The effect of infected external computers on the spread of viruses: A compartment modeling study

Inevitably, there exist infected computers outside of the Internet. This paper aims to understand how infected external computers affect the spread of computer viruses. For that purpose, a new virus–antivirus spreading model, which takes into account the effect of infected/immune external computers, is established. A systematic study shows that, unlike most previous models, the proposed model admits no virus-free equilibrium and admits a globally asymptotically stable viral equilibrium. This result implies that it would be practically impossible to eradicate viruses on the Internet. As a result, inhibiting the virus prevalence to below an acceptable level would be the next best thing. A theoretical study reveals the effect of different parameters on the steady virus prevalence. On this basis, a number of suggestions are made so as to contain virus spreading.     

Depth above a Drop of the Channel Bottom after Free-Surface Discontinuity Decay

This paper reports experimental data on the depth above a bottom drop in a rectangular channel after removal of a shield that produces the initial difference in the free-surface level. It is shown that at a sufficiently large height of the drop, this depth is approximately 40 % smaller than that obtained in the first shallow-water approximation.     

乌尔逊凹陷滑脱型构造样式与油气成藏

乌尔逊凹陷伊敏期构造演化以盖层滑脱型构造样式的发育为特征，这一构造样式的形成是构造的幕式活动、乌西断裂持续的低角度倾滑和夹持在3个刚性基岩块体之间的区域构造位置等三方面因素相互作用的结果．该期构造演化活动强烈、持续时间长，对于乌尔逊凹陷的油气生成、运移、聚集和保存等诸方面均有不同程度的控制．     

Droplet dynamics on patterned substrates

We present a lattice Boltzmann algorithm which can be used to explore the spreading of droplets on chemically and topologically patterned substrates. As an example we use the method to show that the final configuration of a drop on a substrate comprising hydrophobic and hydrophilic stripes can depend sensitively on the dynamical pathway by which the state is reached. We also consider a substrate covered with micron-scale posts and investigate how this can lead to superhydrophobic behaviour. Finally we model how a Namibian desert beetle collects water from the wind.     

Randomized rumor spreading in poorly connected small‐world networks

The Push‐Pull protocol is a well‐studied round‐robin rumor spreading protocol defined as follows: initially a node knows a rumor and wants to spread it to all nodes in a network quickly. In each round, every informed node sends the rumor to a random neighbor, and every uninformed node contacts a random neighbor and gets the rumor from her if she knows it. We analyze the behavior of this protocol on random ‐trees, a class of power law graphs, which are small‐world and have large clustering coefficients, built as follows: initially we have a ‐clique. In every step a new node is born, a random ‐clique of the current graph is chosen, and the new node is joined to all nodes of the ‐clique. When is fixed, we show that if initially a random node is aware of the rumor, then with probability after rounds the rumor propagates to nodes, where is the number of nodes and is any slowly growing function. Since these graphs have polynomially small conductance, vertex expansion and constant treewidth, these results demonstrate that Push‐Pull can be efficient even on poorly connected networks. On the negative side, we prove that with probability the protocol needs at least rounds to inform all nodes. This exponential dichotomy between time required for informing almost all and all nodes is striking. Our main contribution is to present, for the first time, a natural class of random graphs in which such a phenomenon can be observed. Our technique for proving the upper bound successfully carries over to a closely related class of graphs, the random ‐Apollonian networks, for which we prove an upper bound of rounds for informing nodes with probability when is fixed. Here, © 2015 Wiley Periodicals, Inc. Random Struct. Alg., 49, 185–208, 2016     

Study on the Friction and Wear Properties of PEEK against Cortical Bone Tissue Under Different Lubricating Conditions

The tribological behavior between orthopedic implants and cortical bone is important but usually neglected. Poly(ether-ether-ketone) (PEEK) is a promising material for orthopedic applications. To further understand and improve the interfacial tribological properties between PEEK implant and host bone tissue, a PEEK-cortical bone tribo-pair is designed and fabricated. The frictional and wear performance of such tribo-pair is investigated under different lubricants, i.e., simulated body fluid (SBF), calf serum (CS), hyaluronic acid (HA), and mucin (MUC). The results suggest that MUC solution can be utilized as an artificial natural synovial fluid to improve the tribological properties of PEEK-based implants.     

Characterization of the transportation of berberine in Coptidis rhizoma extract through rat primary cultured cortical neurons

The aim of this study was to investigate the transport behavior and efflux of berberine through the primary culture cortical neurons. High-performance liquid chromatography coupled with an UV-vis detector at 347 nm was applied. The mobile phase was 0.05 m potassium dihydrogen phosphate solution (containing 0.5% triethylamine, pH 3.0)-acetonitrile (73:27, v/v). Neurons were incubated with Coptidis rhizoma extract 6.5 microg/mL (containing 1.91 microg/mL berberine) and verapamil, KCN or cimetidine for 2 h, and then lysed in methanol to extract intracellular berberine. A 20 microL aliquot of sample was injected into the HPLC system to determine berberine concentration. The results showed that metabolic inhibitor KCN and P-glycoprotein inhibitor verapamil could increase berberine concentration within the neurons, indicating that efflux of berberine was energy-dependent and P-glycoprotein was likely to be involved. Moreover, the organic cation transporter inhibitor cimetidine could decrease berberine concentration within the neurons, suggesting that the organic cation transporter might be involved in the berberine transport process.     

Virus spreading in wireless sensor networks with a medium access control mechanism

In this paper, an extended version of standard susceptible-infected (SI) model is proposed to consider the influence of a medium access control mechanism on virus spreading in wireless sensor networks. Theoretical analysis shows that the medium access control mechanism obviously reduces the density of infected nodes in the networks, which has been ignored in previous studies. It is also found that by increasing the network node density or node communication radius greatly increases the number of infected nodes. The theoretical results are confirmed by numerical simulations.