A knee brace design to reduce the energy consumption of walking

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaves 51-52).Recent research into the mechanics of walking indicates that a quasi passive wearable device could be created which dramatically reduces the metabolic energy used in walking especially when the wearer is carrying additional torso weight. Target population groups include military personnel who must carry heavy battle packs and body armor, hikers, letter carriers, and the quasi disabled. This latter group includes a significant fraction of the elderly who have reduced leg strength and/or higher weight torsos. The device is called PUUMA, an acronym for Personal Unpowered Universal Mobility Assistant. Though walking has been studied extensively, there appears to be a limited understanding of the interplay between the kinetic and potential energy of the torso when driven by legs that can store and release energy. This thesis introduces a simplified model which enables simulation of the entire walking process including the epoch following heel strike. One simulation goal was to explore the knee spring properties which enable lossless walking. Simulations show that there are two knee spring configurations which allow for lossless walking. It is also shown that the percentage of kinetic energy transferred to a knee spring can be a significant fraction of the torso kinetic energy.(cont.) PIJUMA's basic idea is the incorporation of torsion springs at the knee joints which absorb torso kinetic energy following heel strike and then release that stored energy later in the step. An application of the capstan effect is introduced which enables a practical implementation of two knee spring configurations. In particular, the design allows the thigh and shank to be dynamically coupled to a microprocessor controlled knee spring thereby allowing both unimpeded leg swing and kinetic energy transfer to the knee spring. Another use of the capstan effect is introduced which allows for a microprocessor controlled brake that can freeze the knee at its maximum torsion and then release it later in the walking cycle. A design is shown which embodies the architectural ideas created. Several of the key components were designed, prototyped and tested.by Matthew R. Carvey.S.B

The Effects of Psychostimulant Drugs on Blood Brain Barrier Function and Neuroinflammation

The blood brain barrier (BBB) is a highly dynamic interface between the central nervous system (CNS) and periphery. The BBB is comprised of a number of components and is part of the larger neuro(glio)vascular unit. Current literature suggests that psychostimulant drugs of abuse alter the function of the BBB which likely contributes to the neurotoxicities associated with these drugs. In both preclinical and clinical studies, psychostimulants including methamphetamine, MDMA, cocaine, and nicotine, produce BBB dysfunction through alterations in tight junction protein expression and conformation, increased glial activation, increased enzyme activation related to BBB cytoskeleton remodeling, and induction of neuroinflammatory pathways. These detrimental changes lead to increased permeability of the BBB and subsequent vulnerability of the brain to peripheral toxins. In fact, abuse of these psychostimulants, notably methamphetamine and cocaine, has been shown to increase the invasion of peripheral bacteria and viruses into the brain. Much work in this field has focused on the co-morbidity of psychostimulant abuse and human immunodeficiency virus (HIV) infection. As psychostimulants alter BBB permeability, it is likely that this BBB dysfunction results in increased penetration of the HIV virus into the brain thus increasing the risk of and severity of neuro AIDS. This review will provide an overview of the specific changes in components within the BBB associated with psychostimulant abuse as well as the implications of these changes in exacerbating the neuropathology associated with psychostimulant drugs and HIV co-morbidity

Rapid detection of human facial attractiveness in groups

In a world full of great visual repetition, humans have evolved to simplify visual processing, taking redundant information and compressing it into a simpler form (Alvarez, 2011). This compressed form is an ensemble representation, an abstract singular entity that conveys the relevant information about its constituents.Haberman & Whitney (2009) demonstrated that even with stimuli as complex as human faces, and specifically their emotional expressions, such a representation can be generated, and the mean expression of a group can be accurately identified from brief presentations. Other research has shown that the attractiveness of faces can be rapidly assessed from very brief exposures (Olson & Marshuetz, 2005; Willis & Todorov, 2006), but this has not considered more than a single face in a presentation. Those that have, only considered estimates of frequency of attractiveness comparing between brief exposures and longer presentation times, not taking into account how accurate these estimates were.The aim of this thesis was to explore the accuracy with which participants could judge the attractiveness of a group of faces, either as a two-alternative-forced-choice task judging which of two groups contained more attractive faces, whether a single group contained more attractive or more unattractive faces, and estimating the number of attractive faces in a group. The results showed that the judgements of attractiveness were accurate from brief exposures, but this judgement was modulated partially by the task at hand. This modulation was further explored by comparing various ratings of attractiveness of the groups, and suggested that the ensemble representation might be formed by some combination of statistical and visual averaging. Finally, the use of eye-tracking technology showed no bias in visual attention towards more attractive faces, and that fixation duration patterns were, to some extent, also modulated by the task

Effectiveness of the Introduction to Critical Care in Emergency Medicine Curriculum\u27s Implementation Among Trainees Interested in Intensive Care

Background: Emergency physicians and trainees provide the initial care for critically ill patients. In times of emergency department boarding, this care may extend beyond the first few hours. To meet the needs of this population, a standardized novel critical care curriculum targeting third- and fourth-year medical students was developed. Objectives: We hypothesized that the institution of such a curriculum is feasible and will provide an increased understanding of the underlying critical care principles within this learner population. Methods: We developed a 2-month-long critical care curriculum (February–April) and carried out the course twice from 2022–2023. Our pilot study deployed this curriculum to medical students interested in critical care through the American Academy of Emergency Medicine/Resident and Student Association. The primary outcome included was the overall composite score comparison of the pre- and post-course evaluations, with a higher score indicating that the student improved their comprehension. Secondary outcomes included the individual factors of the pre- and post-course surveys. Results: Fifty-one trainees completed the pilot course, including 11/51 (21.6%) third-year medical students and 40/51 (78.4%) fourth-year medical students. Overall, 39 had “no experience” in critical care and 12 indicated that they had “previous experience.” The students’ baseline pre-course from the pooled 2022 and 2023 Introduction to Critical Care in Emergency Medicine (ICCEM) curriculum data was 3 (interquartile range 4–3) and their post-course score was 9 (interquartile range 9–9), p-value 0.015 for the 51/54 students who completed the course. Conclusions: The novel curriculum was found to be effective during its implementation in third- and fourth-year medical students. As such, it indicated that a critical care fundamentals course improves confidence in these topics for students with and without prior experience. Further work is necessary to understand the generalizability and knowledge retention of the proposed pilot curriculum

Observasi Dalam Mencipta Karya Seni

In the beginning of creating a work of art, an observation of the problem is needed. A new representation of an existing form, would not become a newness if not display novelty and actuality, as it will only produce something similar, and repetition, so it will not be a result of creativity

Evaluating the Performance Benefits of a Smart Radiator Device in Small Spacecraft Missions, for Earth Orbits and Beyond

A Smart Radiator Device (SRD) was developed by MPBC to meet the growing demand for advanced thermal control in smaller spacecraft. The SRDs exhibit a temperature-dependent emissivity profile due to the metal insulator phase transition of the thermochromic material of the coating. This results in a reduction in heat radiated from the spacecraft in low temperatures and consequently, a decrease in the power demand of heaters. We compared the expected performance of the SRD’s to that of a traditional radiator through three simulated missions, with an emphasis on power and payload temperature swings

Averaging sets of expressive faces is modulated by eccentricity.

Research has shown that participants can extract the average facial expression from a set of faces when these were presented at fixation. In this study, we investigated whether this performance would be modulated by eccentricity given that neural resources are limited outside the foveal region. We also examined whether or not there would be compulsory averaging in the parafovea as has been previously reported for the orientation of Gabor patches by Parkes, Lund, Angelucci, Solomon, and Morgan (2001). Participants were presented with expressive faces (alone or in sets of nine, at fixation or at 3° to the left or right) and were asked to identify the expression of the central target face or to estimate the average expression of the set. Our results revealed that, although participants were able to extract average facial expressions in central and parafoveal conditions, their performance was superior in the parafovea, suggesting facilitated averaging outside the fovea by peripheral mechanisms. Furthermore, regardless of whether the task was to judge the expression of the central target or set average, participants had a tendency to identify central targets' expressions in the fovea but were compelled to average in the parafovea, a finding consistent with compulsory averaging. The data also supported averaging over substitution models of crowding. We conclude that the ability to extract average expressions in sets of faces and identify single targets' facial expressions is influenced by eccentricity

A metabolically efficient leg brace

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 106-108).Locomotion assistive devices can be broadly classified as either being passive or powered. Both have been created to aid in the leg's generation of a ground reaction force which supports the torso during locomotion, yet their inherent design has limited their functional growth to date. While many differing gait simulations have demonstrated stable solutions for lossless gait cycles, passive orthoses only diminish the user's impediment, and though powered gait exoskeletons can augment strength and endurance, they are limited by their energy demanding actuators. In response to these two extremes, an energy efficient locomotion assist device was developed from the basis of lossless gait models that did not require external power, and augmented locomotion by harvesting the inherent energy associated with the gait cycle. The simplest anthropomorphic leg can be modeled with a peg-leg shank, a knee, a thigh and a point mass for the head, arms and torso. Using a tuned non-linear hardening torsion spring at the knee joint, the torso support that is required between the ground and pelvis for lossless gait simulations can be generated; allowing the close physical realization of the theoretical. It was found that a single torsion spring can generate the leg thrusts necessary for a realistic range of walking and running gait velocities without the addition of any external power. While frictional losses do inhibit the locomotion assist device's efficiency, since the device functions in parallel with the user's leg, any losses can be supplemented with minimal muscular activity. These results give strong indication that a new avenue of gait assistive and gait augmenting devices that require minimal actuation energy is feasible.by Andrew Williams Carvey.S.M