732 research outputs found

    Communication and Control in Collaborative UAVs: Recent Advances and Future Trends

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    The recent progress in unmanned aerial vehicles (UAV) technology has significantly advanced UAV-based applications for military, civil, and commercial domains. Nevertheless, the challenges of establishing high-speed communication links, flexible control strategies, and developing efficient collaborative decision-making algorithms for a swarm of UAVs limit their autonomy, robustness, and reliability. Thus, a growing focus has been witnessed on collaborative communication to allow a swarm of UAVs to coordinate and communicate autonomously for the cooperative completion of tasks in a short time with improved efficiency and reliability. This work presents a comprehensive review of collaborative communication in a multi-UAV system. We thoroughly discuss the characteristics of intelligent UAVs and their communication and control requirements for autonomous collaboration and coordination. Moreover, we review various UAV collaboration tasks, summarize the applications of UAV swarm networks for dense urban environments and present the use case scenarios to highlight the current developments of UAV-based applications in various domains. Finally, we identify several exciting future research direction that needs attention for advancing the research in collaborative UAVs

    Oxidative ethanol dry reforming for production of syngas over Co-based catalyst : Effect of reaction temperature

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    Till date, oxidative ethanol steam reforming use Ni-based catalysts to produce syngas. However, Ni catalysts suffer from easy deactivation due to the coke formation at low temperatures. Therefore, oxidative ethanol dry reforming is a promising method and was investigated over 10 %Co/Al2O3 catalyst due to their high activity and stability to produce high-quality syngas. More importantly, the syngas can be upgraded to produce liquid biofuels and chemicals. The catalyst was evaluated in a quartz fixed-bed reactor under atmospheric pressure at PCO2 =PO2= 5 kPa, PC2H5OH = 15 kPa, with reaction temperature ranging between 773 and 973 K. The γ-Al2O3 support and 10 %Co/Al2O3 catalyst had BET surface areas of 175.2 m2 g−1 and 143.1 m2 g−1, respectively. Co3O4 and spinel CoAl2O4 phases were detected through X-ray diffraction measurements on the 10 %Co/Al2O3 catalyst surface. H2-TPR measurements indicate that the 10 %Co/Al2O3 catalyst was completely reduced at a temperature beyond 1000 K. NH3-TPD measurements indicated the presence of the weak, medium, and strong acid sites on the γ-Al2O3 support and 10 %Co/Al2O3 catalyst. Due to increased reaction temperature from 773 to 973 K, C2H5OH and CO2 conversions improved from 22.5 % to 93.6 % and 16.9–52.8 %, respectively. Additionally, the optimal yield of H2 and CO obtained at 68.1 % and 58.3 %, respectively. Temperature-programmed oxidation experiments indicated that the amount of carbon deposition was the lowest (28,92 %) at 973 K and increased by 41.48 % at 773 K.publishedVersionPeer reviewe

    Rd9 Is a Naturally Occurring Mouse Model of a Common Form of Retinitis Pigmentosa Caused by Mutations in RPGR-ORF15

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    Animal models of human disease are an invaluable component of studies aimed at understanding disease pathogenesis and therapeutic possibilities. Mutations in the gene encoding retinitis pigmentosa GTPase regulator (RPGR) are the most common cause of X-linked retinitis pigmentosa (XLRP) and are estimated to cause 20% of all retinal dystrophy cases. A majority of RPGR mutations are present in ORF15, the purine-rich terminal exon of the predominant splice-variant expressed in retina. Here we describe the genetic and phenotypic characterization of the retinal degeneration 9 (Rd9) strain of mice, a naturally occurring animal model of XLRP. Rd9 mice were found to carry a 32-base-pair duplication within ORF15 that causes a shift in the reading frame that introduces a premature-stop codon. Rpgr ORF15 transcripts, but not protein, were detected in retinas from Rd9/Y male mice that exhibited retinal pathology, including pigment loss and slowly progressing decrease in outer nuclear layer thickness. The levels of rhodopsin and transducin in rod outer segments were also decreased, and M-cone opsin appeared mislocalized within cone photoreceptors. In addition, electroretinogram (ERG) a- and b-wave amplitudes of both Rd9/Y male and Rd9/Rd9 female mice showed moderate gradual reduction that continued to 24 months of age. The presence of multiple retinal features that correlate with findings in individuals with XLRP identifies Rd9 as a valuable model for use in gaining insight into ORF15-associated disease progression and pathogenesis, as well as accelerating the development and testing of therapeutic strategies for this common form of retinal dystrophy

    An Animal Model of Emotional Blunting in Schizophrenia

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    Schizophrenia is often associated with emotional blunting—the diminished ability to respond to emotionally salient stimuli—particularly those stimuli representative of negative emotional states, such as fear. This disturbance may stem from dysfunction of the amygdala, a brain region involved in fear processing. The present article describes a novel animal model of emotional blunting in schizophrenia. This model involves interfering with normal fear processing (classical conditioning) in rats by means of acute ketamine administration. We confirm, in a series of experiments comprised of cFos staining, behavioral analysis and neurochemical determinations, that ketamine interferes with the behavioral expression of fear and with normal fear processing in the amygdala and related brain regions. We further show that the atypical antipsychotic drug clozapine, but not the typical antipsychotic haloperidol nor an experimental glutamate receptor 2/3 agonist, inhibits ketamine's effects and retains normal fear processing in the amygdala at a neurochemical level, despite the observation that fear-related behavior is still inhibited due to ketamine administration. Our results suggest that the relative resistance of emotional blunting to drug treatment may be partially due to an inability of conventional therapies to target the multiple anatomical and functional brain systems involved in emotional processing. A conceptual model reconciling our findings in terms of neurochemistry and behavior is postulated and discussed

    Evolving concepts on the age-related changes in “muscle quality”

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    The deterioration of skeletal muscle with advancing age has long been anecdotally recognized and has been of scientific interest for more than 150 years. Over the past several decades, the scientific and medical communities have recognized that skeletal muscle dysfunction (e.g., muscle weakness, poor muscle coordination, etc.) is a debilitating and life-threatening condition in the elderly. For example, the age-associated loss of muscle strength is highly associated with both mortality and physical disability. It is well-accepted that voluntary muscle force production is not solely dependent upon muscle size, but rather results from a combination of neurologic and skeletal muscle factors, and that biologic properties of both of these systems are altered with aging. Accordingly, numerous scientists and clinicians have used the term “muscle quality” to describe the relationship between voluntary muscle strength and muscle size. In this review article, we discuss the age-associated changes in the neuromuscular system—starting at the level of the brain and proceeding down to the subcellular level of individual muscle fibers—that are potentially influential in the etiology of dynapenia (age-related loss of muscle strength and power)

    Measurement of the t-channel single top quark production cross section in pp collisions at √s =7 TeV

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    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

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    One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI
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