Wei Liu

University of Florida, Gainesville, FL, United States

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Publications (44)36.65 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Objective Use of neomycin eardrops in nonintact tympanic membranes (NITMs) due to tympanic membrane (TM) perforation or tympanostomy tubes (TTs) is controversial because of the potential for ototoxicity. We sought to compare the risk of sensorineural hearing loss (SNHL) in patients with NITMs who received neomycin with those who received fluoroquinolone eardrops.Study DesignRetrospective cohort study.SettingAdministrative claims data analysis, including diagnoses and procedure detail for physician office and hospital visits and pharmacy dispensing events in children eligible for Medicaid fee-for-service benefits in 29 states between 1999 and 2006.Subjects and Methods Eligible patients (age <18 years) had to have received a study eardrop within 12 months after first diagnosis of NITM. The follow-up period started from the first eardrop dispensing.Main Outcome MeasuresWe compared the 12-month risk of SNHL using Cox proportional hazards regression models adjusted for SNHL risk factors.ResultsWe found 982 SNHL cases in 134,598 children treated with neomycin or fluoroquinolone eardrops. The adjusted hazard ratio (HR) for 1, 2, and 3 or more prescriptions of neomycin was 0.90 (95% confidence interval [CI], 0.76-1.07), 1.45 (1.05-2.01), and 1.30 (0.71-2.36), respectively, when adjusted for SNHL risk factors, the interval between initial diagnosis of NITM and eardrop initiation, and total number of eardrop prescriptions. The results remained unchanged for several sensitivity analyses.Conclusion Short-term use of neomycin eardrops in patients with NITMs is not associated with an increased risk of SNHL; however, repeated doses (ie, ≥2 prescriptions) showed a significant association with an increased risk of SNHL.
    Otolaryngology Head and Neck Surgery 12/2012; · 1.73 Impact Factor
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    ABSTRACT: OBJECTIVES/HYPOTHESIS: Although contraindicated, neomycin otic preparations may be administered to children with nonintact tympanic membranes (TMs), such as tympanostomy tubes or TM perforations. The goal of this study was to assess the magnitude of neomycin exposure in children with nonintact TMs. STUDY DESIGN: Retrospective drug utilization study. METHODS: Medicaid claims data (years 1999-2006) from 28 states for children aged 0 to 18 years were analyzed to identify new cases of tube placement or TM perforation. Cases were followed for 12 months to determine neomycin otic utilization. RESULTS: Of the 300,470 children with nonintact TMs, neomycin otic preparations were prescribed in 43,815 (15%). Nontoxic agents (ofloxacin or ciprofloxacin) were used in 48%. In 19%, neomycin preparations were prescribed at the day of initial nonintact TM diagnosis, 52% and 71% within the first 3 or 6 months, respectively. Neomycin otic utilization decreased from 27% in cases diagnosed in 1999 to 7% in 2005 (P < .0001). CONCLUSIONS: Many children with nonintact TMs receive exposure to agents with potential ototoxicity, despite the availability of safer alternatives. Further study is necessary to determine why neomycin otic preparations continue to be prescribed in the presence of nonintact TMs and if such exposure is associated with ototoxicity. Laryngoscope, 2012.
    The Laryngoscope 09/2012; · 1.98 Impact Factor
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    ABSTRACT: This paper addresses energy conservation, a funda- mental issue of paramount importance in heterogeneous mobile ad hoc networks (MANETs) consisting of powerful nodes (i.e., P-nodes) as well as normal nodes (i.e., B-nodes). By utilizing the inherent device heterogeneity, we propose a cross-layer de- signed Device-Energy-Load Aware Relaying framework, named DELAR, to achieve energy conservation from multiple facets, including power-aware routing, transmission scheduling and power control. In particular, we design a novel power-aware routing protocol that nicely incorporates device heterogeneity, nodal residual energy information and nodal load status to save energy. In addition, we develop a hybrid transmission schedul- ing scheme, which is a combination of reservation-based and contention-based medium access control schemes, to coordinate the transmissions. Moreover, the novel notion of "mini-routing" is introduced into the data link layer and an Asymmetric MAC (A-MAC) scheme is proposed to support the MAC-layer ac- knowledgements over unidirectional links caused by asymmetric transmission power levels between powerful nodes and normal nodes. Furthermore, we present a multi-packet transmission scheme to improve the end-to-end delay performance. Extensive simulations show that DELAR can indeed achieve energy saving while striking a good balance between energy efficiency and other network performance metrics.
    IEEE Journal on Selected Areas in Communications 01/2011; 29:1572-1584. · 3.12 Impact Factor
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    ABSTRACT: Wireless sensor networks (WSNs) are appealing in obtaining fine-granular observations about the physical world. Due to the fact that WSNs are composed of a large number of low-cost but energy-constrained sensor nodes, along with the notorious time-varying and error-prone nature of wireless links, scalable, robust, and energy-efficient data disseminating techniques are requisite for the emerging WSN applications such as environment monitoring and surveillance. To meet this challenging demand, we propose a hybrid data dissemination framework for WSNs in this paper. In particular, we conceptually partition a whole sensor field into several functional regions and apply different routing schemes to different regions in order to provide better performance in terms of reliability and fair energy usage. For this purpose, we also propose a novel zone flooding scheme, essentially a combination of geometric routing and flooding techniques. Our scheme features low overhead, high reliability, good scalability, and notable flexibility. Simulation studies are carried out to validate the effectiveness and efficiency of our scheme.
    Global Telecommunications Conference, 2004. GLOBECOM '04. IEEE; 01/2010
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    ABSTRACT: Similarity-based collaborative filtering systems are vulnerable to the data sparsity, cold-start, and robustness problems. Computational trust models are promising alternative solutions to alleviate these problems by replacing similarity metric with trust metric. However, they often have some shortages that rely on users' explicit trust statements. A fine-grained model computing trust from user ratings is more reasonable and gets more nonintrusive for average users. We propose a novel trust-based recommendation model for this purpose. Experiments on a large real dataset show that the proposed model has better performance in terms of MAE, coverage, and F-metric than the conventional collaborative filtering model.
    Proceedings of the IEEE Symposium on Computational Intelligence and Data Mining, CIDM 2009, part of the IEEE Symposium Series on Computational Intelligence 2009, Nashville, TN, USA, March 30, 2009 - April 2, 2009; 01/2009
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    ABSTRACT: Currently, most recommender systems are using collaborative filtering (CF) techniques. The main idea is to suggest new relevant items for an active user based on the judgements from other members in the like-minded community. However, these CF-based methods encounter the obstacles, such as sparse data, cold-start and robustness. This paper proposes to deal with these issues by associating similarity measurement from users'rating patterns with trust metric. After investigating the large data set from Epinions.com, we find that user similarity and trust are strongly correlated. This fact also explains why using trust (instead of user similarity) could lead to very close mean prediction accuracy in a Pearson correlation coefficient-like recommendation algorithm. Our novel method incorporates these two factors into one unified recommendation algorithm. The experimental results indicate that a good prediction strategy can come from filtering the ratings from the users who have high trust and low similarity or vice versa.
    FSKD 2009, Sixth International Conference on Fuzzy Systems and Knowledge Discovery, Tianjin, China, 14-16 August 2009, 6 Volumes; 01/2009
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    ABSTRACT: The development and maintenance of domain knowledge based system need a lot of manual operations, and with the increasing amount of contents in the system, it is more and more difficult to find the relevant information. The keyword based search usually can not return the accurate result. To solve these problems, this paper proposes a semantic knowledge system with ontology engineering approach. It can acquire data and update knowledge system with less human efforts, and the feedback mechanism can help the knowledge system automatically correct the inaccurate metadata. The semantic query improves the keyword based query and returns the answer accurately. The customized interactive user interface is implemented with proper technology to display the knowledge hierarchy and data relationship, and improves the efficiency of the system user.
    FSKD 2009, Sixth International Conference on Fuzzy Systems and Knowledge Discovery, Tianjin, China, 14-16 August 2009, 6 Volumes; 01/2009
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    ABSTRACT: We propose and investigate the SPREAD scheme as a complementary mechanism to enhance secure data deliv- ery in a mobile ad hoc network. The basic idea is to transform a secret message into multiple shares, and then deliver the shares via multiple paths to the destination so that even if a certain number of message shares are compromised, the secret message as a whole is not compromised. We present the overall system architecture and discuss three major de- sign issues: the mathematical model for the generation and reconstruction of the secret message shares, the optimal allo- cation of the message shares onto multiple paths in terms of security, and the multipath discovery techniques in a mobile
    Wireless Networks 01/2009; 15:279-294. · 0.74 Impact Factor
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    ABSTRACT: A typical workflow for a distributed application involves a large number of resources that can fail, including network, hardware and software components. Even when monitoring information from all these components is accessible, it is hard to determine how anomalies and failures during the application execution are related to a given workflow component. However the capability of receiving and interpreting intermediate results and interacting with applications plays a significant role for developing scientific experiments. Considering the complexity of implementation of distributed systems and the large scope of issues the monitoring system should cover, what analysis and planning is required to implement effective scientific grid workflow monitoring? We propose a multi-layer approach which focuses on a clear identification of the workflow-level monitoring abstractions. Through a clear separation between higher and lower level mechanisms, this approach will allow the specification of application monitoring requirements at workflow level, and their implementation upon distinct monitoring technologies, including the ones supported by existing grid middleware.
    Proceedings of the IEEE International Conference on Networking, Sensing and Control, ICNSC 2008, Hainan, China, 6-8 April 2008; 01/2008
  • Proceedings of the 2008 International Conference on Internet Computing, ICOMP 2008, Las Vegas, Nevada, USA, July 14-17, 2008; 01/2008
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    ABSTRACT: The proper functioning of mobile ad hoc networks depends on the hypothesis that each individual node is ready to forward packets for others. This common assumption, however, might be undermined by the existence of selfish users who are reluctant to act as packet relays in order to save their own resources. Such non-cooperative behavior would cause the sharp degradation of network throughput. To address this problem, we propose a credit-based Secure Incentive Protocol (SIP) to stimulate cooperation among mobile nodes with individual interests. SIP can be implemented in a fully distributed way and does not require any pre-deployed infrastructure. In addition, SIP is immune to a wide range of attacks and is of low communication overhead by using a Bloom filter. Detailed simulation studies have confirmed the efficacy and efficiency of SIP.
    Wireless Networks 01/2007; 13:569-582. · 0.74 Impact Factor
  • Proceedings of the 2007 International Conference on Internet Computing, ICOMP 2007, Las Vegas, Nevada, USA, June 25-28, 2007; 01/2007
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    ABSTRACT: This paper studies key management, a fundamental problem in securing mobile ad hoc networks (MANETs). We present IKM, an ID-based key management scheme as a novel combination of ID-based and threshold cryptography. IKM is a certificateless solution in that public keys of mobile nodes are directly derivable from their known IDs plus some common information. It thus eliminates the need for certificate-based authenticated public-key distribution indispensable in conventional public-key management schemes. IKM features a novel construction method of ID-based public/private keys, which not only ensures high-level tolerance to node compromise, but also enables efficient network-wide key update via a single broadcast message. We also provide general guidelines about how to choose the secret-sharing parameters used with threshold cryptography to meet desirable levels of security and robustness. The advantages of IKM over conventional certificate-based solutions are justified through extensive simulations. Since most MANET security mechanisms thus far involve the heavy use of certificates, we believe that our findings open a new avenue towards more effective and efficient security design for MANETs
    IEEE Transactions on Dependable and Secure Computing 11/2006; 3(4):386-399. · 1.06 Impact Factor
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    ABSTRACT: The shared wireless medium of mobile ad hoc networks facilitates passive, adversarial eavesdropping on data communications whereby adversaries can launch various devastating attacks on the target network. To thwart passive eavesdropping and the resulting attacks, we propose a novel anonymous on-demand routing protocol, termed MASK, which can accomplish both MAC-layer and network-layer communications without disclosing real IDs of the participating nodes under a rather strong adversary model. MASK offers the anonymity of senders, receivers, and sender-receiver relationships in addition to node unlocatability and untrackability and end-to-end flow untraceability. It is also resistant to a wide range of attacks. Moreover, MASK preserves the high routing efficiency as compared to previous proposals. Detailed simulation studies have shown that MASK is highly effective and efficient
    IEEE Transactions on Wireless Communications 10/2006; · 2.42 Impact Factor
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    ABSTRACT: The recent Federal Communications Commission regulations for ultra-wideband (UWB) transmission systems have sparked a surge of research interests in the UWB technology. One of the important application areas of UWB is wireless sensor networks. The proper operations of many UWB sensor networks rely on the knowledge of physical sensor locations. However, most existing localization algorithms developed for sensor networks are vulnerable to attacks in hostile environments. As a result, attackers can easily subvert the normal functionalities of location-dependent sensor networks by exploiting the weakness of localization algorithms. In this paper, we first analyze the security of existing localization techniques. We then develop a mobility-assisted secure localization scheme for UWB sensor networks. In addition, we propose a location-based scheme to enable secure authentication in UWB sensor networks.
    IEEE Journal on Selected Areas in Communications 05/2006; · 3.12 Impact Factor
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    ABSTRACT: Node compromise is a serious threat to wireless sensor networks deployed in unattended and hostile environments. To mitigate the impact of compromised nodes, we propose a suite of location-based compromise-tolerant security mechanisms. Based on a new cryptographic concept called pairing, we propose the notion of location-based keys (LBKs) by binding private keys of individual nodes to both their IDs and geographic locations. We then develop an LBK-based neighborhood authentication scheme to localize the impact of compromised nodes to their vicinity. We also present efficient approaches to establish a shared key between any two network nodes. In contrast to previous key establishment solutions, our approaches feature nearly perfect resilience to node compromise, low communication and computation overhead, low memory requirements, and high network scalability. Moreover, we demonstrate the efficacy of LBKs in counteracting several notorious attacks against sensor networks such as the Sybil attack, the identity replication attack, and wormhole and sinkhole attacks. Finally, we propose a location-based threshold-endorsement scheme, called LTE, to thwart the infamous bogus data injection attack, in which adversaries inject lots of bogus data into the network. The utility of LTE in achieving remarkable energy savings is validated by detailed performance evaluation.
    IEEE Journal on Selected Areas in Communications 03/2006; · 3.12 Impact Factor
  • Wei Liu, E.K. Park
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    ABSTRACT: First Page of the Article
    Consumer Communications and Networking Conference, 2006. CCNC 2006. 3rd IEEE; 02/2006
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    ABSTRACT: This paper develops a spatial H2 norm-based computational scheme for finding the optimal locations of sensors and actuators in controlled flexible structures. As the optimization index, the spatial H2 norm of the closed-loop transfer matrix from the disturbance to the distributed controlled output is used. The design of the optimal spatial H2 controller is based on the reduced model of the flexible structure, which contains the dominant modes that have the largest contribution to the system's spatial H2 norm. The proposed genetic algorithm (GA) is subsequently used to solve the resulting nonlinear optimization problem. The effectiveness of the proposed scheme is demonstrated by a numerical example on the vibration control of a plate structure. Simulation results also show that the spatial H2 norm is a better performance index to be used in the structural vibration control when the vibration reduction is required over a continuous area on the structure.
    Mechanical Systems and Signal Processing 01/2006; · 1.91 Impact Factor
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    ABSTRACT: We propose an innovative resource management scheme for TDMA based mobile ad hoc networks. Since communications between some important nodes in the network are more critical, they should be accepted by the network with high priority in terms of network resource usage and quality of service (QoS) support. In this scheme, we design a location-aware bandwidth pre-reservation mechanism, which takes advantage of each mobile node’s geographic location information to pre-reserve bandwidth for such high priority connections and thus greatly reduces potential scheduling conflicts for transmissions. In addition, an end-to-end bandwidth calculation and reservation algorithm is proposed to make use of the pre-reserved bandwidth. In this way, time slot collisions among different connections and in adjacent wireless links along a connection can be reduced so that more high priority connections can be accepted into the network without seriously hurting admissions of other connections. The salient feature of our scheme is the collaboration between the routing and MAC layer that results in the more efficient spatial reuse of limited resources, which demonstrates how cross-layer design leads to better performance in QoS support. Extensive simulations show that our scheme can successfully provide better communication quality to important nodes at a relatively low price. Finally, several design issues and future work are discussed.
    Wireless Networks 01/2006; 12:797-812. · 0.74 Impact Factor
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    ABSTRACT: Wireless sensor networks (WSNs) are appealing in obtaining ne-granular observations about the physical world. Due to the fact that WSNs are composed of a large number of low-cost and energy-constrained sensor nodes, along with the notorious time- varying and error-prone nature of wireless links, scalable, robust and energy-efcient data dissemination techniques are needed for the emerging WSN applications such as environment monitoring and surveillance. In this paper, we examine this emerging eld from the point of view of supply chain management and propose a hybrid data dissemination framework for WSNs. In particular, for each sensing task, the whole sensor eld is conceptually partitioned into several functional regions based on the supply chain management methodology. Different routing schemes are applied to different regions in order to provide better performance in terms of reliability and energy consumption. For this purpose, we also propose a novel zone ooding scheme, essentially a combination of conventional geometric routing and ooding techniques. Our hybrid data dissemination framework features low overhead, high reliability, good scalability and e xibility, and preferable energy efcienc y. Detailed simulation studies are carried out to validate the effectiveness and efcienc y of our scheme.
    Wireless Networks 01/2006; 12:465-479. · 0.74 Impact Factor

Publication Stats

479 Citations
1k Downloads
2k Views
36.65 Total Impact Points

Institutions

  • 2003–2010
    • University of Florida
      • Department of Electrical and Computer Engineering
      Gainesville, FL, United States
  • 2006
    • New Jersey Institute of Technology
      • Department of Electrical and Computer Engineering
      Newark, NJ, United States
  • 2004–2006
    • Worcester Polytechnic Institute
      • • Department of Mechanical Engineering
      • • Department of Electrical and Computer Engineering
      Worcester, MA, United States
  • 2005
    • University of California, Berkeley
      Berkeley, California, United States