4,026 research outputs found

    Joint Channel Assignment and Opportunistic Routing for Maximizing Throughput in Cognitive Radio Networks

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    In this paper, we consider the joint opportunistic routing and channel assignment problem in multi-channel multi-radio (MCMR) cognitive radio networks (CRNs) for improving aggregate throughput of the secondary users. We first present the nonlinear programming optimization model for this joint problem, taking into account the feature of CRNs-channel uncertainty. Then considering the queue state of a node, we propose a new scheme to select proper forwarding candidates for opportunistic routing. Furthermore, a new algorithm for calculating the forwarding probability of any packet at a node is proposed, which is used to calculate how many packets a forwarder should send, so that the duplicate transmission can be reduced compared with MAC-independent opportunistic routing & encoding (MORE) [11]. Our numerical results show that the proposed scheme performs significantly better that traditional routing and opportunistic routing in which channel assignment strategy is employed.Comment: 5 pages, 4 figures, to appear in Proc. of IEEE GlobeCom 201

    K-12教育におけるGOALシステムを用いた文脈的な自己主導学習の促進

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    京都大学新制・課程博士博士(情報学)甲第24734号情博第822号新制||情||138(附属図書館)京都大学大学院情報学研究科社会情報学専攻(主査)教授 緒方 広明, 教授 伊藤 孝行, 准教授 馬 強学位規則第4条第1項該当Doctor of InformaticsKyoto UniversityDFA

    Development Of Single And Array Electro-Chemical Sensors For Real-Time Trace Metal Analysis In Aqueous Environmental Media

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    Detection of trace metals has great importance in environmental and biological applications. While traditional electrochemical techniques have played critical roles in this field, their usefulness is limited by temporal resolution, Hg toxicity and stability concerns. Recently, we developed a method using fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes (CFMs) to achieve rapid measurement of metal ions with high sensitivity, selectivity, and stability. Through optimizations this method showed strengths in real-time trace metal analysis. ‬‬‬‬‬‬ ‪Analytical selectivity was improved via covalent functionalization on CFMs. We employed diazonium electrochemical reduction followed by click chemistry to create robust covalent attachments. We showcased its application through grafting Cu(II) ionophores onto CFMs. The selectivity was further reinforced via inhibition of other species’ adsorption at surface oxygen groups. This stepwise functionalization approach served as a universal platform for elevating CFMs’ selectivity, while retaining sensitivity, response, stability, and lifetime.‬‬‬‬‬‬ In parallel work, pyrolyzed photoresist film (PPF) microelectrode arrays (MEAs) were fabricated to extend the borderlines of FSCV towards simultaneous multi-analyte analysis. The PPF MEAs maintained CFM’s carbon-fiber structures but provided more sensing channels. We employed a two-step pyrolysis process and a dual oxygen plasma treatment to improve fabrication repeatability, surface reactivity, and spatial geometry. Our technique has evident potential to achieve real-time simultaneous detection of various electroactive molecules and be employed for numerous applications in complex biological and environmental systems.‬‬‬‬

    Does Capital Account Liberalization Affect the Financial Stability: Evidence from China

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    This paper seeks to investigate the relationship between capital account liberalization and the financial stability in China. Furthermore, The Finite Distributed Lag Model is employed to quantify relationship between capital account liberalization and monetary crisis. And a general conclusion can be drawn that capital account liberalization is harmful to the stability official market in one year period, while the overall capital account liberalization effect can facilitate China's financial stability in a long run. Moreover, some suggestions are provided on China's capital account liberalization policies

    Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations.

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    The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate

    Application of DMSP/OLS nighttime light images : a meta-analysis and a systematic literature review

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    © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Remote Sensing 6 (2014): 6844-6866, doi:10.3390/rs6086844.Since the release of the digital archives of Defense Meteorological Satellite Program Operational Line Scanner (DMSP/OLS) nighttime light data in 1992, a variety of datasets based on this database have been produced and applied to monitor and analyze human activities and natural phenomena. However, differences among these datasets and how they have been applied may potentially confuse researchers working with these data. In this paper, we review the ways in which data from DMSP/OLS nighttime light images have been applied over the past two decades, focusing on differences in data processing, research trends, and the methods used among the different application areas. Five main datasets extracted from this database have led to many studies in various research areas over the last 20 years, and each dataset has its own strengths and limitations. The number of publications based on this database and the diversity of authors and institutions involved have shown promising growth. In addition, researchers have accumulated vast experience retrieving data on the spatial and temporal dynamics of settlement, demographics, and socioeconomic parameters, which are “hotspot” applications in this field. Researchers continue to develop novel ways to extract more information from the DMSP/OLS database and apply the data to interdisciplinary research topics. We believe that DMSP/OLS nighttime light data will play an important role in monitoring and analyzing human activities and natural phenomena from space in the future, particularly over the long term. A transparent platform that encourages data sharing, communication, and discussion of extraction methods and synthesis activities will benefit researchers as well as public and political stakeholders.This work is supported by the 111 project “Hazard and Risk Science Base at Beijing Normal University” under Grant B08008 (Ministry of Education and State Administration of Foreign Experts Affairs, PRC), the State Key Laboratory of Earth Surface Processes and Resource Ecology of Beijing Normal University (No. 2013-RC-03), and the Fundamental Research Funds for the Central Universities (Grant No. 201413037)
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