New surgical approaches for total hip arthroplasty (THA) are being developed to reduce muscle damage sustained during surgery, in the hope to allow better muscle functioning afterwards. The goal of this study was to compare the muscle sparing anterior (ANT) approach to a traditional lateral (LAT) approach with three-dimensional motion analysis. Kinematics and kinetics were obtained with an infrared camera system and force plates. It was hypothesized that (1) the ANT group would have closer to normal range of motion, moments and powers, compared to the LAT group, and that (2) the ANT group would have higher peak hip abduction moment than the LAT group. Forty patients undergoing unilateral THA for osteoarthritis between the ages of 50 and 75 (20 ANT, 20 LAT) were asked to perform three trials of walking, stair ascent and stair descent. Patients were assessed between six to twelve months postoperatively. Twenty age- and weight-matched control participants (CON) provided normative data. Results indicated that both THA groups had gait anomalies compared to the CON group. Both THA groups had reduced hip abduction moment during walking (CON vs. ANT: p<0.001; CON vs. LAT: p=0.011), and the ANT group had a significantly lower hip abduction moment compared to the LAT group (p=0.008). Similar results were observed during stair descent, where the ANT group had reduced peak hip abduction moment compared to the CON group (p<0.001) and the LAT group (p=0.014). This indicates that the anterior approach did not allow better gait and stair climbing ability after THA. It is therefore thought that other variables, such as preoperative gait adaptations, trauma from the surgery, or postoperative protection mechanisms to avoid loading the prosthetic hip, are factors that might be more important than surgical approach in determining the mechanics of THA patients after surgery.

Mafic magma is the most common magma erupted at the surface of the earth. It is generated from partial melting of the mantle, which has been subdivided into end-members based on unique geochemical signatures. One reason these end members, or heterogeneities, exist is subduction of lithospheric plates back into the mantle. The amount of elements, such as Cl and K, removed during subduction and recycled into the deep mantle, is poorly constrained. Additionally, the amount of volatiles, such as Cl, that are recycled into the deep mantle will strongly affect the behavior of the system. I have looked at Cl and K in HIMU source melts to see how it varies. Cl/Nb and K/Nb suggest that elevated Cl/K ratios are the result of depletion of K rather than increased Cl recycled into the deep mantle. After the mantle has partially melted and mafic melt has migrated to the surface, it usually erupts effusively or with low explosivity because of its low viscosity, but it is possible for larger eruptions to occur. These larger, Plinian eruptions, are not well understood in mafic systems. It is generally thought that basalt has a viscosity that is too low to allow for such an eruption to occur. Plinian eruptions require fragmentation to occur, which means the melt must undergo brittle failure. This may occur if the melt ascends rapidly enough to allow pressure to build in bubbles without the bubbles expanding. To test this, I have done decompression experiments to try to bracket the ascent rate for two Plinian eruptions. One eruption has a fast ascent, faster than those seen in more silicic melts, whereas the other eruption is unable to be reproduced in the lab, however it began with a increased viscosity in the partly crystallized magma. After fragmentation and eruption, it is generally thought that tephra do not continue to crystallize. We have found that crystallinity increases from rim to core in two basaltic pumice. Textural data along with a cooling model has allowed us to estimate growth rates in a natural system, which are similar to experimental data. / text

An analysis of the use of complex-step differentiation (CSD) in optimization problems is presented. Complex-step differentiation is a numerical approximation of the derivative of a function valid for any real-valued analytic function. The primary benefit of this method is that the approximation does not depend on a difference term; therefore round-off error is reduced to the machine word-length. A suitably small choice of the perturbation length, h, then results in the virtual elimination of truncation error in the series approximation. The theoretical basis for this method is derived highlighting its merits and limitations. The Lunar Ascent Problem is used to compare CSD to traditional forward differencing in applications useful to the solution of optimization problems. Complex-step derivatives are shown to sufficiently apply in various interpolation and integration methods, and, in fact, consistently outperform traditional methods. Further, the Optimal Orbit Transfer Problem is used to test the accuracy, robustness, and runtime of CSD in comparison to central differencing. It is shown that CSD is a considerably more accurate derivative approximation which results in an increased robustness and decreased optimization time. Also, it is shown that each approximation is computed in less time using CSD than central differences. Overall, complex-step derivatives are shown to be a fast, accurate, and easy to implement differentiation method ideally suited for most optimization problems. / text

No description available.

Rock climbing is thought to rely upon the interaction of various performance components, and has previously been described as a complex multi-faceted sport. It has been suggested that psychological aspects of performance, such as task perception and the interaction of resulting pre-climb anxieties, contribute greatly to the physiological responses and the overall performance during ascent. However, research which seeks to investigate both psychological and physiological responses during specific bouts of rock climbing are few in number. This thesis attempts to contribute to the novel yet limited body of field based psychophysological research relating to rock climbing. To this end, the studies contained within this thesis investigated psychological and physiological responses as a result of difficult on-sight rock climbing. Elaborating upon previous research, additonal factors which are thought to influence these responses were explored. More specifically, differences in responses between ability groups, style of ascent, and route type were investigated. In study one, differences in psychological and physiological responses with respect to ability level and ascent style were investigated, during a single on-sight ascent. Seventy-two climbers were split into ability groups defined as lower-grade, intermediate, advanced and elite based on self-reported on-sight grades (Ewbank) of ≤17, 18-20, 21-24 and ≥ 25 respectively. Each climber attempted an on-sight ascent of a designated test route set on an indoor artificial climbing wall. A separate test route was set for each ability group which targeted their self-reported ability with respect to best on-sight. Participants were randomly assigned to either a lead or top-rope ascent and climbers were not informed of their style of ascent until 15 min prior to climbing. Responses to the climbing task were measured pre, during, and post-climb using a number of psychological and physiological markers. In total fifty-two participants successfully completed their on-sight ascents, and data for successful ascents were analysed and compared. Pre-climb variables were considered together in order to investigate pre-climb state, more specifically levels of anxiety, prior to ascent. Results indicated that there were no significant differences for grouped pre-climb variables with respect to ascent style. These results suggest that irrespective of ascent style, successful climbers exhibited similar psychophysiological responses prior to attempting an on-sight ascent. Furthermore, this trend was replicated across all ability groups. These findings were thought to be indicative of the high demand and level of uncerainty imposed by the on-sight condition of ascent, lending support to previous suggestion that an on-sight ascent induces the highest anxiety response. During the climb, HR and were measured and averaged across the entirety of the ascent. When expressed as a percentage of and the average HR and responses during ascent were found to be comparable across ability groups. As such, all ability groups appeared to utilise similar fractions of maximal capacity, with elite climbers successfully ascending a route up to eight difficulty grades harder than those of lower ability, whilst still performing at the same workload intensity. It would appear that oxygen uptake during rock climbing may not be directly related to difficulty or personal ability. A technical advantage, personal climbing style, and possible physiological adaptations may be contributors to more strategic and efficient ascents resulting in the capacity to climb at higher grades of difficulty. The second study presented within this thesis was comprised of two phases of investigation; (1) to investigate whether psychological and physiological responses to competition-style climbing differed with respect to ability level, and (2) to investigate potential psychological and physiological differences based on route type and outcome (success and failure). In phase 1 of study two, intermediate, advanced and elite climbers attempted an lead on-sight ascent of a competition-style route which increased in difficulty as the climber progressed. The route was set with the intention of being just beyond the upper limits of the elite climbers self-reported best on-sight ability (~26 Ewbank). This was done in order to ensure that a fall from the route was highly likely, even for the elite climbers. All climbers failed to successfuly ascend the test route and as such all climbed to the point of failure resulting in a fall. The results obtained both prior to, and during ascent suggest that the intermediate and advanced climbers in the current study may have been limited by technical ability as opposed to physical exhaustion, or increased levels of anxiety. Elite climbers were to be able to maintain a more sustained physical effort during the more difficult phases of the climb. This appeared to be reflected in post-climb blood lactate concentration and ratings of task demand with respect to both physical demand and effort. As such it may be that elite climbers are more accustomed to maximal effort and demonstrate an increased tolerance to the higher exercise intensity required during more difficult ascents. In the second phase of study two the psychological and physiological responses of climbers in a competitive setting obtained in phase 1, were compared with those exhibited by participants during both successful and unsuccessful lead on-sight ascents in study one. The aim of study two phase 2 was to determine whether the responses of successful climbers differed from those who succeeded by reaching the top of a route, and performances in a competitive context where success is denoted by the distance achieved by a climbers on their ascent. The main findings in this instance were that although there were no significant differences observed between categories of ascent (successful, unsuccessful and competition) for grouped pre-climb variables, trends in CSAI-2R responses indicated high cognitive anxiety coupled with lower self-confidence prior to unsuccessful ascents. As such it may be that self-confidence acts as a buffer in moderating success in rock climbing, demonstrating the role of positive emotions and their impact upon performance as opposed to the detrimental effect of the negative. A second finding of this study was that there appeared to be a differing HR- relationship based on ascent category. Modest increases in were shown for all ascents, irrespective of ability level. A plateau in response was accompanied by a similar plateau in HR response during successful ascents, yet HR was shown to increase in a linear fashion until point of failure during unsuccessful ascents. It is possible that these findings highlight the presence of a climbing specific limitation.

Many manual biomedical annotation tasks can be categorized as instances of the typical multi-label classification problem where several categories or labels from a fixed set need to assigned to an input instance. MeSH term assignment to biomedical articles and diagnosis code extraction from medical records are two such tasks. To address this problem automatically, in this thesis, we present a way to utilize latent associations between labels based on output label sets. We used random indexing as a method to determine latent associations and use the associations as a novel feature in a learning-to-rank algorithm that reranks candidate labels selected based on either k-NN or binary relevance approach. Using this new feature as part of other features, for MeSH term assignment, we train our ranking model on a set of 200 documents, test it on two public datasets, and obtain new state-of-the-art results in precision, recall, and mean average precision. In diagnosis code extraction, we reach an average micro F-score of 0.478 based on a large EMR dataset from the University of Kentucky Medical Center, the first study of its kind to our knowledge. Our study shows the advantages and potential of random indexing method in determining and utilizing implicit relationships between labels in multi-label classification problems.

New surgical approaches for total hip arthroplasty (THA) are being developed to reduce muscle damage sustained during surgery, in the hope to allow better muscle functioning afterwards. The goal of this study was to compare the muscle sparing anterior (ANT) approach to a traditional lateral (LAT) approach with three-dimensional motion analysis. Kinematics and kinetics were obtained with an infrared camera system and force plates. It was hypothesized that (1) the ANT group would have closer to normal range of motion, moments and powers, compared to the LAT group, and that (2) the ANT group would have higher peak hip abduction moment than the LAT group. Forty patients undergoing unilateral THA for osteoarthritis between the ages of 50 and 75 (20 ANT, 20 LAT) were asked to perform three trials of walking, stair ascent and stair descent. Patients were assessed between six to twelve months postoperatively. Twenty age- and weight-matched control participants (CON) provided normative data. Results indicated that both THA groups had gait anomalies compared to the CON group. Both THA groups had reduced hip abduction moment during walking (CON vs. ANT: p<0.001; CON vs. LAT: p=0.011), and the ANT group had a significantly lower hip abduction moment compared to the LAT group (p=0.008). Similar results were observed during stair descent, where the ANT group had reduced peak hip abduction moment compared to the CON group (p<0.001) and the LAT group (p=0.014). This indicates that the anterior approach did not allow better gait and stair climbing ability after THA. It is therefore thought that other variables, such as preoperative gait adaptations, trauma from the surgery, or postoperative protection mechanisms to avoid loading the prosthetic hip, are factors that might be more important than surgical approach in determining the mechanics of THA patients after surgery.

New surgical approaches for total hip arthroplasty (THA) are being developed to reduce muscle damage sustained during surgery, in the hope to allow better muscle functioning afterwards. The goal of this study was to compare the muscle sparing anterior (ANT) approach to a traditional lateral (LAT) approach with three-dimensional motion analysis. Kinematics and kinetics were obtained with an infrared camera system and force plates. It was hypothesized that (1) the ANT group would have closer to normal range of motion, moments and powers, compared to the LAT group, and that (2) the ANT group would have higher peak hip abduction moment than the LAT group. Forty patients undergoing unilateral THA for osteoarthritis between the ages of 50 and 75 (20 ANT, 20 LAT) were asked to perform three trials of walking, stair ascent and stair descent. Patients were assessed between six to twelve months postoperatively. Twenty age- and weight-matched control participants (CON) provided normative data. Results indicated that both THA groups had gait anomalies compared to the CON group. Both THA groups had reduced hip abduction moment during walking (CON vs. ANT: p<0.001; CON vs. LAT: p=0.011), and the ANT group had a significantly lower hip abduction moment compared to the LAT group (p=0.008). Similar results were observed during stair descent, where the ANT group had reduced peak hip abduction moment compared to the CON group (p<0.001) and the LAT group (p=0.014). This indicates that the anterior approach did not allow better gait and stair climbing ability after THA. It is therefore thought that other variables, such as preoperative gait adaptations, trauma from the surgery, or postoperative protection mechanisms to avoid loading the prosthetic hip, are factors that might be more important than surgical approach in determining the mechanics of THA patients after surgery.

Subir e descer escadas são atividades funcionais habituais e muito relatadas como queixa principal por pacientes com alterações ortopédicas como a síndrome dolorosa femoropatelar - por ser um movimento que acarreta descarga de peso unilateral e assim causa um aumento da dor - e por pacientes com afecções neurológicas - devido à dificuldade na execução deste gesto. Além disso, a subida e descida de escadas é habitualmente utilizada como técnica terapêutica na reabilitação destes pacientes; porém poucos estudos foram realizados com o intuito de caracterizar este gesto e, estes estudos, concluem que a alta variabilidade dos dados não permite confirmar os resultados. Estudos com pacientes com dor femoropatelar usualmente avaliam estes sujeitos com eletromiografia de superfície e sugerem que exista um déficit de equilíbrio na musculatura estabilizadora da patela e que esta é a causa da dor nestes pacientes; porém, também há uma grande variabilidade nos resultados encontrados, não sendo possível confirmar esta hipótese. Neste contexto, este estudo teve o objetivo de verificar quais parâmetros do sinal eletromiográfico apresentaram boa reprodutibilidade e menor variabilidade e são, portanto, mais adequados para caracterizar o gesto proposto, podendo ser utilizado para comparar grupos de indivíduos com e sem dor femoropatelar. Para isto, foi utilizada a eletromiografia para avaliar a atividade dos músculos vasto lateral e vasto medial do quadríceps durante a subida de escada em 39 indivíduos clinicamente saudáveis e 23 indivíduos com dor femoropatelar. Os resultados mostraram que os parâmetros que apresentaram boa reprodutibilidade entre os dois dias de avaliação foram: início de ativação, duração da contração muscular, tempo mediano da contração, intensidade do sinal, co-ativação muscular e frequência mediana. Dentre estes parâmetros, aqueles que permitiram diferenciar os grupos de estudo foram o tempo mediano da ativação, que ocorreu mais tardiamente nos indivíduos com dor e a co-ativação muscular, que demonstrou menor porcentagem de ativação conjunta nos indivíduos com dor. Estes dados indicam uma alteração no controle neuromotor durante a subida de escada, sugerindo que a abordagem clínica deva passar por treinos de equilíbrio, coordenação e propriocepção, para melhorar a estabilidade articular durante a realização de atividades dinâmicas. / Go up and down stairs are functional activities very habitual and reported as complaint for patients with orthopedic alterations as patellofemoral pain syndrome because it is a movement that carries unilateral weight bearing and thus cause an increase in pain and for patients with neurological disorders due to the difficulty in carrying out this gesture. Moreover, the ascent and descent of stairs is usually used as a therapeutic technique in the rehabilitation of these patients, but few studies have been conducted in order to characterize this gesture and, these studies conclude that the high variability of the data does not confirm the results. Studies on patients with patellofemoral pain usually assess these subjects with surface electromyography and suggest that there is a balance deficit in the patella stabilizer muscles and that this is the cause of pain in these patients, but there is also a great variability in the results, that does not allow to confirm this hypothesis. In this context, this study aimed to determine which parameters of electromyographic signals showed good reproducibility and low variability and are, therefore, more appropriate to characterize the proposed gesture and can be used to compare groups of individuals with and without patellofemoral pain. For this, we used electromyography to evaluate the activity of the vastus lateralis and vastus medialis of the quadriceps during stair climbing in 39 clinically healthy individuals and 23 individuals with patellofemoral pain. The results showed that the parameters with good reproducibility between the two days of evaluation were: onset, duration of muscle contraction, median time of contraction, intensity of activation, muscular co-activation and median frequency. Among these parameters, those that could differentiate the groups were the median time of activation, which occurred later in subjects with pain and muscle co-activation, which showed a lower percentage of combined activation in individuals with joint pain. These data indicate a change in neuromotor control during stair climbing, suggesting that the clinical approach should undergo training of balance, coordination and proprioception, in order to improve joint stability while performing dynamic activities.

Studies indicate that voluntary reporting detects relatively few adverse events (AEs) (Ehland et al., 1999, Cooper et al., 1984). At Boston Children’s Hospital (BCH), several systems exist to document AEs. First, anesthesiologists document clinical care and AEs in the patient medical record (the Anesthesia Information Management System (AIMS)). Second, in an effort to capture AEs, the Department of Anesthesiology, Critical Care and Pain Medicine developed an internal tool, the Anesthesia System for Clinical Event Tracking (ASCENT), which is integrated into clinicians’ electronic documentation. Finally, a BCH hospital-wide reporting system, the Safety Event Reporting System (SERS), allows all employees and patients to report an AE.  The goals of this study are 1) to compare the effectiveness of documentation in AIMS, ASCENT, and SERS, 2) to determine the incidence of AEs in January 2018 and June 2019, independently, and 3) compare the effectiveness of documentation AEs in ASCENT after implementation of an improved, integrated reporting system. After IRB approval, a manual chart review of 3,3204 cases requiring anesthesia in January 2018 and 3,387 cases requiring anesthesia in June 2019 was conducted. Anesthesia notes, vital signs, and administered medications documented in AIMS were reviewed to determine if an AE had occurred. Descriptions of each case were recorded, and cases with indications for AEs were verified by clinicians. Next, each AE was categorized by event type. Both ASCENT and SERS were then queried for the reported adverse events during the same time period. The total number of AEs was described using counts with the distribution of types of AEs presented using percentages.     Among the 3,204 cases reviewed in January 2018, there were 569 events documented in AIMS, out of which, 39 (6.9%) were documented in ASCENT, and 2 (0.4%) in SERS. The overall rate of AEs was determined to be 1.8 events/10 cases. For June 2019, a total of 3,387 cases were reviewed for the occurrence of AEs. Among the reviewed cases, there were 396 events documented in AIMS, out of which, 106 (26.8%) were documented in the ASCENT database, and 3 (0.8%) in SERS. The overall rate of AEs was determined to be 1.2 events/10 cases. This study demonstrates that voluntary reporting of AEs may be improved if the reporting systems are better-integrated with patient medical records. In agreement with existing literature, this study also illustrates that hospital-wide reporting systems, such as SERS, fail to collect most adverse events (Levinson, 2012). To achieve comprehensive reporting of AEs, systems must be integrated into clinicians’ workflow. Education regarding the reporting systems along with technology improvements may further enhance the capture of AEs. Further investigation will be conducted to determine severity, preventability and association with anesthesia.