Regression analyses were performed. The results showed that anaerobic power and relative skeletal muscle mass were significant predictors of DVJ performance; however, DVJ performance could not be predicted precisely. The analysis was also carried out by gender. No significant predictors for male’s DVJ performance were found while the significant predictors for female’s DVJ performance were weight, power and knee extension angle. Once again, DVJ performance could not be precisely predicted. On the other hand, results showed that power could be more precisely predicted by body weight than could DVJ performance. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2009-08-19 16:08:52.13

No description available.

The accounting profession has been identified as one of the scarce skills in South Africa. This phenomenon has attracted many students aspiring to tertiary education to enrol for an accounting degree. Regrettably, most of these students drop out of the programmes in the second year of their studies due to many challenges that they were not prepared for and that the institutions are not making any extra efforts to address. The objective of the study is to investigate the key factors that contribute to a high rate of second-year Accounting students drop-out in the Department of Accounting at Tshwane University of Technology in the academic years of 2004 to 2006. The study comprises two phases: the theoretical phase and the empirical phase respectively. The theoretical phase encompasses an in-depth review of relevant literature on issues affecting students to drop out of institutions of higher learning. The empirical phase of the research entails testing the opinions of second-year Accounting students on the factors causing the high drop-out rate among them through the use of a questionnaire and followed by interviews with the relevant stakeholders. The study will further report on the findings and recommendations made by the lecturing staff, academic development practitioners, support staff and students on how to improve on the factors identified as the cause of drop-out of students in institutions of higher learning. The findings and recommendations of the study will assist the institution in formulating appropriate strategies that will provide remedial services and that will lead to the reduction of the drop-out rate, and subsequently lead to high retention rates of students at Tshwane University of Technology. This research should also be extended to other similar institutions. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2009.

The accounting profession has been identified as one of the scarce skills in South Africa. This phenomenon has attracted many students aspiring to tertiary education to enrol for an accounting degree. Regrettably, most of these students drop out of the programmes in the second year of their studies due to many challenges that they were not prepared for and that the institutions are not making any extra efforts to address. The objective of the study is to investigate the key factors that contribute to a high rate of second-year Accounting students drop-out in the Department of Accounting at Tshwane University of Technology in the academic years of 2004 to 2006. The study comprises two phases: the theoretical phase and the empirical phase respectively. The theoretical phase encompasses an in-depth review of relevant literature on issues affecting students to drop out of institutions of higher learning. The empirical phase of the research entails testing the opinions of second-year Accounting students on the factors causing the high drop-out rate among them through the use of a questionnaire and followed by interviews with the relevant stakeholders. The study will further report on the findings and recommendations made by the lecturing staff, academic development practitioners, support staff and students on how to improve on the factors identified as the cause of drop-out of students in institutions of higher learning. The findings and recommendations of the study will assist the institution in formulating appropriate strategies that will provide remedial services and that will lead to the reduction of the drop-out rate, and subsequently lead to high retention rates of students at Tshwane University of Technology. This research should also be extended to other similar institutions. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2009.

Low phosphorus content steels are essential for steel applications where high ductility is required, such as thin sheets, deep drawn, pipelines and automobile exteriors. In the past, phosphorus control was not considered a big challenge in steel production in the US because iron ores with low phosphorus contents were readily available and considered cheap. However, in the last decade, the iron ore price has risen by roughly 400% and lower cost iron sources generally have higher phosphorus content. In integrated steel plants, phosphorus removal usually takes place during the oxygen steelmaking process (OSM) but in Japan a intermediate step for hot metal dephosphorization is commonly used. There are various types of OSM furnaces but the most widely used remains the top-blown Basic Oxygen Furnace (BOF). The BOF slag can be recycled to a sinter plant or directly to the blast furnace, ultimately increasing the phosphorus input in the process. In order to meet new demands for phosphorus control, it is necessary to improve our understanding on the thermodynamics and kinetics of the phosphorus partitioning reaction between slag and metal melts during steelmaking. Therefore, the present work has been divided in three strongly correlated sections: phosphorus equilibrium between metal and slag; analysis of plant data; and observations of the reaction kinetics. Phosphorus equilibrium between liquid metal and slag has been extensively studied since the 1940's. It is well known that CaO and FeO are the main slag constituents that help promote dephosphorization. On the other hand, dephosphorization decreases with temperature due to the endothermic nature of the reaction. Many correlations have been developed to predict the phosphorus partition ratio as a function of metal and slag composition as well as temperature. Nevertheless, there are still disagreements in the laboratory data and the equilibrium phosphorus partition can be predicted with an uncertainty of a factor of up to 5. The first part of the present work focuses on generating more reliable equilibrium data for BOF-type slags by approaching equilibrium from both sides of the reaction. The experimental results were combined with two other sets of data from different authors to produce a new correlation that includes the effect of SiO2 on the phosphorus partition coefficient, LP . Although the quantification of phosphorus equilibrium is extremely important, most industrial furnaces do not operate at equilibrium, usually due to liquid slag formation, kinetics and time constraints. Thus, it is important to know how close to equilibrium different furnaces operate in order to suggest optimal slag compositions to promote dephosphorization. The present work analyzed four large sets of data containing the chemical compositions of both slag and metal phase as well as the tapping temperature of each heat. Each set of data corresponded to different furnaces: one AOD (Argon Oxygen Decarburization), two top-blown BOFs and one Q-BOP or OBM. It was found that the bulk slag composition can greatly \mask" the data due to solid phases coexisting with the liquid slag. The author used the software package FactSage to estimate the amount of solids in the slag and liquid slag composition. It was found that the AOD is the reactor closest to equilibrium, followed by the Q-BOP (OBM) and the two top-blown BOFs. It was noted that the stirring conditions and slag composition are two key variables to enable optimum phosphorus removal. Also, over saturating the slag with CaO and MgO does not seem to benefit the process to any extent. Lastly, interesting observations on the behavior of small metal droplets reacting with slag are presented and discussed. It was found that dynamic interfacial phenomena at the metal-slag interface is likely to play a significant role in the kinetic behavior of the system, due to the exchange of surface active elements, such as oxygen, which dramatically lowers the interfacial tension and cause spontaneous emulsification. Although this phenomenon has been studied, actual quantification of changes in interfacial area remain a challenge. The author developed an experimental method to enable better quantification of spontaneous emulsification and two sets of experiments were carried. One with an Fe containing 0.2 wt.% P and another in a P-free system where pure iron was oxidized. It was found that phosphorus did not play a role in spontaneous emulsification and it was rapidly removed before the onset of dynamic interfacial phenomena. Emulsificaion was maybe caused by de-oxidation of the metal after phosphorus removal took place and the metal became super saturated with oxygen by an unknown reason. The estimated surface area rapidly increases by over an order of magnitude during the beginning and intermediate periods of the reaction. The metal drop breaks into hundreds of small droplets, effectively emulsifying the metal into the slag. With time, the surface area decreases and the metal droplets coalesce. Similar results were observed for an Fe droplet being oxidized. Spontaneous emulsification takes place regardless of the direction of oxygen transfer and the changes in surface area are similar for both cases. The last chapter describes the industrial relevance of the present work, summarizes the findings, revisits the hypotheses and presents potential future work where further research is encouraged.

High Temperature Gas-cooled Reactor (HTGR) is a Generation IV reactor under consideration by Department of Energy and in the nuclear industry. There are two categories of HTGRs, namely, Pebble Bed Modular Reactor (PBMR) and Prismatic reactor. Pebble Bed Modular Reactor is a HTGR with enriched uranium dioxide fuel inside graphite shells (moderator). The uranium fuel in PBMR is enclosed in spherical shells that are approximately the size of a tennis ball, referred to as \fuel spheres". The reactor core consists of approximately 360,000 fuel pebbles distributed randomly. From a reactor design perspective it is important to be able to understand the fluid flow properties inside the reactor. However, for the case of PBMR the sphere packing inside the core is random. Unknown flow characteristics defined the objective of this study, to understand the flow properties in spherically packed geometries and the effect of turbulence models in the numerical solution. In attempt to do so, a steady state computational study was done to obtain the pressure drop estimation in different packed bed geometries, and describe the fluid flow characteristics for such complex structures. Two out of the three Bravais lattices were analyzed, namely, simple cubic (symmetric) and body centered cubic (staggered). STARCCM commercial CFD software from CD- ADAPCO was used to simulate the flow. To account for turbulence effects several turbulence models such as standard k-epsilon, realizable k-epsilon, and Reynolds stress transport model were used. Various cases were analyzed with Modified Reynolds number ranging from 10,000 to 50,000. For the simple cubic geometry the realizable k-epsilon model was used and it produced results that were in good agreement with existing experimental data. All the turbulence models were used for the body centered cubic geometry. Each model produced different results what were quite different from the existing data. All the turbulence models were analyzed, errors and drawbacks with each model were discussed. Finally, a resolution was suggested in regards to use of turbulence model for problems like the ones studied in this particular work.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Rates of recorded crime have been falling in many countries in Western Europe, including Scotland, since the early 1990s. This marks the reversal of a trend of increasing levels of crime seen since the 1950s. Despite this important recent change, most analyses of the ‘crime drop’ have focused on recorded crime or victimisation rates aggregated to national or regional level. It is little known how patterns of offending or conviction have changed at the individual level. As a result it is not known how the crime drop is manifest in changing offending or conviction rates, or how patterns of criminal careers have changed over this period. The aim of this thesis is to explore trends in convictions across a number of criminal careers parameters – the age-crime curve, prevalence and frequency, polarisation and conviction pathways – over the course of the crime drop in Scotland. The results presented here are based on a secondary analysis of the Scottish Offenders Index, a census of convictions in Scottish courts, between 1989 and 2011. Analysis is conducted using a range of descriptive statistical techniques to examine change across age, sex and time. Change in the age-crime curve is analysed using data visualisation techniques and descriptive statistics. Standardisation and decomposition analysis is used to analyse the effects of prevalence, frequency and population change. Trends in conviction are also examined between groups identified statistically using Latent Class Analysis to assess the polarisation of convictions, and trends in the movement between these groups over time provides an indication of changing pathways of conviction. This thesis finds a sharp contrast between falling rates of conviction for young people, particularly young men, and increases in conviction rates for those between their mid-twenties and mid-forties, with distinct periods of change between 1989- 2000, 2000-2007 and 2007-2011. These trends are driven primarily by changes in the prevalence of conviction, and result in an increasingly even distribution of convictions over age. Analysis across latent classes shows some evidence of convictions becoming less polarised for younger men and women but increasingly polarised for older men and women. Similarities in trends analysed across latent classes between men and women of the same age suggest that the process driving these trends is broadly similar within age groups. Increases in conviction rates for those over 21 are explained by both greater onset of conviction and higher persistence in conviction, particularly between 1998 and 2004. The results of this thesis suggest that explanations of the crime drop must have a greater engagement with contrasting trends across age and sex to be able to properly explain falling conviction rates. These results also reinforce the need for criminal careers research to better understand the impact of recent changes social context on patterns of convictions over people’s lives. The distinct periods identified in these results suggest a potential effect of changes in operation of the justice system in Scotland leading to high rates of convictions in the early 2000s. However, the descriptive focus of this analysis and its reliance upon administrative data from a single country mean this thesis cannot claim to definitively explain these trends. As a result, replication of this research in another jurisdiction is encouraged to assess whether trends identified are particular to Scotland.

Solid surfaces featuring a spatial variation of surface wettability along particular directions on their surface, referred to as wettability gradient surfaces, are becoming increasingly important in practical applications such as enhancement of boiling and condensation heat transfer and separation of immiscible liquids in smart micro-fluidic devices. With the aid of an external energy input, such as mechanical vibration or impact kinetic energy, a liquid drop on such surfaces gets propelled towards more wettable region on the surface. A fundamental study of impact dynamics of liquid drops on such solid surfaces is relevant in understanding their effectiveness. The present thesis reports a combined experimental and theoretical study on the impact dynamics of liquid drops on solid surfaces comprising a smooth portion and a groove-textured portion separated by a junction line (dual-textured surfaces). Three different dual-textured surfaces – two made of intrinsically hydrophilic stainless steel and one of intrinsically hydrophobic poly-di-methyl-siloxane (PDMS) – are considered. Liquid drops, with Weber number (We) in the range 1–100, are impacted on the junction of the dual-textured surfaces and the entire impact dynamics across the junction is captured using a high speed video camera. Experiments of drop impact on the homogeneous surface portions of dual-textured surfaces (far away from the junction) are also conducted. The temporal variation of drop contact radius measured from the junction line on smooth and groove-textured portions of the dual-textured surfaces exhibits four distinct stages – primary spreading, primary receding, secondary spreading on more wettable surface portion, and final equilibrium – with the final outcome being the bulk movement and deposition of liquid drop away from the junction towards the more hydrophilic surface portion. Secondary parameters characterizing each of these different stages are extracted from these measurements and a one-to-one comparison between dual-textured and homogenous surfaces is presented. A significant effect of dual-texture nature is seen on the receding process of impacting drops. On the dual-textured surfaces, the receding velocity of impacting drop on the groove-textured portion is always greater than that on the smooth portion. The asymmetry in drop receding results in a drop drift velocity towards the more wettable surface portion leading to an enhanced secondary drop spreading on the more wettable smooth portion. The drop drift velocity shows a decrease with We at low We and remains almost constant at higher We after a particular value of We. Correspondingly, the ratio of the maximum drop spread factor achieved during the secondary spreading (βm2) to that during the primary spreading (βm) is seen to decrease with We at low We and remains constant at higher We. Owing to the differences in the static equilibrium wetting difference, βm2/βm is more on the stainless steel dual-textured surfaces than on the PDMS dual-textured surface. The presence of dual-texture results in a higher final spread on more wettable smooth portion and smaller final spread on less wettable textured portion of the dual-textured surfaces and this difference decreases with We. The difference in final spread factors between the smooth and textured portions is more on the stainless steel dual-textured surfaces than the PDMS dual-textured surface. The bulk drop movement (ξ), characterized in terms of distance measured from the junction to the final drop center, decreases with We at low We and remains constant at higher We on the stainless steel dual-textured surfaces whereas it remains constant at low We and decreases at higher We on the PDMS dual-textured surface. ξ on the PDMS dual-textured surface is always less than that on the stainless dual-textured surface due to the lower wetting difference across the junction of the former. Comparison of the trends of secondary parameters with the predictions from theoretical models reported in literature showed a lack of agreement. This is due to various physical processes encountered by impacting drop on the groove-textured surface, identified through experiments of drop impact on homogeneous groove-textured surfaces, such as (i) convex shape of liquid-vapor interface near contact line at maximum spreading, (ii) impregnation of drop liquid into the grooves during impact, and (iii) contact line pinning of spreading drop at the asperity edges of surface texture, as well as the wetting difference in dual-textured surfaces. The inclusion of these physical processes under conventional energy conservation approach is seen to predict the experimentally observed trends of maximum drop spread factor on the groove-textured portions. A force balance model, applied to the liquid drop configuration at the beginning of drop receding on the dual-textured surfaces, predicts the qualitative trend of ξ with We on all surfaces. Drop liquid impregnation into the grooves of textured portion at We > Wecr (critical We corresponding to transition from Cassie to impaled state) is proposed as a possible physical mechanism to account for the explanation of the specific trends of ξ with We. A theoretical model formulated using force balance at the three phase contact line beneath impacting drop on groove-textured surface is presented for the prediction of Wecr.