3,040 research outputs found

    A continuous media transport protocol

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    A protocol for the transmission of digitized audio and video data must schedule data transmission such that each audio or video sample is available in the receiver\u27s buffer by its play-out deadline without overflowing the allotted buffer space at the receiver. While traditional data communication protocols provide error-free data transmission through the use of time-outs and retransmissions, the unbounded number of retransmissions that a packet may suffer results in an unboundable network transmission delay. Thus, such protocols are not appropriate for the real-time transmission of digitized audio and video data;This dissertation examines the network environments likely to be used for digitized audio and video data transmission and develops an audio/video transport-layer communication protocol which for such network environments. A unique feature of this protocol is the calculation of a transmission schedule which can minimize the buffer requirements at the receiver while still meeting the real-time play-out deadlines of the individual audio and video streams

    Reliability assessment for low-cost unmanned aerial vehicles

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    University of Minnesota Ph.D. dissertation. November 2014. Major: Aerospace engineering and mechanics. Advisors: Gary J. Balas, Peter J. Seiler. 1 computer file (PDF); viii, 110 pages, appendices A-D.Existing low-cost unmanned aerospace systems are unreliable, and engineers must blend reliability analysis with fault-tolerant control in novel ways. This dissertation introduces the University of Minnesota unmanned aerial vehicle flight research platform, a comprehensive simulation and flight test facility for reliability and fault-tolerance research. An industry-standard reliability assessment technique, the failure modes and effects analysis, is performed for an unmanned aircraft. Particular attention is afforded to the control surface and servo-actuation subsystem. Maintaining effector health is essential for safe flight; failures may lead to loss of control incidents. Failure likelihood, severity, and risk are qualitatively assessed for several effector failure modes. Design changes are recommended to improve aircraft reliability based on this analysis. Most notably, the control surfaces are split, providing independent actuation and dual-redundancy. The simulation models for control surface aerodynamic effects are updated to reflect the split surfaces using a first-principles geometric analysis.The failure modes and effects analysis is extended by using a high-fidelity nonlinear aircraft simulation. A trim state discovery is performed to identify the achievable steady, wings-level flight envelope of the healthy and damaged vehicle. Tolerance of elevator actuator failures is studied using familiar tools from linear systems analysis. This analysis reveals significant inherent performance limitations for candidate adaptive/reconfigurable control algorithms used for the vehicle. Moreover, it demonstrates how these tools can be applied in a design feedback loop to make safety-critical unmanned systems more reliable.Control surface impairments that do occur must be quickly and accurately detected. This dissertation also considers fault detection and identification for an unmanned aerial vehicle using model-based and model-free approaches and applies those algorithms to experimental faulted and unfaulted flight test data. Flight tests are conducted with actuator faults that affect the plant input and sensor faults that affect the vehicle state measurements. A model-based detection strategy is designed and uses robust linear filtering methods to reject exogenous disturbances, e.g. wind, while providing robustness to model variation. A data-driven algorithm is developed to operate exclusively on raw flight test data without physical model knowledge. The fault detection and identification performance of these complementary but different methods is compared. Together, enhanced reliability assessment and multi-pronged fault detection and identification techniques can help to bring about the next generation of reliable low-cost unmanned aircraft

    Epidemiologic Questions from Anthrax Outbreak, Hunter Valley, Australia

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    Anthrax was introduced into Australia in 1847 near Sydney, New South Wales, and spread along stock routes throughout New South Wales and southern Queensland. Anthrax was considered endemic to the Hunter Valley, New South Wales, during the 1890s. The last recorded anthrax-related stock losses there occurred on 3 properties in the Upper Hunter Valley in 1939. During the past 4 decades, anthrax has become uncommon in Australia. However, our experience is a timely reminder that veterinary public health authorities should be on high alert for possible anthrax when unexpected livestock deaths follow flooding in areas where anthrax has historically occurred

    Neurophysiology

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    Contains reports on seven research projects.National Institutes of Health (Grant 5 RO1 EY01149-02)Bell Telephone Laboratories, Inc. (Grant)National Institutes of Health (Grant 1 TO1 EY00090-01

    Cannabidiol for the treatment of cannabis use disorder:a phase 2a, double-blind, placebo-controlled, randomised, adaptive Bayesian trial

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordData sharing: We are unable to share data because participants did not provide consent for data sharing.Background A substantial and unmet clinical need exists for pharmacological treatment of cannabis use disorders. Cannabidiol could offer a novel treatment, but it is unclear which doses might be efficacious or safe. Therefore, we aimed to identify efficacious doses and eliminate inefficacious doses in a phase 2a trial using an adaptive Bayesian design. Methods We did a phase 2a, double-blind, placebo-controlled, randomised, adaptive Bayesian trial at the Clinical Psychopharmacology Unit (University College London, London, UK). We used an adaptive Bayesian dose-finding design to identify efficacious or inefficacious doses at a-priori interim and final analysis stages. Participants meeting cannabis use disorder criteria from DSM-5 were randomly assigned (1:1:1:1) in the first stage of the trial to 4-week treatment with three different doses of oral cannabidiol (200 mg, 400 mg, or 800 mg) or with matched placebo during a cessation attempt by use of a double-blinded block randomisation sequence. All participants received a brief psychological intervention of motivational interviewing. For the second stage of the trial, new participants were randomly assigned to placebo or doses deemed efficacious in the interim analysis. The primary objective was to identify the most efficacious dose of cannabidiol for reducing cannabis use. The primary endpoints were lower urinary 11-nor-9-carboxy-Ī“-9-tetrahydrocannabinol (THC-COOH):creatinine ratio, increased days per week with abstinence from cannabis during treatment, or both, evidenced by posterior probabilities that cannabidiol is better than placebo exceeding 0Ā·9. All analyses were done on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov (NCT02044809) and the EU Clinical Trials Register (2013-000361-36). Findings Between May 28, 2014, and Aug 12, 2015 (first stage), 48 participants were randomly assigned to placebo (n=12) and to cannabidiol 200 mg (n=12), 400 mg (n=12), and 800 mg (n=12). At interim analysis, cannabidiol 200 mg was eliminated from the trial as an inefficacious dose. Between May 24, 2016, and Jan 12, 2017 (second stage), randomisation continued and an additional 34 participants were allocated (1:1:1) to cannabidiol 400 mg (n=12), cannabidiol 800 mg (n=11), and placebo (n=11). At final analysis, cannabidiol 400 mg and 800 mg exceeded primary endpoint criteria (0Ā·9) for both primary outcomes. For urinary THC-COOH:creatinine ratio, the probability of being the most efficacious dose compared with placebo given the observed data was 0Ā·9995 for cannabidiol 400 mg and 0Ā·9965 for cannabidiol 800 mg. For days with abstinence from cannabis, the probability of being the most efficacious dose compared with placebo given the observed data was 0Ā·9966 for cannabidiol 400 mg and 0Ā·9247 for cannabidiol 800 mg. Compared with placebo, cannabidiol 400 mg decreased THC-COOH:creatinine ratio by āˆ’94Ā·21 ng/mL (95% interval estimate āˆ’161Ā·83 to āˆ’35Ā·56) and increased abstinence from cannabis by 0Ā·48 days per week (0Ā·15 to 0Ā·82). Compared with placebo, cannabidiol 800 mg decreased THC-COOH:creatinine ratio by āˆ’72Ā·02 ng/mL (āˆ’135Ā·47 to āˆ’19Ā·52) and increased abstinence from cannabis by 0Ā·27 days per week (āˆ’0Ā·09 to 0Ā·64). Cannabidiol was well tolerated, with no severe adverse events recorded, and 77 (94%) of 82 participants completed treatment. Interpretation In the first randomised clinical trial of cannabidiol for cannabis use disorder, cannabidiol 400 mg and 800 mg were safe and more efficacious than placebo at reducing cannabis use.Medical Research Council (MRC

    The polaroid image as photo-object

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    This article is part of a larger project on the cultural history of Polaroid photography and draws on research done at the Polaroid Corporate archive at Harvard and at the Polaroid company itself. It identifies two cultural practices engendered by Polaroid photography, which, at the point of its extinction, has briefly flared into visibility again. It argues that these practices are mistaken as novel but are in fact rediscoveries of practices that stretch back as many as five decades. The first section identifies Polaroid image-making as a photographic equivalent of what Tom Gunning calls the ā€˜cinema of attractionsā€™. That is, the emphasis in its use is on the display of photographic technologies rather than the resultant image. Equally, the common practice, in both fine art and vernacular circles, of making composite pictures with Polaroid prints, draws attention from image content and redirects it to the photo as object

    Health benefits attributed to 17Ī±-estradiol, a lifespan-extending compound, are mediated through estrogen receptor Ī±.

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    Metabolic dysfunction underlies several chronic diseases, many of which are exacerbated by obesity. Dietary interventions can reverse metabolic declines and slow aging, although compliance issues remain paramount. 17Ī±-estradiol treatment improves metabolic parameters and slows aging in male mice. The mechanisms by which 17Ī±-estradiol elicits these benefits remain unresolved. Herein, we show that 17Ī±-estradiol elicits similar genomic binding and transcriptional activation through estrogen receptor Ī± (ERĪ±) to that of 17Ī²-estradiol. In addition, we show that the ablation of ERĪ± completely attenuates the beneficial metabolic effects of 17Ī±-E2 in male mice. Our findings suggest that 17Ī±-E2 may act through the liver and hypothalamus to improve metabolic parameters in male mice. Lastly, we also determined that 17Ī±-E2 improves metabolic parameters in male rats, thereby proving that the beneficial effects of 17Ī±-E2 are not limited to mice. Collectively, these studies suggest ERĪ± may be a drug target for mitigating chronic diseases in male mammals
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