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Bifurcation Analysis of a Stage-Structured Prey-Predator System with Discrete and Continuous Delays  [PDF]
Shunyi Li, Wenwu Liu, Xiangui Xue
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.47144
Abstract:

A three-stage-structured prey-predator model with discrete and continuous time delays is studied. The characteristic equations and the stability of the boundary and positive equilibrium are analyzed. The conditions for the positive equilibrium occurring Hopf bifurcation are given, by applying the theorem of Hopf bifurcation. Finally, numerical simulation and brief conclusion are given.

The Association of Psychological Stress Related Cytokines (TNF Alpha, IFN-Gamma) with Essential Hypertension in Ningxia Hui Autonomous Region  [PDF]
Zhaodi Niu, Jian Zhou, Wenwu Ji, Haixia Li, Dan Bai, Huifang Yang
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2013, DOI: 10.4236/ojemd.2013.37038
Abstract:

The study aimed to explore the association between psychological stress-related cytokines and essential hypertension to provide the theoretical basis for the prevention and control of the essential hypertension. We screened hypertension patients in six communities in Wuzhong City of Ningxia, and chose the healthy people who had lived in the same community for full 5 years as a control group. Finally, we selected 210 pairs of cases and controls randomly, including 108 pairs of Hui and 102 pairs of Han (50% male; age 35 -74). The results showed that the serum TNF alpha levels of hypertension group were higher than the control group (ρ < 0.01), and the serum IFN-gamma levels were lower than the control group both in Hui and Han (ρ < 0.01). Further analysis showed that the serum TNF alpha level of the Hui hypertension group was higher than the Han hypertension group (ρ < 0.01),

Distance to the SNR CTB 109/AXP 1E 2259+586 by HI absorption and self-absorption
Wenwu Tian,Denis Leahy,Di Li
Physics , 2010, DOI: 10.1111/j.1745-3933.2010.00822.x
Abstract: We suggest a revised distance to the supernova remnant (SNR) G109.1-1.0 (CTB 109) and its associated anomalous X-ray pulsar (AXP) 1E 2259+586 by analyzing 21cm HI-line and 12CO-line spectra of CTB 109, HII region Sh 152, and the adjacent molecular cloud complex. CTB 109 has been established to be interacting with a large molecular cloud (recession velocity at v=-55 km s^-1). The highest radial velocities of absorption features towards CTB 109 (-56 km s^-1) and Sh 152 (-65 km s^-1) are larger than the recombination line velocity (-50 km s^-1) of Sh 152 demonstrating the velocity reversal within the Perseus arm. The molecular cloud has cold HI column density large enough to produce HI self-absorption (HISA) and HI narrow self-absorption (HINSA) if it was at the near side of the velocity reversal. Absence of both HISA and HINSA indicates that the cloud is at the far side of the velocity reversal within the Perseus Arm, so we obtain a distance for CTB 109 of 4+/-0.8 kpc. The new distance still leads to a normal explosion energy for CTB 109/AXP 1E 2259+586.
Noise Simulation Analysis of a Variable Displacement External Gear Pump and Unloading Groove Optimization  [PDF]
Yongkang Zhou, Wenwu Li, Dongpo Yang
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1105030
Abstract:
The oil pump is an important part of vehicle engine, whose noise and vibration characteristics affect the engine performance significantly. The noises generat-ed by both the pressure and flow fluctuations are the main contributors to the oil pump noise. In this paper, noise analysis of an external gear pump is carried out by using the computational fluid dynamics (CFD) method and The Lighthill’s acoustic analogy (LAA) algorithm. The fluid pressure and velocity distributions of the flowfield are firstly calculated by using a CFD model. The noises generated by flowfield are simulated and their sound pressure spectra are obtained by using an LAA-based finite element model. By analyzing the phenomenon of oil trapping, the optimum design of unloading groove is put forward, and then the simulation analysis is carried out. According to the finite element model, the noise level of gear pump is reduced and the effect of noise reduction is achieved. The technique presented in this paper can be regarded as a useful tool for optimization design of gear pumps in vehicle engineering.
A comparison and evaluation of five biclustering algorithms by quantifying goodness of biclusters for gene expression data
Li Li,Guo Yang,Wu Wenwu,Shi Youyi
BioData Mining , 2012, DOI: 10.1186/1756-0381-5-8
Abstract: Background Several biclustering algorithms have been proposed to identify biclusters, in which genes share similar expression patterns across a number of conditions. However, different algorithms would yield different biclusters and further lead to distinct conclusions. Therefore, some testing and comparisons between these algorithms are strongly required. Methods In this study, five biclustering algorithms (i.e. BIMAX, FABIA, ISA, QUBIC and SAMBA) were compared with each other in the cases where they were used to handle two expression datasets (GDS1620 and pathway) with different dimensions in Arabidopsis thaliana (A. thaliana) GO (gene ontology) annotation and PPI (protein-protein interaction) network were used to verify the corresponding biological significance of biclusters from the five algorithms. To compare the algorithms’ performance and evaluate quality of identified biclusters, two scoring methods, namely weighted enrichment (WE) scoring and PPI scoring, were proposed in our study. For each dataset, after combining the scores of all biclusters into one unified ranking, we could evaluate the performance and behavior of the five biclustering algorithms in a better way. Results Both WE and PPI scoring methods has been proved effective to validate biological significance of the biclusters, and a significantly positive correlation between the two sets of scores has been tested to demonstrate the consistence of these two methods. A comparative study of the above five algorithms has revealed that: (1) ISA is the most effective one among the five algorithms on the dataset of GDS1620 and BIMAX outperforms the other algorithms on the dataset of pathway. (2) Both ISA and BIMAX are data-dependent. The former one does not work well on the datasets with few genes, while the latter one holds well for the datasets with more conditions. (3) FABIA and QUBIC perform poorly in this study and they may be suitable to large datasets with more genes and more conditions. (4) SAMBA is also data-independent as it performs well on two given datasets. The comparison results provide useful information for researchers to choose a suitable algorithm for each given dataset.
Potentiation of Scutellarin on Human Tongue Carcinoma Xenograft by Low-Intensity Ultrasound
Haixia Li, Haixia Fan, Zhu Wang, Jinhua Zheng, Wenwu Cao
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0059473
Abstract: Scutellarin 7-O-β-d-glucuronide (scutellarin) has shown great potential as a chemotherapeutic agent for cancer treatment, but only at high dosage. Here we investigate the possibility of using low intensity ultrasound to reduce the scutellarin dosage. Ultrasound intensities of 1.0 W/cm2 and 0.05 W/cm2 were used for in vivo and in vitro experiments, respectively, and a very low dosage of scutellarin (15 nM) was used. Tumor-bearing Balb/c mice and SAS human-tongue squamous carcinoma cell suspensions were used for the in vivo and in vitro experiments, respectively. Each kind of subjects was divided into control, ultrasound-alone, scutellarin-alone, and combined ultrasound-scutellarin treatment groups. Only the combined treatment showed strong anticancer effects. In the in vivo case, the combined treatment significantly delayed tumor growth, initiated cellular chromatin changes (including a decrease in the number of cytoplasmic organelles and fragmentation of condensed nuclear chromatin), inhibited tumor angiogenesis and lymphangiogenesis, stopped cancer-cell proliferation, decreased MMP-2 and MMP-9 expression levels and caused cancer-cell apoptosis. In the in vitro case, the combined treatment produced cancer cell-shape irregularity in a manner seriously fractured microvilli, inhibited cancer-cell migratory and invasion activities, and induced cancer-cell apoptosis. Because the combined treatment did not increase intracellular ROS production, scutellarin is not a sonosensitizer so that the anticancer effect is not through sonodynamic therapy. Low-intensity ultrasound is merely increasing the permeability of scutellarin into cancer cells. Based on our results, one may perform localized chemotherapy using much reduced dosage of the drug with the help of low intensity ultrasound, which will greatly minimize side effects.
Impedance spectroscopy study on post-annealing-tuned polycrystalline CaCu3Ti4O12 films: Evidence of Barrier Layer Capacitor Effects
Liang Fang,Mingrong Shen,Zhenya Li,Wenwu Cao
Physics , 2004,
Abstract: In this paper, impedance spectroscopy study was performed to establish the electrical property and microstructure relations of the as-deposited and post-annealed polycrystalline CCTO films prepared on Pt/Ti/SiO2/Si (100) substrates by pulsed-laser deposition (PLD). Our results demonstrated that the as-deposited polycrystalline CCTO film was made of insulating grain boundaries with semiconducting grains, indicating that the high-dielectric-constant is attributed to the barrier layer capacitor (BLC) effects. The simple resistor-capacitor (RC) equivalent circuit and the modified constant phase element (CPE) circuit were used to describe the impedance spectroscopy, and excellent agreement between the calculated and measured curves was obtained in the CPE circuit. The resistance and capacitance of the grains and grain boundaries can be tuned by changing the annealing atmosphere and temperature. Under oxygen-absent annealing atmosphere, the electric resistances of the grain boundaries changed greatly but the resistance of the grains has almost no change. While under oxygen annealing atmosphere, the reverse happened. On the basis of this result, it is demonstrated that the origin of the semiconductivity of the grains in CCTO polycrystalline films arises from their oxygen-loss, while the grain boundaries are close to oxygen- stoicheometry.
Dispersing Instant Social Video Service Across Multiple Clouds
Zhi Wang,Baochun Li,Lifeng Sun,Wenwu Zhu,Shiqiang Yang
Computer Science , 2015,
Abstract: Instant social video sharing which combines the online social network and user-generated short video streaming services, has become popular in today's Internet. Cloud-based hosting of such instant social video contents has become a norm to serve the increasing users with user-generated contents. A fundamental problem of cloud-based social video sharing service is that users are located globally, who cannot be served with good service quality with a single cloud provider. In this paper, we investigate the feasibility of dispersing instant social video contents to multiple cloud providers. The challenge is that inter-cloud social \emph{propagation} is indispensable with such multi-cloud social video hosting, yet such inter-cloud traffic incurs substantial operational cost. We analyze and formulate the multi-cloud hosting of an instant social video system as an optimization problem. We conduct large-scale measurement studies to show the characteristics of instant social video deployment, and demonstrate the trade-off between satisfying users with their ideal cloud providers, and reducing the inter-cloud data propagation. Our measurement insights of the social propagation allow us to propose a heuristic algorithm with acceptable complexity to solve the optimization problem, by partitioning a propagation-weighted social graph in two phases: a preference-aware initial cloud provider selection and a propagation-aware re-hosting. Our simulation experiments driven by real-world social network traces show the superiority of our design.
ERROR ANALYSIS OF ORBIT DETERMINED BY GPS BROADCAST EPHEMERIS
GPS广播星历的轨道误差分析

Li Zhenghang,Ding Wenwu,Li Zhao,
李征航
,丁文武,李 昭

大地测量与地球动力学 , 2008,
Abstract: The variations of orbit error of GPS broadcast ephemeris from 2002 to 2006 are analyzed, and some effects on the orbit accuracy are discussed.The results show that the orbit accuracy of GPS broadcast ephemeris in 2006 was much better than that in 2002 especially after the implementation of L-AII project.
Training Set Selection for the Prediction of Essential Genes
Jian Cheng, Zhao Xu, Wenwu Wu, Li Zhao, Xiangchen Li, Yanlin Liu, Shiheng Tao
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0086805
Abstract: Various computational models have been developed to transfer annotations of gene essentiality between organisms. However, despite the increasing number of microorganisms with well-characterized sets of essential genes, selection of appropriate training sets for predicting the essential genes of poorly-studied or newly sequenced organisms remains challenging. In this study, a machine learning approach was applied reciprocally to predict the essential genes in 21 microorganisms. Results showed that training set selection greatly influenced predictive accuracy. We determined four criteria for training set selection: (1) essential genes in the selected training set should be reliable; (2) the growth conditions in which essential genes are defined should be consistent in training and prediction sets; (3) species used as training set should be closely related to the target organism; and (4) organisms used as training and prediction sets should exhibit similar phenotypes or lifestyles. We then analyzed the performance of an incomplete training set and an integrated training set with multiple organisms. We found that the size of the training set should be at least 10% of the total genes to yield accurate predictions. Additionally, the integrated training sets exhibited remarkable increase in stability and accuracy compared with single sets. Finally, we compared the performance of the integrated training sets with the four criteria and with random selection. The results revealed that a rational selection of training sets based on our criteria yields better performance than random selection. Thus, our results provide empirical guidance on training set selection for the identification of essential genes on a genome-wide scale.
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