784 research outputs found

    Technology requirements for post-1985 communications satellites

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    The technical and functional requirements for commercial communication satellites are discussed. The need for providing quality service at an acceptable cost is emphasized. Specialized services are postulated in a needs model which forecasts future demands. This needs model is based upon 322 separately identified needs for long distance communication. It is shown that the 1985 demand for satellite communication service for a domestic region such as the United States, and surrounding sea and air lanes, may require on the order of 100,000 MHz of bandwith. This level of demand can be met by means of the presently allocated bandwidths and developing some key technologies. Suggested improvements include: (1) improving antennas so that high speed switching will be possible; (2) development of solid state transponders for 12 GHz and possibly higher frequencies; (3) development of switched or steered beam antennas with 10 db or higher gain for aircraft; and (4) continued development of improved video channel compression techniques and hardware

    Technology requirements for communication satellites in the 1980's

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    The key technology requirements are defined for meeting the forecasted demands for communication satellite services in the 1985 to 1995 time frame. Evaluation is made of needs for services and technical and functional requirements for providing services. The future growth capabilities of the terrestrial telephone network, cable television, and satellite networks are forecasted. The impact of spacecraft technology and booster performance and costs upon communication satellite costs are analyzed. Systems analysis techniques are used to determine functional requirements and the sensitivities of technology improvements for reducing the costs of meeting requirements. Recommended development plans and funding levels are presented, as well as the possible cost saving for communications satellites in the post 1985 era

    The pre-shock gas of SN1006 from HST/ACS observations

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    We derive the pre-shock density and scale length along the line of sight for the collisionless shock from a deep HST image that resolves the H alpha filament in SN1006 and updated model calculations. The very deep ACS high-resolution image of the Balmer line filament in the northwest (NW) quadrant shows that 0.25 < n_0 < le$ 0.4 cm-3 and that the scale along the line of sight is about 2 x 10^{18} cm, while bright features within the filament correspond to ripples with radii of curvature less than 1/10 that size. The derived densities are within the broad range of earlier density estimates, and they agree well with the ionization time scale derived from the Chandra X-ray spectrum of a region just behind the optical filament. This provides a test for widely used models of the X-ray emission from SNR shocks. The scale and amplitude of the ripples are consistent with expectations for a shock propagating though interstellar gas with ~ 20% density fluctuations on parsec scales as expected from studies of interstellar turbulence. One bulge in the filament corresponds to a knot of ejecta overtaking the blast wave, however. The interaction results from the rapid deceleration of the blast wave as it encounters an interstellar cloud.Comment: 16 pages, 6 figures, to appear in Ap

    Combined SEM-FIB-SPM-TOF-EDX-EBSD as a Multifunctional Tool

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    Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 201

    Minute Pirate Bug and Big-Eyed Bug Populations in Pyramided Bt Sweet Corn Bordered by Native Perennial and Pasture Border Rows

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    Sweet corn is an important vegetable crop grown in Kentucky. The major sweet corn ear pests are European corn borer, Ostrinia nubilalis, and corn earworm, Helicoverpa zea. Ecological control measures have been introduced to manage these pests, reducing use of broad spectrum insecticides. Conservation biological control (CBC) is a component of these approaches. CBC manages pests in agroecosystems using habitat management to enhance populations of natural enemies that are already present in the system. Another important advancement is the cultivation of Bacillus thuringiensis (Bt) sweet corn resistant to the Lepidopteran corn ear pests. This study used CBC of corn ear pests using pyramided Bt-protected sweet corn. The research was conducted at the Kentucky State University Harold R. Benson Research and Demonstration farm in Franklin County, Kentucky, during the summers of 2021 and 2022. Sixteen plots were created by splitting each of the eight larger existing plots into 25 m × 10 m plots with an unplanted strip between them and 2 m wide native perennial or pasture border rows. Yellow sticky traps 15 cm × 15 cm were deployed and replaced weekly to trap beneficial insects. Results revealed that minute pirate bug populations were more abundant than big-eyed bug populations. Both species were slightly more abundant in pasture than native perennial habitats. Similarly, minute pirate bug populations were significantly larger in all four sweet corn habitats. Results will be discussed with respect to the Bt corn bordered by native perennial, Bt corn bordered by pasture, non Bt corn bordered by native perennial, and non Bt corn bordered by pasture border rows

    Multilocus sequence typing of Scedosporium apiospermum and Pseudallescheria boydii isolates from cystic fibrosis patients

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    Background: Scedosporium and Pseudallescheria species are the second most common lung-colonising fungi in cystic fibrosis (CF) patients. For epidemiological reasons it is important to trace sources of infection, routes of transmission and to determine whether these fungi are transient or permanent colonisers of the respiratory tract. Molecular typing methods like multilocus sequence typing (MLST) help provide this data. Methods: Clinical isolates of the P. boydii complex (including S. apiospermum and P. boydii) from CF patients in different regions of Germany were studied using MLST. Five gene loci, ACT, CAL, RPB2, BT2 and SOD2, were analysed. Results: The S. apiospermum isolates from 34 patients were assigned to 32 sequence types (STs), and the P. boydii isolates from 14 patients to 8 STs. The results revealed that patients can be colonised by individual strains for years. Conclusions: The MLST scheme developed for S. apiospermum and P. boydii is a highly effective tool for epidemiologic studies worldwide. The MLST data are accessible at http://mlst.mycologylab.org/

    Cutting Edge: The Heat Shock Protein gp96 Activates Inflammasome-Signaling Platforms in APCs

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    Several heat shock proteins (HSPs) prime immune responses, which are, in part, a result of activation of APCs. APCs respond to these immunogenic HSPs by upregulating costimulatory molecules and secreting cytokines, including IL-1beta. These HSP-mediated responses are central mediators in pathological conditions ranging from cancer, sterile inflammation associated with trauma, and rheumatoid arthritis. We tested in this study the requirement of inflammasomes in the release of IL-1beta by one immunogenic HSP, gp96. Our results show that murine APCs activate NLRP3 inflammasomes in response to gp96 by K(+) efflux. This is shown to initiate inflammatory conditions in vivo in the absence of additional known inflammasome activators or infection. These results document a novel mechanism by which proteins of endogenous origin, the HSPs, can modulate an inflammatory response following their release from aberrant cells

    Clinical and humoral determinants of congestion in heart failure. potential role of adiponectin

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    Background: Some patients with heart failure (HF) are more prone to systemic congestion than others. The goal of this study was to identify clinical and humoral factors linked to congestion and its prognostic impact in HF patients. Methods: A total of 371 advanced HF patients underwent physical examination, echocardiography, right heart catheterization, blood samplings, and Minnesota Living with HF Questionnaire. Subjects were followed-up for adverse events (death, urgent transplantation, or assist device implantation without heart transplantation). Results: Thirty-one percent of patients were classified as prone to congestion. During a median follow-up of 1,093 days, 159 (43%) patients had an adverse event. In the Cox analysis, the congestion-prone (CP) status was associated with a 43% higher event risk. The CP status was strongly (p ? 0.001) associated with body weight loss, right ventricular dysfunction (RVD), dilated inferior vena cava (IVC), diuretics, and beta-blockers prescription and the majority of tested hormones in the univariate analysis. In the multivariate analysis, the only independent variables associated with the CP status were adiponectin, albumin, IVC diameter, and RVD. Adiponectin by itself was predictive of adverse events. In a multivariate model, CP status was no longer predictive of adverse events, in contrast to adiponectin. Conclusions: CP patients experienced more severe symptoms and had shorter survival. Potential role of adiponectin, a new independent predictor of CP status, should be further examined
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