Further studies on bovine muscle composition

The average occurrences of fibre types, I,IIA and IIB in the longissimus dorsi (LD) of female cattle were 18%, 59% and 23%, respectively. The IIB occurrence lay between that for bulls and steers, reported in Young & Bass (1984). Since IIB fibres were absent from the splenius (Sp) of females, its composition was more akin to that of bulls than steers. However, the relative area of I and IIA fibres in female Sp was more like that of steers than bulls since IIA fibres were not disproportionately large in females. Evidence suggests that the occurrence of type I (or II) fibres in the LD is rather static and that changes in the occurrence of IIA fibres, reciprocal to IIB, are more common, irrespective of sexual status-bull, steer or female. The route by which IIA and IIB fibres interconvert is discussed. In animals where both the LD and Sp were sampled, the fibre composition of one muscle was a poor predictor of the other's composition. The correlation between the occurrence of I fibres in Sp and succinate dehydrogenese activity in whole muscle was poor, and reasons are advanced to explain this unexpected result. When dark-cutting muscles were excluded from analysis, the average ultimate pH of LD muscles was lower than that of Sp. This result was consistent with the higher type II fibre content of the LD. Ultimate pH of Sp muscles was correlated with occurrence of I fibres, but in the LD a similar relationship could not be established. A link between occurrence of IIB fibres and proneness to the dark-cutting condition is suggested.     

Dufour Gland Contents of Ants of the Cataglyphis bicolor Group

The species of desert-dwelling ants of the Cataglyphis bicolor (Hymenoptera: Formicidae) group are difficult to distinguish by morphological features. Analysis of the secretion from the Dufour glands of workers of a number of colonies was undertaken to see if it provided a clear test of species. Linked 6c-ms showed in all samples straight and branched-chain alkanes, linear alkenes, ketones, aldehydes, acetates, and a group of C₂₂ to C₂₈ esters not previously identified in this genus. Contents of the Dufour glands of C. savignyi from Tunisia and Egypt were similar, and comprised straight and branched-chain alkanes, alkenes and small amounts of esters. C. bicolor from Tunisia contained compounds similar to C. savignyi but was distinguished from the latter by larger amounts of the esters. The major compound in the glands of C. viaticus was tridecane, in contrast to the pentadecane of other species. It also contained a branched alkane, 3-methyltridecane as a major component. Branched-chain esters and a wide variety of acetates were also found in this species. C. diehlii had a limited range of compounds, with branched alkanes almost completely absent and high proportions of pentadecene and dodecyl acetate. C. bombycinus, a sympatric species, but recognized as not belonging to the bicolor group by its different mandibular gland substances, was notable in having butanoate esters in its Dufour glands. Despite these differences among species, both the great variability of individuals from a single colony and the among between conspecific colonies make species diagnosis from a few individuals difficult, in contrast with postpharyngeal glands, which, as recently reported, give a clearer indication of species.     

Power spectrum and Allan variance methods for calibrating single-molecule video-tracking instruments

Single-molecule manipulation instruments, such as optical traps and magnetic tweezers, frequently use video tracking to measure the position of a force-generating probe. The instruments are calibrated by comparing the measured probe motion to a model of Brownian motion in a harmonic potential well; the results of calibration are estimates of the probe drag, α, and spring constant, κ. Here, we present both time- and frequency-domain methods to accurately and precisely extract α and κ from the probe trajectory. In the frequency domain, we discuss methods to estimate the power spectral density (PSD) from data (including windowing and blocking), and we derive an analytical formula for the PSD which accounts both for aliasing and the filtering intrinsic to video tracking. In the time domain, we focus on the Allan variance (AV): we present a theoretical equation for the AV relevant to typical single-molecule setups and discuss the optimal manner for computing the AV from experimental data using octave-sampled overlapping bins. We show that, when using maximum-likelihood methods to fit to the data, both the PSD and AV approaches can extract α and κ in an unbiased and low-error manner, though the AV approach is simpler and more robust.     

电脑鼠走迷宫算法仿真设计

主要研究电脑鼠走迷宫的算法,主要包括迷宫生成算法、原始全迷宫搜索算法和修正后的泛洪算法.改进后的算法可以搜索到从起点到终点的所有可行路径中的一条最佳路径,以实现快速、高效求解迷宫的目的.     

浅谈汽车涂装同步工程涂胶密封分析

介绍了新车型产品设计阶段,涂装的涂胶密封工艺同步工程分析内容.结合典型实例,对影响涂胶密封效果、涂胶施工等问题的产品结构提出合理的优化建议,以有效提升车身密封结构的工艺合理性和施工性,也为后续汽车涂装的涂胶密封同步工程分析工作提供借鉴.     

《石油钻机液压盘式刹车》标准技术分析

液压盘式刹车作为石油钻机的关键装置,其质量的好坏直接关系到钻井作业能否安全实施。因此,急需制定一个高水平的石油钻机液压盘式刹车标准。阐述了将制动力矩确定为液压盘式刹车型号主参数的根据和技术内涵,确定了石油钻机液压盘式刹车型号的表示方法。介绍了液压盘式刹车的制动方式、制动力矩的确定方法及制动力矩公式中载荷的取值方法,得到了SY/T6727—2008《石油钻机液压盘式刹车》标准的基本参数。     

一种粒子群优化原型模式修正力度的协同分类方法

协同模式识别是一种有着抗噪声、抗缺损、强鲁棒性等诸多优良特性的模式识别方法,其中原型模式的选取模式识别结果有着决定性的作用,其选取直接决定着模式识别的结果和效果,各种方法中信息反馈修正的方法能获得较的效果,但易出现信息饱和的问题;提出了一种粒子群优化修正力度的处理机制,能有效改善此问题,获得最优原型;改进的算法应用于纹理和鼻咽癌细胞图像识别,结果表明,该方法能有效地提高协同神经网络的识别率和可靠性,且识速度也有提高.     

湾坝河水电站软基加固中的振冲施工技术

湾坝河水电站闸基坐落在第四纪砂砾石覆盖层上，属于软基上建闸。为了确保闸坝基础能满足坝基稳定、承载、变形的要求，设计上采用了振冲法对覆盖层进行加固处理。该工程振冲加固技术的施工方法、技术措施、质量控制措施可供类似工程参考。     

白禅寺电站7号闸底板混凝土补强灌浆施工技术

白禅寺电航工程7号闸底板混凝土是在流动水下浇筑的，混凝土浇筑完毕后，水下部分混凝土相当于第四系覆盖层，混凝土与基岩接触面有淤沙，为使7号闸底板混凝土达到常态下浇筑混凝土的性态而进行了补强灌浆处理，介绍了混凝土补强灌浆的施工方法，施工措施，检查手段并对其质量进行了评价。     

一种前向型神经网络基准地价预测模型的研究

土地是国家重要资产,对地价的全面监测、分析和预测,有助于城市基准地价的快速更新和政府对土地资源的宏观控制。现阶段基准地价水平调整的预测模型有明显的不足。应用一种非线性预测方法:多层前向神经网络建立基准地价预测模型,采用时间预测序列。在介绍误差反向修正算法的基础上,通过预测实例计算,表明预测结果与实际情况吻合较好