2,937 research outputs found

    UAV Swarm Mission Planning in Dynamic Environment Using Consensus-Based Bundle Algorithm.

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    To solve the real-time complex mission-planning problem for Multiple heterogeneous Unmanned Aerial Vehicles (UAVs) in the dynamic environments, this paper addresses a new approach by effectively adapting the Consensus-Based Bundle Algorithms (CBBA) under the constraints of task timing, limited UAV resources, diverse types of tasks, dynamic addition of tasks, and real-time requirements. We introduce the dynamic task generation mechanism, which satisfied the task timing constraints. The tasks that require the cooperation of multiple UAVs are simplified into multiple sub-tasks to perform by a single UAV independently. We also introduce the asynchronous task allocation mechanism. This mechanism reduces the computational complexity of the algorithm and the communication time between UAVs. The partial task redistribution mechanism has been adopted for achieving the dynamic task allocation. The real-time performance of the algorithm is assured on the premise of optimal results. The feasibility and real-time performance of the algorithm are validated by conducting dynamic simulation experiments

    Conformal Quivers and Melting Molecules

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    Quiver quantum mechanics describes the low energy dynamics of a system of wrapped D-branes. It captures several aspects of single and multicentered BPS black hole geometries in four-dimensional N=2\mathcal{N} = 2 supergravity such as the presence of bound states and an exponential growth of microstates. The Coulomb branch of an Abelian three node quiver is obtained by integrating out the massive strings connecting the D-particles. It allows for a scaling regime corresponding to a deep AdS2_2 throat on the gravity side. In this scaling regime, the Coulomb branch is shown to be an SL(2,R)SL(2,\mathbb{R}) invariant multi-particle superconformal quantum mechanics. Finally, we integrate out the strings at finite temperature---rather than in their ground state---and show how the Coulomb branch `melts' into the Higgs branch at high enough temperatures. For scaling solutions the melting occurs for arbitrarily small temperatures, whereas bound states can be metastable and thus long lived. Throughout the paper, we discuss how far the analogy between the quiver model and the gravity picture, particularly within the AdS2_2 throat, can be taken.Comment: 49 pages, 16 figure

    An unusual case of ST-segment elevation myocardial infarction following a late bare-metal stent fracture in a native coronary artery: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>A bare-metal stent fracture as a cause of acute coronary thrombosis and consequently of acute coronary syndrome is a rare clinical event that, to the best of our knowledge, has previously not been reported. A stent fracture is a rare complication arising from percutaneous coronary intervention.</p> <p>Case presentation</p> <p>We present, to the best of our knowledge, the first documented case of ST-segment elevation myocardial infarction in a patient following a late bare-metal stent fracture and thrombosis in a native coronary artery. The patient, a 51-year-old Caucasian man, was treated successfully with primary percutaneous coronary intervention and a new stent implantation.</p> <p>Conclusion</p> <p>A coronary stent fracture is a rare complication that has been described in venous bypass grafts deploying either a drug-eluting stent or a bare-metal stent. Stent fractures rarely occur in coronary arteries. In light of the non-specific presentation of stent fracture, it is also an easily missed complication. Patients may present with a non-specific symptom of angina. The angina could either be stable or unstable as a result of restenosis or in-stent thrombosis, or both. Our case demonstrates the most severe consequences of a bare-metal stent fracture (sudden coronary thrombosis and subsequent myocardial infarction) in a native coronary artery. It was diagnosed angiographically and treated early and effectively.</p

    In vitro and In vivo wound healing studies of methanolic fraction of Centella asiatica extract

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    Ethnopharmacological relevance: Asiaticoside is claimed as a bioactive compound capable of wound healing. In order to ensure that the pharmacological activity of the extract is traceable and measurable, the present study attempted to evaluate the bioactivity of rich fractionated extract of asiaticoside. Aim of the study: The current study evaluates the wound healing efficacy via in vitro scratch assay and in vivo circular wound excision model. Materials and methods: The ethanol extract was fractionated into seven fractions via vacuum liquid chromatography. The compound of interest in the fractions was qualitatively identified using thin layer chromatography and the positive fraction containing asiaticoside was further quantified using reverse-phase HPLC. The asiaticoside-rich fraction was subjected to (i) colorimetric MTT (methylthiazoltetrazolium) cytotoxicity assay following incubation with human dermal fibroblast (HDF) and human dermal keratinocyte (HaCaT); (ii) in vitro 12-well plate scratch assay (using HDF and HaCaT cells) and (iii) topically apply (40%, 10% and 2.5%, w/w) on in vivo circular wound excision of rabbits. Data on wound contraction, epithelisation period, hydroxyproline content and histophatological analysis was collected from in vivo study. Results: The results showed that the methanol fraction of the extract contained about 2.4% asiaticoside. Based on the results of colorimetric MTT (methylthiazoltetrazolium) cytotoxicity assay, both HDF and HaCaT showed significant stimulation upon application of the methanolic fraction of extract at concentrations of 100 μg/mL and 0.19 μg/mL. The methanol fraction showed almost no toxicity effect at the concentrations tested since their IC50 could not be determined in concentrations ranging from 100 μg/mL to 0.19 μg/mL. Since all the concentrations tested allowed for more than 90% cell viability, the concentrations chosen for the scratch assay were randomly chosen and designated as highest (100 μg/mL), medium (6 μg/mL) and lowest (0.2 μg/mL) concentrations. In the scratch assay, methanol fraction of extract with concentration of 0.2 μg/mL and 100 μg/mL showed significant effect on HDF and HaCaT compared to the positive control (p < 0.05). In vivo, it was shown that the methanol fraction of the extract induced collagen synthesis. Histopathology data also concluded that dose-dependent effect of the tested extract as a wound healer was present. Conclusions: Taken together, recent findings suggest that methanol fraction of C. asiatica demonstrated remarkable polyvalent activity, and thus has potential as an effective wound healer. In conclusion, the claim of the presence of wound healing properties in C. asiatica had been well supported based on the results obtained in this study

    A cross-sector analysis of human and organisational factors in the deployment of data-driven predictive maintenance

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    Domains such as utilities, power generation, manufacturing and transport are increasingly turning to data-driven tools for management and maintenance of key assets. Whole ecosystems of sensors and analytical tools can provide complex, predictive views of network asset performance. Much research in this area has looked at the technology to provide both sensing and analysis tools. The reality in the field, however, is that the deployment of these technologies can be problematic due to user issues, such as interpretation of data or embedding within processes, and organisational issues, such as business change to gain value from asset analysis. 13 experts from the field of remote condition monitoring, asset management and predictive analytics across multiple sectors were interviewed to ascertain their experience of supplying data-driven applications. The results of these interviews are summarised as a framework based on a predictive maintenance project lifecycle covering project motivations and conception, design and development, and operation. These results identified critical themes for success around having a target or decision-led, rather than data-led, approach to design; long-term resourcing of the deployment; the complexity of supply chains to provide data-driven solutions and the need to maintain knowledge across the supply chain; the importance of fostering technical competency in end-user organisations; and the importance of a maintenance-driven strategy in the deployment of data-driven asset management. Emerging from these themes are recommendations related to culture, delivery process, resourcing, supply chain collaboration and industry-wide cooperation

    Antibacterial activity of some selected medicinal plants of Pakistan

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    <p>Abstract</p> <p>Background</p> <p>Screening of the ethnobotenical plants is a pre-requisite to evaluate their therapeutic potential and it can lead to the isolation of new bioactive compounds.</p> <p>Methods</p> <p>The crude extracts and fractions of six medicinal important plants (<it>Arisaema flavum</it>, <it>Debregeasia salicifolia</it>, <it>Carissa opaca</it>, <it>Pistacia integerrima</it>, <it>Aesculus indica</it>, and <it>Toona ciliata</it>) were tested against three Gram positive and two Gram negative ATCC bacterial species using the agar well diffusion method.</p> <p>Results</p> <p>The crude extract of <it>P. integerrima </it>and <it>A. indica </it>were active against all tested bacterial strains (12-23 mm zone of inhibition). Other four plant's crude extracts (<it>Arisaema flavum</it>, <it>Debregeasia salicifolia</it>, <it>Carissa opaca</it>, and <it>Toona ciliata</it>) were active against different bacterial strains. The crude extracts showed varying level of bactericidal activity. The aqueous fractions of <it>A. indica </it>and <it>P. integerrima </it>crude extract showed maximum activity (19.66 and 16 mm, respectively) against <it>B. subtilis</it>, while the chloroform fractions of <it>T. ciliata </it>and <it>D. salicifolia </it>presented good antibacterial activities (13-17 mm zone of inhibition) against all the bacterial cultures tested.</p> <p>Conclusion</p> <p>The methanol fraction of <it>Pistacia integerrima</it>, chloroform fractions of <it>Debregeasia salicifolia </it>&<it>Toona ciliata </it>and aqueous fraction of <it>Aesculus indica </it>are suitable candidates for the development of novel antibacterial compounds.</p

    Protein Conformation and Supercharging with DMSO from Aqueous Solution

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    The efficacy of dimethyl sulfoxide (DMSO) as a supercharging reagent for protein ions formed by electrospray ionization from aqueous solution and the mechanism for supercharging were investigated. Addition of small amounts of DMSO to aqueous solutions containing hen egg white lysozyme or equine myoglobin results in a lowering of charge, whereas a significant increase in charge occurs at higher concentrations. Results from both near-UV circular dichroism spectroscopy and solution-phase hydrogen/deuterium exchange mass spectrometry indicate that DMSO causes a compaction of the native structure of these proteins at low concentration, but significant unfolding occurs at ~63% and ~43% DMSO for lysozyme and myoglobin, respectively. The DMSO concentrations required to denature these two proteins in bulk solution are ~3–5 times higher than the concentrations required for the onset of supercharging, consistent with a significantly increased concentration of this high boiling point supercharging reagent in the ESI droplet as preferential evaporation of water occurs. DMSO is slightly more basic than m-nitrobenzyl alcohol and sulfolane, two other supercharging reagents, based on calculated proton affinity and gas-phase basicity values both at the B3LYP and MP2 levels of theory, and all three of these supercharging reagents are significantly more basic than water. These results provide additional evidence that the origin of supercharging from aqueous solution is the result of chemical and/or thermal denaturation that occurs in the ESI droplet as the concentration of these supercharging reagents increases, and that proton transfer reactivity does not play a significant role in the charge enhancement observed

    Interfacing low-energy SAW nebulization with liquid chromatography-mass spectrometry for the analysis of biological samples

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    Soft ionization methods for the introduction of labile biomolecules into a mass spectrometer are of fundamental importance to biomolecular analysis. Previously, electrospray ionization (ESI) and matrix assisted laser desorption-ionization (MALDI) have been the main ionization methods used. Surface acoustic wave nebulization (SAWN) is a new technique that has been demonstrated to deposit less energy into ions upon ion formation and transfer for detection than other methods for sample introduction into a mass spectrometer (MS). Here we report the optimization and use of SAWN as a nebulization technique for the introduction of samples from a low flow of liquid, and the interfacing of SAWN with liquid chromatographic separation (LC) for the analysis of a protein digest. This demonstrates that SAWN can be a viable, low-energy alternative to ESI for the LC-MS analysis of proteomic samples
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