914 research outputs found

    Assessment of cockpit interface concepts for data link retrofit

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    The problem is examined of retrofitting older generation aircraft with data link capability. The approach taken analyzes requirements for the cockpit interface, based on review of prior research and opinions obtained from subject matter experts. With this background, essential functions and constraints for a retrofit installation are defined. After an assessment of the technology available to meet the functions and constraints, candidate design concepts are developed. The most promising design concept is described in detail. Finally, needs for further research and development are identified

    Analysis of observations of the middle atmosphere from satellites

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    Satellite data are being used to investigate problems in middle atmosphere chemistry and dynamics. Efforts have been focused primarily on studies to determine the quality of observed distributions of trace species and derived dynamical quantities. Those data have been used as diagnostics for model-derived constituent profiles and fields and for improving our understanding of some of the fundamental processes occurring in the middle atmosphere. Temperatures and derived winds from Nimbus 7 Limb Infrared Monitoring of the Stratosphere (LIMS) data were compared with long-time series of rawinsonde data at Invercargill, New Zealand, and Berlin, West Germany, and the results are excellent for both quantities. It was also demonstrated that more highly-derived dynamical quantities can be obtained reliably from those LIMS fields. Furthermore, both the diabatic and residual-mean circulations derived using LIMS data agree qualitatively with changes in the distribution of trace species determined independently with the Nimbus 7 SAMS and LIMS experiments. Subsequently, an examination of LIMS data at mid to high latitudes of the Southern Hemisphere has revealed a synoptic-scale, upper stratospheric instability during late autumn that is associated with the development of the stratospheric polar jet. Investigation of this phenomenon continues with Stratospheric Sounding Unit (SSU) data sets

    EVERYTHING COUNTS: Building a Control Regime for Nonstrategic Nuclear Warheads in Europe

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    Before the Russian invasion of Ukraine, the Biden administration insisted in arms control talks with Russia that a follow-on agreement to the New Strategic Arms Reduction Treaty (New START) should cover all nuclear weapons and that such an agreement should focus on the nuclear warheads themselves. This would represent a significant change from previous agreements, which focused on delivery vehicles, such as missiles. The United States has been particularly interested in potential limits on nonstrategic nuclear warheads (NSNW). Such weapons have never been subject to an arms control agreement. Because Russia possesses an advantage in the number of such weapons, the US Senate has insisted that negotiators include them in a future agreement, making their inclusion necessary if such an accord is to win Senate approval and ultimately be ratified by Washington. In the wake of Russian nuclear threats in the Ukraine conflict, such demands can only be expected to grow if and when US and Russian negotiators return to the negotiating table

    Minnesota's forest trees

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    24 pages; includes drawings. This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

    Tumor Vasculature in Young and Old Hosts: Scanning Electron Microscopy of Microcorrosion Casts with Microangiography, Light Microscopy and Transmission Electron Microscopy

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    Tumor growth in vivo is dependent upon new blood vessel formation. When B16-F10 melanoma cells are implanted subcutaneously in young (3 mo) and old (24 mo) C57BL/6 mice the rate of growth is dependent on the age of the mice. This study involved a wide range of histological and microscopic techniques but was limited primarily to the initial phase of tumor growth. Stereological point counting from light microscopy (LM) of standard histological sections has been used to yield data regarding blood content. Tumor-bearing mice were perfused through the aorta with a fixation solution and were infused with a low-viscosity radiopaque gel (Microfil) or resin (Mercox). Soft x-rays of the whole animal were used for identifying the feeding vessels to the tumor. Tumors with Microfil were sliced and used for microangiography and light-microscopic observation while those with resin were used to make corrosion casts for scanning electron microscopy (SEM). The different characteristics of the tumor blood vessels in different aged mice were most obvious through SEM of vascular corrosion casts. In comparison with tumors in young mice those of similar size in old hosts had more necrosis, reduced presence of angiogenic features, decreased vessel density, reduced penetration into the tumor, and enhanced tortuosity of the vessel lumen. Transmission electron microscopy (TEM) revealed incompletely developed wall structure of the vessels regardless of host. The above results are consistent with the hypothesis that retarded angiogenesis may be responsible in part for the limited growth of tumors in old hosts

    Changes in Myosin and Myosin Light Chain Kinase During Myogenesis

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    Myosins and myosin light chain kinases have been isolated from a cloned line of myoblasts (L5/A10) as this cell line undergoes differentiation toward adult muscle. At least three myosin isozymes were obtained during this developmental process. Initially a nonmuscle type of myosin was found in the myoblasts. The molecular weights of the myoblast light chains were 20 000 and 15 000. Myosin isolated from early myotubes had light chains with molecular weights of 20 000 and 19 500. Myosin isolated from myotubes which contained sarcomeres had light chains with molecular weights of 23 000, 18 500, and 16000. This last myosin was similar in light chain complement to adult rat thigh muscle. Two forms of the myosin light chain kinase activity were detected: a calciumindependent kinase in the myoblasts and a calcium-dependent kinase in the myotubes with sarcomeres. No myosin light chain kinase activity was detected in the early myotubes
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