202 research outputs found
EMG-informed neuromusculoskeletal models accurately predict knee loading measured using instrumented implants
No full textObjective: Using a musculoskeletal modelling framework, we aimed to (1) estimate knee joint loading using static optimization (SO); (2) explore different calibration functions in electromyogram (EMG)-informed models used in estimating knee load; and (3) determine, when using an EMG-informed stochastic method, if the measured joint loadings are solutions to the muscle redundancy problem when investigating only the uncertainty in muscle forces. Methods: Musculoskeletal models for three individuals with instrumented knee replacements were generated. Muscle forces were calculated using SO, EMG-informed, and EMGinformed stochastic methods. Measured knee joint loads from the prostheses were compared to the SO and EMGinformed solutions. Root mean square error (RMSE) in joint load estimation was calculated, and the muscle force ranges were compared. Results: The RMSE ranged between 192-674 N, 152-487 N, and 7-108 N for the SO, the calibrated EMG-informed solution, and the best fit stochastic result, respectively. The stochastic method produced solution spaces encompassing the measured joint loading up to 98% of stance. Conclusion: Uncertainty in muscle forces can account for total knee loading and it is recommended that, where possible, EMG measurements should be included to estimate knee joint loading. Significance: This work shows that the inclusion of EMG-informed modelling allows for better estimation of knee joint loading when compared to SO.Kieran J. Bennett, Claudio Pizzolato, Saulo Martelli, Jasvir S. Bahl, Arjun Sivakumar, Gerald J. Atkins, Lucian Bogdan Solomon, and Dominic Thewli
Reevaluating the perception of Space:Is Space Truly Black or colorless?
No full textThis research explores a fundamental question in astrophysics: Is space truly black, or does it only appear so due to the absence of light? Challenging the conventional view that space is inherently black, the author proposes that space is actually colorless, and the perception of blackness is a result of the lack of light particles reaching the observer’s eye. The paper evaluates the nature of natural light, including that from stars and the Sun, and argues that no natural source emits black as part of its spectrum. This independent research is authored by Sivakumar, an original thinker based in India, and aims to stimulate deeper inquiry into cosmic perception, light behavior, and the limitations of human visual understanding in interpreting space
Reevaluating the perception of Space:Is Space Truly Black or Colorless?
No full textThis research explores a fundamental question in astrophysics: Is space truly black, or does it only appear so due to the absence of light? Challenging the conventional view that space is inherently black, the author proposes that space is actually colorless, and the perception of blackness is a result of the lack of light particles reaching the observer’s eye. The paper evaluates the nature of natural light, including that from stars and the Sun, and argues that no natural source emits black as part of its spectrum. This independent research is authored by Sivakumar, an original thinker based in India, and aims to stimulate deeper inquiry into cosmic perception, light behavior, and the limitations of human visual understanding in interpreting space. The paper has been submitted to OSF to ensure transparent sharing, open feedback, and archival of this work for the scientific community
Diaphragmatic crural eventration
No full textAim: We evaluated patients with gastric volvulus secondary to diaphragmatic pathology. Materials and Methods: Eight patients (5 males and 3 females) presented to the author in a tertiary care center during 1997-2006 were analyzed in terms of age, sex, symptomatology, diagnosis and predisposing factors. Observations: Six had an acute presentation and rest had chronic symptomatology. The two patients who had total gangrene stomach died postoperatively and one patient died preoperatively due to aspiration. All the cases presented with acute symptoms had diaphragmatic pathology, and out of these, three cases had the specific entity, which is named as diaphragmatic crural eventration. Conclusions: Diaphragmatic crural eventration is characterized by the defective development of the right crus of diaphragm, and this is embryologically significant as the right crus and ligaments of the stomach develop from dorsal mesoesophagus and mesogastrium. The author recommends a closer look for this defect of diaphragm while operating a case of gastric volvulus
Gait biomechanics after proximal femoral nailing of intertrochanteric fractures
No full textPublished April 2023Proximal femur fractures in the elderly are associated with significant loss of independence, mobility, and quality of life. This prospective study aimed to: (1)investigate gait biomechanics in intertrochanteric fracture (ITF) patients (A1 and A2AO/OTA) managed via femoral nailing at 6 weeks and 6 months postoperative and how these compared with similarly aged elderly controls; and (2) investigate whether femoral offset shortening (FOS) and lateral lag screw protrusion (LSP) were associated with changes in gait biomechanics at postoperative time points. Hipradiographs and gait data were collected for 34 patients at 6 weeks and 6 monthspostoperatively. Gait data were also collected from similarly aged controls. FOS andLSP were measured from radiographs. Joint angles, external moments, and powerswere calculated for the hip, knee, and ankle and compared between time points inITF patients and healthy controls using statistical parametric mapping. The relationship between radiographic measures with gait speed, step length, peak hip abduction, and maximum hip abduction moment was assessed using a Pearson correlation. External hip adduction moments and hip power generation improved inthe first 6 months postoperative, but differed significantly from healthy controls during single limb stance. LSP showed a moderate correlation with maximum hip abduction moment at 6 weeks postoperative (r=−0.469,p= 0.048). These results provide new detail on functional outcomes after ITF and potential mechanisms that functional deficiencies may stem from. Lag screw prominence may be an important factor in maintaining functional independence and minimizing the risk of secondary falls after ITF in the elderly.Arjun Sivakumar, Mark Rickman, Dominic Thewli
Owners Playing it Safe: A Law and Economics Explanation of Why Sports Franchises Relocate
No full text(10 Willamette Sports L.J., no. 1, 2012, at 1). This article analyzes how state and local taxes can drive a franchise’s decision to relocate.
First, the article analyzes the benefits a sports franchise provides that will be lost if a team relocates. Next, the article uses an example to illustrate how unfavorable state and local taxes can influence relocation decision-making by risk-averse team owners, provides empirical evidence from recent relocation cases, and describes how state and local taxes affect the everyday operation of a sports franchise. The article concludes by proposing a revenue-neutral income tax carve-out that corrects the distortionary effect of state and local taxes on sports franchises and allows high-tax cities to keep their teams in an effective and fair manner
Gait Biomechanics after Femoral Nailing of Intertrochanteric Fractures
No full textIntertrochanteric fractures of the hip are highly prevalent in the elderly and commonly managed using single and dual lag screw femoral nails. Biomechanical studies show differences between devices in the mechanics of maintaining fracture stability, however, clinical outcomes have been conflicting. An understanding of joint biomechanics and gait following surgical management will allow us to quantify functional outcomes in detail and understand femoral nail parameters that influence joint biomechanics. The central aim of this thesis was to investigate clinical and functional outcomes after femoral nailing of intertrochanteric fractures in the elderly.
Following an introduction in chapter one, the second chapter in this thesis was a systematic review and meta-analysis that determined aseptic reoperation rates and failure mechanisms contributing to reoperation in patients managed with single and dual screw devices. This study identified no difference between patients managed with single and dual separated screw devices in reoperation rates. It also identified insufficient clinical outcome data available for patients managed with dual integrated screw devices.
The third chapter presented a protocol for a randomised controlled trial investigating the effects of using single or dual integrated screw devices and lag screw locking mode on clinical outcomes. This chapter incorporated the use of gait biomechanics outcomes using objective measures from gait analysis and formed the methodological underpinnings of this thesis.
The fourth chapter, a critical methodological component of this thesis, developed an instrumented walking frame and musculoskeletal modelling framework that allowed for gait analysis of walker-reliant individuals. Additionally, effects of including handle-reaction forces on residual forces during modelling were evaluated. Results showed improved estimates of musculoskeletal loads of the torso by reducing residual forces.
The fifth chapter investigated changes in joint biomechanics between six weeks and six months post-operative and associations between femoral offset shortening and lateral lag screw protrusion with gait analysis outcomes. Results found improvements in hip, knee and ankle biomechanics between six weeks and six months. Additionally, deficiencies in hip abduction and power generation of patients at six months were found in comparison with elderly controls. Results further revealed a moderate association between larger amounts of lateral lag screw protrusion with decreased hip abduction moments at six weeks.
In the sixth chapter, hip joint reaction forces were investigated between patients treated with a single and dual integrated lag screw femoral nail. Results showed higher hip joint reaction forces at six weeks in the dual integrated screw group along with an average double peak hip loading profile that was not displayed in the single screw group at this timepoint. Results further indicated higher force generation of the hip abductor muscles in the dual integrated screw group. Additionally, no differences were identified between groups at six months.
The collection of studies presented in this thesis provide new detail on functional outcomes following femoral nailing of elderly intertrochanteric fractures by describing gait biomechanics outcomes for the first time. Minimising the amount of lateral lag screw protrusion has been identified as an important factor in maintaining biomechanical outcomes of the hip that are crucial to medio-lateral stability. It also provided evidence that using a dual integrated screw device is associated with superior hip joint loading patterns and force generation of the hip abductors at earlier timepoints when compared to using single lag screw devices. This may be clinically useful in allowing for faster recovery of function in intertrochanteric fracture patients undergoing fracture fixation via proximal femoral nail.Thesis (Ph.D.) -- University of Adelaide, Adelaide Medical School, 202
Detecting sepsis in the ICU using machine learning
No full textSepsis is a complex syndrome that has been reportedly causing 1 among 5 deaths worldwide. Presently, sepsis can be defined as, “a life-threatening organ dysfunction caused by dysregulated host response to infection”. The definitions of sepsis have been varying over the years and there is no particular gold standard definition as the guidelines are being constantly revised. However, there is a need for appropriate treatment on the diagnosis of sepsis since it can cause organ failure and eventually lead to death.
Culturing the blood samples of the patient to check for the presence of an infection that could lead to sepsis is the most accurate method to diagnose sepsis however, blood culturing takes a minimum of 24 hours to detect the presence of an infection and would take additional days to identify the type of micro-organism for treatment. Hence, few scoring strategies to screen for sepsis such as SIRS and SOFA have been devised. But owing to the complexity of the syndrome, a combination of various data points from the laboratory, medication, vital signs and, patient demographics etc. will be needed to effectively detecting sepsis. Hence, a machine learning model is trained to detect the presence of sepsis in a patient more reliably and in a faster manner than existing conventional rule-based scoring methods.
Based on the availability of critical care data of patients, a machine learning classifier that could combine all the information obtained in a user-specified time window, process the obtained data, and detect the presence of sepsis is being built. The efficiency of the model and reliability in earlier detection is compared with the conventional SOFA scoring method. It could be observed that the gradient boosting model has an AUC score of 0.82 with a 6 hour time window on an unseen patient population, which is higher than the AUC score of 0.74 obtained by SOFA scoring to detect sepsis. By looking for hidden patterns in the data, the classifier would be able to advise on the presence of sepsis that a human eye cannot visualize. This classifier would enable earlier treatment of patients who are found to be septic, thereby reducing the number of deaths caused due to sepsis. This could also directly help in reducing the costs incurred, since non-septic patients if found to be stable could be discharged from the hospital, as ICU costs are the highest hospital costs incurred owing to continuous surveillance of patients
The Effects of Information And Communication Technology In Hungarian Economic Sectors
No full textAs the author could not find a reassuring mathematical and statistical method in the literature for studying the effect of information communication technology on enterprises, the author suggested a new research and analysis method that he also used to study the Hungarian economic sectors. After a
brief introduction to the theoretical background of the Information Age, the author examines the question of what factors have an effect on their net income is essential for enterprises. First, the potential indicators related to economic sectors were studied, then the author compared those indicators to the net income of the surveyed enterprises. The data resulting from the comparison showed that the growing
penetration of electronic marketplaces contributed to the change of the net income of enterprises in various economic sectors. Among all the potential indicators, only the indicator of electronic marketplaces has a direct influence on the net income of enterprises. It was practical to determine two clusters based on the potential indicators
The impact of climatic variability over the period 1961- 1990 on the soil water balance of upland soils in the North East Arid Zone of Nigeria
No full textOver the period 1961 – 90 the North East Arid Zone of Nigeria experienced a decline
in annual rainfall totals and increased aridity which placed increasing pressure on
rain fed, millet-based farming systems. The changes in seasonal rainfall total and
distribution have been examined and it has been shown that the rate of decline has
been consistent across the region. The decline has been dominated by reduction in
the number of rain days during the middle of the rainy season and there is no
evidence of a significant change in the length of the growing season. Over the same
time period, there has been a small, but significant, increase in mean air temperature
which has resulted in a small increase in potential evapotranspiration. Other climatic
parameters (vapour pressure, solar radiation and wind speed) appear to have
remained stable, although the paucity and dubious quality of much of the historical
meteorological data make rigorous statistical analysis difficult.
A water balance model (BALANCE) developed by the author, was calibrated for a
millet crop grown on a typical sandy loam soil in Maiduguri (Nigeria). The model
was necessarily parsimonious, but was shown to perform well when calibrated
against observed soil water content. However, the empirical nature and high
sensitivity of key parameters relating to bare soil evaporation and drainage mean that
it is difficult to parameterise the model by laboratory, or independent field
measurements.
Applying the calibrated model to daily rainfall and average evapotranspiration data
from Nguru (Nigeria) for the period 1961 – 93 showed that, with the exception of
extreme drought years, the increased aridity would have had little impact on the
viability of traditional millet and millet-cowpea intercropping systems prior to the
early 1980s. However, after that date, predicted seasonal millet transpiration, and
hence predicted yields, have declined, and long duration cowpea intercrops, which
were traditionally matured on residual soil moisture after the millet harvest have had
insufficient water.
Whilst the BALANCE model has been useful in examining the impact of climatic
variability on agro-hydrology, it is not a crop physiological model and the interaction
between soil water and crop development is poorly represented. The model cannot, therefore be applied with confidence to investigate the potential yield benefits of
physical or agronomic interventions to alleviate the impacts of aridity. Although
more complex models exist to do this, they require detailed parameterisation of the
crop physiology, which was not possible within the scope of this study
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