Addressing design challenges in mechanical counter pressure spacesuit design and space-inspired informal education policy

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 155-161).Extravehicular activity (EVA), or spacewalks allows astronauts to accomplish some of the most important endeavors in space history. The importance of EVA will continue to increase as people venture further into our solar system. The spacesuit, used to protect the astronaut during EVA, is an anthropomorphic spacecraft that provides the physical environment a person needs to survive in the harsh environment of space. Although the suits are safe and effective, the pressurized suit becomes rigid in the vacuum of space, causing the astronaut to waste energy. Mechanical counterpressure (MCP) suits offer an alternative to gas pressurized suits by using elastic garments to provide pressure against the skin. Despite their many advantages, MCP suits are very difficult to put on, or don, making them infeasible for use today. A network of gas pressurized tubes is proposed as a solution to the donning problem. When pressurized, the tubes expand to become rigid, opening the MCP garment in the process. The system was modeled and a functional prototype was developed using a novel construction process. The model can be used as a design tool for future designs and the prototype serves as a proof-of-concept for this solution to the donning problem. The spectacular feats accomplish through spacewalks and space exploration inspire students to pursue an interest and career in science, technology, engineering, and math (STEM). Since its inception, the National Aeronautics and Space Administration (NASA) has been dedicated to educating the public about its compelling mission, fascinating discoveries, and the complicated technologies it develops. However, as the United States slips in indicators of student performance in STEM subjects, many look toward informal education, or education that occurs outside the classroom, to spur interest in STEM subjects. To maximize educational outcomes, NASA has developed a strategic framework to guide its educational programs. This framework is analyzed in the context of strategic management literature and suggests that the framework could be more easily implemented if NASA were to refine its education structure using the strengths of each of its directorates. The proposed framework was implemented in an informal education project and evaluated to determine if a projects implemented under the framework achieves the intended learning objectives. Students showed an increased understanding of NASA's mission and the complicated nature of space exploration. Suggestions to improve future projects are also given.by Allison P. Anderson.S.M.in Technology and PolicyS.M

Galvanic vestibular stimulation produces cross-modal improvements in visual thresholds

Background: Stochastic resonance (SR) refers to a faint signal being enhanced with the addition of white noise. Previous studies have found that vestibular perceptual thresholds are lowered with noisy galvanic vestibular stimulation (i.e., "in-channel" SR). Auditory white noise has been shown to improve tactile and visual thresholds, suggesting "cross-modal" SR. Objective: We aimed to study the cross-modal impact of noisy galvanic vestibular stimulation (nGVS) (n=9 subjects) on visual and auditory thresholds. Methods: We measured auditory and visual perceptual thresholds of human subjects across a swath of different nGVS levels in order to determine if a subject-specific best nGVS level elicited a reduction in thresholds as compared the no noise condition (sham). Results: We found an 18% improvement in visual thresholds (p = 0.026). Among the 7 of 9 subjects with reduced thresholds, the average improvement was 26%. Subjects with higher (worse) visual thresholds with no stimulation (sham) improved more than those with lower thresholds (p = 0.005). Auditory thresholds were unchanged by vestibular stimulation. Conclusions: These results are the first demonstration of cross-modal improvement with nGVS, indicating galvanic vestibular white noise can produce cross-modal improvements in some sensory channels, but not all.Comment: 15 pages, 7 figure

Too little, too late: reduced visual span and speed characterize pure alexia

Whether normal word reading includes a stage of visual processing selectively dedicated to word or letter recognition is highly debated. Characterizing pure alexia, a seemingly selective disorder of reading, has been central to this debate. Two main theories claim either that 1) Pure alexia is caused by damage to a reading specific brain region in the left fusiform gyrus or 2) Pure alexia results from a general visual impairment that may particularly affect simultaneous processing of multiple items. We tested these competing theories in 4 patients with pure alexia using sensitive psychophysical measures and mathematical modeling. Recognition of single letters and digits in the central visual field was impaired in all patients. Visual apprehension span was also reduced for both letters and digits in all patients. The only cortical region lesioned across all 4 patients was the left fusiform gyrus, indicating that this region subserves a function broader than letter or word identification. We suggest that a seemingly pure disorder of reading can arise due to a general reduction of visual speed and span, and explain why this has a disproportionate impact on word reading while recognition of other visual stimuli are less obviously affected

Determination of the LEP beam energy using radiative fermion-pair events

We present a determination of the LEP beam energy using “radiative return” fermion-pair events recorded at centre-of-mass energies from 183 to 209 GeV. We find no evidence of a disagreement between the OPAL data and the LEP Energy Working Group's standard calibration. Including the energy-averaged 11 MeV uncertainty in the standard determination, the beam energy we obtain from the OPAL data is higher than that obtained from the LEP calibration by View the MathML source0±34(stat.)±27(syst.)MeV

Visualizing Mutation-Specific Differences in the Trafficking-Deficient Phenotype of Kv11.1 Proteins Linked to Long QT Syndrome Type 2

KCNH2 encodes the Kv11.1 α-subunit that underlies the rapidly activating delayed-rectifier K+ current in the heart. Loss-of-function KCNH2 mutations cause long QT syndrome type 2 (LQT2), and most LQT2-linked missense mutations inhibit the trafficking of Kv11.1 channel protein to the cell surface membrane. Several trafficking-deficient LQT2 mutations (e.g., G601S) generate Kv11.1 proteins that are sequestered in a microtubule-dependent quality control (QC) compartment in the transitional endoplasmic reticulum (ER). We tested the hypothesis that the QC mechanisms that regulate LQT2-linked Kv11.1 protein trafficking are mutation-specific. Confocal imaging analyses of HEK293 cells stably expressing the trafficking-deficient LQT2 mutation F805C showed that, unlike G601S-Kv11.1 protein, F805C-Kv11.1 protein was concentrated in several transitional ER subcompartments. The microtubule depolymerizing drug nocodazole differentially affected G601S- and F805C-Kv11.1 protein immunostaining. Nocodazole caused G601S-Kv11.1 protein to distribute into peripheral reticular structures, and it increased the diffuse immunostaining of F805C-Kv11.1 protein around the transitional ER subcompartments. Proteasome inhibition also affected the immunostaining of G601S- and F805C-Kv11.1 protein differently. Incubating cells in MG132 minimally impacted G601S-Kv11.1 immunostaining, but it dramatically increased the diffuse immunostaining of F805C-Kv11.1 protein in the transitional ER. Similar results were seen after incubating cells in the proteasome inhibitor lactacystin. Differences in the cellular distribution of G601S-Kv11.1 and F805C-Kv11.1 protein persisted in transfected human inducible pluripotent stem cell derived cardiomyocytes. These are the first data to visually demonstrate mutation-specific differences in the trafficking-deficient LQT2 phenotype, and this study has identified a novel way to categorize trafficking-deficient LQT2 mutations based on differences in intracellular retention

Multi-photon events with large missing energy in e+e−e+e− collisions at s=192–209 GeV

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Flavour independent search for Higgs bosons decaying into hadronic final states in e^(+)e^(−)e^(+)e^(−) collisions at LEP

A search for the Higgsstrahlung process e^(+)e^(−)→hZ is described, where the neutral Higgs boson h is assumed to decay into hadronic final states. In order to be sensitive to a broad range of models, the search is performed independent of the flavour content of the Higgs boson decay. The analysis is based on e^(+)e^(−) collision data collected by the OPAL detector at energies between 192 and 209 GeV. The search does not reveal any significant excess over the Standard Model background prediction. Results are combined with previous searches at energies around 91 and at 189 GeV. A limit is set on the product of the cross-section and the hadronic branching ratio of the Higgs boson, as a function of the Higgs boson mass. Assuming the hZ coupling predicted by the Standard Model, and a Higgs boson decaying only into hadronic final states, a lower bound of 104 GeV/c2104 GeV/c^(2) is set on the mass at the 95% confidence level

W boson polarisation at LEP2

This is the publisher's version, also available electronically from http://www.sciencedirect.com/science/article/pii/S0370269304002576