Structural Origins of the Stiffness and Work Contributions of the Human Foot

Human foot mechanics have been extensively studied over the last century to understand human evolution and treat foot pathologies.Much of this understanding has centered on the foot\u27s longitudinal arch that runs from heel to toe, especially its role in making human feet stiff enough to withstand many times our bodyweight during walking and running. But numerous studies on foot biomechanics, orthopedic surgical reconstructions, and human evolution point to substantial gaps in the understanding based on the longitudinal arch alone. In this thesis, I present two new findings related to foot stiffness and how it produces the mechanical power needed for propulsion. First, I show that the transverse arch that runs across its width contributes more to foot stiffness than the longitudinal arch. Second, I show that a mechanism involving the plantar fascia and the longitudinal arch, called the windlass mechanism, has no effect on stiffness as previously assumed. Instead, it helps transmit power from muscles outside the foot to locations within the foot for efficient walking. These findings hinge upon a combination of mathematical models, mechanical foot models, mechanical tests on cadaveric feet, and measurements on live walking and running human volunteers. Together, these studies show how the foot\u27s function emerges from the combined roles of the longitudinal and transverse arches, and how those features may have evolved to enable human walking and running. After an introduction in chapter 1 to the current understanding of foot biomechanics and evolution, chapter 2 will present a series of studies using mechanical foot mimics and three-point bending tests in cadaveric human feet to show how the curvature of the transverse arch contributes to sagittal plane stiffness.Chapter 3 extends this result to in vivo foot stiffness measurements in walking humans and shows that despite active muscle contraction changes during walking, the transverse arch continues to influence sagittal foot stiffness. The evidence indicates that the evolution of a transverse arch played a key role in human evolution by enabling a stiff foot for propulsion. Chapter 4 turns to the longitudinal arch with an experimental examination of the windlass mechanism in walking and running humans, and finds that the windlass does not increase foot stiffness but plays an important role in power transmission so that the foot can output mechanical power without the need for heavy muscles within the foot itself. This thesis advances the understanding of structure-function relationships in the human foot and impacts the fields of evolutionary biology, podiatry and robotics. The renewed understanding of the windlass mechanism, taken together with other studies that compare feet across many primate species, suggests that the power transmission function of the windlass is important for walking, and could have emerged well before the longitudinal arch evolved in humans. Future clinical studies have to consider the transverse arch in evaluating foot function and may find that to be a potential target for the design of foot reconstructive surgeries, design of orthotic implants, and evaluation and classification of flatfoot disorders. Finally, the mechanical foot mimics that were developed may inspire the design of lightweight robotic and prosthetic feet with tunable stiffness properties that exploit the curvature induced stiffening of the human foot

On angled bounce-off impact of a drop impinging on a flowing soap film

Small drops impinging angularly on thin flowing soap films frequently demonstrate the rare emergence of bulk elastic effects working in-tandem with the more common-place hydrodynamic interactions. Three collision regimes are observable: (a) drop piercing through the film, (b) it coalescing with the flow, and (c) it bouncing off the film surface. During impact, the drop deforms along with a bulk elastic deformation of the film. For impacts that are close-to-tangential, the bounce-off regime predominates. We outline a reduced order analytical framework assuming a deformable drop and a deformable three-dimensional film, and the idealization invokes a phase-based parametric study. Angular inclination of the film and the ratio of post and pre impact drop sizes entail the phase parameters. We also perform experiments with vertically descending droplets impacting against an inclined soap film, flowing under constant pressure head. Model predicted phase domain for bounce-off compares well to our experimental findings. Additionally, the experiments exhibit momentum transfer to the film in the form of shed vortex dipole, along with propagation of free surface waves. On consulting prior published work, we note that for locomotion of water-walking insects using an impulsive action, the momentum distribution to the shed vortices and waves are both significant, taking up respectively 2/3-rd and 1/3-rd of the imparted streamwise momentum. In view of the potentially similar impulse actions, this theory is applied to the bounce-off examples in our experiments, and the resultant shed vortex dipole momenta are compared to the momenta computed from particle imaging velocimetry data. The magnitudes reveal identical order ($10^{-7}$ N$\cdot$s), suggesting that the bounce-off regime can be tapped as a simple analogue for interfacial bio-locomotion relying on impulse reactions

Dormant Account Reactivation at Al–Shajar Capital

The case study highlights the importance of finding a simple and cost effective solution to a core business problem. It elaborates the cost effective approach of Al-Shajar Capital’s Management in reactivating its dormant client base in order to capitalize the post Polling Stock Market rally. In order to analyze its dormant client base, Al-Shajar Capital remodeled the exercise as a capstone project and awarded it to final year MBA students of IoBM-CBM. The study used a modified form of Doreén Pick’s Customer win back model to reactivate customers’ accounts, not actively trading in the market. A five-week, non-scripted warm calling session was conducted, followed by a detailed report and formal presentation. Due to operational issues and human resource limitation, the exercise was conducted on weekends. The study was a success as not only it was able to revert and activate majority of dormant client accounts but also left a positive impression on many non-returning clients

ショクブツニセイイクソクシンヲユウドウスルコウカカラミタバチルスバイオヒリョウガホウノキノウケンキュウ

博士（農学）東京農工大

On synthesis and optimization of floating point units

This work describes the effect of architectural/system level design decisions on the performance, of floating point arithmetic units. By modeling with VHDL and using design synthesis techniques, different architectures of floating point adders, multipliers and multiply-accumulate fused units, are compared using different technologies and cell libraries. Some modifications to recent published works have been proposed to minimize the energy delay product with special emphasis on power reduction. A new low power, high performance, transition activity scaled, double data path floating point multiplier has been proposed and its validity is proved by comparing it to a single data path floating point multiplier. A transition activity scaled, triple data path floating point adder has been compared with a high speed, single data path floating point adder using an optimized Leading Zero Anticipatory logic. Three different architectures of floating point multiply-accumulate fused units are evaluated for their desirability for high speed, low power and minimum area. The findings of this work validate different higher level design methodologies of floating point arithmetic units irrespective of the rapidly changing underneath technology

Ameloplasty is counterproductive in reducing microleakage around resin modified glass ionomer and resin based fissure sealants

Objective: To compare the microleakage around resin modified glass ionomer cement (RMGIC) based sealants and flowable resin based sealants placed with or without ameloplasty in extracted human teeth.Methods: This in-vitro experimental study was conducted at the Operative Dentistry Department, Dow University of Health Sciences, Karachi, Pakistan from June 2017 to December 2018. Sixty extracted human molars and premolars were assigned to four groups (n=15) each, according to the type of fissure sealant (flowable resin based sealant or resin modified glass ionomer based sealant) used and either placed with or without ameloplasty. Specimens were thermocycled and then immersed in 1% methylene blue for 24 hours. Specimens were then sectioned and examined using stereo-microscope (50X) for microleakage that was scored on an ordinal scale. Mann-Whitney U test and Ordinal regression were applied. Level of significance kept at 0.05.Results: There was a statistically significant difference (p-value \u3c0.001) between the two sealant types for the microleakage scores. Sealants placed with ameloplasty demonstrated significantly higher microleakage values (p-value \u3c0.001).Conclusion: Microleakage was found to be more pronounced in RMGIC based sealants compared to the resin based sealants. Ameloplasty resulted in higher leakage around the sealants irrespective of the chemistry of material

Characteristics of patients with guillain barre syndrome at a tertiary care centre in Pakistan, 1995-2003

Objective: To study the clinical presentation, hospital course and outcome of patients admitted with Guillain Barre Syndrome (GBS) to a tertiary care hospital in Karachi, Pakistan. Methods: The charts of patients conforming to International Classification of Diseases (ICD) code 9.0, for GBS, from September 1995 to January 2003 were reviewed. Clinical data was recorded on a standardized questionnaire, which included patients\u27 age, sex, antecedent events, neurological signs and symptoms and ventilation requirement. The hospital course was analyzed, including nosocomial infections, therapy given and the functional status of patients, using the Rankin scale (0-6). Standard SPSS 11.5 software (Windows) was used for data analysis. Results: Thirty-four cases of GBS were admitted to the hospital during the study period, with an age range of 3 to 70 years. The mean age for disease onset was 35.2 years for female patients, compared to 30 years for males; the male/female ratio was 1.6:1.Gastrointestinal infections (12/22, 54.6%) were the most common antecedent event, followed by upper respiratory tract infections (9/22, 40.9%) and skin lesions (1/22, 4.5%). Most patients developed GBS within one month of the preceding infection. Cranial nerve abnormalities (30/34, 88.2%), autonomic dysfunction (21/34, 61.8%) and respiratory failure requiring intubation (19/34, 55.9%) were also common. The median Rankin score of patients at admission, and at 30 and 60 days thereafter was 5, 4 and 3.5 respectively. The in-patient mortality was 1 of 34 (2.4%). Conclusion: We found that GBS occurred at all ages and was slightly more common in males. Majority of patients had an antecedent history of infection and had severe disease on presentation. The patients were treated with either plasmapheresis or intravenous immunoglobulins and there was no significant difference in outcome in the two groups. Despite severe persistent disability, in-hospital mortality was low (JPMA 55:493;2005)

Integrated geophysical analysis of the Sembar Formation, Central Indus Basin, as an unconventional resource

The ever-increasing demand for new energy sources witnessed at present is leading to a shortage of oil and gas resources throughout the world. At the same time, polluting energy sources such as coal are being gradually replaced by gas, new fuel types and electricity produced by renewable methods. Unconventional shale gas reserves, relying on the presence of substantial volumes of good quality, thermally mature organic matter, are therefore crucial in shaping the economic future of multiple regions in the world. Using seismic reflection data to estimate Total Organic Carbon (TOC) in the underexplored Sembar Formation of the Qadirpur Area, Central Indus Basin, this study investigates the potential of a new unconventional resource in Pakistan. We estimate TOC based on well-log data using Passey's Δ Log R, Schmoker's, and Schwarzkopf's methods. In a second stage, thermal maturity modelling was carried out for the formations encountered in Well Qadirpur Deep-01, while focusing primarily on the Sembar Formation. Petrophysical and petroelastic properties were determined and cross-plotted to identify potential zones favourable to hydraulic fracturing. The results show calculated TOC values ranging from 2 to 4 wt% based on the multiple methods indicated above, proving that the Sembar Formation is a good to excellent unconventional oil gas play. Thermal maturity modelling further confirms that the organic matter in the Sembar Formation is mature. Our seismic based spatial distribution indicates that TOC values are particularly favourable in the lower part of the formation, which is also prone to hydraulic fracturing based on its petroelastic evaluation. This study presents a valid approach to characterise source-rock potential in sedimentary basins throughout South Asia and around the world

Incremental composition process for the construction of component-based management

Cyber-physical systems (CPS) are composed of software and hardware components. Many such systems (e.g., IoT based systems) are created by composing existing systems together. Some of these systems are of critical nature, e.g., emergency or disaster management systems. In general, component-based development (CBD) is a useful approach for constructing systems by composing pre-built and tested components. However, for critical systems, a development method must provide ways to verify the partial system at different stages of the construction process. In this paper, for system architectures, we propose two styles: rigid architecture and flexible architecture. A system architecture composed of independent components by coordinating exogenous connectors is in flexible architecture style category. For CBD of critical systems, we select EX-MAN from flexible architecture style category. Moreover, we define incremental composition mechanism for this model to construct critical systems from a set of system requirements. Incremental composition is defined to offer preservation of system behaviour and correctness of partial architecture at each incremental step. To evaluate our proposed approach, a case study of weather monitoring system (part of a disaster management) system was built using our EX-MAN tool