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A FAST SEAMLESS HANDOVER SCHEME AND ITS CDT OPTIMIZATION FOR PING-PONG TYPE OF MOVEMENT 被引量:3
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作者 Wang Yumlng Yang Zongkai +2 位作者 Zhao Dasheng He Jianhua Fu Xiaoming 《Journal of Electronics(China)》 2006年第2期298-303,共6页
In mobile IPv6 networks, the ping-pong type of movement brings about frequent handovers and thus increases signaling burden. This letter proposes a fast seamless handover scheme where the access router keeps the mobil... In mobile IPv6 networks, the ping-pong type of movement brings about frequent handovers and thus increases signaling burden. This letter proposes a fast seamless handover scheme where the access router keeps the mobile node's old reservation till the offline Count Down Timer (CDT) expires in order to reduce handover signaling and delay while the mobile node returns in a very short period of time. Based upon a pois son mobility model, an simple expression for CDT optimization is given out for the scheme to achieve the best cost performance of resource reservation. 展开更多
关键词 Mobile IPv6 Ping-pong type of movement QoS signaling Handover delay Cost performance.
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Optimal Node Scheduling for Desired Percentage of Coverage in Wireless Sensor Networks 被引量:4
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作者 Hamid Khosravi 《Wireless Sensor Network》 2012年第5期127-132,共6页
Recent developments in wireless communication and embedded computing technologies have led to the advent of wireless sensor network technology. Hundreds of thousands of these micro sensors can be deployed in many area... Recent developments in wireless communication and embedded computing technologies have led to the advent of wireless sensor network technology. Hundreds of thousands of these micro sensors can be deployed in many areas including health, environment and battlefield in order to monitor the domain with desired level of accuracy. When wireless sensors are deployed in an area, the lifetime of the network should last as long as possible according to the original amount of energy. Therefore, reducing energy consumption in WSNs is of primary concern. We have proposed a node scheduling solution that solves the coverage and connectivity problem in sensor networks in an integrated manner. In this way we will divide network life time to finite number of rounds and in each round we will generate a coverage bitmap of sensors of the domain and based on this bitmap it will decided which sensors remain active or go to sleep. We will check the connection of the sensor network by using Laplacian of adjancy graph of active nodes in each round. Also the network will be capable of producing desired percentage of coverage by using coverage bitmap. We will define the connected coverage problem as an optimization problem and we will seek a solution for the problem by using Genetic Algorithm optimization method. 展开更多
关键词 Wireless SENSOR Networks Connected SENSOR COVER CONNECTIVITY COVERAGE Energy Conservation
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Purine and Pyrimidine-Linked Enzymes and Genes are Strongly Responsible for the Development of Tumors, Particularly Glioblastoma Multiforme
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作者 Kristine Edgar Danielyan Tatul Ashot Yeghiazaryan +3 位作者 Samvel Grigoriy Chailyan Levon Ruben Harutyunyan Ruben Levon Harutyunyan Gurgen Sergei Petrosyan 《Computational Molecular Bioscience》 2020年第3期73-80,共8页
We were aiming to delineate, by the utility of the biological data results, in our investigations the link between the purine and pyrimidine metabolism and development of the glioblastoma. We analyzed the sets of the ... We were aiming to delineate, by the utility of the biological data results, in our investigations the link between the purine and pyrimidine metabolism and development of the glioblastoma. We analyzed the sets of the genes, belonging to the purine and pyrimidine metabolism by the utility of GSEA software as well as MSIgnDB application of the GSEA. The GEO database, GEOR2 tools were serving for the visualization of the genes expression profiles of the disease. The Cancer Proteome Atlas as well as the tools of the data sets were also used to collect and analyze the results. We concluded and came to the following consequential results. 1) Neurogenesis and Glioblastoma are sharing some common genes. 2) Purine and pyrimidine metabolism-linked enzymes and genes are responsible for the upregulation of DNA and mRNA synthesis in the settings of the tumor development. 3) EGFR expression responsible genes, mRNA as well as protein is upregulated during the development of the glioblastoma. 4) GMPS genes are more strongly upregulated in the settings of the glioblastoma than ADSL. 5) PRPS1 is strongly synthetized in neurospheres in contrast to the mature tissue during glioblastoma development. 展开更多
关键词 Data Bases PURINE PYRIMIDINE Metabolism GLIOBLASTOMA PRPS1
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Web Portal for Photonic Technologies Using Grid Infrastructures
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作者 Hrachya Astsatryan Tigran Gevorgyan Anna Shahinyan 《Journal of Software Engineering and Applications》 2012年第11期864-869,共6页
The modeling of physical processes is an integral part of scientific and technical research. In this area, the Extendible C++ Application in Quantum Technologies (ECAQT) package provides the numerical simulations and ... The modeling of physical processes is an integral part of scientific and technical research. In this area, the Extendible C++ Application in Quantum Technologies (ECAQT) package provides the numerical simulations and modeling of complex quantum systems in the presence of decoherence with wide applications in photonics. It allows creating models of interacting complex systems and simulates their time evolution with a number of available time-evolution drivers. Physical simulations require massive amounts of calculations are often executed on distributed computing infrastructures. It is often difficult for non expert users to use such computational infrastructures or even to use advanced libraries over the infrastructures, because they often require being familiar with middleware and tools, parallel programming techniques and packages. The Parallel Grid Run-time and Application Development Environment (P-RADE) Grid Portal is a Grid portal solution that allows users to manage the whole life-cycle for executing a parallel application on the computing Grid infrastructures. The article describes the functionality and the structure of the web portal based on ECAQT package. 展开更多
关键词 ECAQT ArmGrid P-Grade QSD Quantum Trajectories WIGNER Function
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自然科学与人文科学大数据——第六届中德前沿探索圆桌会议综述 被引量:15
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作者 郭华东 陈润生 +11 位作者 徐志伟 孙建军 毕军 王力哲 骆健俊 沈华伟 顾东晓 梁栋 沈文庆 张旭 Hans Wolfgang Spiess Thomas Lengauer 《中国科学院院刊》 CSCD 2016年第6期707-716,共10页
大数据是知识经济时代的战略高地,是国家和全球的新型战略资源。作为思维的革命性创新,大数据为科学研究带来了新的方法论。第六届中德前沿探索圆桌会议以"自然科学与人文科学大数据"为主题,在"生物医药大数据"、&q... 大数据是知识经济时代的战略高地,是国家和全球的新型战略资源。作为思维的革命性创新,大数据为科学研究带来了新的方法论。第六届中德前沿探索圆桌会议以"自然科学与人文科学大数据"为主题,在"生物医药大数据"、"物理、化学与地球科学领域大数据"、"人文与社会科学领域大数据"和"大数据处理技术与方法"4个领域进行研讨,总结了大数据对于科学发现的重要作用、意义以及面临的重大问题,形成了关于发展科学大数据研究的相关建议。 展开更多
关键词 大数据 科学大数据 生命科学 地球科学 人文科学 社会科学 计算机技术 中德前沿探索圆桌会议
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Science Letters:Crossover randomized controlled trial of the electronic version of the Chinese SF-36 被引量:3
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作者 CHEN Tian-hui LI Lu +3 位作者 SIGLE Joerg M. DU Ya-ping WANG Hong-mei LEI Jun 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2007年第8期604-608,共5页
Objectives:to verify the feasibility and reliability of the electronic version of Chinese SF-36 based on the Quality-of-Life-Recorder. Design: A crossover randomized controlled trial, comparing a paper-based and an el... Objectives:to verify the feasibility and reliability of the electronic version of Chinese SF-36 based on the Quality-of-Life-Recorder. Design: A crossover randomized controlled trial, comparing a paper-based and an electronic version of the Chinese SF-36, was conducted. According to generated random numbers, interviewees were asked to fill out either the electronic version or the paper version first. The second version was filled in after a pause of at least 10 min. Settings and participants: One group of 100 medical students at the School of Medicine of Zhejiang University and the other group of 50 outpatients at a clinic for general practice in Hangzhou City (China) were eventually recruited in this study. Results: The acceptance of the electronic version was good (60% of medical students and 84% of outpatients preferred the electronic version). At the level of eight-scale scores, the mean-difference for each scale (except for general health) between the two versions was less than 5%. At the level of 36 questions, the percentage of "exact agreement" ranged within 64%~99%; the percentage of "global agreement" ranged within 72%~99%; 77% of the kappa coefficients demonstrated "good/excellent agreement" and 23% of the kappa coefficients demonstrated "medium agreement". Conclusion: This study, for the first time, can provide empirical basis for the confirmation of the feasibility and reliability of the electronic version of the Chinese SF-36 and may provide an impulse towards widespread deployment of the Quality-of-Life-Recorder in Chinese populations. 展开更多
关键词 Health-related quality of life (HRQoL) SF-36 Electronic questionnaire Computer based testing General practice Randomized control trial Feasibility Reliability
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Scientometric Implosion that Leads to Explosion: Case Study of Armenian Journals 被引量:1
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作者 Shushanik Sargsyan Edita Gzoyan +1 位作者 Aram Mirzoyan Viktor Blaginin 《Journal of Data and Information Science》 CSCD 2020年第3期187-196,共10页
Purpose: The purpose of this study is to introduce a new concept and term into the scientometric discourse and research—scientometric implosion—and test the idea on the example of the Armenian journals. The article ... Purpose: The purpose of this study is to introduce a new concept and term into the scientometric discourse and research—scientometric implosion—and test the idea on the example of the Armenian journals. The article argues that the existence of a compressed scientific area in the country makes pressure on the journals and after some time this pressure makes one or several journals explode—break the limited national scientific area and move to the international arena. As soon as one of the local journals breaks through this compressed space and appears at an international level, further explosion happens, which makes the other journals follow the same path.Design/methodology/approach: Our research is based on three international scientific databases—WoS, Scopus, and RISC CC, from where we have retrieved information about the Armenian journals indexed there and citations received by those journals and one national database—the Armenian Science Citation Index. Armenian Journal Impact Factor(ArmJIF) was calculated for the local Armenian journals based on the general impact factor formula. Journals were classified according to Gl?nzel and Schubert(2003). Findings: Our results show that the science policy developed by the scientific authorities of Armenia and the introduction of ArmJIF have made the Armenian journals comply with international standards and resulted in some local journals to break the national scientific territory and be indexed in international scientific databases of RISC, Scopus, and WoS. Apart from complying with technical requirements, the journals start publishing articles also in foreign languages. Although nearly half of the local journals are in the fields of social sciences and humanities, only one journal from that field is indexed in international scientific databases. Research limitation: One of the limitations of the study is that it was performed on the example of only one state and the second one is that more time passage is needed to firmly evaluate the results. However, the introduction of the concept can inspire other similar case study. Practical implications: The new term and relevant model offered in the article can practically be used for the development of national journals.Originality/value: The article proposes a new term and a concept in scientometrics. 展开更多
关键词 Sceintometric implosion Armenian Journal Impact Factor(ArmJIF) National scientific databases Armenian Science Citation Index(ASCI) International scientific databases
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An explainable AI framework for robust and transparent data-driven wind turbine power curve models 被引量:1
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作者 Simon Letzgus Klaus-Robert Müller 《Energy and AI》 EI 2024年第1期312-327,共16页
In recent years,increasingly complex machine learning methods have become state-of-the-art in modelling wind turbine power curves based on operational data.While these methods often exhibit superior performance on tes... In recent years,increasingly complex machine learning methods have become state-of-the-art in modelling wind turbine power curves based on operational data.While these methods often exhibit superior performance on test sets,they face criticism due to a perceived lack of transparency and concerns about their robustness in dynamic,non-stationary environments encountered by wind turbines.In this work,we address these issues and present a framework that leverages explainable artificial intelligence methods to gain systematic insights into data-driven power curve models.At its core,we propose a metric to quantify how well a learned model strategy aligns with the underlying physical principles of the problem.This novel tool enables model validation beyond the conventional error metrics in an automated manner.We demonstrate,for instance,its capacity as an indicator for model generalization even when limited data is available.Moreover,it facilitates understanding how decisions made during the machine learning development process,such as data selection,pre-processing,or training parameters,affect learned strategies.As a result,we obtain physically more reasonable models,a prerequisite not only for robustness but also for meaningful insights into turbine operation by domain experts.The latter,we illustrate in the context of wind turbine performance monitoring.In summary,the framework aims to guide researchers and practitioners alike toward a more informed selection and utilization of data-driven wind turbine power curve models. 展开更多
关键词 Explainable AI(XAI) Machine learning Wind energy Wind turbine power curve SCADA Condition monitoring
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International visibility of Armenian domestic journals:the role of scientific diaspora
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作者 Edita Gzoyan Aram Mirzoyan +3 位作者 Anush Sargsyan Mariam Yeghikyan Domenico AMaisano Shushanik Sargsyan 《Journal of Data and Information Science》 CSCD 2023年第2期93-117,共25页
Purpose:Nearly 122 scientific journals are currently being published in Armenia-of which only six are indexed by WoS and/or Scopus databases.The majority of the national journals are published in the Armenian language... Purpose:Nearly 122 scientific journals are currently being published in Armenia-of which only six are indexed by WoS and/or Scopus databases.The majority of the national journals are published in the Armenian language,solely possessing abstracts written in English,although there are also English-language and multi-language journals with articles not only in Armenian but also in other foreign languages.The aim of this article is to study the visibility of the(non-indexed)national Armenian journals in the WoS database through citation analysis.In consideration of the existence of a relevant Armenian“diaspora”in the world,this article also attempts to estimate its impact in terms of citation statistics.Design/methodology/approach:For this end,we have identified citations to the national/domestic Armenian journals in the WoS database in comparison with the share of citations received from“diaspora”researchers(researchers of Armenian origin born in foreign countries and those originally from Armenia who have emigrated to foreign countries).Findings:Among the 116 Armenian domestic journals analyzed(not indexed by WoS),only 47 were found to be cited in WoS.Of these journals,almost 12%are citations by“diaspora”researchers,most of which concern Social Science and Humanities journals.Research limitations:Although the surnames of Armenians end with-i(y)an,sometimes,the Diaspora Armenians,surnames are changed or modified or they are not ending with-i(y)an,in this case we may fail to identify them.Practical implications:This study can help to build new,more deep and comprehensive relations with scientific diasporas.Originality/value:This study offers a new understanding of multifaced research collaboration with scientific diasporas and their role in internationalization of domestic journals. 展开更多
关键词 Citation analysis National/domestic journal Armenian diaspora Scientific diaspora
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On a Number of Colors in Cyclically Interval Edge Colorings of Simple Cycles
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作者 Rafayel R. Kamalian 《Open Journal of Discrete Mathematics》 2013年第1期43-48,共6页
A proper edge t-coloring of a graph G is a coloring of its edges with colors 1,2,???,t such that all colors are used, and no two adjacent edges receive the same color. A cyclically interval t-coloring of a graph G is ... A proper edge t-coloring of a graph G is a coloring of its edges with colors 1,2,???,t such that all colors are used, and no two adjacent edges receive the same color. A cyclically interval t-coloring of a graph G is a proper edge t-coloring of G such that for each its vertex x, either the set of colors used on edges incident to x or the set of colors not used on edges incident to x forms an interval of integers. For an arbitrary simple cycle, all possible values of t are found, for which the graph has a cyclically interval t-coloring. 展开更多
关键词 PROPER Edge COLORING Cyclically INTERVAL COLORING SIMPLE CYCLE
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NAMD Package Benchmarking on the Base of Armenian Grid Infrastructure
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作者 Armen Poghosyan Levon Arsenyan +3 位作者 Hrachya Astsatryan Mikayel Gyurjyan Hovsep Keropyan Aram Shahinyan 《Communications and Network》 2012年第1期34-40,共7页
The parallel scaling (parallel performance up to 48 cores) of NAMD package has been investigated by estimation of the sensitivity of interconnection on speedup and benchmark results—testing the parallel performance o... The parallel scaling (parallel performance up to 48 cores) of NAMD package has been investigated by estimation of the sensitivity of interconnection on speedup and benchmark results—testing the parallel performance of Myrinet, Infiniband and Gigabit Ethernet networks. The system of ApoA1 of 92 K atoms, as well as 1000 K, 330 K, 210 K, 110 K, 54 K, 27 K and 16 K has been used as testing systems. The Armenian grid infrastructure (ArmGrid) has been used as a main platform for series of benchmarks. According to the results, due to the high performance of Myrinet and Infiniband networks, the ArmCluster system and the cluster located in the Yerevan State University show reasonable values, meanwhile the scaling of clusters with various types of Gigabit Ethernet interconnections breaks down when interconnection is activated. However, the clusters equipped by Gigabit Ethernet network are sensitive to change of system, particularly for 1000 K systems no breakdown in scaling is observed. The infiniband supports in comparison with Myrinet, make it possible to receive almost ideally results regardless of system size. In addition, a benchmarking formula is suggested, which provides the computational throughput depending on the number of processors. These results should be important, for instance, to choose most appropriate amount of processors for studied system. 展开更多
关键词 Parallel MOLECULAR Dynamics NAMD BENCHMARKING GRID
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Drug-Treatment Generation Combinatorial Algorithm Based on Machine Learning and Statistical Methodologies
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作者 Karen Gishyan 《Open Journal of Applied Sciences》 CAS 2023年第4期548-561,共14页
Finding out the desired drug combinations is a challenging task because of the number of different combinations that exist and the adversarial effects that may arise. In this work, we generate drug combinations over m... Finding out the desired drug combinations is a challenging task because of the number of different combinations that exist and the adversarial effects that may arise. In this work, we generate drug combinations over multiple stages using distance calculation metrics from supervised learning, clustering, and a statistical similarity calculation metric for deriving the optimal treatment sequences. The combination generation happens for each patient based on the characteristics (features) observed during each stage of treatment. Our approach considers not the drug-to-drug (one-to-one) effect, but rather the effect of group of drugs with another group of drugs. We evaluate the combinations using an FNN model and identify future improvement directions. 展开更多
关键词 Combinatorial Treatments Health Informatics Machine Learning
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USEVis:Visual analytics of attention-based neural embedding in information retrieval
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作者 Xiaonan Ji Yamei Tu +3 位作者 Wenbin He Junpeng Wang Han-Wei Shen Po-Yin Yen 《Visual Informatics》 EI 2021年第2期1-12,共12页
Neural attention-based encoders,which effectively attend sentence tokens to their associated context without being restricted by long-term distance or dependency,have demonstrated outstanding performance in embedding ... Neural attention-based encoders,which effectively attend sentence tokens to their associated context without being restricted by long-term distance or dependency,have demonstrated outstanding performance in embedding sentences into meaningful representations(embeddings).The Universal Sentence Encoder(USE)is one of the most well-recognized deep neural network(DNN)based solutions,which is facilitated with an attention-driven transformer architecture and has been pre-trained on a large number of sentences from the Internet.Besides the fact that USE has been widely used in many downstream applications,including information retrieval(IR),interpreting its complicated internal working mechanism remains challenging.In this work,we present a visual analytics solution towards addressing this challenge.Specifically,focused on semantics and syntactics(concepts and relations)that are critical to domain clinical IR,we designed and developed a visual analytics system,i.e.,USEVis.The system investigates the power of USE in effectively extracting sentences’semantics and syntactics through exploring and interpreting how linguistic properties are captured by attentions.Furthermore,by thoroughly examining and comparing the inherent patterns of these attentions,we are able to exploit attentions to retrieve sentences/documents that have similar semantics or are closely related to a given clinical problem in IR.By collaborating with domain experts,we demonstrate use cases with inspiring findings to validate the contribution of our work and the effectiveness of our system. 展开更多
关键词 Interactive visual system Neural embedding Attention mechanism Document understanding Information retrieval Clinical decision-making
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Will artificial intelligence widen the therapeutic gap between children and adults? 被引量:1
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作者 Matthew Nagy Bryan Sisk +1 位作者 Albert Lai Eric Kodish 《Pediatric Investigation》 CAS CSCD 2024年第1期1-6,共6页
The impending rise of artificial intelligence(AI)-powered healthcare offers exciting hope for improved care and outcomes in children with serious illnesses.1 The historical precedent in healthcare,however,suggests tha... The impending rise of artificial intelligence(AI)-powered healthcare offers exciting hope for improved care and outcomes in children with serious illnesses.1 The historical precedent in healthcare,however,suggests that advancements in adult care do not necessarily result in proportional progress in pediatrics.This disparity was first noted in the mid-20th century when tragedies that involved drugs with well-studied and known adult safety profiles,such as sulfonamide elixir and thalidomide,resulted in harm to children due to limited pediatric clinical trial inclusion.2 As a result,legislation in 1962 required drug companies to include package labels that restricted or dissuaded the use of medications in children that were not properly studied in this population.2 Subsequently,physicians became reluctant to prescribe many medications,and pharmaceutical companies had little incentive to enroll children in trials as an unfavorable result could negatively impact sales in the adult market,and a successful outcome would only marginally increase the market pool.3 This lack of access led Dr.Harry Shirkey to describe children as"therapeutic orphans"in 1968.2 After more than half a century of legislation aimed at increasing pediatric representation in research and drug development(Figure 1),enrollment of children in clinical trials remains disproportionately low,4 with children included in as few as 12%of trials for diseases with a burden equal to,or greater in,the pediatric versus adult population. 展开更多
关键词 COMPANIES FIGURE PROPERLY
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Transcomplementation, but not Physical Association of the CC-NB-ARC and LRR Domains of Tomato R Protein Mi-1.2 is Altered by Mutations in the ARC2 Subdomain 被引量:1
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作者 Gerben van Ooijen Gabriele Mayr +2 位作者 Mario Albrecht Ben J. C. Cornelissen Frank L.W. Takken 《Molecular Plant》 SCIE CAS CSCD 北大核心 2008年第3期401-410,共10页
Race-specific disease resistance in plants is mediated by Resistance (R) proteins that recognize pathogen at- tack and initiate defence responses. Most R proteins contain a central NB-ARC domain and a C-terminal leu... Race-specific disease resistance in plants is mediated by Resistance (R) proteins that recognize pathogen at- tack and initiate defence responses. Most R proteins contain a central NB-ARC domain and a C-terminal leucine-rich repeat (LRR) domain. We analyzed the intramolecular interaction of the LRR domain of tomato R protein Mi-1.2 with its N- terminus. We expressed the CC-NB-ARC and LRR parts in trans and analyzed functional transcomplementation and physical interactions. We show that these domains functionally transcomplement when expressed in trans. Known autoactivating LRR domain swaps were found to induce a hypersensitive response (HR) upon co-expression. Likewise, autoactivating mutants in the NB subdomain transcomplemented to induce HR. Point mutations in the ARC2 subdomain that induce strong autoactivation in the full-length Mi-1.2 protein, however, fail to induce HR in the transcomplementation assay, These data indicate distinct functions for the NB-ARC subdomains in induction of HR signalling. Furthermore, dissociation of the LRR is not required to release its negative regulation, as in all combinations of CC-NB-ARC and LRR domains tested, a physical interaction was observed. 展开更多
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The ARTICONF approach to decentralized car-sharing
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作者 Nishant Saurabh Carlos Rubia +6 位作者 Anandakumar Palanisamy Spiros Koulouzis Mirsat Sefidanoski Antorweep Chakravorty Zhiming Zhao Aleksandar Karadimce Radu Prodan 《Blockchain(Research and Applications)》 2021年第3期1-16,共16页
Social media applications are essential for next-generation connectivity.Today,social media are centralized platforms with a single proprietary organization controlling the network and posing critical trust and govern... Social media applications are essential for next-generation connectivity.Today,social media are centralized platforms with a single proprietary organization controlling the network and posing critical trust and governance issues over the created and propagated content.The ARTICONF project funded by the European Union's Horizon 2020 program researches a decentralized social media platform based on a novel set of trustworthy,resilient and globally sustainable tools that address privacy,robustness and autonomy-related promises that proprietary social media platforms have failed to deliver so far.This paper presents the ARTICONF approach to a car-sharing decentralized application(DApp)use case,as a new collaborative peer-to-peer model providing an alternative solution to private car ownership.We describe a prototype implementation of the car-sharing social media DApp and illustrate through real snapshots how the different ARTICONF tools support it in a simulated scenario. 展开更多
关键词 Social media Car-sharing DECENTRALIZATION Blockchain
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Aberrant DNA methylation reprogramming during induced pluripotent stem cell generation is dependent on the choice of reprogramming factors
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作者 Aline C Planello Junfeng Ji +7 位作者 Vivek Sharma Rajat Singhania Faridah Mbabaali Fabian Müller Javier A Alfaro Christoph Bock Daniel D De Carvalho Nizar N Batada 《Cell Regeneration》 2014年第1期30-43,共14页
The conversion of somatic cells into pluripotent stem cells via overexpression of reprogramming factors involvesepigenetic remodeling. DNA methylation at a significant proportion of CpG sites in induced pluripotent st... The conversion of somatic cells into pluripotent stem cells via overexpression of reprogramming factors involvesepigenetic remodeling. DNA methylation at a significant proportion of CpG sites in induced pluripotent stem cells(iPSCs) differs from that of embryonic stem cells (ESCs). Whether different sets of reprogramming factors influencethe type and extent of aberrant DNA methylation in iPSCs differently remains unknown. In order to help resolvethis critical question, we generated human iPSCs from a common fibroblast cell source using either the Yamanakafactors (OCT4, SOX2, KLF4 and cMYC) or the Thomson factors (OCT4, SOX2, NANOG and LIN28), and determinedtheir genome-wide DNA methylation profiles. In addition to shared DNA methylation aberrations present in all ouriPSCs, we identified Yamanaka-iPSC (Y-iPSC)-specific and Thomson-iPSC (T-iPSC)-specific recurrent aberrations.Strikingly, not only were the genomic locations of the aberrations different but also their types: reprogrammingwith Yamanaka factors mainly resulted in failure to demethylate CpGs, whereas reprogramming with Thomsonfactors mainly resulted in failure to methylate CpGs. Differences in the level of transcripts encoding DNMT3b andTET3 between Y-iPSCs and T-iPSCs may contribute partially to the distinct types of aberrations. Finally, de novoaberrantly methylated genes in Y-iPSCs were enriched for NANOG targets that are also aberrantly methylated insome cancers. Our study thus reveals that the choice of reprogramming factors influences the amount, location,and class of DNA methylation aberrations in iPSCs. These findings may provide clues into how to produce humaniPSCs with fewer DNA methylation abnormalities. 展开更多
关键词 SOX2 programming THOMSON
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