This thesis examines three computational problems in sports. The first problem addressed is determining the minimum number of points needed to guarantee qualification for the playoffs and the minimum number of points needed to have a possibility of qualification for the playoffs of the National Hockey League (NHL). The problem is solved using a phased approach that incrementally adds more complicated tie-breaking constraints if a solution is not found. Each of the phases is solved using a combination of network flows, enumeration and constraint programming. The experimental results show that the solver efficiently solves instances at any point of the season. The second problem addressed is determining the complexity, either worst-case theoretical or practical, of manipulation strategies in sports tournaments. The two most common types of competitions, cups and round robins, are considered and it is shown that there exists a number of polynomial time algorithms for finding manipulation strategies in basic cups and round robins as well as variants. A different type of manipulation, seeding manipulation, is examined from a practical perspective. While the theoretical worst-case complexity remains open, this work shows that, at least on random instances, seeding manipulation even with additional restrictions remains practically manipulable. The third problem addressed is determining whether manipulation strategies can be detected if they were executed in a real tournament. For cups and round robins, algorithms are presented which identify whether a coalition is manipulating the tournament with high accuracy. For seeding manipulation, it is determined that even with many different restrictions it is difficult to determine if manipulation has occurred.

Introduction Many chiropractic articles and textbooks discuss gait, but there actually has been little research into the effects of chiropractic adjustment on gait. This pilot study used a quantitative method of gait evaluation before and after a series of chiropractic visits. Hypotheses: (1) adults with chronic low back pain (CLBP) would show increased variability in vertical ground reaction forces (VGRF) while walking, as compared to healthy control subjects, and (2) that, following chiropractic care, will show decreased variability. Methods VGRF data were collected for 6 controls and compared to 9 CLBP participants, who were also evaluated before and after the first visit of care and over 7 visits. Data were analyzed by Mean Standard Deviation (MSD), Mean Coefficient of Variation (MCV), and the Coefficient of Variation of loading rate. Chiropractic care consisted of “high velocity low amplitude” thrust type procedures, flexion-distraction, pelvic wedges, light mobilization, and stretching. Results CLBP participants had somewhat greater variability and became slightly less variable post-care; differences were not significant. Limitations: Some participants had no impairment of walking at baseline; MSD is an uncommon measure, and more research is needed; these results (small group seen by a single doctor) may not be generalizable. Conclusions Participants with CLBP had slightly more variability and had slight decreases in variability following chiropractic care. Differences were not statistically significant. With this small pilot study as a guide, more research should be done with larger groups and improved participant selection.

Thesis (M.Tech.:Chiropractic)-Dept. of Chiropractic, Durban Institute of Technology, 2005 xi, 123 leaves ; 30 cm / The differential diagnosis of back and leg pain should include sacroiliac joint disease as the prevalence of sacroiliac joint pain appears to range from 13%-30%, thus making the sacroiliac joint a significant source of pain in patients with chronic low back pain. Sacroiliac syndrome is well-defined and usually presents with pain over the sacroiliac joint in the region of the posterior superior iliac spine, with possible referral to the buttock, groin, and leg. Most patients with sacroiliac syndrome seem to present with spastic or hyperactive muscles which leads to increased pain and decreased range of motion. Because of the close proximity of the Piriformis muscle to the sacroiliac joint, it is likely to be one of these hyperactive muscles. Various studies on low back pain, including a study on sacroiliac syndrome, have shown a correlation between low back pain, hip rotation range of motion asymmetry, and decreased hip mobility. In addition, the muscles responsible for movements of the hip have an overlapping innervation with the hip joint (L2 to S1) and sacroiliac joint (L2 to S3). It is assumed that the hypertonic muscles associated with sacroiliac syndrome decrease hip joint proprioception as the proprioceptors are facilitated erratically in a highly facilitated neuronal pool common to the innervation levels of the sacroiliac joint and the hip and associated with the level of the involved hypertonic muscle. This is thought to result in aberrant proprioceptive function at the identified levels, affecting the hip. Thus the aim of this study was to investigate the effect which sacroiliac joint manipulation had on hip functional ability in patients suffering from sacroiliac syndrome by means of various measurement tools: . Active hip joint ranges of motion were assessed using an Inclinometer, . Pressure threshold of the Piriformis muscle was measured by using an Algometer, and . Hip joint proprioception was assessed by measuring joint position sense of the hip joint using an Inclinometer.

Thesis (M.Tech.: Chiropractic) -Dept. of Chiropractic, Durban Institute of Technology, 2002 xiii, 93 leaves / The purpose of this study was to determine the short to medium term effectiveness of Proprioceptive Neuromuscular Facilitaion (P.N.F.) stretching [using the Contract- Relax-Antagonist-Contract (C.R.A.C.) technique] as an adjunct treatment to cervical manipulation in the treatment of Mechanical Neck Pain.

In Ni, Pearson and Poteshmans' (2005) Journal of Financial Economics-article, they claim that the expiration-day price-distribution of optionable stocks is subject to inefficiencies caused by stock price manipulation and portfolio rebalancing by delta hedgers. In this thesis, two main shortcomings of Ni et al.'s (2005) study are identified. In particular, they appear to have been ignorant of fundamental microstructure factors, and they did not derive an expression to represent the theoretical price-distribution of the relevant assets. After accounting for essential microstructure variables, and calculating the theoretical distribution, results that contradict Ni et al. (2005) are found. In particular, optionable stocks are found to experience efficiency gains on expiration days, and the distribution of underlying asset prices is closer to its theoretical benchmark on expiration days relative to non-expiration days.

The first part of the thesis gives a systematic overview and conceptual analysis of the literature on studying misinformation and disinformation in social media, with a special focus on research projects using large scale data obtained from Twitter and Facebook. The literature review gives a detailed overview of the scope of data collected by the various research projects; the means of accessing the data, which are rooted in the concrete socio-technical arrangement of the various platforms, and the type of analytical tools they apply. Furthermore, it also maps the various theoretical questions behind the research projects. The author of the thesis also gives his own definition of information manipulation and describes a conceptual model of information manipulation in the context of social media. The second part of the thesis applies some of the insights from the literature review to a large Twitter data set collected during the monitoring of African elections. The analysis follows a qualitative approach and focuses on case studies created from specific incidents during the elections. Each of these incidents illustrates a special aspect of the problem of information manipulation in online social media.

Doctor of Philosophy (PhD) / Allegations of market manipulation abound in the popular press, particularly during the recent financial turmoil. However, many aspects of manipulation are poorly understood. The purpose of this thesis is to enhance our understanding of market manipulation by providing empirical evidence on the prevalence, effects and determinants of closing price manipulation. The first issue examined in this thesis is the prevalence of closing price manipulation. This thesis uses a hand collected sample of prosecuted closing price manipulation cases from US and Canadian stock exchanges, and methods that explicitly model the incomplete and non-random detection of manipulation. The results suggest that approximately 1.1% of closing prices are manipulated. For every prosecuted closing price manipulation there are approximately 300 instances of manipulation that remain undetected or not prosecuted. Closing price manipulation is more prevalent on larger exchanges than smaller ones, but is detected at a higher rate on small exchanges. Second, this thesis examines the effects of closing price manipulation. Using a sample of prosecution cases, this thesis finds that closing price manipulation is associated with large day-end returns, subsequent return reversals, increases in day-end spreads and increases in day-end trading activity. At the broader level of market quality, this thesis provides evidence from a laboratory experiment that closing price manipulation decreases both price accuracy and liquidity. Even the mere possibility of manipulation decreases liquidity and increases trading costs. The third issue analysed in this thesis is the determinants of closing price manipulation and its detection. Estimating an empirical model of manipulation and detection, this thesis finds that the likelihood of closing price manipulation is increased by smaller regulatory budgets, greater information asymmetry, mid to low levels of liquidity, month-end days and lower volatility. Manipulation is more likely to be detected when regulatory budgets are larger and when the manipulation causes abnormal trading characteristics. Further evidence from laboratory experiments suggests that regulation helps restore price accuracy by deterring some manipulation and making remaining manipulation less aggressive. These experiments also show that regulation has an insignificant effect on liquidity because participants in regulated markets still face relatively high uncertainty about the presence of manipulators. This thesis also examines how closing price manipulation is conducted and how other market participants respond. It develops an index of closing price manipulation that can be used to study manipulation in markets or time periods in which prosecution data are not available. It also provides a tool for the detection of manipulation, which can be used by regulators in automated surveillance systems. Finally, this thesis has implications for economic efficiency and policy. Closing price manipulation is significantly more prevalent than the number of prosecution cases suggests. Further, it harms both pricing accuracy and liquidity and therefore undermines economic efficiency. The prevalence of closing price manipulation can be reduced by increasing regulatory budgets, improving the accuracy of market surveillance systems by using the detection tools developed in this thesis, structuring markets such that participants are better able to identify manipulation, and implementing closing mechanisms that are difficult to manipulate. These actions would enhance market integrity and economic efficiency.

This is an original study to quantify and grade defect healing in a large animal cranial bone substitute model. The study of various therapies to heal cranial defects requires an appropriate ?critical? animal model. An experimental animal model should be analogous and recognizable as an appropriate challenge to human physiology. In addition, the defect must fail to heal unless treated with the tissue engineering therapy under study. Sheep as a large animal model was chosen because of its ability to tolerate creation of large skull defects analogous to clinical scenario, and its biology of healing as a high order mammal would be closer human beings. There is no agreement on the critical size limits for cranial defects. Various sizes have been termed "critical" in publications utilizing sheep. These ranged from 20-22mm. This study will investigate whether a 20mm defect is adequate. Bilateral circular cranial defects of 10, 20 and 25mm diameters were created in 12 adult sheep. Based on guided tissue engineering principles, defect protection was utilized to prevent in-growth of fibroblasts and other connective tissue cells from the surroundings. As bone tissue regeneration strategies usually involve osteoconduction element, an animal model that considered the defect protection role of osteoconduction would be more appropriate. Repopulation and regeneration of the defect was maximized as an added challenge Bioresorbable polylactic acid co-polymer mesh (MacroPoreTM) and Titanium mesh (TiMeshTM) was used as defect protection. The cranial defects were harvested at 8 and 16 weeks. The end-point analysis included Faxitron X-ray images, DEXA (Dual Energy X-ray Absorptiometry), and histology. The defects were graded to assess their ability to eventually heal. 10mm defects fully healed at 16 weeks. There was new bone formation spanning the entire defect seen on histology. 25mm defects were spanned by thin fibrous tissue only. There was variability in the healing potential of 20mm defect. Based on presence of bone islands within the defect, half of the 20mm defects demonstrated ability to heal while the other half actually had new bone spanning the defects on histology. Critical size cranial defect in sheep for the study of bone graft substitute has to be larger than 25mm diameter. The model is then utilized to study the use of Pro Osteon and AGF compared with the gold standard of autologous bone graft.

Neck manipulation is commonly used in the management of some musculoskeletal disorders to reduce pain and improve movement. There is, however, little understanding about the underlying mechanism. Recent research has alluded to a neurophysiological mechanism mediated through supraspinal pathways in the central nervous system, that may alter motor activity. The purpose of this study was to determine the effect of neck manipulation on the excitability of cortical motoneurons by means of activating corticospinal pathways to the flexor carpi radialis (FCR) muscle in an active motor system using the transcranial magnetic stimulation (TMS) technique.Motor evoked potentials (MEPs) were elicited by TMS and recorded in 20 normal subjects using established procedures. The peak-to-peak amplitude of MEPs were measured both before and after C6/7 manipulation and before and after neck positioning. Both interventions were applied to the normal subjects in random order on two different days. MEPs were recorded immediately after the intervention, then seven minutes and 14 minutes later to assess the time course of the effect. Five neck pain subjects participated in the manipulation experiments. The effects of manipulation, resulting in joint cavitation, were also explored. Two trials were undertaken before the intervention and these served as control measures. MEP data was represented in two ways. Firstly, 40 MEPs were averaged over 120 seconds; secondly, 15 MEPs were average over 60 seconds. A percentage change calculation was used to express the data relative to the baseline. Alterations in cortical excitability before and after manipulation were analysed by repeated measure analysis of variance (ANOVA) on the MEP data, and percentage change scores.Cortical neurons projecting to FCR were significantly facilitated up to 60 seconds after the manipulation of the non-painful segment, relative to baseline values and the positioning control. A small but significant latent increase in excitability was also observed 15 minutes after manipulation. The response to manipulation of the painful cervical segment was significantly different from that of the non-painful segment. When manipulation of the painful segment did not result in joint cavitation, an inhibitory effect was observed. In contrast, however, cortical motoneurons were facilitated when joint cavitation was associated with manipulation.In conclusion, motor activity is enhanced with neck manipulation when cortical motoneuron excitability is measured by TMS in human subjects performing a voluntary contraction. This may explain the clinically observed improvement in spinal motion and motor control with spinal manipulation. Further, joint cavitation may be important in signifying the success of the joint manipulation. The excitatory effect on cortical motoneurons is probably mediated through a transcortical pathway by means of the activation of muscle afferents with the manipulative thrust.These findings assist in understanding the neurophysiological mechanism underlying the effect of spinal manipulation.

Only a small amount of the available literature is concerned with venous control in lower vertebrates, such as fish. It has even been suggested that veins in fish are not important factors in active regulation of venous return. Preliminary work carried out for this thesis strongly refuted this assumption, highlighting gaps in the existing literature. As a result of the lack of information pertaining to the physiology of the central venous compartment of the circulation, my objective has been to investigate various aspects of this in the hagfish Eptatretus cirrhatus. Hagfishes, with the lowest arterial blood pressures and highest blood volumes amongst the chordates, are the earliest surviving group to separate off from the chordate lineage. They provide a unique opportunity to investigate likely physiological mechanisms in ancestral chordates. The data presented in this thesis suggest thtat 1) E. cirhatus exhibit some cardiovascular compensation during volume manipulation, however this only occurs with volume loading and not during volume depletion, 2) Veins from E. cirrhatus can respond vasoactively to adrenergic stimulation in vitro and 3) Plasma catecholamines in E. cirrhatus also respond to volume manipulation and provide a potential in vivo mechanism for the control of changes in cardiovascular parameters that were observed during volume loading.