2,023 research outputs found

    Proposal for a Universal Particle Detector Experiment

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    The Universal Particle Detector Experiment (UPDE), which consists of parallel planes of two diode laser beams of different wavelengths and a large surface metal oxide semiconductor (MOS) impact detector, is proposed. It will be used to perform real-time monitoring of contamination particles and meteoroids impacting the spacecraft surface with high resolution of time, position, direction, and velocity. The UPDE will discriminate between contaminants and meteoroids, and will determine their velocity and size distribution around the spacecraft environment. With two different color diode lasers, the contaminant and meteroid composition will also be determined based on laboratory calibration with different materials. Secondary particles dislodged from the top aluminum surface of the MOS detector will also be measured to determine the kinetic energy losses during energetic meteoroid impacts. The velocity range of this instrument is 0.1 m/s to more than 14 km/s, while its size sensitivity is from 0.2 microns to millimeter-sized particles. The particulate measurements in space of the kind proposed will be the first simultaneous multipurpose particulate experiment that includes velocities from very slow to hypervelocities, sizes from submicrometer- to pellet-sized diameters, chemical analysis of the particulate composition, and measurements of the kinetic energy losses after energetic impacts of meteroids. The experiment will provide contamination particles and orbital debris data that are critically needed for our present understanding of the space environment. The data will also be used to validate contamination and orbital debris models for predicting optimal configuration of future space sensors and for understanding their effects on sensitive surfaces such as mirrors, lenses, paints, and thermal blankets

    Coordinating Diverse Public Programs in the Library

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    In spring of 2015, the University of Oregon Libraries (UO Libraries) co-sponsored a release event for the Urban League of Portland’s State of Black Oregon 2015 Report to increase campus diversity initiatives and community engagement. The event inspired collaboration across the campus and state to bring together multiple university and community partners, including UO Libraries, the University of Oregon’s Planning, Public Policy, and Management Program (PPPM), and the Urban League of Portland (ULPDX). Collaborations between libraries, nonprofit organizations, and other stakeholders highlight one aspect of the central role libraries serve as connectors in the local and regional communities. By co-sponsoring this event, UO Libraries furthered the University of Oregon’s educational mission to promote public scholarship and civic engagement, support community development, and increase diversity through meaningful and thoughtful programs. This article will detail how this partnership materialized, from buy-in to execution, as well as recommendations for libraries interested in coordinating with local community-centered nonprofit organizations to develop opportunities for diverse public programs throughout Oregon

    Polarity in Spanish, French, and English

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    Legislation

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    Disruption of State Estimation in the Human Lateral Cerebellum

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    The cerebellum has been proposed to be a crucial component in the state estimation process that combines information from motor efferent and sensory afferent signals to produce a representation of the current state of the motor system. Such a state estimate of the moving human arm would be expected to be used when the arm is rapidly and skillfully reaching to a target. We now report the effects of transcranial magnetic stimulation (TMS) over the ipsilateral cerebellum as healthy humans were made to interrupt a slow voluntary movement to rapidly reach towards a visually defined target. Errors in the initial direction and in the final finger position of this reach-to-target movement were significantly higher for cerebellar stimulation than they were in control conditions. The average directional errors in the cerebellar TMS condition were consistent with the reaching movements being planned and initiated from an estimated hand position that was 138 ms out of date. We suggest that these results demonstrate that the cerebellum is responsible for estimating the hand position over this time interval and that TMS disrupts this state estimate
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