Mortality forecasting using neural networks and an application to cause‐specific data for insurance purposes

Mortality forecasting is important for life insurance policies, as well as in other areas. Current techniques for forecasting mortality in the USA involve the use of the Lee–Carter model, which is primarily used without regard to cause. A method for forecasting morality is proposed which involves the use of neural networks. A comparative analysis is done between the Lee–Carter model, linear trend and the proposed method. The results confirm that the use of neural networks performs better than the Lee–Carter and linear trend model within 5% error. Furthermore, mortality rates and life expectancy were formulated for individuals with a specific cause based on prevalence data. The rates are broken down further into respective stages (cancer) based on the individual's diagnosis. Therefore, this approach allows life expectancy to be calculated based on an individual's state of health. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of Co substitution on the structural, electrical, and magnetic properties of Bi0.9La0.1FeO3 by sol-gel synthesis

Cobalt (Co)-doped Bi_0.9La_0.1FeO₃ multiferroics were synthesized by a sol-gel method based on the autocombustion technique. As-synthesized powder was examined using various characterization techniques to explore the effect of Co substitution on the properties of Bi_0.9La_0.1FeO₃. X-ray diffraction reveals that Co-doped Bi_0.9La_0.1FeO₃ preserves the perovskite-type rhombohedral structure of BiFeO₃, and the composition without Co preserves the original structure of the phase; however, a second-phase Bi₂Fe₄O₉ has been identified in all other compositions. Surface morphological studies were performed by scanning electron microscopy. Temperature-dependent resistivity of the samples reveals the characteristic insulating behavior of the multiferroic material. The resistivity is found to decrease with the increase both in temperature and Co content. Room temperature frequency-dependent dielectric measurements were also reported. Magnetic measurements show the enhancement in magnetization with the increase in Co content.     

Atom-by-atom substitution of Mn in GaAs and visualization of their hole-mediated interactions

The discovery of ferromagnetism in Mn-doped GaAs has ignited interest in the development of semiconductor technologies based on electron spin and has led to several proof-of-concept spintronic devices. A major hurdle for realistic applications of Ga(1-x)Mn(x)As, or other dilute magnetic semiconductors, remains that their ferromagnetic transition temperature is below room temperature. Enhancing ferromagnetism in semiconductors requires us to understand the mechanisms for interaction between magnetic dopants, such as Mn, and identify the circumstances in which ferromagnetic interactions are maximized. Here we describe an atom-by-atom substitution technique using a scanning tunnelling microscope (STM) and apply it to perform a controlled study at the atomic scale of the interactions between isolated Mn acceptors, which are mediated by holes in GaAs. High-resolution STM measurements are used to visualize the GaAs electronic states that participate in the Mn-Mn interaction and to quantify the interaction strengths as a function of relative position and orientation. Our experimental findings, which can be explained using tight-binding model calculations, reveal a strong dependence of ferromagnetic interaction on crystallographic orientation. This anisotropic interaction can potentially be exploited by growing oriented Ga(1-x)Mn(x)As structures to enhance the ferromagnetic transition temperature beyond that achieved in randomly doped samples.     

Tunability of physical properties of (Cd:Zn)S thin film by Close Space Sublimation Process (CSSP)

The present paper reports on a systematic study of the influence of Zn alloying on the structural and optical properties of Cd1 xZnxS thin films. X-ray diffraction study for structural analysis reveals that the two binary compounds have been completely transformed into ternary compound with hexagonal (wurtzite) structure with preferred orientation along c-direction with (002) planes. The optical properties such as optical constants and band gap energy of the films were examined by using spectroscopic ellipsometer and Photospectrometery. It was found that the optical constants (n and k) decrease with the addition of Zn content in the alloy. It was also confirmed that the band gap increases with increasing Zn amount in the alloy and is attributed to quantum size effect in the grain size. Raman spectroscopy analysis shows one dominant phonon band at 326 cm 1, the so-called longitudinal optical (LO) mode for all the alloy composition (x). The appearance of a single phonon band in the Raman spectra established the formation of single phase hexagonal structured Cd1 xZnxS thin film. The LO band is asymmetrically broaden and high frequency shifted due to potential fluctuation caused by the dopant material. The AFM results showed that the surface roughness was decreased with increasing Zn content.     

薄膜显微结构的研究

采用复型技术,在透射电镜中观察到厚度大于0.5μm的蒸发淀积Al膜的显微结构,实验结果表明,膜的表面呈岛状结构,侧面呈柱状结构,同时也探讨了影响“柱”直径大小的因素。     

响应面法优化微波辅助提取豆腐柴果胶工艺及其抗氧化研究

豆腐柴含有丰富的果胶,具有多样的药理活性.在单因素试验基础上,以果胶提取率为指标,采用Box-Behnken优化其微波辅助提取工艺,并通过测定果胶对羟基自由基和超氧阴离子的清除率来研究豆腐柴果胶体外抗氧化活性.结果显示,豆腐柴果胶的最佳提取工艺为:微波功率635 W、提取时间29 s、液料比20:1(m L/g),该条件下果胶提取率平均值为20.31%.豆腐柴果胶对羟基自由基和超氧阴离子自由基有较强的清除作用,显示其具有良好的抗氧化活性.     

Control of gene expression by a natural metabolite-responsive ribozyme

Most biological catalysts are made of protein; however, eight classes of natural ribozymes have been discovered that catalyse fundamental biochemical reactions. The central functions of ribozymes in modern organisms support the hypothesis that life passed through an 'RNA world' before the emergence of proteins and DNA. We have identified a new class of ribozymes that cleaves the messenger RNA of the glmS gene in Gram-positive bacteria. The ribozyme is activated by glucosamine-6-phosphate (GlcN6P), which is the metabolic product of the GlmS enzyme. Additional data indicate that the ribozyme serves as a metabolite-responsive genetic switch that represses the glmS gene in response to rising GlcN6P concentrations. These findings demonstrate that ribozyme switches may have functioned as metabolite sensors in primitive organisms, and further suggest that modern cells retain some of these ancient genetic control systems.     

强力生发灵甲液中非皂化物的分析

将强力生发灵甲液皂化，用加压快速柱层析对其非皂化物进行分离，得７种类型非皂化物，分别为：烷烃，酮，醇，酯，菲，含氮化合物，含硅化合物，再再气相色谱（ＧＣ）和气－质联用（ＧＣ－ＭＳ）等方法对每类皂化物进行分离，分析，共发现４０种组分，鉴定了其中的３３种。