h-ADAPTIVITY ANALYSIS BASED ON MULTIPLE SCALE REPRODUCING KERNEL PARTICLE METHOD

IntroductionAs one of the meshfree methods, multiple scale reproducing kernel particle method(RKPM)[1,2]bears, besides the common features of all meshfree methods, a uniqueinherent feature of multiresolution analysis by which the structural response can b…     

Physics of sinking and selection of plankton cell size

Gravitational sinking in the water column is known to affect size composition of planktonic communities. One important driver toward the reduction of plankton size is the fact that larger cells tend to sink faster below the euphotic layer. In this work, we discuss the role of gravitational sinking in driving cell size selection, showing that the outcome of phytoplankton competition is determined by the dependence of sinking velocity on cell size, shape, and on the temporal variability associated with turbulence. This opens a question on whether regional modulations of the turbulence intensity could affect size distribution of planktonic communities.     

Letter: Axial Torsion-Dirac Spin Effect in Rotating Frame with Relativistic Factor

In the framework of spacetime with torsion and without curvature, the Dirac particle spin precession in the rotational system is studied. We write out the equivalent tetrad of the rotating frame, in the polar coordinate system, through considering the relativistic factor, and the resultant equivalent metric is a flat Minkowski one. The obtained rotation-spin coupling formula can be applied to the high speed rotating case, which is consistent with the expectation.     

光学尘埃粒子计数器自动校正的实现

光学尘埃粒子计数器是利用尘埃粒子在强光照射下产生散射光,通过检测散射光强度设计而成,仪器接收灵敏度的稳定性是保证测量准确度的关键。提出了一种尘埃粒子计数器实现自动校正的方法,使仪器始终处于定标时的接收灵敏度。     

Phospholipid lung surfactant and nanoparticle surface toxicity: Lessons from diesel soots and silicate dusts

Because of their small size, the specific surface areas of nanoparticulate materials (NP), described as particles having at least one dimension smaller than 100 nm, can be large compared with micrometer-sized respirable particles. This high specific surface area or nanostructural surface properties may affect NP toxicity in comparison with micrometer-sized respirable particles of the same overall composition. Respirable particles depositing on the deep lung surfaces of the respiratory bronchioles or alveoli will contact pulmonary surfactants in the surface hypophase. Diesel exhaust ultrafine particles and respirable silicate micrometer-sized insoluble particles can adsorb components of that surfactant onto the particle surfaces, conditioning the particles surfaces and affecting their in vitro expression of cytotoxicity or genotoxicity. Those effects can be particle surface composition-specific. Effects of particle surface conditioning by a primary component of phospholipid pulmonary surfactant, diacyl phosphatidyl choline, are reviewed for in vitro expression of genotoxicity by diesel exhaust particles and of cytotoxicity by respirable quartz and aluminosilicate kaolin clay particles. Those effects suggest methods and cautions for assaying and interpreting NP properties and biological activities.     

Multiple closed trajectories of a relativistic particle

In this paper we study in some particular cases, the existence and multiplicity of closed trajectories of a relativistic particle moving in some electromagnetic fields. To solve this problem, we use Hamiltonian systems and variational methods.     

Behavior of a quantum particle in contact with a classical heat bath

We investigate the behavior of a two-level quantum system in contact with a classical heat bath, e.g., a solute particle with internal degrees of freedom immersed in a solvent of massive particles. Using a combination of analytical and numerical methods, we obtain precise information about localization, time-displaced correlation functions, and the frequency-dependent susceptibility of such solute particles. We find that these quantities can have a strong dependence on the density of the solvent fluid, with the maximum changes from the behavior of the corresponding isolated quantum system occurring in many cases at very low densities. We compare the exact results with those obtained by path integral Monte Carlo. There is good agreement with the imaginary time correlations, but analytic continuation to real time proves elusive: even with the best numerical data on the former, we can only get very gross features of the latter.     

Eigenvalue Spectrum of a Dirac Particle in Static and Spherical Complex Potential

It has been observed that a quantum theory need not be Hermitian to have a real spectrum. We study the non-Hermitian relativistic quantum theories for many complex potentials, and obtain the real relativistic energy eigenvalues and corresponding eigenfunctions of a Dirac-charged particle in complex statically and spherically symmetric potentials. Complex Dirac–Eckart, complex Dirac–Rosen–Morse II, complex Dirac–Scarf and complex Dirac–Poschl–Teller potential are investigated.     

光复散射对消光法粒径测量的影响:复散射模型与数值模拟

复散射效应在光散射颗粒测量中不仅重要．且尚未得到很好解决。采用蒙特卡罗方法,对不同的光波长,颗粒浓度以及收接器条件下的光复散射进行了数值模拟．数值算法程序经与四通量模型进行对比验证,数值结果与单散射条件的郎伯-比尔模型进行比较．进而讨论了复散射效应对消光法颗粒粒径测量影响。表明复散射对消光法颗粒测量的影响不仅取决于颗粒系自身的浓度．而且接收器的几何尺寸和接收位置起着非常重要的作用,减小颗粒介质层厚度和减小光接收器接收面积．增大接收距离以及减小接收角都能减小复散射效应对消光法粒径测量的影响。