The influence of ethylene on primary attraction of the olive beetle,Phloeotribus scarabaeoides (Bern.) (Col., Scolytidae)

Two experiments have been carried out to verify the effect of ethylene on the primary attraction ofPhloeotribus scarabaeoides under both laboratory and field conditions. The experiments were based on the enhancement of ethylene production by olive branches and trunks after the application of (2-chloroethyl)phosphonic acid. Under laboratory conditions, the beetles' response was strongly stimulated on the treated branches. Under field conditions, the treatment aided the location of the olive wood by the flying beetles, and the attack density was significantly greater in the treated wood at the end of the experiment.     

Bias in the estimation of non‐linear transformations of the integrated variance of returns

Volatility models such as GARCH, although misspecified with respect to the data‐generating process, may well generate volatility forecasts that are unconditionally unbiased. In other words, they generate variance forecasts that, on average, are equal to the integrated variance. However, many applications in finance require a measure of return volatility that is a non‐linear function of the variance of returns, rather than of the variance itself. Even if a volatility model generates forecasts of the integrated variance that are unbiased, non‐linear transformations of these forecasts will be biased estimators of the same non‐linear transformations of the integrated variance because of Jensen's inequality. In this paper, we derive an analytical approximation for the unconditional bias of estimators of non‐linear transformations of the integrated variance. This bias is a function of the volatility of the forecast variance and the volatility of the integrated variance, and depends on the concavity of the non‐linear transformation. In order to estimate the volatility of the unobserved integrated variance, we employ recent results from the realized volatility literature. As an illustration, we estimate the unconditional bias for both in‐sample and out‐of‐sample forecasts of three non‐linear transformations of the integrated standard deviation of returns for three exchange rate return series, where a GARCH(1, 1) model is used to forecast the integrated variance. Our estimation results suggest that, in practice, the bias can be substantial. Copyright © 2006 John Wiley & Sons, Ltd.     

An organic thyristor

Thyristors are a class of nonlinear electronic device that exhibit bistable resistance--that is, they can be switched between two different conductance states. Thyristors are widely used as inverters (direct to alternating current converters) and for the smooth control of power in a variety of applications such as motors and refrigerators. Materials and structures that exhibit nonlinear resistance of this sort are not only useful for practical applications: they also provide systems for exploring fundamental aspects of solid-state and statistical physics. Here we report the discovery of a giant nonlinear resistance effect in the conducting organic salt theta-(BEDT-TTF)2CsCo(SCN)4, the voltage-current characteristics of which are essentially the same as those of a conventional thyristor. This intrinsic organic thyristor works as an inverter, generating an alternating current when a static direct-current voltage is applied. Whereas conventional thyristors consist of a series of diodes (their nonlinearity comes from interface effects at the p-n junctions), the present salt exhibits giant nonlinear resistance as a bulk phenomenon. We attribute the origin of this effect to the current-induced melting of insulating charge-order domains, an intrinsically non-equilibrium phenomenon in the sense that ordered domains are melted by a steady flow.     

低捻转杯纺纱实验与理论分析--提高低捻转杯纱强力探索

研究在转杯纺加捻区中加装阻扭件,然后选用相同的棉条纺制不同捻系数的转杯纱(加装阻扭件和不加装阻扭件)和环锭纱,并测试其成纱的强伸性能、表面形态和扭转性能.测试结果表明,加装阻扭件的转杯纱可以适当改善转杯纺的加捻效果,进而适当提高了转杯纱的成纱强力.     

Treatment of PC-3 cells with ultrasound combined with microbubbles induces distinct alterations in the expression of Bcl-2 and Bax

The objective of the present study was to investigate whether ultrasound combined with microbubbles induces apoptotic cell death in androgen-independent prostate cancer cells and to identify the probable mechanism. We used ultrasound in continuous wave mode with a frequency of 21 kHz and a spatial-average temporal-average intensity of 46 mW/cm². Ultrasound combined with microbubbles (200 μL SonoVue?) was used to treat androgen-independent human prostate cancer PC-3 cells for 30 s. PC-3 cells were divided into three groups: the control group, the ultrasound group and the ultrasound combined with microbubbles group. Immediately after treatment, trypan blue exclusion was used to assess cell viability. Cell apoptosis at 24 h after treatment was measured using transmission electron microscopy and flow cytometry. Western blotting was used to evaluate the expression of the apoptosis-related proteins, Bcl-2 and Bax. Ultrasound combined with microbubbles had a minimal effect on the viability of PC-3 cells and induced minimal levels of cell lysis. The level of apoptosis in PC-3 cells induced by this modality was significantly higher than in controls (12.77 ± 0.31% vs. 2.56 ± 0.22%, P<0.01). Treatment with ultrasound combined with microbubbles increased the expression of Bax, a pro-apoptotic protein, and decreased the expression of Bcl-2, an anti-apoptotic protein. It was concluded that ultrasound combined with microbubbles induces apoptotic cell death in human prostate cancer PC-3 cells through down-regulation of Bcl-2 and up-regulation of Bax.     

基于坐标逻辑的形态图像处理器的硬件实现

在阐述坐标逻辑运算的基础上,论述了基于坐标逻辑形态学硬件实现的图像处理系统,该系统采用DSP FPGA的框架结构,利用FPGA的可重构特性将其中一片FPGA作为协处理器可以实现不同的图像处理功能,将坐标逻辑和传统形态学硬件实现的形态图像处理器在处理效果和速度两个方面作了比较,算法在FPGA芯片上的高速实现特征使数学形态学在图像实时处理领域的应用成为可能。     

求解最小覆盖问题的快速近似算法的进一步研究

分析了已有求覆盖平面上给定的若干个点的尽可能小的圆的问题的算法。给出了一个新的求解最小覆盖问题的算法，其计算时间复杂度为平面上给定的点数量的线性函数，该算法已编程实现，通过几万例随机算例的实际计算比较，表明算法所得结果的平均精度比已有的各种快速近似算法所得的精度要高，而且具体每例所需的计算时间均比已有快速近似算法对应的计算时间要短。     

同轴式水下局部干法TIG电弧焊接

本文主要介绍同轴式水下局部干法TIG电弧焊工艺及装置。其装置特点是能够轴向直接观察电弧和熔池状态,从而便于控制焊接过程,保证焊缝的对中性。试验结果表明:采用此装置能较好地解决湿法焊接时可见度差。焊缝含氢量高,冷却速度快等问题。焊缝的机械性能指标达到有关海上结构规程所提出的要求。     

Si基片各向异性腐蚀特性研究

为了制备高性能铁电薄膜红外探测器 ,对Si微桥的湿化学腐蚀工艺进行了研究 .利用Si基片各向异性腐蚀特性 ,在四甲基氢氧化铵 (简称TMAH )水溶液中加入氢氧化钾 (KOH)作为各向异性腐蚀液 (简称KTMAH) ,研究了TMAH与KOH摩尔比、腐蚀浓度、腐蚀温度对Si基片腐蚀特性的影响 .结果表明 :Si(1 0 0 )面的腐蚀速度随着腐蚀液浓度和温度的升高而增大 ,随着TMAH与KOH摩尔比的降低 ,KTMAH腐蚀液对掩膜层的腐蚀程度加剧 .选用 5 g/L的过硫酸盐 (PDS)与TMAH质量分数为 2 5 %、TMAH与KOH摩尔比为2的KTMAH混合液作为腐蚀液 ,并在 80℃× 2 .5h的腐蚀条件下能得到平整的腐蚀面 ,可以制备质量较好的微桥结构