An Anatomical and Biomechanical Study of the Human Iliotibial Band's Role in Elastic Energy Storage

The iliotibial band (ITB) is a complex structure that is unique to humans among apes and is derived from the fascia lata (FL) of the thigh. Although the ITB evolved in the hominin lineage, it is unclear whether it evolved to improve locomotor economy, increase stability, or serve a different function. This dissertation tests the hypothesis that the ITB stores and recovers elastic energy during walking and running.Human Evolutionary Biolog

Spinning a superfiber

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 34).Spider silk is a material of extraordinary beauty and utility. From the spider's perspective, it is foremost a building material, but also a safety net, a sensory organ, a weapon. From a human perspective, it is a material of extraordinary mechanical properties, an object of artistic and cultural interest, and a valuable window into the evolutionary history of spiders. Historically, there have been a mere handful of spider silk textiles, the most recent example of which was constructed by Simon Peers and Nicholas Godley. This was an extravagant work of art, and the silk was collected entirely by hand. Though the finished article is a testament to the beauty of spider silk, it also illustrates the technical challenges associated with obtaining it in any significant quantity. The effects of this scarcity are evident in the lab of David Kaplan at Tufts University. His group has developed a wide variety of applications for silk, but has focused mainly on silkworm silk in spite of spider silk's greater variety and superior mechanical properties. In the wild, spiders use silk for everything from weaving webs and capturing prey to breathing underwater. Shaped by almost every environment on Earth, spider silk has evolved into endless variations and permutations, offering a vast wealth of material knowledge if we can find a way to tap it. A visit to Cheryl Hayashi's spider silk genetics lab at the University of California, Riverside offers a look inside a spider and a glimpse of how genetic research can illuminate the evolution of silk. At the same time, it puts the limits of our knowledge into stark relief. The scarcity of natural spider silk has helped to drive a small industry in bioengineered and synthetic silk research, and also motivated projects that seek to apply the structural principles of silk fibers to other materials. But so far, these efforts are only a pale imitation of the real thing. For now, the spider is keeping her secrets.by Gillian S. Conahan.S.M.in Science Writin

Initiation and control of gait from first principles: a mathematically animated model of the foot

The initiation of bipedal gait is a willed action that causes a body at rest to move. Newton's first principle of motion is applied to experimental footprint data. leading to the premise that the big toe is the source of the body action force that initiates and controls bipedal gait

Evaluation of the Thorax of Manduca Sexta for Flapping-Wing Micro Air Vehicle Applications

The tobacco hornworm hawkmoth (Manduca sexta) provides an excellent model from which to garner knowledge pertaining to the development of a Flapping Wing Micro Air Vehicle (FWMAV). Insect-sized FWMAVs will be used by the future warfighter for reconnaissance, nuclear/chemical/biological hazard sensing, and targeting. One of the major challenges facing FWMAV developers is the energetically demanding nature of low Reynolds flapping flight. Investigating the Manduca sexta thorax/wing flapping mechanism as a mechanical system will provide insight into its inherent efficiency. This thesis examined the energetics of the thorax under static loading and dynamic loading using an innovative load-application technique. It was discovered that the thorax resists compression by a spring constant k=0.62 N/mm under the action of the dorsoventral flight muscles (DVMs). Constant stiffness measurement (CSM) nanoindentation of a major component of the thoracic exoskeleton, the tergum, revealed an elastic modulus of 5 GPa. This value is a benchmark for engineers seeking energy-storing materials for a FWMAV fuselage. Finally, a truly groundbreaking device was developed and used to directly measure the power requirement of the DVMs at Manduca sexta\u27s natural flapping frequency (25 Hz). This effort yielded a mechanical power output of 72-143 W*kg-1 for the DVMs. The feasibility of the author\u27s approach was confirmed by the agreement of this conclusion with published results. The power output requirement confirms the need for lightweight and energy-dense power sources for the fruition of fully-capable FWMAVs

Development of a Probabilistic Chimpanzee Glenohumeral Model: Implications for Human Function

Modern human shoulder function is affected by the evolutionary adaptations that have occurred to ensure survival and prosperity of the species. Robust examination of behavioral shoulder performance and injury risk can be holistically improved through an interdisciplinary approach that integrates anthropology and biomechanics. Anthropological research methods have attempted to resolve gaps in human shoulder evolution, while biomechanics research has attempted to explain the musculoskeletal function of the modern human shoulder. Coordination of these two fields can allow different perspectives to contribute to a more complete interpretation of, not only how the modern human shoulder is susceptible to specific injuries, but also why. How the modern human shoulder arose from a, likely, weight-bearing, arboreal past to its modern form, and what this has meant for modern behaviors, is not well understood. Despite a weight-bearing, locomotor ancestral usage, the modern human upper extremity is highly fatigable in repetitive, low to moderate force tasks, such as overhead reaching. The closest living human relative, modern chimpanzees, has retained an arboreal, locomotor upper extremity. Interdisciplinary comparative research on humans and chimpanzees could lead to greater insight on modern human shoulder function. The purpose of this research was to explore the modern human capacity for ancestral, brachiating behaviors and resultant injury mechanisms through comparative experimental, computational modeling and probabilistic modeling approaches with chimpanzees. The first study experimentally explored the modern human ability to perform a horizontal bimanual arm-suspensory climbing task. EMG of 12 upper extremity muscles and motion capture of the arm and thorax were monitored in experienced and inexperienced climbers. Results were also compared to previously published or collected data on chimpanzees performing an analogous task. While all human climbers used a high proportion of their muscular reserve to perform the task, experienced climbers had moderately reduced muscle activity in most muscles, particularly during phasic shifts of the climb cycle and moderately more efficient kinematics. Climbing kinematics and muscle activity were very similar between humans and chimpanzees. However, chimpanzees appear to have a different utility of the posterior deltoid, suggesting an influence of their habitual arboreal behaviors. The second and third studies describe the development of a deterministic chimpanzee musculoskeletal glenohumeral model. Study 2 developed geometric parameters of chimpanzee shoulder rhythm and glenoid stability ratios for the construction of a chimpanzee glenohumeral model. The chimpanzee glenohumeral model of Study 3 was designed to parallel an existing human glenohumeral model, enabling comparative analyses. The chimpanzee glenohumeral model consists of three modules – an external torque module, musculoskeletal geometric module, and an internal muscle force prediction module. Together, these modules use postural kinematics, subject specific anthropometrics and hand forces to estimate joint reaction forces and moments, subacromial space dimensions, and muscle and tissue forces. Using static postural data from Study 1, predicted muscle forces and subacromial space were compared between chimpanzees and humans during an overhead, weight-bearing climbing task. Compared to chimpanzees, the human model predicted a 2mm narrower subacromial space, deltoid muscle forces that were often double those of chimpanzees and a strong reliance on infraspinatus and teres minor (60-100% maximal force) over other rotator cuff muscles. Finally, the deterministic chimpanzee and human glenohumeral models were expanded in Study 4 to a probabilistic analysis of rotator cuff function between species. Using probabilistic software and the same postural climbing inputs, both models had anthropologically relevant musculoskeletal features perturbed in a series of Monte Carlo simulations – muscle origins and insertions, glenoid inclination and glenoid stability – to determine if rotator cuff muscle force prediction distributions would converge between species. Human rotator cuff muscle behavior did not converge with chimpanzees using probabilistic simulation. The human model continued to predict strong dependence on infraspinatus and teres minor, with 99% confidence intervals of [0-100]% maximal force, over supraspinatus and subscapularis, with confidence intervals of [0-5]% maximal force. Chimpanzee rotator cuff confidence intervals were typically between [0-40]% maximal force, with median force for all four rotator cuff muscles typically 5-20% maximal force. While perturbation of muscle origins and insertions had the greatest effect on muscle force output distributions, no musculoskeletal variation notably modified human climbing performance. Structural musculoskeletal differences between species dictated differences in glenohumeral function. The results from all studies indicate susceptibility for the fatigue-induced initiation of subacromial impingement syndrome and rotator cuff pathology in modern humans during overhead and repetitive tasks. Lower muscle absolute PCSA in humans, combined with a laterally oriented glenohumeral joint and laterally projecting acromion reduced the capacity for overhead postures and weight-bearing postures. These evolutionary differences may have been vestigial consequences, concurrent with necessary adaptions for important, evolutionary human-centric behaviors such as throwing. However, they have influenced the high rates of rotator cuff pathology in humans compared to closely related primates. The present work represents an important first step toward a broad scope of future research. Interdisciplinary computational modeling offers an evolving and improving alternative to traditional methods to study human evolution and function. Computational and probabilistic simulations can be expanded to numerous other biomechanical and evolutionary queries. The results of this thesis are a promising initial step to examining the evolutionary structural connection to biomechanical human function through comparative computational modeling

Pink Concrete

(From Reader Report Reflection) - I started this course believing I was not a writer. I knew that I loved to write, I knew that it was innate to how I perceived the world. I had written a novel previously, it was an outpouring, uncontrollable imagination spew. I was often scared and doubted myself throughout writing it, but I took comfort in my reading. I picked up all the classics, modern and old, rewriting the words into notebooks alongside my own, retracing the sounds, the rhythms, the symbols and their little links, the pauses. I collected pieces rereading them with reverence, my fingers curling over the lines sunken into the page. I didn’t understand what I was doing, it felt natural to hide in the skirts of other writers peering behind the curtain to see how they built the illusion. And yet, even after finishing my novel I still didn’t think I was a writer; it was a hobby, it was something extra to me, a backpack I could take off and on. I denied what was innate, and said it was not that important to me. I applied for this Master’s in Creative Writing (MACW)7 course because I wanted external validation on my first novel and an application was probably the only way, I was going to get someone to read it. It is sad and stunted that I needed this external validation to believe I could try, to believe that I could learn to control this compulsion, to believe that I could become a writer. In our first course contact week,8 lecturers and supervisors kept saying again again that we were already writers, that this is what we are. I was scared of this, that they would find out I was not really meant to be here. Writing, taking those solitary thoughts that are too much for my skull and making them real, something tangible; this is how I move through my existence. I take pieces of myself and paste them to the page, otherwise the thoughts build up like snow around a car until you are suffocating in an icebox. And by removing this part of myself to just a hobby, a silly backpack that I can pick up and put down, was just me running away. This MACW course gave me the tools to tap into what I am, that I have a why that I must write to and that I have an audience for this why. By sharing pieces of myself, I make them real again, something I can study, tracing their edges, their dark underbelly, the light hillocks. I sat with my fear for two years slowly, piece by piece, cracking it open. I learnt to love my voice and believe in it without needing external validation, without needing the gold star of acceptance, because I accept and love what I am trying to build with my writing.Thesis (MACW) -- Faculty of Arts, School of Languages and Literatures, 202

Recognition, Analysis, and Assessments of Human Skills using Wearable Sensors

One of the biggest social issues in mature societies such as Europe and Japan is the aging population and declining birth rate. These societies have a serious problem with the retirement of the expert workers, doctors, and engineers etc. Especially in the sectors that require long time to make experts in fields like medicine and industry; the retirement and injuries of the experts, is a serious problem. The technology to support the training and assessment of skilled workers (like doctors, manufacturing workers) is strongly required for the society. Although there are some solutions for this problem, most of them are video-based which violates the privacy of the subjects. Furthermore, they are not easy to deploy due to the need for large training data. This thesis provides a novel framework to recognize, analyze, and assess human skills with minimum customization cost. The presented framework tackles this problem in two different domains, industrial setup and medical operations of catheter-based cardiovascular interventions (CBCVI). In particular, the contributions of this thesis are four-fold. First, it proposes an easy-to-deploy framework for human activity recognition based on zero-shot learning approach, which is based on learning basic actions and objects. The model recognizes unseen activities by combinations of basic actions learned in a preliminary way and involved objects. Therefore, it is completely configurable by the user and can be used to detect completely new activities. Second, a novel gaze-estimation model for attention driven object detection task is presented. The key features of the model are: (i) usage of the deformable convolutional layers to better incorporate spatial dependencies of different shapes of objects and backgrounds, (ii) formulation of the gaze-estimation problem in two different way, as a classification as well as a regression problem. We combine both formulations using a joint loss that incorporates both the cross-entropy as well as the mean-squared error in order to train our model. This enhanced the accuracy of the model from 6.8 by using only the cross-entropy loss to 6.4 for the joint loss. The third contribution of this thesis targets the area of quantification of quality of i actions using wearable sensor. To address the variety of scenarios, we have targeted two possibilities: a) both expert and novice data is available , b) only expert data is available, a quite common case in safety critical scenarios. Both of the developed methods from these scenarios are deep learning based. In the first one, we use autoencoders with OneClass SVM, and in the second one we use the Siamese Networks. These methods allow us to encode the expert’s expertise and to learn the differences between novice and expert workers. This enables quantification of the performance of the novice in comparison to the expert worker. The fourth contribution, explicitly targets medical practitioners and provides a methodology for novel gaze-based temporal spatial analysis of CBCVI data. The developed methodology allows continuous registration and analysis of gaze data for analysis of the visual X-ray image processing (XRIP) strategies of expert operators in live-cases scenarios and may assist in transferring experts’ reading skills to novices