Tsinghua Science and Technology


  • Prediction of Cancer-Associated piRNA–mRNA and piRNA–lncRNA Interactions by Integrated Analysis of Expression and Sequence Data

    Yajun Liu;Junying Zhang;Aimin Li;Zhaowen Liu;Zhongzhen He;Xiguo Yuan;Shouheng Tuo;

    piwi-interactingRNAs(piRNAs) are valuable biomarkers, but functional studies are still very limited.Recent research shows that piRNA-mediated cleavage acts on Transposable Elements(TEs), messengerRNAs(mRNAs), and long non-codingRNAs(lncRNAs). This study aimed to predict cancer-associated piRNA-mRNA and piRNA-lncRNA interactions as well as piRNA regulatory functions. Four cancer types(BRCA, HNSC, KIRC,and LUAD) were investigated. Interactions were identified by integrated analysis of the expression and sequence data. For the expression analysis, only piRNA–mRNA and piRNA–lncRNA pairs with expression profiles that were significantly inversely correlated were retained to reduce false-positive rates during the prediction. For the sequence analysis, miRanda was used for the target prediction. We identified 198 piRNA–mRNA and 10 piRNA–lncRNA pairs. Unlike mRNA and lncRNA expressions, the piRNA expression was relatively consistent across the cancer types. Furthermore, the identified piRNAs were consistent with previously published cancer biomarkers, such as piRNA-36741, piR-21032, and piRNA-57125. More importantly, predicted piRNA functions were determined by constructing an interaction network, and piRNA targets were placed in gene ontology categories related to the cancer hallmarks "activating invasion and metastasis" and "sustained angiogenesis".

    2018年02期 v.23 115-125页 [查看摘要][在线阅读][下载 726K]
    [下载次数:19 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Achievable Secrecy Rate Region of Two-Way Communication with Secret Key Feedback

    Tao Li;Shidong Zhou;

    This paper investigates the achievable secrecy rate region of the Gaussian two-way wiretap channel,which describes the simultaneous secure two-way transmission of a confidential message. Through adjusting the time-sharing factor and the rate at which the random secret key is fed back, the allocation and optimization for the secrecy rates of two-way communication are achieved. Under peak and average power constraints, the achievable secrecy rate regions of the two-way communication are derived respectively.

    2018年02期 v.23 126-134页 [查看摘要][在线阅读][下载 542K]
    [下载次数:2 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Comparison of Travel Mode Choice Between Taxi and Subway Regarding Traveling Convenience

    Li Li;Shuofeng Wang;Meng Li;Jiyuan Tan;

    In this study, we investigate travel mode choice behavior between taxi and subway with an emphasis on the influence of traveling convenience. In the first stage, we examine the Origin-Destination(OD) points of Beijing taxi trips and compare these locations with the respective nearest subway station. Statistics reveal several interesting conclusions. First, for approximately 24.89% of all trips, no convenient subway connections exist between the OD pairs. As such, a taxi becomes the only viable choice. Second, for 80.23% of the remaining 75.11%of trips(equivalent to 60.26% of all trips), access distance from either the origin or the destination to the nearest subway station is greater than 500 meters. This phenomenon indicates that walking distance plays an important role in travel mode choice. In the second stage, we examine groups of taxi trips with similar travel distances and travel times to reveal common features. We establish a preference rule in terms of travel distance and travel time.This determines whether an individual driver will take a taxi or the subway, using a pairwise comparison-based preference regression model. Tests indicate that more than 95% of taxi trips can be correctly predicted by this preference rule. This conclusion reveals that traveling convenience dominates the travel model choice between taxi and subway. All these findings shed light on the factors that influence travel mode choice behavior.

    2018年02期 v.23 135-144页 [查看摘要][在线阅读][下载 851K]
    [下载次数:16 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Improved Bag-of-Words Model for Person Re-identification

    Lu Tian;Shengjin Wang;

    Person re-identification(person re-id) aims to match observations on pedestrians from different cameras.It is a challenging task in real word surveillance systems and draws extensive attention from the community.Most existing methods are based on supervised learning which requires a large number of labeled data. In this paper, we develop a robust unsupervised learning approach for person re-id. We propose an improved Bag-of-Words(i Bo W) model to describe and match pedestrians under different camera views. The proposed descriptor does not require any re-id labels, and is robust against pedestrian variations. Experiments show the proposed i Bo W descriptor outperforms other unsupervised methods. By combination with efficient metric learning algorithms, we obtained competitive accuracy compared to existing state-of-the-art methods on person re-identification benchmarks, including VIPe R, PRID450 S, and Market1501.

    2018年02期 v.23 145-156页 [查看摘要][在线阅读][下载 608K]
    [下载次数:20 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Safety Analysis of the Eco-Approach and Departure Application at a Signalized Corridor

    Weixia Li;Guoyuan Wu;Yi Zhang;Matthew J.Barth;

    Various intelligent transportation systems and strategies for reducing vehicle fuel consumption and emissions have been developed. Energy and emissions could be reduced with the compromise of travel time in some environment-focused Connected Vehicle(CV) applications, which highlighted performance measures in terms of mobility and sustainability. Nevertheless, few studies have focused on safety assessment of such CV applications. In this study, a CV-based eco-driving application, namely, Eco-Approach and Departure(EAD), is selected as an example. A microscopic safety analysis tool, Surrogate Safety Assessment Model(SSAM), is utilized to assess the safety influence of EAD application in multiple scenarios. Further analysis is performed from two perspectives:(1) application users, i.e., EAD-equipped vehicles versus unequipped vehicles; and(2) traffic operators, i.e., overall traffic performance with and without the introduction of EAD. For each perspective, conflict statistics(e.g., frequency, time-to-collision distribution), overall and by type, are analyzed. Results indicate EAD is beneficial in improving the safety performance of equipped vehicles. The influence of EAD on overall traffic is scenario dependent, and a high penetration rate shows positive effects on network-wide safety benefits for most scenarios.

    2018年02期 v.23 157-171页 [查看摘要][在线阅读][下载 2197K]
    [下载次数:25 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Effects of Power Inversion Spatial Only Adaptive Array on GNSS Receiver Measurements

    Hailong Xu;Xiaowei Cui;Mingquan Lu;

    The Spatial Only Processing Power Inversion(SOP-PI) algorithm is frequently used in Global Navigation Satellite System(GNSS) adaptive array receivers for interference mitigation because of its simplicity of implementation. This study investigates the effects of SOP-PI on receiver measurements for high-precision applications. Mathematical deductions show that if an array with a centro-symmetrical geometry is used, ideally,SOP-PI is naturally bias-free; however, this no longer stands when non-ideal factors, including array perturbations and finite-sample effect, are added. Simulations are performed herein to investigate how exactly the array perturbations affect the carrier phase biases, while diagonal loading and forward-backward averaging are proposed to counter the finite-sample effect. In conclusion, whether SOP-PI with a centro-symmetrical array geometry will satisfy the high precision demands mainly depends on the array perturbation degree of the element amplitude and the phase center.

    2018年02期 v.23 172-183页 [查看摘要][在线阅读][下载 1002K]
    [下载次数:4 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Greedy Optimization for K-Means-Based Consensus Clustering

    Xue Li;Hongfu Liu;

    Consensus clustering aims to fuse several existing basic partitions into an integrated one; this has been widely recognized as a promising tool for multi-source and heterogeneous data clustering. Owing to robust and high-quality performance over traditional clustering methods, consensus clustering attracts much attention, and much efforts have been devoted to develop this field. In the literature, the K-means-based Consensus Clustering(KCC) transforms the consensus clustering problem into a classical K-means clustering with theoretical supports and shows the advantages over the state-of-the-art methods. Although KCC inherits the merits from K-means,it suffers from the initialization sensitivity. Moreover, the current consensus clustering framework separates the basic partition generation and fusion into two disconnected parts. To solve the above two challenges, a novel clustering algorithm, named Greedy optimization of K-means-based Consensus Clustering(GKCC) is proposed.Inspired by the well-known greedy K-means that aims to solve the sensitivity of K-means initialization, GKCC seamlessly combines greedy K-means and KCC together, achieves the merits inherited by GKCC and overcomes the drawbacks of the precursors. Moreover, a 59-sampling strategy is conducted to provide high-quality basic partitions and accelerate the algorithmic speed. Extensive experiments on 36 benchmark datasets demonstrate the significant advantages of GKCC over KCC and KCC++ in terms of the objective function values and standard deviations and external cluster validity.

    2018年02期 v.23 184-194页 [查看摘要][在线阅读][下载 624K]
    [下载次数:10 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Lightweight Trusted Security for Emergency Communication Networks of Small Groups

    Fugang Liu;Jiawei Xu;Feng Hu;Chao Wang;Jie Wu;

    Public communication infrastructures are susceptible to disasters. Thus, the Emergency Communication Networks(ECNs) of small groups are necessary to maintain real-time communication during disasters. Given that ECNs are self-built by users, the unavailability of infrastructures and the openness of wireless channels render them insecure. ECN security, however, is a rarely studied issue despite of its importance. Here, we propose a security scheme for the ECNs of small groups. Our scheme is based on the optimized Byzantine Generals' Problem combined with the analysis of trusted security problems in ECNs. Applying the Byzantine Generals' Problem to ECNs is a novel approach to realize two new functions, debugging and error correction, for ensuring system consistency and accuracy. Given the limitation of terminal devices, the lightweight fast ECDSA algorithm is introduced to guarantee the integrity and security of communication and the efficiency of the network. We implement a simulation to verify the feasibility of the algorithm after theoretical optimization.

    2018年02期 v.23 195-202页 [查看摘要][在线阅读][下载 635K]
    [下载次数:6 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
  • Literature Review on Wireless Sensing——Wi-Fi Signal-Based Recognition of Human Activities

    Chao Wang;Siwen Chen;Yanwei Yang;Feng Hu;Fugang Liu;Jie Wu;

    With the rapid development and wide deployment of wireless technology, Wi-Fi signals have no longer been confined to the Internet as a communication medium. Wi-Fi signals will be modulated again by human actions when propagating indoors, carrying rich human body state information. Therefore, a novel wireless sensing technology is gradually emerging that can realize gesture recognition, human daily activity detection, identification,indoor localization and human body tracking, vital signs detection, imaging, and emotional recognition by extracting effective feature information about human actions from Wi-Fi signals. Researchers mainly use channel state information or frequency modulated carrier wave in their current implementation schemes of wireless sensing technology, called "Walls have eyes", and these schemes cover radio-frequency technology, signal processing technology, and machine learning. These available wireless sensing systems can be used in many applications such as smart home, medical health care, search-and-rescue, security, and with the high precision and passively device-free through-wall detection function. This paper elaborates the research actuality and summarizes each system structure and the basic principles of various wireless sensing applications in detail. Meanwhile, two popular implementation schemes are analyzed. In addition, the future diversely application prospects of wireless sensing systems are presented.

    2018年02期 v.23 203-222页 [查看摘要][在线阅读][下载 900K]
    [下载次数:16 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]

  • Information for Contributors

    <正>Tsinghua Science and Technology(Tsinghua Sci Technol),an academic journal sponsored by Tsinghua University,is published bimonthly.This journal aims at presenting the up-to-date scientific achievements with high creativity and great significance in computer and electronic engineering.Contributions all over the world are welcome.Tsinghua Sci Technol is indexed by SCI.Engineering index(Ei,USA),INSPEC,SA,Cambridge Abstract,and

    2018年02期 v.23 223页 [查看摘要][在线阅读][下载 64K]
    [下载次数:2 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:1 ]
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