2,701 research outputs found

    Extended Life Qualification of the Magnetically Shielded Miniature (MaSMi) Hall Thruster

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    We present an update on the life qualification of the Magnetically Shielded Miniature (MaSMi) Hall thruster (also known as the ASTRAEUS Thruster Element), which was developed at the Jet Propulsion Laboratory and was recently licensed to ExoTerra Resource for flight production (renamed Halo12). In 2020-2021, the thruster successfully completed a 7205-hour wear test at operating powers from 200-1350 W, processing over 100 kg of xenon propellant and producing 1.55 MN-s total impulse with no measurable degradation in performance. The wear test is being extended to further demonstrate the service life capability of the thruster. In separate tests, prot-flight MaSMi hollow cathodes demonstrated \u3e 25000 ignition cycles and \u3e 13000 hours of operation at 4 A discharge current, and a set of three MaSMi electromagnets underwent \u3e 3000 deep thermal cycles (-123 °C to 495 °C). Laser-induced fluorescence (LIF) measurements of ion velocities and plasma modeling with Hall2De, a widely published numerical plasma code, have been carried out to elucidate the physical mechanisms driving pole erosion trends observed in thruster wear testing. Survival probabilities for micrometeoroid impacts and other random failure modes in flight were also analyzed

    PTF10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99

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    The Palomar Transient Factory (PTF) is systematically charting the optical transient and variable sky. A primary science driver of PTF is building a complete inventory of transients in the local Universe (distance less than 200 Mpc). Here, we report the discovery of PTF10fqs, a transient in the luminosity "gap" between novae and supernovae. Located on a spiral arm of Messier 99, PTF 10fqs has a peak luminosity of Mr = -12.3, red color (g-r = 1.0) and is slowly evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by intermediate-width H (930 km/s) and narrow calcium emission lines. The explosion signature (the light curve and spectra) is overall similar to thatof M85OT2006-1, SN2008S, and NGC300OT. The origin of these events is shrouded in mystery and controversy (and in some cases, in dust). PTF10fqs shows some evidence of a broad feature (around 8600A) that may suggest very large velocities (10,000 km/s) in this explosion. Ongoing surveys can be expected to find a few such events per year. Sensitive spectroscopy, infrared monitoring and statistics (e.g. disk versus bulge) will eventually make it possible for astronomers to unravel the nature of these mysterious explosions.Comment: 12 pages, 12 figures, Replaced with published versio

    SparCML: High-Performance Sparse Communication for Machine Learning

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    Applying machine learning techniques to the quickly growing data in science and industry requires highly-scalable algorithms. Large datasets are most commonly processed "data parallel" distributed across many nodes. Each node's contribution to the overall gradient is summed using a global allreduce. This allreduce is the single communication and thus scalability bottleneck for most machine learning workloads. We observe that frequently, many gradient values are (close to) zero, leading to sparse of sparsifyable communications. To exploit this insight, we analyze, design, and implement a set of communication-efficient protocols for sparse input data, in conjunction with efficient machine learning algorithms which can leverage these primitives. Our communication protocols generalize standard collective operations, by allowing processes to contribute arbitrary sparse input data vectors. Our generic communication library, SparCML, extends MPI to support additional features, such as non-blocking (asynchronous) operations and low-precision data representations. As such, SparCML and its techniques will form the basis of future highly-scalable machine learning frameworks

    Assessment of algorithms for mitosis detection in breast cancer histopathology images

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    The proliferative activity of breast tumors, which is routinely estimated by counting of mitotic figures in hematoxylin and eosin stained histology sections, is considered to be one of the most important prognostic markers. However, mitosis counting is laborious, subjective and may suffer from low inter-observer agreement. With the wider acceptance of whole slide images in pathology labs, automatic image analysis has been proposed as a potential solution for these issues. In this paper, the results from the Assessment of Mitosis Detection Algorithms 2013 (AMIDA13) challenge are described. The challenge was based on a data set consisting of 12 training and 11 testing subjects, with more than one thousand annotated mitotic figures by multiple observers. Short descriptions and results from the evaluation of eleven methods are presented. The top performing method has an error rate that is comparable to the inter-observer agreement among pathologists

    National Survey of Patients’ Bill of Rights Statutes

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    BACKGROUND Despite vigorous national debate between 1999–2001 the federal patients' bill of rights (PBOR) was not enacted. However, states have enacted legislation and the Joint Commission defined an accreditation standard to present patients with their rights. Because such initiatives can be undermined by overly complex language, we surveyed the readability of hospital PBOR documents as well as texts mandated by state law. METHODS State Web sites and codes were searched to identify PBOR statutes for general patient populations. The rights addressed were compared with the 12 themes presented in the American Hospital Association's (AHA) PBOR text of 2002. In addition, we obtained PBOR texts from a sample of hospitals in each state. Readability was evaluated using Prose, a software program which reports an average of eight readability formulas RESULTS Of 23 states with a PBOR statute for the general public, all establish a grievance policy, four protect a private right of action, and one stipulates fines for violations. These laws address an average of 7.4 of the 12 AHA themes. Nine states' statutes specify PBOR text for distribution to patients. These documents have an average readability of 15th grade (range, 11.6, New York, to 17.0, Minnesota). PBOR documents from 240 US hospitals have an average readability of 14th grade (range, 8.2 to 17.0) CONCLUSIONS While the average U.S. adult reads at an 8th grade reading level, an advanced college reading level is routinely required to read PBOR documents. Patients are not likely to learn about their rights from documents they cannot read.Pfizer Clear Health Communication Initiativ

    Prevalence of adulteration in dietary supplements and recommendations for safe supplement practices in sport

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    The prevalence of dietary supplement use among athletes continues to rise with 60–80% of athletes often reporting current or previous use of dietary supplements. While select dietary ingredients have been shown to improve acute performance and enhance training adaptations over time, it is important to still consider the risk vs. reward for athletes before opting to consume a dietary supplement. Previous work has indicated that certain dietary supplements may pose risks for inadvertent doping, may be susceptible to mislabelling, could be banned by certain governing bodies of sport, or pose health risks for certain populations. The purpose of the current narrative review is to summarize the prevalence of adulteration in dietary sport supplement products, outline the risks of inadvertent doping for athletes, and highlight best practices regarding safe supplementation strategies. Analytical studies have found anywhere from 14 to 50% of samples analyzed from dietary supplement products have tested positive for anabolic agents or other prohibited substances. It is important for the consumer to adhere to safe supplementation strategies, which include following serving size recommendations, cross-referencing ingredient profiles with the list of prohibited substances, choosing quality products that have been verified by a third-party certification program, and being cognizant of consuming multiple dietary supplement products with overlapping ingredient profiles. Once these practices have been considered, it is reasonable for an athlete to utilize dietary supplements as a strategy to optimize performance and health, with a low risk of failing a drug test (adverse analytical finding) and experiencing adverse events

    Protecting biodiversity in British Columbia: Recommendations for developing species at risk legislation

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    British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act

    Protecting biodiversity in British Columbia: Recommendations for developing species at risk legislation

    Get PDF
    British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act
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