54 research outputs found

    A proposed bare tether experiment on board a sounding rocket

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    A sounding rocket experiment is proposed to carry out two experiments by the conductive bare-tether; 1) the test of the OML (Orbital-Motion-Limited) theory to collect electron, and II) the test of techniques to determine (neutral) density profile in critical E-layer. The main driver of the mission is provide a space tether technology experiment in low-Earth-Orbit (LEO) deploying a long tape tether in space and verify the performance of the bare electrodynamic tape tether. The sounding rocket experiment will show no danger to other satellites as the tether missions YES1, SEDSAT, and ProCEDS, which is cancelled just for afraid of collision with the ISS orbit. Also, the sounding rocket mission is possible to demonstrate the bare tether technology in low cost, simple mission concept, fast realization for space structures. The present sounding rocket experiment is expected to be the first conductive bare tether experiment

    Space demostration of bare electrodynamic tape-tether technology on the sounding rocket S520-25

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    A spaceflight validation of bare electro dynamic tape tether technology was conducted. A S520-25 sounding rocket was launched successfully at 05:00am on 31 August 2010 and successfully deployed 132.6m of tape tether over 120 seconds in a ballistic flight. The electrodynamic performance of the bare tape tether employed as an atmospheric probe was measured. Flight results are introduced through the present progressive report of the demonstration and the results of flight experiment are examined as the premier report of the international cooperation between Japan, Europe, USA and Australia. Future plans for maturing space tether technology, which will play an important role for future space activities, are also discussed

    T-REX: Bare electro-dynamic tape-tether technology experimetn on sounding rocket S520

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    The project to verify the performance of space tether technology was successfully demonstrated by the launch of the sounding rocket S520 the 25tu. The project is the space demonstration of science and engineering technologies of a bare tape electrodynamic tether (EDT) in the international campaign between Japan, USA, Europe and Australia. Method of "Inverse ORIGAMI (Tape tether folding)" was employed in order to deploy the bare tape EDT in a short period time of the suborbital flight. The deployment of tape tether was tested in a various experimental schemes on ground to show high reliability of tape tether deployment. The rocket was launched on the summer of 2010 and deployed a bare electro-dynamic tape tether with length 132.6 m, which is the world record of the length deployment of tape tether. The verification of tether technology has found a variety kind of science and technology results as the first in the humankind and will lead a large number of applications of space tether technologie

    Rate accelerations in nuclear 18S rDNA of mycoheterotrophic and parasitic angiosperms

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    Rate variation in genes from all three genomes has been observed frequently in plant lineages with a parasitic and mycoheterotrophic mode of life. While the loss of photosynthetic ability leads to a relaxation of evolutionary constraints in genes involved in the photosynthetic apparatus, it remains to be determined how prevalent increased substitution rates are in nuclear DNA of non-photosynthetic angiosperms. In this study we infer rates of molecular evolution of 18S rDNA of all parasitic and mycoheterotorphic plant families (except Lauraceae and Polygalaceae) using relative rate tests. In several holoparasitic and mycoheterotrophic plant lineages extremely high substitution rates are observed compared to other photosynthetic angiosperms. The position and frequency of these substitutions have been identified to understand the mutation dynamics of 18S rRNA in achlorophyllous plants. Despite the presence of significantly elevated substitution rates, very few mutations occur in major functional and structural regions of the small ribosomal molecule, providing evidence that the efficiency of the translational apparatus in non-photosynthetic plants has not been affected

    Exploring, exploiting and evolving diversity of aquatic ecosystem models: a community perspective

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    Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

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    A systematic review and meta-analysis of endovascular and surgical revascularization techniques in acute limb ischemia

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    BACKGROUND: The initial treatment of patients with acute limb ischemia (ALI) remains undefined. The aim of this article was to compare the safety and effectiveness of catheter-driven thrombolysis (CDT) with surgical revascularization and evaluate the various fibrinolytic agents, endovascular, and pharmacochemical approaches that aim for thrombectomy. METHODS: PubMed, Embase, and the Cochrane Library were searched for studies on the management of ALI by means of surgical or endovascular recanalization, returning 520 studies. All randomized, controlled trials, nonrandomized prospective, and retrospective studies were included comparing treatment of ALI. RESULTS: Twenty-five studies, investigating a total of 4689 patients, were included for meta-analysis spread across nine different comparisons. No differences were found in limb salvage between thrombectomy and thrombolysis. More major vascular events were seen in the thrombolysis group (6.5% compared with 4.4% in the surgically treated group; odds ratio [OR], 0.33; 95% confidence interval [CI], 0.13-0.87; P = .02; I2 = 20%). Comparable limb salvage was found for high- and low-dose recombinant tissue plasminogen activator (r-tPA). No significant differences were found in major vascular event between low r-tPA (14%) and high r-tPA (10.5%; P = .13). The 30-day limb salvage rate was 79.7% for r-tPA treatment and 60.4% for streptokinase (OR, 3.14; 95% CI, 1.26-7.85; P = .01; I2 = 0%). AngioJet showed more limb salvage at 6 months compared with r-tPa (OR, 2.21; 95% CI, 1.17-4.18; P = .01; I2 = 0%). CONCLUSIONS: Both CDT and surgery have comparable limb salvage rates in patients with ALI; however, CDT is associated with a higher risk of hemorrhagic complications. No conclusions can be drawn regarding the risk of hemorrhagic complications regarding thrombolytic therapy by means of r-tPA, streptokinase, or urokinase. Insufficient data are available to conclude the preference of using a hybrid approach, ultrasound-accelerated CDT, heated r-tPA. or novel endovascular (rheolytical) thrombectomy systems. Future trials regarding ALI need to be constructed carefully, ensuring comparable study groups, and should follow standardized practices of outcome reporting

    Early onset post-transplant lymphoproliferative disease is associated with allograft localization

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    Post-transplant lymphoproliferative disease (PTLD) is a major complication after solid organ transplantation. We analyzed incidence, patient characteristics, clinical presentation, and prognostic factors for treatment outcome and survival of PTLD patients transplanted at our center. Records from adult kidney and lung transplant recipients, transplanted between January 1985 and December 2002 with a histologically confirmed diagnosis of PTLD, were retrieved. Histology was reviewed and prognostic factors for treatment outcome were evaluated by multivariable analysis. Of 1354 kidney and 206 lung transplants, PTLD was diagnosed in 40 transplant recipients (2.6%). Lung transplant recipients had a significantly higher incidence of PTLD (8.3%) than kidney transplant recipients (1.7%). Sites of presentation were highly heterogeneous. Notably, PTLD localized in the allograft occurred significantly earlier after transplantation than PTLD localized outside the allograft (p = 0.001). This was true for lung (p = 0.006) as well as for kidney transplant recipients (p = 0.03). In multivariable Cox regression, performance status (p = 0.01) and advanced stage (p = 0.04) were factors negatively predictive for response to first-line treatment. Only performance status remained as negative predictive factor for survival (p = 0.002) and freedom from tumor progression (p = 0.01). In conclusion, the allograft is significantly more often involved as primary site of PTLD presentation during the first post-transplant year. This may have clinical consequences and give new insights in pathogenesis of PTLD. Performance status and stage are important risk factors for outcome of PTL
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