263 research outputs found

    #civilrightscybertorts: Utilizing Torts to Combat Hate Speech in Online Social Media

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    Advocacy in the Preparation and Presentation of Medical Evidence

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    Fairness Issues in Law and Mental Health: Directions for Future Social Work Research

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    Concepts from the procedural justice literature in social psychology are examined that offer useful guidance for social work researchers with interests in investigating informal adjudications, speciality treatment courts, and other areas of the administrative process previously neglected in mental health services research. These theoretical concepts are offered as an alternative to the therapeutic jurisprudence framework being adopted by some social workers in the field of law and mental health. The issues outlined in this paper also draw on the health services and psychotherapy literature to highlight issues involving process and procedure as social justice and their significance for advancing a new role for social work researchers in the field of law and mental health research

    Low spring index, large displacement Shape Memory Alloy (SMA) coil actuators for use in macro- and micro-systems

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    Shape memory alloys (SMA) offer unique shape changing characteristics that can be exploited to produce low­ mass, low-bulk, large-stroke actuators. We are investigating the use of low spring index (defined as the ratio of coil diameter to wire diameter) SMA coils for use as actuators in morphing aerospace systems. Specifically, we describe the development and characterization of minimum achievable spring index coiled actuators made from 0.3048 mm (0.012") diameter shape memory alloy (SMA) wire for integration in textile architectures for future compression space suit applications. Production and shape setting of the coiled actuators, as well as experimental test methods, are described. Force, length and voltage relationships for multiple coil actuators are reported and discussed. The actuators exhibit a highly linear (R[superscript 2] < 0.99) relationship between isometric blocking force and coil displacement, which is consistent with current SMA coil models; and SMA coil actuators demonstrate the ability to produce significant linear forces (i.e., greater than 8 N per coil) at strains up to 3x their initial (i.e., fully coiled) length. Discussions of both the potential use of these actuators in future compression space suit designs, and the broader viability of these actuators in both macro- and micro-systems, are presented.United States. National Aeronautics and Space Administration. Office of the Chief Technologist (Space Technology Research Fellowship Grant NNX11AM62H)MIT-Portugal Progra

    Space exploration challenges : characterization and enhancement of space suit mobility and planetary protection policy analysis

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    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, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 189-193).This thesis addresses two challenges associated with advanced space and planetary exploration: characterizing and improving the mobility of current and future gas pressurized space suits; and developing effective domestic Planetary Protection policies for the emerging private space industry. Gas-pressurized space suits are known to be highly resistive to astronaut movement. As NASA seeks to return to planetary exploration, there is a critical need to improve full body space suit mobility for planetary exploration. Volume effects (the torque required to displace gas due to internal volume change during movement) and structural effects (the additional torque required to bend the suit materials in their pressurized state) are cited as the primary contributors to suit rigidity. Constant volume soft joints have become the design goal of space suit engineers, and simple joints like the elbow are believed to have nearly achieved such performance. However, more complex joints like the shoulder and waist have not yet achieved comparable optimization. As a result, it is hypothesized that joints like the shoulder and waist introduce a third, and not well studied, contributor to space suit rigidity: pressure effects (the additional work required to compress gas in the closed operating volume of the suit during movement). This thesis quantifies the individual contributors to space suit rigidity through modeling and experimentation. An Extravehicular Mobility Unit (EMU) space suit arm was mounted in a -30kPa hypobaric chamber, and both volume and torque measurements were taken versus elbow angle. The arm was tested with both open and closed operating volumes to determine the contribution of pressure effects to total elbow rigidity. These tests were then repeated using a full EMU volume to determine the actual impact of elbow pressure effects on rigidity when connected to the full suit. In both cases, structural and volume effects were found to be primary contributors to elbow joint rigidity, with structural effects dominating at low flexion angles and volume effects dominating at high flexion angles; pressure effects were detected in the tests that used only the volume of the arm, but were found to be a secondary contributor to total rigidity (on average 75°) flexion angles, suggesting that the underlying mechanisms of these effects are not yet fully understood, and that current models predicting structural effects behavior do not fully represent the actual mechanisms at work. The detection of pressure effects in the well-optimized elbow joint, even if only in a limited volume, suggests that these effects may prove significant for sub-optimized, larger, multi-axis space suit joints. A novel, fast-acting pressure control system, developed in response to these findings, was found to be capable of mitigating pressure spikes due to volume change (and thus, pressure effects). Implementation of a similar system in future space suit designs could lead to improvements in overall suit mobility. A second study, which focused on the implications of the development of the US private space industry on domestic Planetary Protection policy, is also presented. As signatories of the 1967 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space (commonly known as the Outer Space Treaty), the United States is responsible for implementing Planetary Protection procedures designed to prevent biological contamination of the Solar System, as well as contamination of the Earth by any samples returned from extra-terrestrial bodies. NASA has established policies and procedures to comply with this treaty, and has successfully policed itself independently and autonomously since the signing of the treaty. However, for the first time in the history of the American space program, private entities outside of NASA have developed the capability and interest to send objects into space and beyond Earth orbit, and no current protocol exists to guarantee these profit-minded entities comply with US Planetary Protection obligations (a costly and time-consuming process). This thesis presents a review of US Planetary Protection obligations, including NASA's procedures and infrastructure related to Planetary Protection, and based on these current protocols provides policy architecture recommendations for the emerging commercial spaceflight industry. It was determined that the most effective policy architecture for ensuring public and private compliance with Planetary Protection places NASA in control of all domestic Planetary Protection matters, and in this role NASA is charged with overseeing, supporting, and regulating the private spaceflight industry. The underlying analysis and architecture tradeoffs that led to this recommendation are presented and discussed.by Bradley Thomas Holschuh.S.M.in Technology and PolicyS.M

    Low Spring Index NiTi Coil Actuators for Use in Active Compression Garments

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    This paper describes the modeling, development, and testing of low spring index nickel titanium (NiTi) coil actuators designed for use in wearable compression garments, and presents a prototype tourniquet system using these actuators. NiTi coil actuators produce both large forces (>1 N) and large recoverable displacements (>100% length) that are well suited for compression garment design. Thermomechanical coil models are presented that describe temperature and force as a function of nondimensionalized coil geometry, extensional strain, and applied voltage. These models suggest that low spring index coils maximize activation force, and an analytical model is presented to predict garment counter-pressure based on actuator architecture. Several low spring index (C = 3.08) coils were manufactured, annealed, and tested to assess their detwinning and activation characteristics. Results suggest both annealing and applied stress affect activation thresholds. Actuator force increases both with extensional strain and applied voltage up to 7.24 N. A first-generation compression tourniquet system using integrated actuators with direct voltage control of applied pressure is presented, demonstrating >70% increase in applied pressure during activation. This approach enables new, dynamic garments with controllable activation and low effort donning and doffing, with applications ranging from healthcare solutions to advanced space suit design

    An Archaeology of Capitalism: Exploring Ideology through Ceramics from the Fort Vancouver and Village Sites

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    The Hudson\u27s Bay Company (HBC), a mercantile venture that was founded by royal charter in 1670, conceived, constructed and ran Fort Vancouver as its economic center in the Pacific Northwest, a colonial outpost at the edge of the company\u27s holdings in North America. Research into the history of the HBC revealed that the company was motivated by mercantile interests, and that Fort Vancouver operated under feudal land policies while steadily adopting a hierarchical structure. Following the work of Marxist archaeologist Mark Leone whose work in Annapolis, Maryland explored the effects of capitalist ideology on archaeological assemblages of ceramics, this study sought to locate the material signatures of ideologies in the ceramic assemblages recovered from the Fort and its adjacent multi-ethnic Village sites. In Annapolis, matching sets of ceramics were used as a material indicator of the successful penetration of capitalist ideals of segmentation, division and standardization that accompanied the carefully cultivated ideology of individualism, into working class households. Following this model, this study analyzed six assemblages for the presence of matched sets of ceramic tablewares using the diversity measures of richness and evenness. The results of this analysis for five assemblages from households in the Village were then compared to those expected for a model assemblage that was inferred to represent the ultimate model of participation in and dissemination of the same ideals of segmentation and division: that recovered from the Chief Factor\u27s House within the fort. Documentary research confirmed that ideology was used to indoctrinate workers into the unique relations of production at Fort Vancouver however it was an ideology of paternal allegiance to the company rather than one of possessive individualism, as in Annapolis. At Fort Vancouver the notion of individuality was subtly downplayed in favor of one that addressed the company\u27s responsibility to its workers and encouraged them to view its hierarchy, which was reinforced spatially, socially and economically, as natural. Analysis of the archaeological assemblages revealed that it is unlikely that the Village assemblages are comprised of complete sets of matching ceramicwares. The lack of these sets is likely the result of the multivalent nature of the economic system at the fort and its distinct ideology of paternalism, as well as the diverse backgrounds and outlooks of the Village occupants themselves, who appear to have purchased and used these European ceramics in unique ways

    Basal characteristics of the main sticky spot on the ice plain of Whillans Ice Stream, Antarctica

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    Understanding the processes that affect streaming ice flow and the mass balance of glaciers and ice sheets requires sound knowledge of their subglacial environments. Previous studies have shown that an extensive deformable subglacial sediment layer favors fast ice-stream flow. However, areas of high basal drag, termed sticky spots, are of particular interest because they inhibit the fast flow of the overriding ice. The stick-slip behavior of Whillans Ice Stream (WIS) is perhaps the most conspicuous manifestation of a subglacial sticky spot. We present new ice-thickness and seismic-reflection measurements collected over the main sticky spot in the ice plain of WIS, allowing us to elucidate its role in the behavior of the ice stream. Ice-thickness and surface-elevation data show that the sticky spot occupies a subglacial topographic high. Water flow in response to the hydrological potential gradient will be routed around the sticky spot if effective pressures are similar on the sticky spot and elsewhere. The seismic experiment imaged a laterally continuous basal layer approximately 6 m thick, having compressional wave velocities of greater than 1800 m s−1 and density greater than 1800 kg m−3, indicative of a till layer that is stiffer than corresponding till beneath well-lubricated parts of the ice stream. This layer likely continues to deform under the higher shear stress of the sticky spot, and some water may be pumped up onto the sticky spot during motion events

    Robotic Joint Torque Testing: A Critical Tool in the Development of Pressure Suit Mobility Elements

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    Pressure suits allow pilots and astronauts to survive in extreme environments at the edge of Earth’s atmosphere and in the vacuum of space. One obstacle that pilots and astronauts face is that gas-pressurized suits stiffen when pressurized and greatly limit user mobility. As a result, a critical need exists to quantify and improve the mobility characteristics of pressure suits. A historical survey and critique of pressure-suit testing methodologies is first presented, followed by the results of recent pressure suit testing conducted at the MIT Man-Vehicle Laboratory (MVL). MVL researchers, in cooperation with the David Clark Company (Worcester, MA), used an anthropometrically-realistic robotic space suit tester to quantify pressure suit mobility characteristics of the S1034 Pilot Protective Assembly (PPA), a pressure suit worn by U-2 pilots. This suit was evaluated unpressurized, at a vent pressure of 5.5 kPa (0.8 psi), and at an emergency gauge pressure of 20.7 kPa (3 psi). Joint torque data was collected for elbow flexion/extension, shoulder flexion/extension, shoulder abduction/adduction, and knee flexion/extension motions. The aim of this study was to generate a robust baseline mobility database for the S1034 PPA to serve as a point of comparison for future pressure suit designs, and to provide recommendations for future pressure garment testing

    Contributions to projection pursuit learning

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    Orientadores: Fernando Jose Von Zuben, Clodoaldo Aparecido de Moraes LimaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de ComputaçãoResumo: A obtenção de modelos parcimoniosos é uma necessidade em vários problemas de engenharia, como no caso de projeto de sistemas embarcados. Algoritmos construtivos para treinamento supervisionado têm apresentado efetividade como metodologias de projeto de redes neurais artificiais (RNAs) parcimoniosas, de boa acurácia e capacidade de generalização, embora requeiram mais recursos computacionais durante o processo de síntese da RNA. O aprendizado por busca de projeção está entre os métodos construtivos mais utilizados, mas ainda apresenta algumas limitações, sendo que aqui se procura tratar três delas: a inicialização da direção de projeção, o emprego de entrada de polarização junto aos neurônios da camada intermediária e a seleção de variáveis visando a redução no número de entradas, ou seja, na dimensão do vetor de projeção. Utilizou-se uma técnica de seleção de variáveis denominada wrapper, cuja implementação envolveu o emprego de um algoritmo genético, e realizaram-se experimentos de análise de desempenho no contexto de predição de séries temporais, indicando que as três propostas sugeridas trazem contribuições para o processo de aprendizado construtivoAbstract: The production of parsimonious models is a common demand on a wide variety of engineering problems, as in the design of embedded systems. Constructive algorithms for supervised learning have shown to be effective methodologies for the synthesis of parsimonious artificial neural networks, with high levels of accuracy and generalization capability, though requiring more computational resources during the training phase. Even being one of the most frequently adopted constructive learning methods, the projection pursuit learning algorithm still presents some limitations, and three of them will be treated here: the initialization of the direction of projection, the use of a bias term at the input of the hidden-layer neurons, and the selection of input variables as a form of reducing the number of inputs, i.e. the dimension of the vector of projection. The variable selection technique adopted here is denoted wrapper, and a genetic algorithm was considered as the search engine. The performance analysis has been carried out by experiments involving time series prediction, indicating that the three propositions suggested to deal with limitation of projection pursuit learning contribute favorably to the process of constructive learningMestradoEngenharia de ComputaçãoMestre em Engenharia Elétric
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