Average values of symmetric square -functions at the edge of the critical strip

Let be the set of all normalized newforms of weight 2 and level , and let be the symmetric square -function associated to . If is a prime, then there is a positive constant such that

This improves a recent result of Akbary, which requires in place of .

     

Estimation of the mean lifetime in non-parametric model under modified type I censoring

The methods to estimate the means of the lifetimes under modified Type I Censoring are discussed, in which case the distribution function of the lifetimes is unknown and the information about the individuals is cut by the fixed timeC. As a slight modification, we suggest observing small percentage of the lifetimes to construct the estimations. These estimations are unbiased and consistent.     

A simple model for high fluence ultra-short pulsed laser metal ablation

The ultra-short laser metal ablation is a very complex process, the complete simulation of which requires applications of complicated hydrodynamics or molecular dynamics models, which, however, are often time-consuming and difficult to apply. For many practical applications, where the laser ablation depth is the main concern, a simplified model that is easy to apply but at the same time can also provide reasonably accurate predictions of ablation depth is very desirable. Such a model has been developed and presented in this paper, which has been found to be applicable for laser pulse duration up to 10 ps based on comparisons of model predictions with experimental measurements.     

Fast spin state initialization in a singly charged InAs-GaAs quantum dot by optical cooling

Quantum computation requires a continuous supply of rapidly initialized qubits for quantum error correction. Here, we demonstrate fast spin state initialization with near unity efficiency in a singly charged quantum dot by optically cooling an electron spin. The electron spin is successfully cooled from 5 to 0.06 K at a magnetic field of 0.88 T applied in Voigt geometry. The spin cooling rate is of order 10(9) s-1, which is set by the spontaneous decay rate of the excited state.     

Evolution of the electronic structure of 1T-Cu(x)TiSe(2)

The electronic structure of a new charge-density-wave system or superconductor, 1T-Cu(x)TiSe(2), has been studied by photoemission spectroscopy. A correlated semiconductor band structure is revealed for the undoped case, which resolves a long-standing controversy in the system. With Cu doping, the charge-density wave is suppressed by the raising of the chemical potential, while the superconductivity is enhanced by the enhancement of the density of states, and possibly suppressed at higher doping by the strong scattering.     

巨磁电阻效应——2007年诺贝尔物理学奖简介

瑞典皇家科学院宣布，法国科学家阿尔伯特·费尔（Albert Vert）和德国科学家彼得·格鲁伯格（Peter Grunberg），共同获得2007年诺贝尔物理学奖．获奖的原因是这两位科学家先后独立发现了“巨磁电阻”（giant magnetoresistance，GMR）效应．这个发现引发的技术进步极大地提高了计算机硬盘磁头的数据读取能力，使硬盘无论从容量还是体积上都产生了质的飞越．这个发现还导致了新一代磁传感器的出现，而且巨磁电阻被认为是纳米技术最重要的应用之一．     

Issues on nanoimprint lithography with a single-layer resist structure

We summarize our key developments in nanoimprint lithography (NIL) that employs a single layer resist lift-off process: lowering of the imprint temperature (for thermal imprint) and pressure, achieving uniform resist thickness and low residual resist layer thickness in the trenches, and eliminating metal ‘rabbit ears’ for the single-layer lift-off. In thermal NIL, our requirements for lower operating temperature and pressure motivated us to develop an alternative resist that is a viscous fluid at room temperature and cures at a lower temperature of 70 °C than the operating temperature of the conventional thermal NIL (≈200 °C). For UV NIL, we devised a method to dispense the resist onto a hydrophobic mold and use the hydrophilic substrate surface to spread the resist via surface wetting to engineer a continuous and uniform film. We also explored the use of Si(110) substrates as molds to produce features with perfectly vertical side walls, and the use of aqua regia to directly etch away rabbit ears. PACS 86.65.+h; 81.16.Nd; 81.16.Rf     

Polymer-assisted complexing controlled orientation growth of ZnO nanorods

The growth of the oriented zinc oxide (ZnO) nanorods on silicon substrates based on a simple novel chemical transformation and thermal hydrolysis by using polyvinyl alcohol (PVA) as self-assembling complex polymer was introduced in this paper. All the polymers were removed after chemical oxidation and only the carbonized grid backbones remained that confines the ZnO nanorod’s diameter and enhance the absorption and diffusion of ZnO at the tips of the nanorods during growth. The ZnO nanorods are investigated by FTIR, XRD and FE-SEM. The results indicated that these nanorods have fine hexagonal wurtzite crystal structure and their diameter varies from 20 to 90 nm and the length up to about 1 μm. A polymer-localized ZnO growth model is proposed, which well explains the growth behavior of ZnO nanorods.This revised version was published online in August 2005 with a corrected issue number.     

Improvement of all-optical switching effect based on azobenzene-containing polymer films

A method for improving the quality of all-optical switching is presented. Pumping poly(methyl methacrylate) (PMMA) films doped with azobenzene chromophore Disperse Red 1 (DR1) with two beams (a linearly and a circularly polarized), all-optical switching effects with very low background and high stability are demonstrated. High frequency switching, which is hard to be realized under pump of a single beam, is obtained. The circularly polarized pump beam can erase the photoinduced birefringence and quicken the relaxation process, thus lowering the background and improving the stability and the extinction ratio of the switching signal. PACS 42.70.Jk; 42.25.Lc; 82.30.Qt; 78.20.Fm; 77.80.Fm     

Absorption-induced confinement of lasing modes in diffusive random media

We present a numerical study of lasing modes in diffusive random media with local pumping. The reabsorption of emitted light suppresses the feedback from the unpumped part of the sample and effectively reduces the system size. The lasing modes are dramatically different from the quasi modes of the passive system (without gain or absorption). Even if all the quasi modes of a passive diffusive system are extended across the entire sample, the lasing modes are still confined in the pumped volume with an exponential tail outside it. The reduction of effective system volume by absorption broadens the distribution of decay rates of quasi modes and facilitates the occurrence of discrete lasing peaks.