896 research outputs found

    Spacecraft Low Thrust Propulsion Optimization System

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    As we advance into a modern space-age there is a need to obtain better trajectories for spacecraft missions, in which optimization plays an integral role. These improved trajectories will provide a more cost efficient means of conducting space missions. Throughout this paper such optimization will be discussed in terms of accomplishment and potential problems. Previous trajectory optimization research efforts include using the idea that the shape-based solution is only near-optimal and as a result there should exist a neighboring solution with a lower cost. Using Linear Quadratic Regulator (LQR) control and linearized equations about the nominal shape-based trajectory, a shape-smoothing algorithm is built that improves the cost of the trajectory. This LQR algorithm also addresses the 2 drawbacks. First, the LQR removes the constraint that the in-plane thrust vector be parallel to the velocity vector. This improves the thrust pointing angle guess for any further optimization method. Second, since the overall thrust level does typically (but is not guaranteed to) decrease, the initial thrust acceleration for the LQR trajectory is lower than that of the shape-based method. This helps (but still does not guarantee that) the initial thrust acceleration for the LQR trajectory to be equal to or less than what the physical hardware can provide. As a continuation of previous research the LQR optimization method was used for multi-body target trajectory. Multiple examples were created ranging from one body to three body trajectories in order to verify the accuracy of the method compared to others that have been used

    Draft Genome Sequences of 29 Helicobacter pylori Strains Isolated from Colombia

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    Here, we present the draft genome sequences of 29 Colombian Helicobacter pylori strains. These strains were isolated in Bogotá, Colombia, from patients diagnosed with chronic gastritis. The genomic characterization of these strains will provide more information on the genetic composition of H. pylori strains from Colombia.We thank the entities that financially supported the development of this work. A.B.M. is a recipient of a scholarship from the Centro de Estudios Interdisciplinarios Básicos y Aplicados (CEIBA) Foundation, Colombia; and A.B.M., C.A., J.S., and A.A.T.-R. are recipients of a project grant (120380763025/2018) from MinCiencias, Colombia. The work is partially supported by Research Vice-Rectory, Pontificia Universidad Javeriana (PPTA_7676) and F.P.I.T. BanRepCultural (project 3956). F.F.V. is financed by national funds from the Fundação para a Ciência e a Tecnologia (FCT) through an assistant researcher grant (CEECIND/03023/2017), a project grant (PTDC/BTM-SAL/28978/2017), and projects UIDB/04138/2020 and UIDP/04138/2020; these funds partially supported this work. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.info:eu-repo/semantics/publishedVersio

    Report on the second run of the ESO Large Programme

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    The ground–based spectro- scopic observations complementing the COROT ones have con- tinued in June and July 2007. The log of the observations, a few preliminary results, tips for the next observers and a look to the future are given

    Topical application of a peptide inhibitor of transforming growth factor-beta1 ameliorates bleomycin-induced skin fibrosis

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    Transforming growth factor-beta (TGF-beta) plays a crucial role in the pathogenesis of skin fibrotic diseases. Systemic TGF-beta inhibitors effectively inhibit fibrosis in different animal models; however, systemic inhibition of TGF-beta raises important safety issues because of the pleiotropic physiological effects of this factor. In this study, we have investigated whether topical application of P144 (a peptide inhibitor of TGF-beta1) ameliorates skin fibrosis in a well-characterized model of human scleroderma. C3H mice received daily subcutaneous injections of bleomycin for 4 wk, and were treated daily with either a lipogel containing P144 or control vehicle. Topical application of P144 significantly reduced skin fibrosis and soluble collagen content. Most importantly, in mice with established fibrosis, topical treatment with P144 lipogel for 2 wk significantly decreased skin fibrosis and soluble collagen content. Immunohistochemical studies in P144-treated mice revealed a remarkable suppression of connective tissue growth factor expression, fibroblast SMAD2/3 phosphorylation, and alpha-smooth muscle actin positive myofibroblast development, whereas mast cell and mononuclear cell infiltration was not modified. These data suggest that topical application of P144, a peptide inhibitor of TGF-beta1, is a feasible strategy to treat pathological skin scarring and skin fibrotic diseases for which there is no specific therapy

    Prenatal gunshot wound, a rare cause of maternal and fetus trauma, a case report

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    Background: Gunshot wounds in pregnant women, although rare, represent an important cause of fetal and maternal mortality. Understanding the mechanism of injury is essential to identify the possible injuries and to adequately manage the complexity of these emergency scenarios. Case presentation: We present a case of a 27-year-old woman and her 37 week fetus who were the victims of a gunshot wound. The trajectory of the bullet injured not only the mother but also the developing fetus. An emergency c-section was performed and the bullet was removed from the infant's abdomen. The two patients fully recovered and on follow up controls both patients are doing well. Conclusions: Trauma events, and particularly gunshot wounds in pregnant women requires promptly and adequate intervention. Coordinated efforts from multidisciplinary clinical teams are needed as well as the appropriate training in maternal and infant resuscitative measures and surgical techniques

    LanderPick, a Remote Operated Trawled Vehicle to cost-effectively deploy and recover lightweight oceanographic landers.

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    Landers are modular structures equipped with miscellaneous sensors and monitoring equipment which are positioned directly on the seabed to operate autonomously for a defined timeframe. A drawback of landers intended to operate for prolonged periods in the deep ocean is the high cost of recovery systems, typically depending on buoyancy modules plus expendable ballast, or requiring ROVs assistance. LanderPick concept consists of the design of a specific trawled vehicle to deploy and recover lightweight oceanographic landers not provided with recovery elements, but having a capture mesh that facilitates their hitching. The LanderPick vehicle is technically a ROTV (Remote Operated Trawled Vehicle) controlled through a standard coaxial electromechanical cable that allows real-time control from the vessel. Navigation is enabled by a low-light high-definition camera, aided by spotlights and laser pointers. Small propellers aid in the final precision approach maneuvers. A mechanical release allows the precise placement at the sea bottom of landers carried as a payload, as well as their recovery by means of a triple hook. First sea missions of the system were carried out successfully in 2021 in southern Biscay. A 4-month deployment of a lander array equipped with current-meters along an energetic canyon axis provided unprecedented detail in the progression of the internal tidal bore. Short (48-hours) deployments of a fully-instrumented lander, including lapse-time image and baits in a deep seamount summit within a marine protected area, provided insights on the biodiversity of a unique ecosystem. The LanderPick novel approach to cost-effectively and precisely deploy and recover lightweight oceanographic landers allows to conceive (i) monitoring systems based on the deployment of arrays or fleets of low-cost landers and (ii) experiments associated with deep habitats such as coral reefs in which it is necessary to locate landers with great precision

    LanderPick, a Remote Operated Trawled Vehicle to cost-effectively deploy and recover lightweight oceanographic landers.

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    Landers are modular structures equipped with miscellaneous sensors and monitoring equipment which are positioned directly on the seabed to operate autonomously for a defined timeframe. A drawback of landers intended to operate for prolonged periods in the deep ocean is the high cost of recovery systems, typically depending on buoyancy modules plus expendable ballast, or requiring ROVs assistance. LanderPick concept consists of the design of a specific trawled vehicle to deploy and recover lightweight oceanographic landers not provided with recovery elements, but having a capture mesh that facilitates their hitching. The LanderPick vehicle is technically a ROTV (Remote Operated Trawled Vehicle) controlled through a standard coaxial electromechanical cable that allows real-time control from the vessel. Navigation is enabled by a low-light high-definition camera, aided by spotlights and laser pointers. Small propellers aid in the final precision approach maneuvers. A mechanical release allows the precise placement at the sea bottom of landers carried as a payload, as well as their recovery by means of a triple hook. First sea missions of the system were carried out successfully in 2021 in southern Biscay. A 4-month deployment of a lander array equipped with current-meters along an energetic canyon axis provided unprecedented detail in the progression of the internal tidal bore. Short (48-hours) deployments of a fully-instrumented lander, including lapse-time image and baits in a deep seamount summit within a marine protected area, provided insights on the biodiversity of a unique ecosystem. The LanderPick novel approach to cost-effectively and precisely deploy and recover lightweight oceanographic landers allows to conceive (i) monitoring systems based on the deployment of arrays or fleets of low-cost landers and (ii) experiments associated with deep habitats such as coral reefs in which it is necessary to locate landers with great precision
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