Phase Transitions of an Epidemic Spreading Model in Small-World Networks

We propose a modified susceptible-infected-refractory-susceptible (SIRS) model to investigate the global oscillations of the epidemic spreading inWatts-Strogatz (WS) small-world networks. It is found that when an individual immunity does not change or decays slowly in an immune period, the system can exhibit complex transition from an infecting stationary state to a large amplitude sustained oscillation or an absorbing state with no infection. When the immunity decays rapidly in the immune period, the transition to the global oscillation disappears and there is no oscillation. Furthermore, based on thespatio-temporal evolution patterns and the phase diagram, it is disclosed that a long immunity period takes an important role in the emergence of the global oscillation in small-world networks.     

反向NQ6非协调元

为通过强式分片试验,NQ6单元对Q6单元的非协调内部形函数进行了线性修正,但抗畸变性能下降了。论文提出对线性修正项进行反向调整以恢复甚至提高抗畸变性能。调整过程是把线性修正项看成影响单元性能的一维方向,进行反向搜索确定有利的计算步长。进行了典型算例测试,结果表明反向调整是有效的,调整系数取镜像值-1以及扩展到-2时新单元的畸变敏感性优于原Q6、NQ6,特别地在-2附近可有效消除剪切闭锁;除弱式分片试验外,总体性能和精度达到或接近各类4节点四边形单元的最好水平。     

自动固相萃取-液相色谱-飞行时间质谱法快速筛查与确证血液中抗抑郁类药物

建立了血液中抗抑郁类药物快速筛查的自动固相萃取-液相色谱-飞行时间质谱（ASPE-LC-Q-TOF/MS）方法。样品经HLB固相萃取柱提取后,采用LC-Q-TOF/MS进行测定,外标法定量。结果表明：目标物的线性范围为1~500 μg/L,相关系数为0.9976~0.9997,检出限为0.01~0.5 μg/L。在10、100和500 μg/L 3个添加水平的平均回收率为79.6%~96.4%,相对标准偏差为4.1%~6.4%。利用Agilent MassHunter PCDL Manager软件建立了抗抑郁类药物数据库,并应用于加标样品的筛查分析,本方法能够全部筛查出样品中添加的抗抑郁类药物,鉴定准确度达到100%,且保留时间偏差均小于0.1 min,质量偏差均小于1 mDa,同位素丰度匹配得分、同位素间距得分和MS匹配得分均大于95,MS/MS图谱匹配得分均大于70。利用本方法对实际案例进行筛查分析,检出阿米替林、卡马西平和多虑平,说明该方法可用于法庭与临床毒物分析。     

Dynamics of Symmetric Conserved Mass Aggregation Model on Complex Networks

We investigate the dynamical behaviour of the aggregation process in the symmetric conserved mass aggregation model under three different topological structures. The dispersion a（t, L） = （∑i（mi - ρo ） ^2 / L ）1/2 is defined to describe the dynamical behaviour where Po is the density of particle and mi is the particle number on a site. It is found numerically that for a regular lattice and a scale-free network, σ（t, L） follows a power-law scaling σ（ t, L） ~ t^δ1 and σ（ t, L） ~ t^δ4 from a random initial condition to the stationary states, respectively. However, for a small-world network, there are two power-law scaling regimes, σ（t, L） ~ t^δ2 when t 〈 T and 〈（t, L） ~ t^δ3 when t 〉 T. Moreover, it is found numerically that 62 is near to 61 for small rewiring probability q, and 63 hardly changes with varying q and it is almost the same as 64. We speculate that the aggregation of the connection degree accelerates the mass aggregation in the initial relaxation stage and the existence of the long-distance interactions in the complex networks results in the acceleration of the mass aggregation when t 〉 T for the small-world networks. We also show that the relaxation time r follows a power-law scaling τ ~ L^z and σ（t, L） in the stationary state follows a power-law Gs（L） - L^α for three different structures.     

Annealing Induced Aggregations and Sign Alterations of Nonlinear Absorption and Refraction of Dense Au Nanoparticles in TiO2 Films

Au-TiO2 dis-conductive composite films with Au atom concentrate as high as 82% are prepared by using reactive co-sputtering technique. The annealing effect on the nanostructures and optical nonlinearities of the composite films are investigated. A u nanoparticles aggregated to semi-continuum network structures during the annealing processes. As the annealing temperature increases from 25℃ to 400℃, the surface plasmon absorption band is shifted and its strength is increased, consequently, the nonlinear absorption coefficient β decreases from 5.6 × 10^4 cm/GW to -1.7 × 10^4 cm/GW, while the nonlinear refractive index ~ increases from -0.95 cm^2/GW to 1.3 cm^2/GW.     

关于Pb~(208)附近原子核的γ跃迁(Ⅱ)—M1跃迁

用组态混合的方法,对原子核Pb~(205)的M1γ跃迁进行比较仔细的分析,结论是在定性上与实验完全没有矛盾,可以解释全部理论上存在、而实验上尚未观察到的能级;在定量上,也与实验符合较好。     

零电阻温度超过90K的超导氧化物群体

已成功地合成了零电阻温度超过90K的七个ABO_3型结构的超导氧化物体系:Sr_(0.4)Y_(0.6)CuO_(3-y)和Ba_(0.4)Ln_(0.6)CuO_(3-Y)(Ln为Y,T,Tm,Dy,Gd,Er,Yb)。电测量结果表明,尽管各体系中的原子A的外层电子有明显的差别,其R(T)规律及高温超导转变行为几乎一致,而交流磁化率的测量则显示出由于磁性原子A不同所带来正常态△M(T)规律的差别。作者认为:在这些氧化物超导体中,ABO_3型结构中的Cu-O键会对电子的行为有着十分重要的作用,而且,在这种结构中,电子之间存在着很强的关联,磁散射的影响不足以破坏高温超导电性。     

细胞光阱刚度与折射率关系理论计算

为了探讨用光镊技术进行细胞折射率的测量方法,用几何光线理论对可作为米氏粒子模型的生物细胞(半径a=10μm,折射率n=1.35~1.70),在单光束梯度力光阱[激光波长λ=780 nm,功率P=6 mW,焦斑半径w(0)=0.6μm、0.8μm和1.0μm]中的轴向光阱刚度与细胞折射率关系进行了数值计算。结果表明,光阱刚度随折射率的变化关系与三次多项式曲线拟合得较好;用测量光阱刚度计算细胞的折射率时,需要用折射率已知的四种标准粒子对三次多项式曲线进行标定。     

Formation of Vegetation Patterns and Hysteresis Phenomena in Arid and Semiarid Zones

Considering the spatial effect of the complicated interactions between plant and resource （soil water） and the stochastic character of the complicated ecological processes in an ecosystem, we introduce a lattice gas model to investigate the vegetation pattern formation in the arid and the semiarid ecosystems with Monte Carlo sim- ulations. With consistency of some previous mean-field models, the model reproduces a wide range of patterns observed in the arid and the semiarid regions. The sequences of vegetation states are also investigated with scanning three parameters, i.e., the precipitation and the plant growth rate, and then the parameter ranges are identified where a hysteresis loop appears and two different stable states coexist. The simulation results denote that the complex structures occur only when the precipitation parameter decreases. Moreover, based on the model, it is found that an increase of the competition of the plant for the resource along the slope direction results in the regular stripes parallel to the hill＇s contours. The model provides an interesting mechanism to understand the formation of the other regular vegetation stripe in a limited resource condition.     

Kinetic Phase Transition in A2 ＋ B2 → 2AB Reaction System with Particle Diffusion

A lattice gas model for the A2 ＋ B2→2AB reaction system was studied by Monte Carlo simulation in a two- dimensional triangular lattice surface [Phys. Rev. E 69 （2004）046114]. In the model, a reactive window appears and the system exhibits a continuous phase transition to an ＇A＋vaoancy＇ covered state with infinitely many absorbing states. The critical behaviour was shown to belong to the robust directed percolation （DP） universality class. In this study, we find that as the particle A diffusion is considered, the infinitely many absorbing states for the continuous phase transition change into only two： one is that in which all sites are occupied by particle A and the other is that in which there is only one vacant site and other sites are occupied by particle A. Fhrthermore, a parity conserving character appears in the system when the particle A diffusion is included. It is found that the critical behaviour of the continuous phase transition changes from the DP class into the pair contact process with diffusion model （PCPD） class and the parity conserving character has no influence on the critical behaviour in the model.