11,125 research outputs found

    An economic comparison of three heavy lift airborne systems

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    Current state of art trends indicate that a 50-ton payload helicopter could be built by the end of the decade. However, alternative aircraft that employ LTA principles are shown to be more economically attractive, both in terms of investment and operating costs for the ultra-heavy lift role. Costing methodology follows rationale developed by airframe manufacturers, and includes learning curve factors

    A case study of technical change and rehabilitation: Intervention design and interdisciplinary team interaction

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    The design of effective interventions in sport psychology often requires a subtle blend of techniques, tailored to meet the client’s specific needs. Input from a variety of disciplinary support specialists, working as a team, is also frequently needed. Accordingly, this study investigated an interdisciplinary team approach to the technical change and rehabilitation of an elite weight lifter following injury; necessitating the avoidance of regression when performing under competitive pressure. Multiple coaching approaches were used and complimented by targeting specific mental skills. Kinematic analyses indicated progressive technical, and subsequently permanent, change even after 2 years. Self-report measures of self-efficacy and imagery use were deemed essential in facilitating the change. Finally, a discussion focuses on the intervention’s multifactorial nature, its application within high performance coaching, and how this may advise future research into the refinement of already existing and well-established skills

    The NASA firefighter's breathing system program

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    The research is reported in the development of a firefighter's breathing system (FBS) to satisfy the operational requirements of fire departments while remaining within their cost constraints. System definition for the FBS is discussed, and the program status is reported. It is concluded that the most difficult problem in the FBS Program is the achievement of widespread fire department acceptance of the system

    Long term frequency stability analysis of the GPS NAVSTAR 6 Cesium clock

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    Time domain measurements, taken between the NAVSTAR 6 Spacecraft Vehicle (SV) and the Vandenberg Global Positioning System (GPS) Monitor Site, by a pseudo random noise receiver, were collected over an extended period of time and analyzed to estimate the long term frequency stability of the NAVSTAR 6 onboard frequency standard, referenced to the Vandenberg MS frequency standard. The technique employed separates the clock offset from the composite signal by first applying corrections for equipment delays, ionospheric delay, tropospheric delay, Earth rotation and the relativistic effect. The data are edited and smoothed using the predicted SV ephemeris to calculate the geometric delay. Then all available passes from each of the four GPS monitor stations, are collected at 1-week intervals and used to calculate the NAVSTAR orbital elements. The procedure is then completed by subtracting the corrections and the geometric delay, using the final orbital elements, from the composite signal, thus leaving the clock offset and random error

    Establishment, Impacts, and Current Range of Spotted Knapweed (\u3ci\u3eCentaurea Stoebe\u3c/i\u3e Ssp. \u3ci\u3eMicranthos\u3c/i\u3e) Biological Control Insects in Michigan

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    Centaurea stoebe L. ssp. micranthos (Gugler) Hayek (spotted knapweed) is an invasive plant that has been the target of classical biological control in North America for more than four decades. Work in the western U.S. and Canada has shown the seedhead-feeding weevils Larinus minutus Gyllenhal and Larinus obtusus Gyllenhal (Coleoptera: Curculionidae) and the root-boring weevil Cyphocleonus achates (Fahraeus) (Coleoptera: Curculionidae) to be the most effective C. stoebe control agents. These three weevils have recently been introduced into the eastern U.S., including sites in Michigan in 2007 and 2009. In 2010, we made additional releases at six sites in Michigan, monitoring them for three years 2011-13. Here we report on the establishment, impact, and cur- rent range of L. minutus, L. obtusus, and C. achates in Michigan. We also report on the initial results of native plant overseeding treatments that were applied to biological control release sites with the aim of supplementing the nectar source C. stoebe provides. We found that L. minutus has established at all of its Michigan release sites and is widespread in the southwestern part of the state, while L. obtusus has established at the single site where it was released in 2007 and is spreading to adjoining counties. We also found C. achates to be present at four sites and established at one additional site in Michigan, but in all cases abundances are low and dispersal has been minimal (\u3c 10 m). In the three years following the 2010 releases, we found no measurable impacts of these biological control agents on C. stoebe growth, demographics, or plant community metrics. We also found little evidence of native flowering plant establishment at seeded sites. These baseline data will be useful in monitoring the spread and potential impacts of biological control agents on C. stoebe in Michigan

    The Rachel Carson Letters and the Making of Silent Spring

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    Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance
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