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J.W. Aleri B.C. Hine M.F. Pyman P.D. Mansell W.J. Wales B. Mallard M.A. Stevenson A.D. Fisher 《Journal of dairy science》2019,102(4):3282-3294
The objectives of this study were to assess antibody and cellular immune responses in first-lactation dairy heifers reared under a pasture-based production system and to investigate associations between immune competence and stress responsiveness, health, and productivity. A commercial vaccine was used to induce antibody and cellular immune responses and, based on measured responses, animals were classified as above average, average, and below average for each trait independently and in combination (overall immune competence). Overall immune competence phenotypic rankings were generated by combining standardized residual values for antibody and cellular responses measured in individual heifers. Cortisol responses to handling and yarding were used to assess stress responsiveness, worm egg counts were used to assess internal parasite burden, somatic cell counts to assess udder health and estimates of total daily milk volume, and milk fat and milk protein contents to assess productivity. A total of 393 Holstein-Friesian and Holstein-Friesian × Jersey crossbred heifers from 2 herds practicing seasonal calving in a pasture-fed production system were enrolled in the study. The immune competence phenotypes of individual heifers were assessed before their first mating and their subsequent performance during their first lactation was monitored. Animals with below-average antibody and cellular immune competence had higher serum cortisol concentrations compared with their counterparts following handling, suggesting they had a reduced ability to cope with management-induced stress. Furthermore, a significant negative (favorable) correlation was observed between antibody responses and stress responsiveness. Similarly, correlations between antibody responses and internal parasite burden were significant and negative (favorable). No correlations were observed between overall immune competence and milk yield, milk fat, and milk protein content. 相似文献
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为研究蜗杆传动的多目标优化问题,提出一种自适应差分进化的元胞多目标遗传算法。该算法针对元胞遗传算法的特点,对基本的差分进化策略进行改进,得到一种参数自适应控制策略。将该算法与目前性能优异的4种多目标进化算法在三目标的基准测试函数进行对比实验,结果表明所提算法相对于其他算法具有明显的优势,能够在保证良好收敛性的同时,使获得的Pareto前端分布性更加均匀,覆盖范围更广;工程实例求解结果也表明了算法的工程可行性。 相似文献
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This study aims to develop a new type of peristaltic pump that transports high-viscosity and solid–liquid mixture fluids. Pumps capable of transporting such fluids are essential in various situations such as factory transportation, outdoors, and emergencies. These fluids are conventionally transported by positive-displacement and rotodynamic pumps. However, solid–liquid fluids could collide with the impeller of the rotodynamic pump and thereby damage the pump, whereas the positive-displacement pump must be sufficiently large to apply high pressure to the transported fluid. A small pump that can transport these fluids would save factory space and enable outdoor applications such as dredging operations. Thus, we adopted earthworm peristalsis as a model mechanism of fluid transport within a standard plumbing infrastructure. The insertion-type peristaltic pump developed in this study uses an artificial rubber muscle to achieve an earthworm-like mechanism. The capability and energy efficiency of the mechanism is evaluated in water transportation experiments. 相似文献
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针对高校焊接实验室埋弧自动焊机在长期使用后出现的行走小车减速器和导电嘴故障现象,分析小车行走减速器产生故障的原因,排查故障点,详细介绍了故障的维修技巧。针对焊机原有的滚轮式导电嘴磨损严重导致与焊丝接触不良,借鉴二氧化碳导电嘴的特点将其设计改造为满足直径3.0 mm焊丝的导电嘴,确保了焊接电流的稳定,经实践证明改造是成功的,可以满足使用要求。同时,针对埋弧焊机具有下降的外特性,利用埋弧焊机进行焊条电弧焊,并通过实践证明这些方法的可行性和有效性,为埋弧焊机的使用积累了一定的经验。 相似文献
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文章提出了一种基于序列比对的蠕虫特征自动提取模型,该模型针对现有蠕虫特征自动提取系统的可疑蠕虫样本流量单来源和粗预处理等问题,提出了对网络边界可疑流量和蜜罐捕获网络流量统一的聚类预处理,并使用改进的T-Coffee多序列比对算法进行蠕虫特征提取。实验分别对Apache-Knacker和TSIG这两种蠕虫病毒进行特征提取,从实验结果可以看出文章提出的模型产生的特征质量优于比较流行的Polygraph、Hamsa两种技术。 相似文献
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针对现有的网络蠕虫检测系统大多不能有效快速检测慢速蠕虫的问题,本文提出使用本地失败连接分析(LF-CA)算法在蠕虫传播早期高效实时的检测本地局域网内的蠕虫,并在全局上建立可扩展性强非集中式的基于Chord算法的全网协作P2P检测机制,以信息共享的方式对慢速传播蠕虫进行检测。通过实验仿真验证了LFCA算法对本地网络的快速蠕虫有高效的检测效果和较低的误报率,证明了基于P2P技术进行信息共享协同检测比单点检测能更快更有效地检测到慢速蠕虫。 相似文献