Magnetic order in lightly doped La2-xSrxCuO4

We study long wavelength magnetic excitations in lightly doped La2-xSrxCuO4 (x相似文献   

Detection of single-electron charging in an individual InAs quantum dot by noncontact atomic-force microscopy

Single-electron charging in an individual InAs quantum dot was observed by electrostatic force measurements with an atomic-force microscope (AFM). The resonant frequency shift and the dissipated energy of an oscillating AFM cantilever were measured as a function of the tip-back electrode voltage, and the resulting spectra show distinct jumps when the tip was positioned above the dot. The observed jumps in the frequency shift, with corresponding peaks in dissipation, are attributed to a single-electron tunneling between the dot and the back electrode governed by the Coulomb blockade effect, and are consistent with a model based on the free energy of the system. The observed phenomenon may be regarded as the "force version" of the Coulomb blockade effect.     

Both electron and hole Dirac cone states in Ba(FeAs)2 confirmed by magnetoresistance

Quantum transport of Dirac cone states in the iron pnictide Ba(FeAs)(2) with a d-multiband system is studied by using single crystal samples. Transverse magnetoresistance develops linearly against the magnetic field at low temperatures. The transport phenomena are interpreted in terms of the zeroth Landau level by applying the theory predicted by Abrikosov. The results of the semiclassical analyses of a two carrier system in a low magnetic field limit show that both the electron and hole reside as the high mobility states. Our results show that pairs of electron and hole Dirac cone states must be taken into account for an accurate interpretation in iron pnictides, which is in contrast with previous studies.     

A high-sensitivity terahertz sensing method using a metallic mesh with unique transmission properties

Metallic meshes work as band-pass filters in the terahertz (THz) region, with their transmission spectra acutely affected by the refractive index of the material inside and above the metallic-mesh openings. We used a metallic mesh for high-sensitivity observations by focusing on the “dip,” that is, a sudden change in transmittance that only appeared when the THz wave was obliquely incident onto the metallic mesh. Here we consider the interference between apertures of the metallic mesh in the diagonal direction and explain the dip using finite-difference time-domain (FDTD) electromagnetic simulations.     

Sharpness Matching between Digital Image Display Devices

A method is presented for matching apparent sharpness between digital image display devices with different characteristics. The sharpness is most precisely described by the point spread function (PSF) as opposed to dot density such as DPI (dot per inch). The difference between devices is expressed as difference between transfer functions obtained from the PSFs. In the presented method, spatial frequency filtering for one digital image is carried out where the ratio of the transfer functions or its modified version is used as filter. The modification is introduced as a clipping operation to reduce excessive enhancement when the ratio of the transfer functions has a high pass characteristic with large gain. Through computer simulation including a subjective evaluation experiment and numerical evaluation, the effectiveness of filtering operation for sharpness matching is demonstrated.     

超流氦噪声沸腾过程中的压力振动分析: 小试样几何尺寸对噪声沸腾状态的影响

小试样的几何形状尺寸是影响噪声沸腾状态的一个重要的因素. 对于不同几何尺寸的小试样, 沸腾发生时所产生的气泡的尺寸不同, 因而所产生的压力振动的幅度和特征频率就不同. 采用一个归一化因子将不同几何形状尺寸下的实验数据进行统一, 发现振动的特征频率与几何尺寸因子之间存在对数曲线的关系.     

Lattice path counting andM/M/c queueing systems

We apply the lattice path counting method to the analysis of the transientM/M/c queueing system. A closed-form solution is obtained for the probability of exactlyi arrivals andj departures within a time interval of lengtht in anM/M/c queueing system that is empty at the initial time. The derivation of the probability is based on the counting of paths from the origin to(i,j) on thexy-plane, that have exactly r_d x-steps whose depth from the liney=x isd (d=0,1,...,c–1). The closed-form solution has an expression useful for numerical calculation.     

GLOBAL STABILITY OF SIRS EPIDEMIC MODELS WITH A CLASS OF NONLINEAR INCIDENCE RATES AND DISTRIBUTED DELAYS＊

In this article,we establish the global asymptotic stability of a disease-free equilibrium and an endemic equilibrium of an SIRS epidemic model with a class of nonlinear incidence rates and distributed...