机构影响系数和并联机器人雅克比矩阵的研究

基于刚体运动学的原理，对机构影响系数进行了研究，用运动坐标系和拟牵连速度的概念给出了机构速度影响系数求解公式，揭示了机构影响系数的物理意义，明确地论证了机构速度影响系数只与机构瞬时位姿有关而与机构的真实速度无关的结论。并将该方法用于并联机器人的运动学研究，由此而给出了求解并联机器人的雅克比矩阵的方法。     

人体压力分布测量及其传感技术

体压分布测量系统是测试病人坐卧时,人体与接触面之间压力的可视化工具.介绍了人体压力分布测量系统的一般结构,对其关键点--传感器技术作了较为详细的叙述.它们分别是电容式压力传感器;用电阻油墨制成的电阻式压力传感器阵列;压电电阻传感器等.有针对的介绍了国外三种典型的人体压力测试产品,Xsensor、Tekscan和FSA;论述了它们的主要特点及优缺点,并对其主要性能作了对比.最后介绍了自行设计的体压分布测量系统,并给出了实测结果.     

基于Cross-EKF定位的多机器人协作围捕策略研究

针对目前多机器人协作围捕过程中收敛速度慢、稳定性差、定位精度低的问题,提出一种新的围捕策略.设计出Cross-EKF定位算法,对目标位置的后验估计协方差进行交叉计算,以取得最小协方差区域.以区域边缘点到均值中心最大距离为半径,构建收敛圆,将对动态点的收敛扩展为对动态面的收敛.实验结果表明,系统能快速平稳地收敛该圆,从而实现对目标的精确围捕,该方法具有较高的实用价值.     

RF/wireless-interconnect: The next wave of connectivity

In the era of the nanometer CMOS technology, due to stringent system requirements in power, performance and other fundamental physical limitations (such as mechanical reliability, thermal constraints, overall system form factor, etc.), future VLSI systems are relying more on ultra-high data rates (up to 100 Gbps/pin or 20 Tbps aggregate), scalable, re-configurable, highly compact and reliable interconnect fabric. To overcome such challenges, we first explore the use of multiband RF/wireless-interconnects wh...     

Centriacinar remodeling and sustained procollagen gene expression after exposure to ozone and nitrogen dioxide

Sprague-Dawley rats were exposed to 0.8 ppm ozone (O3), to 14.4 ppm nitrogen dioxide (NO2), or to both gases simultaneously for 6 h per day for up to 90 d. The extent of histopathologic changes within the central acinus of the lungs was compared after 7 or 78 to 90 d of exposure using morphometric analysis by placement of concentric arcs radiating outward from a single reference point at the level of the bronchiole- alveolar duct junction. Lesions in the lungs of rats exposed to the mixture of gases extended approximately twice as far into the acinus as in those exposed to each individual gas. The extent of tissue involvement was the same at 78 to 90 d as noted at 7 d in all exposure groups. At the end of exposure, in situ hybridization for procollagen types I and III demonstrated high levels of messenger RNA within central acini in the lungs of animals exposed to the combination of O3 and NO2. In contrast, animals exposed to each individual gas had a similar pattern of message expression compared with that seen in control animals, although centriacinar histologic changes were still significantly different from control animals. We conclude that the progressive pulmonary fibrosis that occurs in rats exposed to the combination of O3 and NO2 is due to sustained, elevated expression of the genes for procollagen types I and III. This effect at the gene level is correlated with the more severe histologic lesions seen in animals exposed to both O3 and NO2 compared with those exposed to each individual gas. In contrast, the sustained expression of the procollagen genes is not associated with a shift in the distribution of the lesions because the area of change in each group after 7 d of exposure was the same as after 78 to 90 d of exposure.     

Perception of solar UVB radiation by phytophagous insects: behavioral responses and ecosystem implications

Most of our present knowledge about the impacts of solar UVB radiation on terrestrial ecosystems comes from studies with plants. Recently, the effects of UVB on the growth and survival of consumer species have begun to receive attention, but very little is known about UVB impacts on animal behavior. Here we report that manipulations of the flux of solar UVB received by field-grown soybean crops had large and consistent effects on the density of the thrips (Caliothrips phaseoli, Thysanoptera: Thripidae) populations that invaded the canopies, as well as on the amount of leaf damage caused by the insects. Solar UVB strongly reduced thrips herbivory. Thrips not only preferred leaves from plants that were not exposed to solar UVB over leaves from UVB-exposed plants in laboratory and field choice experiments, but they also appeared to directly sense and avoid exposure to solar UVB. Additional choice experiments showed that soybean leaf consumption by the late-season soybean worm Anticarsia gemmatalis (Lepidoptera: Noctuidae) was much less intense in leaves with even slight symptoms of an early thrips attack than in undamaged leaves. These experiments suggest that phytophagous insects can present direct and indirect behavioral responses to solar UVB. The indirect responses are mediated by changes in the plant host that are induced by UVB and, possibly, by other insects whose behavior is affected by UVB.     

Aurothioglucose inhibits murine thioredoxin reductase activity in vivo

Gold (I)-containing compounds, including aurothioglucose (ATG), are potent in vitro inhibitors of several selenocysteine-containing enzymes. Gold compounds have also been shown to potentiate the virulence of several viruses in mice, including coxsackievirus, implicated as a possible infectious agent in Keshan disease. One possible mechanism by which gold compounds may be increasing the virulence of viral infections in mice is by acting as a selenium antagonist in vivo and inducing oxidative stress. To investigate the possible role of gold compounds in inducing oxidative stress in mice, we assessed the ability of ATG administered in vivo to inhibit the activity of the selenocysteine-containing enzymes thioredoxin reductase (TR) and glutathione peroxidase (GPX1). Doses as low as 0. 025 mg ATG/g body weight caused significant and prolonged inhibition of TR activity in all tissues examined. No such inhibition of GPX1 activity was seen, indicating differential in vivo sensitivity of the enzymes to inhibition by ATG. In liver and heart, some recovery of TR activity was observed after a 7-d period, but no recovery was observed in pancreas or kidney. Because TR is involved in several important cellular redox functions, its inhibition most likely will affect multiple cellular processes. These results indicate that in vivo administration of ATG results in significant and long-lasting inhibition of TR activity. Such inhibition of TR could lead to increased levels of oxidative stress in vivo, thereby increasing the virulence of several viruses including the coxsackievirus.     

Regulation of cytokine expression and leukotriene formation in human basophils by growth factors, chemokines and chemotactic agonists

Basophils stimulated with IL-3 plus C5a selectively express IL-4 and IL-13 and continuously produce leukotrienes (LT) for hours. C5a combined with IL-5 or granulocyte-macrophage colony-stimulated factor was, however, much less effective in promoting cytokine expression and a late continuous phase of LTC4 production, possibly due to lower expression levels of their receptor alpha chains. Basophils also express several chemoattractant receptors, including high levels of C5a receptors, macrophage chemotactic protein (MCP) receptors (CCR2) and eotaxin receptors (CCR3), intermediate levels of CXCR1, CXCR2 and platelet-activating factor receptors, and lower levels of N-formyl-Met-Leu-Phe (fMLP) receptors. However, among the corresponding agonists, only C5a, fMLP and much more weakly MCP1, were found to induce cytokine expression and continuous LTC4 release, and only when combined with IL-3. CCR3, which is highly expressed on basophils and has been shown to mediate strong migratory but weak release responses, does not regulate cytokine expression. The weakly expressed fMLP receptor is an efficient activator of several cell functions including LTC4 formation, while CXCR2 hardly affects basophil function despite considerable expression. Thus, chemoattractant-receptors mediate different cellular responses unrelated to their expression levels.