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Isovitexin Is a Direct Inhibitor of Staphylococcus aureus Coagulase
( Hua Xiang ),( Panpan Yang ),( Li Wang ),( Jiaxin Li ),( Tiedong Wang ),( Junze Xue ),( Dacheng Wang ),( Hongxia Ma ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.10
Staphylococcus aureus (S. aureus) is a major pathogen that causes human pneumonia, leading to significant morbidity and mortality. S. aureus coagulase (Coa) triggers the polymerization of fibrin by activating host prothrombin, which then converts fibrinogen to fibrin and contributes to S. aureus pathogenesis and persistent infection. In our research, we demonstrate that isovitexin, an active traditional Chinese medicine component, can inhibit the coagulase activity of Coa but does not interfere with the growth of S. aureus. Furthermore, we show through thermal shift and fluorescence quenching assays that isovitexin directly binds to Coa. Dynamic simulation and structure-activity relationship analyses suggest that V191 and P268 are key amino acid residues responsible for the binding of isovitexin to Coa. Taken together, these data indicate that isovitexin is a direct Coa inhibitor and a promising candidate for drug development against S. aureus infection.
Coverage and Energy Modeling of HetNet Under Base Station On-Off Model
Sida Song,Yongyu Chang,Xianling Wang,Dacheng Yang 한국전자통신연구원 2015 ETRI Journal Vol.37 No.3
Small cell networks, as an important evolution path for next-generation cellular networks, have drawn much attention. Different from the traditional base stations (BSs) always-on model, we proposed a BSs on-off model, where a new, simple expression for the probabilities of active BSs in a heterogeneous network is derived. This model is more suitable for application in practical networks. Based on this, we develop an analytical framework for the performance evaluation of small cell networks, adopting stochastic geometry theory. We derive the system coverage probability; average energy efficiency (AEE) and average uplink power consumption (AUPC) for different association strategies; maximum biased received power (MaBRP); and minimum association distance (MiAD). It is analytically shown that MaBRP is beneficial for coverage but will have some loss in energy saving. On the contrary, MiAD is not advocated from the point of coverage but is more energy efficient. The simulation results show that the use of range expansion in MaBRP helps to save energy but that this is not so in MiAD. Furthermore, we can achieve an optimal AEE by establishing an appropriate density of small cells.
Quasi-distributed Interference Coordination for HSPA HetNet
Chi Zhang,장용구,Shuqi Qin,Dacheng Yang 한국전자통신연구원 2014 ETRI Journal Vol.36 No.1
The heterogeneous network (HetNet) has been discussedin detail in the Long-Term Evolution (LTE) and LTEAdvanced standards. However, the standardization ofHigh-Speed Packet Access HetNet (HSPA HetNet)launched by 3GPP is pushing at full steam. Interferencecoordination (IC), which is responsible for dealing withthe interference in the system, remains a subject worthy ofinvestigation in regard to HSPA HetNet. In this paper,considering the network framework of HSPA HetNet, wepropose a quasi-distributed IC (QDIC) scheme to lowerthe interference level in the co-channel HSPA HetNet. OurQDIC scheme is constructed as slightly different energyefficientnon-cooperative games in the downlink (DL) anduplink (UL) scenarios, respectively. The existence anduniqueness of the equilibrium for these games are firstrevealed. Then, we derive the closed-form best responsesof these games. A feasible implementation is finallydeveloped to achieve our QDIC scheme in the practicalDL and UL. Simulation results show the notable benefitsof our scheme, which can indeed control the interferencelevel and enhance the system performance.
Distributed Resource Allocation in Two-Hierarchy Networks
Shuhui Liu,Yongyu Chang,Guangde Wang,Dacheng Yang 한국전자통신연구원 2012 ETRI Journal Vol.34 No.2
In this paper, a new distributed resource allocation algorithm is proposed to alleviate the cross-tier interference for orthogonal frequency division multiplexing access macrocell and femtocell overlay. Specifically, the resource allocation problem is modeled as a non-cooperative game. Based on game theory, we propose an iterative algorithm between subchannel and power allocation called distributed resource allocation which requires no coordination among the two-hierarchy networks. Finally, a macrocell link quality protection process is proposed to guarantee the macrocell UE's quality of service to avoid severe cross-tier interference from femtocells. Simulation results show that the proposed algorithm can achieve remarkable performance gains as compared to the pure waterfilling algorithm.
Pilot Sequence Assignment for Spatially Correlated Massive MIMO Circumstances
( Pengxiang Li ),( Yuehong Gao ),( Zhidu Li ),( Dacheng Yang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.1
For massive multiple-input multiple-output (MIMO) circumstances with time division duplex (TDD) protocol, pilot contamination becomes one of main system performance bottlenecks. This paper proposes an uplink pilot sequence assignment to alleviate this problem for spatially correlated massive MIMO circumstances. Firstly, a single-cell TDD massive MIMO model with multiple terminals in the cell is established. Then a spatial correlation between two channel response vectors is established by the large-scale fading variables and the angle of arrival (AOA) span with an infinite number of base station (BS) antennas. With this spatially correlated channel model, the expression for the achievable system capacity is derived. To optimize the achievable system capacity, a problem regarding uplink pilot assignment is proposed. In view of the exponential complexity of the exhaustive search approach, a pilot assignment algorithm corresponding to the distinct channel AOA intervals is proposed to approach the optimization solution. In addition, simulation results prove that the main pilot assignment algorithm in this paper can obtain a noticeable performance gain with limited BS antennas.
Fast Quadtree Structure Decision for HEVC Intra Coding Using Histogram Statistics
( Yuchen Li ),( Yitong Liu ),( Hongwen Yang ),( Dacheng Yang ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.5
The final draft of the latest video coding standard, High Efficiency Video Coding (HEVC), was approved in January 2013. The coding efficiency of HEVC surpasses its predecessor, H.264/MPEG-4 Advanced Video Coding (AVC), by using only half of the bitrate to encode the same sequence with similar quality. However, the complexity of HEVC is sharply increased compared to H.264/AVC. In this paper, a method is proposed to decrease the complexity of intra coding in HEVC. Early pruning and an early splitting strategy are applied to the quadtree structure of coding tree units (CTU) and residual quadtree (RQT). According to our experiment, when our method is applied to sequences from Class A to Class E, the coding time is decreased by 44% at the cost of a 1.08% Bjontegaard delta rate (BD-rate) increase on average.