A study of indoor radon levels in Indian dwellings,influencing factors and lung cancer risks

Passive integrating solid state nuclear track detectors (SSNTDs) were used to study the Radon-222 (Rn) concentrations in Indian dwellings. The study was made in 300 dwellings in the cities of Lucknow and Kanpur in northern India. The influence of some factors e.g. age of the house, number of floors and ventilation conditions, etc. on indoor Rn concentrations were studied. The equilibrium factor in 65 dwellings were also investigated. Average Rn concentrations in living rooms were found to be 34±8 Bq.m⁻³ and 40±10 Bq.m⁻³ respectively, with equilibrium factors of 0.35 and 0.38. Assuming an occupancy factor of 0.8, the annual average effective dose equivalents in living rooms of the two places are estimated as 0.8 and 1.0 mSv respectively.The average life-time risks of lung cancer for radon exposure of the Lucknow and Kanpur populations at home would be about 0.26% and 0.34% respectively and the mean relative loss of life expectancies were 0.06% and 0.074% respectively.     

光学透视式头戴显示设备标定结果量化评价分析

精确的注册是光学透视式头戴增强现实显示系统的核心技术,而光学透视式头戴显示设备的精准量化标定是精准注册的基础。为了实现对标定结果精准程度的衡量,结合光学透视式头戴显示设备的显示特性,提出了一套量化虚实匹配程度的用户评价方法。与传统方法相比,方法对不同用户的视觉反馈信息进行量化分析,克服了在标定结果评价上无法量化虚实配准效果的困难。进一步以导引插线的增强现实场景直观地评价了用户可接受的虚实匹配场景精细程度。实验结果定量地给出了用户对标定结果精度的评价,给增强现实场景设计提供了参考。     

A simple method to calculate dispersion coefficients for isolated and condensed-phase species

(Molecular Physics, 1998, 95, 549–570)     

A holographic method for the determination of all linear electrooptic coefficients applied to Ce-doped strontium-barium-niobate

Using c- and a-cut plates of strontium-barium-niobate doped with 0.66 mol.% cerium all nonzero components of the linear electrooptic tensor r₁₃, r₄₂, r₃₃ including the sign are determined from angular dependence of the two-beam coupling coefficient Γ using transmission and reflection geometry of holographic recording. We found: r₁₃=56 pm/V, r₄₂=38 pm/V, and r₃₃=333 pm/V. In addition we calculated the effective trap density N_eff to be 2.2×10¹⁷ cm^-3. The advantages of this method as well as the values obtained are discussed. Received: 19 November 1998 / Revised version: 15 January 1999 / Published online: 7 April 1999     

Radius of curvature measurements for laser beams: A simple method

A simple method for measuring the radius of curvature of laser beams is introduced. It has been developed to estimate the astigmatic aberration of a diode laser. Compared with the interferometry, this method is convenient and straightforward.     

求大摆角单摆周期近似解的"局部常化"方法

建构“局部常化”的近似处理方法,对一类非线性动力学方程进行了一种简洁的近似修正,得到大摆角单摆运动周期的一个新结论,并且给出了精确度很高的三个推论,同时得到了第一类完全椭圆积分的一种简洁的近似公式．     

A simple method to estimate the magnetic moment of magnetic micro-particles

Micro-particles in suspension in a fluid are an example of a very low Reynolds number problem. In this case, no inertial effects are observed. Magnetic micro-particles with magnetic moment m, suspended in a fluid orient to applied external magnetic fields B due to the interaction between the field and the magnetic moment. In this work, we present a simple method to estimate the total magnetic moment of magnetic micro-organisms. The method is based on the application of an external oscillating magnetic field in the sites where the micro-organisms are. In this case, it is possible to obtain theoretically the solution of the equation of motion (rotation of the organism and its trajectory). The solution is a transcendental equation relating the orientation angle and m and can be solved by numerical methods. Changing the frequency and/or the field intensity, it is possible to obtain a situation in which the crystal rotates uninterruptedly (a resonance regime). This condition is related to the applied field intensity, to the frequency, to the medium viscosity, to the crystal dimension, and to the micro-crystal magnetic moment m. The method can be used to estimate the total cellular magnetic moment of magnetic micro-particles.     

A simple stochastic lattice gas model for H1N1 pandemic. Application to the Italian epidemiological data

We construct a very simple epidemic model for influenza spreading in an age-class-distributed population, by coupling a lattice gas model for the population dynamics with a SIR stochastic model for susceptible, infected and removed/immune individuals. We use as a test case the age-distributed Italian epidemiological data for the novel influenza A(H1N1). The most valuable features of this model are its country-independent and virus-independent structure (few demographic, social and virological data are used to fix some parameters), its large statistic due to a very short run-time machine, and its easy generalizability to include mitigation strategies. In spite of its simplicity, the model presented reproduces the epidemiological Italian data, with sensible predictions for the reproduction number and theoretically interesting results for the generation time distribution.     

A simple solution to systematic errors in density determination by X-ray reflectivity: The XRR-density evaluation (XRR-DE) method

X-ray reflectivity (XRR) is a non-destructive, accurate and fast technique for evaluating film density. Indeed, sample-goniometer alignment is a critical experimental factor and the overriding error source in XRR density determination. With commercial single-wavelength X-ray reflectometers, alignment is difficult to control and strongly depends on the operator. In the present work, the contribution of misalignment on density evaluation error is discussed, and a novel procedure (named XRR-density evaluation or XRR-DE method) to minimize the problem will be presented. The method allows to overcome the alignment step through the extrapolation of the correct density value from appropriate non-specular XRR data sets. This procedure is operator independent and suitable for commercial single-wavelength X-ray reflectometers. To test the XRR-DE method, single crystals of TiO₂ and SrTiO₃ were used. In both cases the determined densities differed from the nominal ones less than 5.5%. Thus, the XRR-DE method can be successfully applied to evaluate the density of thin films for which only optical reflectivity is today used. The advantage is that this method can be considered thickness independent.     

A simple theoretical extension to the analysis of photothermal deflection signal for low thermal diffusivity evaluation

A modified amplitude method to analyze the photothermal probe beam deflection signal for the determination of low thermal diffusivity values of materials is proposed. This simple theoretical model, which is an extension of the amplitude method proposed by Quelin et al., takes into account the dependence of the photothermal signal on the height of the probe beam above the sample surface which affects mirage measurements when the thermal diffusivity of the coupling medium is greater than that of the sample. The present work is similar to the modification to the phase method proposed by Bertolotti et al. for determination of low thermal diffusivity. The method can be applied irrespective of whether the sample is optically transparent or optically opaque and is independent of thickness.     

非线性演化方程椭圆函数解的一种简单求法及其应用

非线性演化方程的许多行波解可以写成满足投影Riccati方程的两个基本函数的多项式形式.利用这一性质，通过建立一般的椭圆方程与投影Riccati方程解之间的关系，导出了一个构造这些解的新方法.该方法对类型Ⅰ的方程和类型Ⅱ的方程均有效，同时也回答了如何求出非线性演化方程分式形式椭圆函数解的问题. 关键词： 非线性演化方程 椭圆函数解     

A simple method for measuring the refractive index of a plate

A simple and reliable method for measuring the refractive indices of plate samples is introduced. The method exploits the maximum separation distance of the beams reflected from the surfaces of the plate. The precision of the technique is comparable by that is obtained for prism samples using available techniques. The technique can be also applied to liquids and gases at high pressures.     

A simple method for boosting the beam quality of commercial DPL

A simple method for boosting the beam quality of a commercial laser diode pumped laser (DPL) is put forward. By keeping one of the mirrors unchanged and the moving the other mirror a proper distance away from the laser rod, high beam quality laser output is realized.     

用局部常化三倍角公式研究单摆周期

应用局部常化方法对三倍角公式进行局部常化处理,对一类非线性动力学方程进行了一种简洁的近似修正,得到精确度较高的大摆角单摆运动周期的两个新结论,同时用此结论推导出一个简洁的推论,并且用3种方法进行了具体比较.     

测量气体分子平均速率的一种简易方法

用一种简易的方法测量了常温下气体分子运动的平均速率.根据易挥发性液体的质量随时间逐渐减少的特点和盛放液体的容器加盖前后挥发的气体分子对容器作用力的变化,通过分析天平测量液体质量的改变得到挥发出来的气体分子对容器的作用力,利用变质量物体的动量守恒定理,测量得到了易挥发性气体分子的平均速率,实验结果较好地与理论值符合.     

A simple method for the preparation of colloidal polymer-supported silver nanoparticles

Polysulfone?silver composite nanoparticles have been prepared by combining polymer nanoprecipitation and redox synthesis of silver, in the presence of a glucose-modified cyclosiloxane as stabilizing agent. Based on previous kinetic investigations and on model reactions, we concluded that the reducing agent in this case is the tetrahydrofuran (THF) used as solvent for polysulfone. Dynamic light scattering measurements on the obtained polymer-silver composite particles indicated particle average diameter of 176 nm with a polydispersity index of 0.25. The UV–vis spectrum exhibited the silver plasmon resonance. By different microscopic methods (atomic force microscopy—AFM, high resolution transmission electron microscopy—HRTEM, and scanning electron microscopy—SEM), larger polymer particles coated with silver nanoprticles were observed. The Energy Dispersive X-Ray analysis—EDX; confirmed the presence of Ag on the surface of the particles, while the selected area electron diffraction showed single crystalline silver nanospheres with face-centered cubic structure.     

导出圆电流的磁感应强度的简便方法

避开繁琐的椭圆积分推导,用微积分导出了圆电流在空间各点的磁感应强度的定积分公式,再变换成用椭圆积分表示的精确解.