2,521 research outputs found

    The Distribution of \u3ci\u3eCorydalus Cornutus\u3c/i\u3e (Linnaeus) and \u3ci\u3eNigronia Serricornis (Say) (Megaloptera: Corydalidae) in Michigan

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    (excerpt) The distribution of the hellgrammite [Corydalus cornutus (Linnaeus)] and the sawcombed fishfly [Nigronia serricornis (Say)] in Michigan was determined as part of an investigation of the biology of these large Megalopterans (Knight and Simmons, 1975a, 1975b). Megalopteran larvae are some of the largest aquatic insects, with a maximum length of approximately 84 mm. They are robust larvae with paired lateral abdominal appendages on segments 1-8 and a pair of anal prolegs bearing two strong hooks. They are fiercely predaceous and generally insectivorous, feeding chiefly on larvae of Simulium, Cheumatopsyche, Hydropsyche and Chironomidae, but eating almost anything they can subdue, including their own kind (Chandler, 1956; Stewart et al., 1973)

    STUDIES ON PLANT BILE PIGMENTS.

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    The (4 Z, 10 2, 15Ej-2,3-dihydrobilindione 4, along with the fully unsaturated (E, 2, Z)-analogue 8, has been prepared from the corresponding (Z, Z, Z)-isomer by a variation of Falk's method (Falk et ul., 1980). The photochemical and acid-catalyzed back-reactions have been studied by UV-vis and 'H-NMR spectroscopy

    Paper Session I-B - Maximization of Benefits From the Space Exploration Initiative

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    On the 20th anniversary, in 1989, of our country\u27s triumphant first landing on the surface of our moon, the President of the United States once again challenged the nation to excel in space. Since that time, a series of outreach efforts was initiated by NASA to the aerospace industry, federal agencies, and the public. In addition, the Vice President of the United States chartered an Advisory Committee on the Future of the U.S. Space Program. At this writing, the AIAA has submitted a report on their canvass of the aerospace community, and the Advisory Committee report has been published. The synthesis group is in the conclusion preparation phase and should have the report completed by the time of this conference. Although each of these groups has taken different approaches, a consensus does appear that agrees with the President\u27s objectives. Whether the schedule or architectures agree, they all recommend a ...\u27 \u27balanced Space Program for America. We will, within budgetary limits, reenergize our country\u27s thrust into space through a renewed dedication toward the long-term magnet for the manned space program ... the human exploration of Mars. This, of course, is the long-term goal coupled with the science, mission-to-planet Earth, expanded technology and development of a robust space transportation system that make up the balanced program recommended. The authors do not disagree with the goals, objectives, or recommendations of the two reports published to date nor will we differ with the synthesis conclusions after they become apparent. We will briefly summarize the results of an .analysis conducted by McDonnell Douglas and Eagle Engineering in the second and third quarters of CY9Q. The results will show the benefits of space programs and suggest an overall approach to space architecture that could help maximize the world benefits of space while still meeting the overall objectives of the three sets of recommendations mentioned above. We acknowledge the work of the con- \u27 tributors to the AIAA report and to numerous NASA studies of specific endeavors such as the Lunar Energy Enterprise study. This paper is a much shortened version of the entire treatment. A more complete presentation will be available from the authors at the conference if desired

    Silicon Satellites: Picosats, Nanosats, and Microsats

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    Silicon, the most abundant solid element in the Earth's lithosphere, is a useful material for spacecraft construction. Silicon is stronger than stainless steel, has a thermal conductivity about half that of aluminum, is transparent to much of the infrared radiation spectrum, and can form a stable oxide. These unique properties enable silicon to become most of the mass of a satellite, it can simultaneously function as structure, heat transfer system, radiation shield, optics, and semiconductor substrate. Semiconductor batch-fabrication techniques can produce low-power digital circuits, low-power analog circuits, silicon-based radio frequency circuits, and micro-electromechanical systems (MEMS) such as thrusters and acceleration sensors on silicon substrates. By exploiting these fabrication techniques, it is possible to produce highly-integrated satellites for a number of applications. This paper analyzes the limitations of silicon satellites due to size. Picosatellites (approximately 1 gram mass), nanosatellites (about 1 kg mass), and highly capable microsatellites (about 10 kg mass) can perform various missions with lifetimes of a few days to greater than a decade

    Could CuB be the site of redox linkage in cytochrome c oxidase?

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    This paper explores the proton pumping function of cytochrome c oxidase [ferrocytochrome-c:oxygen oxidoreductase (EC 1.9.3.1)] based upon redox linkage at the "high-potential" CU(B) center. A model is proposed that is derived from a redox-linked ligand exchange mechanism previously described for the Cu(A) site. Qualitative analysis of this mechanism indicates that such a mechanism is feasible. However, the relatively short distance between Cu(B) and cytochrome a3 implies that the uncoupling electron transfers are quite facile. In addition, the position of the Cu(B) center with respect to the inner mitochondrial membrane argues against redox linkage at the Cu(B) site

    A Concept for Attribute-Based Authorization on D-Grid Resources

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    In Germany's D-Grid project numerous Grid communities are working together to provide a common overarching Grid infrastructure. The major aims of D-Grid are the integration of existing Grid deployments and their interoperability. The challenge lies in the heterogeneity of the current implementations: three Grid middleware stacks and different Virtual Organization management approaches have to be embraced to achieve the intended goals. In this article we focus oil the implementation of an attribute-based authorization infrastructure that not only leverages the well-known VO attributes but also campus attributes managed by a Shibboleth federation

    Image-Formation at a Nation’s Edge: Thai Perceptions of its Border Dispute with Cambodia - Implications for South Asia

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    Frontier friction has been a recurring phenomenon in much of the world, including in South and Southeast Asia. Yet the social construction of antagonistic border perceptions offers lessons about how not to frame a country's views of its  neighbors. Though boundary disputes in South Asia are currently much more muted than in the past, this investigation provides a message for South Asia that ultra-patriotism over borders continues to endanger inter-state relations in other parts of Asia and can always rear its head again in South Asia. It is thus essential to examine the case of Thai perceptions towards its border with Cambodia to understand the clash between nationalist and moderate societal groups. The objective is to learn from this case that excessive border patriotism is ultimately harmful to national interests. This study focuses specifically on Thai perceptions toward the Thai-Cambodian border disputes with three questions in mind. First, how have Thai elite actor perceptions evolved toward their present state? Second, what appears to be hindering a more moderate Thai stance with regard to parts of its border conflict with Cambodia? Third, what implications are there from Thai-Cambodian border conflicts, if any, and what patterns can we generalize out of Thai border perceptions which might have implications for South and Southeast Asia? This study, focusing on image formation of boundaries, seeks to answer these questions
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