57,384 research outputs found

    Advanced satellite workstation: An integrated workstation environment for operational support of satellite system planning and analysis

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    A prototype integrated environment, the Advanced Satellite Workstation (ASW), is described that has been developed and delivered for evaluation and operator feedback in an operational satellite control center. The current ASW hardware consists of a Sun Workstation and Macintosh II Workstation connected via an ethernet Network Hardware and Software, Laser Disk System, Optical Storage System, and Telemetry Data File Interface. The central mission of ASW is to provide an intelligent decision support and training environment for operator/analysts of complex systems such as satellites. There have been many workstation implementations recently which incorporate graphical telemetry displays and expert systems. ASW is a considerably broader look at intelligent, integrated environments for decision support, based upon the premise that the central features of such an environment are intelligent data access and integrated toolsets. A variety of tools have been constructed in support of this prototype environment including: an automated pass planner for scheduling vehicle support activities, architectural modeler for hierarchical simulation and analysis of satellite vehicle subsystems, multimedia-based information systems that provide an intuitive and easily accessible interface to Orbit Operations Handbook and other relevant support documentation, and a data analysis architecture that integrates user modifiable telemetry display systems, expert systems for background data analysis, and interfaces to the multimedia system via inter-process communication

    Fungal alkaloid occurrence during seedling establishment and early growth in Lolium perenne seedlings infected with Epichloë festucae var. lolii and the influence of adult Argentine stem weevil (Listronotus bonariensis) feeding on alkaloid concentrations : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science (MSc) in Agriculture Science at Massey University, Palmerston North, New Zealand

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    Fungal endophytes of the genus Epichloë often form stable, symbiotic, and mutualistic relationships with grasses of the Pooideae, including perennial ryegrass (Lolium perenne L.). The endophyte provides various benefits to its grass host, through the production of secondary metabolites, which are exploited in New Zealands pastoral agriculture systems. The endophyte can give its host grass an ecological advantage in certain challenging environments, such as during seedling establishment, where young plants are especially vulnerable to insect predation, such as feeding by adult Argentine stem weevil (ASW, Listronotus bonariensis). This thesis focuses on understanding the alkaloid concentrations that occur in endophyte-infected perennial ryegrass seedlings during the early establishment phase. A glasshouse experiment was conducted in which fungal alkaloid concentrations (peramine, lolitrem B, ergovaline, and epoxy-janthitrems) were measured in perennial ryegrass seedlings infected with Epichloë festucae var. lolii strains AR1, AR37, NEA2, and NZCT for 69 days after sowing. From the data it is inferred that an initial translocation of alkaloids stored in seed during maturation into the developing shoot of the germinating seedling occurs, followed by a period of alkaloid dilution due to seedling expansion, and finally production of newly metabolised alkaloids in the plant. Alkaloid concentration were found to peak in 8–10 day old seedlings, giving the seedling a “kick start” in protection of the emerging seedling from adult ASW feeding during the first 11 days after sowing. The influence of adult ASW feeding on alkaloid concentrations in endophyte-infected perennial ryegrass seedlings was also tested. The study demonstrated that adult ASW feeding can influence alkaloid production, although peramine, the main alkaloid responsible for ASW deterrence was not significantly affected. Findings from this thesis improve understanding of the role of fungal alkaloids in endophyte-infected perennial ryegrass seedlings during establishment, and help explain results from earlier studies describing seedling susceptibility to adult ASW

    Comparison of radiative energy loss models in a hot QCD medium

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    The suppression of high pTp_{T} hadron production in heavy ion collisions is thought to be due to energy loss by gluon radiation off hard partons in a QCD medium. Existing models of QCD radiative energy loss in a color-charged medium give estimates of the coupling strength of the parton to the medium which differ by a factor of 55. We will present a side-by-side comparison of two different formalisms to calculate the energy loss of light quarks and gluons: the multiple soft scattering approximation (ASW-MS) and the opacity expansion formalism (ASW-SH and WHDG-rad). A common time-temperature profile is used to characterize the medium. The results are compared to the single hadron suppression RAAR_{AA} at RHIC energies. In addition the influcence of homogeneous and non-homogeneous distribution of scattering centers is discussed. We find that using an equivalent brick overestimates the energy loss for long parton trajectories.Comment: Proceedings Hard Probes 2010, October 10-15, Eilat (Israel

    Physiology and cell biology of acupuncture observed in calcium signaling activated by acoustic shear wave

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    This article presents a novel model of acupuncture physiology based on cellular calcium activation by an acoustic shear wave (ASW) generated by the mechanical movement of the needle. An acupuncture needle was driven by a piezoelectric transducer at 100 Hz or below, and the ASW in human calf was imaged by magnetic resonance elastography. At the cell level, the ASW activated intracellular Ca 2+ transients and oscillations in fibroblasts and endothelial, ventricular myocytes and neuronal PC-12 cells along with frequency-amplitude tuning and memory capabilities. Monitoring in vivo mammalian experiments with ASW, enhancement of endorphin in blood plasma and blocking by Gd 3+ were observed; and increased Ca 2+ fluorescence in mouse hind leg muscle was imaged by two-photon microscopy. In contrast with traditional acupuncture models, the signal source is derived from the total acoustic energy. ASW signaling makes use of the anisotropy of elasticity of tissues as its waveguides for transmission and that cell activation is not based on the nervous system. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201

    Gap Renormalization in Dirty Anisotropic Superconductors: Implications for the Order Parameter of the Cuprates

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    We contrast the effects of non-magnetic impurities on the properties of superconductors having a \dw\ order parameter, and a highly anisotropic s-wave (ASW) gap with the same nodal structure. The non-vanishing, impurity induced, off-diagonal self-energy in the ASW state is shown to gap out the low energy excitations present in the clean system, leading to a qualitatively different impurity response of the single particle density of states compared to the \dw\ state. We discuss how this behaviour can be employed to distinguish one state from the other by an analysis of high-resolution angle-resolved photoemission spectra.Comment: 12 pages, uuencoded Postscrip

    The cost of firms' debt financing

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    We provide an assessment of the determinants of the risk remia paid by non-financial corporations on long-term bonds. By looking at 5,500 issues over the period 2005-2012, we find that in recent years the sovereign debt market turbulence has been a major driver of corporate risk. Compared with the three-year period 2005-07 before the global financial crisis, in the years 2010-12 Italian, Spanish and Portuguese firms paid on average between 70 and 120 basis points of additional premium due to the negative spillovers from the sovereign debt crisis, while German firms got a discount of 40 basis points

    An infrared measurement of chemical desorption from interstellar ice analogues

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    In molecular clouds at temperatures as low as 10 K, all species except hydrogen and helium should be locked in the heterogeneous ice on dust grain surfaces. Nevertheless, astronomical observations have detected over 150 different species in the gas phase in these clouds. The mechanism by which molecules are released from the dust surface below thermal desorption temperatures to be detectable in the gas phase is crucial for understanding the chemical evolution in such cold clouds. Chemical desorption, caused by the excess energy of an exothermic reaction, was first proposed as a key molecular release mechanism almost 50 years ago. Chemical desorption can, in principle, take place at any temperature, even below the thermal desorption temperature. Therefore, astrochemical net- work models commonly include this process. Although there have been a few previous experimental efforts, no infrared measurement of the surface (which has a strong advantage to quantify chemical desorption) has been performed. Here, we report the first infrared in situ measurement of chemical desorption during the reactions H + H2S -> HS + H2 (reaction 1) and HS + H -> H2S (reaction 2), which are key to interstellar sulphur chemistry. The present study clearly demonstrates that chemical desorption is a more efficient process for releasing H2S into the gas phase than was previously believed. The obtained effective cross-section for chemical desorption indicates that the chemical desorption rate exceeds the photodesorption rate in typical interstellar environments
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