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101.
Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. Recently, it was shown that some CYP isoforms have been subject to positive selection. However, it is unknown whether the highly conserved phase I detoxification enzyme, FMO, has undergone similar positive Darwinian selection. We used maximum-likelihood models of codon substitution, evolutionary fingerprinting, and cross species comparison to investigate the occurrence of adaptive evolution in FMO sequences. We used recent genomic data from a range of species, including vertebrates and invertebrates. We present the evidence for the occurrence of adaptive evolution in mammalian FMO 3, 4, 5, and fugu FMOs but not in mammalian FMO 1, FMO 2, frog FMOs, other fish FMOs and invertebrate FMOs. The sites under adaptive evolution were significantly associated with the insertion domain in mammalian FMO 5. We identified specific amino acid sites in FMOs 3–5 that are likely targets for selection based on the patterns of parallel amino acid change. The most likely role of adaptive evolution is the repair of mutations that permitted optimal NADP+ binding and improved catalytic efficiency. The occurrence of positive selection during the evolution of phase I detoxification enzymes such as FMOs 3–5 and fugu FMO suggests the occurrence of both high selection pressure acting on species within their unique habitats and significant changes in intensity and direction (forms of xenobiotics and drugs) resulting from changes in microhabitat and food. 相似文献
102.
自适应模糊控制和PLC在中央空调控制系统中的应用 总被引:1,自引:0,他引:1
郑卓 《甘肃联合大学学报(自然科学版)》2011,25(1):74-77
为克服中央空调控制系统舒适度调节能力差,能源浪费严重,可靠性低,通信实时性控制不高的不足,提出了一套基于自适应模糊控制方法,从系统的硬件构成、软件设计两个方面探讨了Simatic S7-300在中央空调控制系统中的应用.实际运行表明,该系统运行稳定、可靠、同时降低了能耗. 相似文献
103.
A stronger canonical model was developed to improve the performance of automatic pronunciation evaluations.Three different strategies were investigated with speaker adaptive training to normalize variations among speakers,minimum phone error training to identify easily confused phones and maximum likelihood linear regression(MLLR) adaptation to compensate for accent variations between native and non-native speakers.The three schemes were combined to improve the correlation coefficient between machine scores and human scores from 0.651 to 0.679 on the sentence level and from 0.788 to 0.822 on the speaker level. 相似文献
104.
The problem of constructing a model dimensional parabolic system is considered in this reference adaptive control law for an uncertain 1- article. The controller designed here involves only the plant state but no its derivatives. A priori bounds on the plant's uncertain parameters are used to propose switching laws which serve as an adaptive mechanism. The exponential decay to zero of the state error with any prescribed rate is guaranteed by choosing a controller parameter correspondingly. Numerical studies are also presented to illustrate the applicability of the control law. 相似文献
105.
提出一类自适应扩散方程并将其相应的模型用于乘性去噪, 该类模型能针对乘性噪声的特点, 根据局部梯度信息自适应地选择扩散模式: 其扩散速度和噪声大小成正比, 没有噪声的区域不扩散, 同时结合了热方程各向同性扩散和全变差流各向异性扩散的特点. 理论分析和实验结果表明, 该类模型能自适应地光滑区域内部, 增强边界, 避免阶梯效应. 相似文献
106.
This paper proposes a unified clutter model incorporating the effects of range walk and array rotation for space-time adaptive processing (STAP) in airborne multi-channel early-warning radar. Based on this clutter model, STAP performance is then analyzed from the perspective of covariance matrix tapering (CMT). For STAP performance degradation due to array rotation, a determinate compensation method is proposed based on the CMT method. Numerical examples are provided to verify the analysis and the proposed compensation method. 相似文献
107.
基于LQR-IMCS算法的智能结构振动主动控制 总被引:1,自引:0,他引:1
为了解决最小控制综合(MCS)算法在快速扰动下缺乏鲁棒性和线性二次调节器(LQR)在非线性扰动下容易失稳的问题,构造了一种自适应增益补偿函数,对标准的MCS算法进行改进.提出了基于LQR-IMCS(改进的最小控制综合)算法的新策略,并通过波波夫准则验证了该系统的稳定性.以实验室压电壁板结构的第1阶振动模态为研究对象,分别施加随机扰动和高次谐波扰动.仿真和实验结果表明:该方法相对于标准的MCS算法具有更快的收敛速度和更小的跟踪误差,对壁板的第1阶模态抑制具有良好的控制效果和鲁棒性. 相似文献
108.
研究的目的是查找出化妆品中易导致人体化妆品皮炎的原料成分,以减少化妆品皮炎的发生几率。采用临床试验筛选研制出的过敏原60种,然后将其中20种过敏原作为实验组和瑞典化学诊断试剂公司生产的"瑞敏"相同成分20种过敏原作为对照组,为临床疑因接触化妆品而导致的过敏性皮炎患者做斑贴试验。156例患者使用研制的60种过敏原斑贴试验有145例出现阳性反应,总阳性率92.95%;其中有9种过敏原斑贴试验的阳性率超过10%。50例患者用研制的20种过敏原与"瑞敏"20种相同成分过敏原对照斑贴试验,结果完全一致的37例,占74%。206例患者均没有出现不良反应。本试验的60种化妆品筛选过敏原用于临床斑贴试验安全、有效。 相似文献
109.
针对一类非线性离散系统 ,利用 Lyapunov方法和加权最小二乘估计设计了一种自适应控制器 ,在对非线性 (不加增长条件约束 )的情况下 ,得到了闭环系统的全局跟踪性能 . 相似文献
110.
Moving object extraction and classification are important problems in automated video surveillance systems. A background model based on region segmentation is proposed. An adaptive single Gaussian background model is used in the stable region with gradual changes, and a nonparametric model is used in the variable region with jumping changes. A generalized agglomerative scheme is used to merge the pixels in the variable region and fill in the small interspaces. A two-threshold sequential algorithmic scheme is used to group the background samples of the variable region into distinct Gaussian distributions to accelerate the kernel density computation speed of the nonparametric model. In the feature-based object classification phase, the surveillance scene is first partitioned according to the road boundaries of different traffic directions and then re-segmented according to their scene localities. The method improves the discriminability of the features in each partition. AdaBoost method is applied to evaluate the relative importance of the features in each partition respectively and distinguish whether an object is a vehicle, a single human, a human group, or a bike. Experimental results show that the proposed method achieves higher performance in comparison with the existing method. 相似文献