Possibility of metabolic control of membrane excitation

In the guinea pig taenia coli, when glycogen is depleted by repeating Ca-induced contracture in excess K solution containing no glucose, the tension cannot be maintained. The decrease in tension is accompanied by reduction of high energy phosphate compounds and oxygen consumption. When substrate is readmitted to the glycogen-depleted preparation in the presence of 2.4 mM Ca and 20 mM K, the first response is hyperpolarization of the membrane and relaxation, and this is followed by depolarization and development of contracture. The latter response is blocked by verapamil, suggesting that energy supply increases the Ca conductance of the plasma membrane. The early response is considered to be due to activation of electrogenic Ca pump, since this is not affected by ouabain as well as removal of Na and K. ATP produced by substrate readmission is probably preferentially utilized for Ca pump activation to reduce the intracellular Ca. The recovery of tension is likely to be brought about by ATP supply not only to the contractile machinery but also to the plasma membrane to remove inactivation of Ca conductance. It is postulated that as the energy source is depleted, energy consumption is automatically limited by suppressing Ca influx, as a self-defence mechanism. Since beta HB is as effective as glucose in the recovery of these processes, and also in the activation of electrogenic Na pump, the metabolic pathway of oxidative phosphorylation alone can support these functions without a contribution of the glycolytic pathway.     

顺煤层水力割缝抽采煤层瓦斯渗流规律数值模拟

为得到顺煤层水力割缝抽采瓦斯渗流规律以及预测水力割缝后瓦斯气体抽采量,结合渗流力学和弹塑性力学理论,建立了水力割缝抽采煤层瓦斯的固流耦合数学模型,同时给出了相应初始条件及边界条件。利用Madab计算得到顺煤层水力割缝后煤体应力场、瓦斯压力场以及瓦斯抽采量变化规律。数值模拟结果显示：水力割缝后,煤体有效体积应力得到释放;沿割缝方向储层卸压效果明显;煤层内裂隙、裂缝数量增加,长度和张开度增大;煤体渗透性能增强;煤层气抽采量较普通钻孔有较大幅度的提高。模拟结果显示了顺煤层水力割缝抽采煤层气的优势。此模拟方法对煤层气增产工业中确定水力割缝工艺参数以及预测瓦斯产量具有重要的指导意义。     

Modifications de l'excitabilité des centres vasopresseurs hypothalamiques par des injections locales de catécholamines

Summary The blood pressure is not disturbed by a local injection of norepinephrine into the hypothalamus, but the excitability of vasopressor centres is affected. Often, the excitability of these centres is decreased; sometimes, it is increased, and, more rarely, it is first potentiated and then inhibited. Epinephrine has the same action, but dopamine is less potent; isoprenaline produces both facilitation and inhibition of these centres, but the facilitating effect is more frequent than with norepinephrine.     

基于高斯法的自由衰减振动频率和阻尼比校正

提出一种对自由衰减振动信号的频率进行校正的方法。该方法先搜索信号频谱的峰值，利用峰值和其临近的极大的四个点来逼近由这四个点形成的谱线，求出拟合曲线的参教；再对拟合曲线求导，找出具体的峰值，同时利用两次拟合得到的曲线峰值计算阻尼比。仿真分析及工程试验结果都表明，该方法可以有效提高检测精度，而且计算量相对较小。     

露天矿土-岩复合边坡形态优化及失稳机理研究

针对露天矿土-岩复合边坡构成及失稳破坏模式的复杂多样性,以依兰露天矿为研究背景,应用极限平衡分析法和强度折减法分别对采场、排土场及二者构成的土-岩复合边坡稳定性进行了分析,优化边坡最终形态,研究其滑坡模式与机制。结果表明：当采场边坡角41°,与排土场相距80m时,复合边坡达最优形态,边坡破坏模式为在自重力作用下,坡面向外蠕变引发的圆弧滑动;极限平衡法简单、可靠,其与强度折减法相结合可弥补各自的不足,结果可靠,便于复合边坡的优化设计。     

Cell kinetics and radiation pathology

Conclusion Radiation pathology is a general term describing the damage that occurs in tissues after irradiation. After the very low doses, received by the normal working population, no major pathology is seen. There is a hazard of cancer induction if DNA damage that has been inflicted in an individual cell is repaired in such a way that the DNA remains intact but rearranged. This radiation carcinogenesis is however a low risk compared with many chemical carcinogens in the environment and in cancer chemotherapy.The treatment of cancer by radiation is now commonly accepted as one of the most effective forms of treatment. It can kill tumour cells effectively, but the dose that can be given is limited by the normal tissues that are inevitably included in the beam. Cell function is maintained for some time even after very large doses. However normal tissues show a loss of function and structure because the proliferating subcompartment of each tissue is depleted as the radiation injured cells fail to divide and die. The time at which the cell deficit is detected varies from hours in some tissues to months or years in others. It depends upon the normal rate of cell turnover. The apparent sensitivity of each tissue therefore depends upon the time at which the assessment is made. Lung and kidney would appear very resistant at 1–3 months post irradiation, but would seem very radiosensitive at 6–12 months as their latent damage is expressed.The ultimate expression of radiation pathology is the death of the whole animal as the essential organ function fails. The time of this death is only comprehensible if the time sequence and the proliferation kinetics of the target cells are taken into account. It must be recognised that it is initial damage to the clonogenic cells, not to the differentiated cells per se that is important.     

Scepticism,relativism and the argument from the criterion

This article explores the relationship between epistemic relativism and Pyrrhonian scepticism. It is argued that a fundamental argument for contemporary epistemic relativism derives from the Pyrrhonian problem of the criterion. Pyrrhonian scepticism is compared and contrasted with Cartesian scepticism about the external world and Humean scepticism about induction. Epistemic relativism is characterized as relativism due to the variation of epistemic norms, and is contrasted with other forms of cognitive relativism, such as truth relativism, conceptual relativism and ontological relativism. An argument from the Pyrrhonian problem of the criterion to epistemic relativism is presented, and is contrasted with three other arguments for epistemic relativism. It is argued that the argument from the criterion is the most fundamental argument for epistemic relativism. Finally, it is noted how the argument of the present paper fits with the author’s previous suggestion that a particularist response to the Pyrrhonian sceptic may be combined with a naturalistic view of epistemic warrant to meet the challenge of epistemic relativism.     

基于人眼状态识别的驾驶员疲劳检测方法研究

提出一种基于眼睛状态识别的驾驶员疲劳状态检测的方法。首先通过建立肤色模型分割出人脸区域,再利用搜索连通域的方法实现眼睛区域的定位;然后计算出眼睛区域的垂直积分投影曲线,提取并比较曲线的特征参数,从而识别眼睛的状态;最后以眼睛闭合时间比率为测量标准实现对驾驶员疲劳程度的检测。实验表明,该方法简单、有效、实时性较好,疲劳检测的正确率较高。     

Seeking representations of phenomena: Phenomenological models

A distinction is made between theory-driven and phenomenological models. It is argued that phenomenological models are significant means by which theory is applied to phenomena. They act both as sources of knowledge of their target systems and are explanatory of the behaviors of the latter. A version of the shell-model of nuclear structure is analyzed and it is explained why such a model cannot be understood as being subsumed under the theory structure of Quantum Mechanics. Thus its representational capacity does not stem from its close link to theory. It is shown that the shell model yields knowledge about the target and is explanatory of certain behaviors of nuclei. Aspects of the process by which the shell model acquires its representational capacity are analyzed. It is argued that these point to the conclusion that the representational status of the model is a function of its capacity to function as a source of knowledge and its capacity to postulate and explain underlying mechanisms that give rise to the observed behavior of its target.     

The physiology of the smooth muscle: an interdisciplinary review—part II

Summary In the guinea pig taenia coli, when glycogen is depleted by repeating Ca-induced contracture in excess K solution containing no glucose, the tension cannot be maintained. The decrease in tension is accompanied by reduction of high energy phosphate compounds and oxygen consumption. When substrate is readmitted to the glycogendepleted preparation in the presence of 2.4 mM Ca and 20 mM K, the first response is hyperpolarization of the membrane and relaxation, and this is followed by depolarization and development of contracture. The latter response is blocked by verapamil, suggesting that energy supply increases the Ca conductance of the plasma membrane. The early response is considered to be due to activation of electrogenic Ca pump, since this is not affected by ouabain as well as removal of Na and K. ATP produced by substrate readmission is probably preferentially utilized for Ca pump activation to reduce the intracellular. Ca. The recovery of tension is likely to be brought about by ATP supply not only to the contractile machinery but also to the plasma membrane to remove inactivation of Ca conductance. It is postulated that as the energy source is depleted, energy consumption is automatically limited by suppressing Ca influx, as a selfdefence mechanism. Since HB is as effective as glucose in the recovery of these processes, and also in the activation of electrogenic Na pump, the matabolic pathway of oxidative phosphorylation alone can support these functions without a contribution of the glycolytic pathway.     

On the physiology of metazoa

The problem of integration and control of the various processes of the metazoan organism is a major challenge to the physiologist. The traditional research strategy in dealing with the problem is neuron-oriented and its roots extend back into the last century when knowledge of hormones was lacking. In the present article, the traditional strategy is analyzed in the light of available data and its logical basis is questioned. Different levels of communication are supposed to occur in the animal or human body. Circulating hormones are responsible for the highest level of communication that occurs between organs or tissues. The central concept in the article is that regulation of circulating hormones constitutes a higher level of control relative to regulation of intercellular hormones. This is regardless of whether the latter occurs in the nervous system or elsewhere. The approach is utilized in defining the mechanism that integrates and controls the part processes of the body. The mechanism is defined as endothelial; the vascular endothelial system is the controlling part and the nervous system is one of the subordinate parts. Thanks to the new approach, meaningful biological explanations of major psychiatric disorders are now possible.     

基于真实机器的装配公差分析方法

机器上目标要素的位置误差是零件几何误差和装配误差共同作用的结果．为了研究装配基准的几何误差在装配链中的传递和变换,提出基于真实机器模型的装配积累误差建模与分析方法．首先,采用控制点变动模型表示零件几何要素,利用蒙特卡罗模拟方法生成几何要素相对于公称位置的变动实例．然后,根据理论正确尺寸确定几何要素相对于基准参考框架的公称位置．第三,提出基准参考框架建立方法,根据基准要素实例确定目标要素的测量基准参考框架．最后,提出装配接触模型,根据装配顺序和基准要素位置实例确定测量基准参考框架相对于装配基准体系的位置．通过以上4个过程计算装配链中所有关联要素在机器坐标系下的位置,获得装配基准体系的几何误差在装配链中的转递和变换关系．将真实机器装配情况模拟分解为4个模块化过程,可以实现装配误差分析的自动化．以三平面定位的轴孔装配的装配间隙计算为实例,验证了本文提出的方法．     

知识创新的Markov控制模型研究

本文在已有的知识创新的相关理论基础上研究知识创新问题。完善了知识创新的机理模型，并对其进行了理论说明，指出知识创新的原理和作用；在对其机理分析的基础上，用Markov模型描述了企业的知识创新过程，分析了影响知识创新的关键因素——隐性知识；并提出了有关知识创新的相应策略框架。     

体外预应力加固钢筋混凝土梁式空心板桥的有限元分析

以内蒙古通辽市境内的公德屯桥为工程实例,通过静载荷试验说明桥梁需要加固,采用有限元程序ANSYS进行有限元建模研究和施加横向预应力的仿真计算,把均匀设计理论引入加固设计中.研究了各因素对挠度校验系数、应变校验系数的变化规律,综合考虑确定了优化设计方案.通过对加固前、后主梁跨中截面对比分析可知,采用施加横向预应力的方法来对钢筋混凝土空心板桥进行加固,能有效改善荷载横向分布情况,增加空心板结构间的横向联系,避免单板受力现象,且加固效果明显.     

中国农业的未来发展方向

中国农业的发展是世界关注的问题，是我国近代社会发展的研究主题。随着社会和科技的进步，我国农业未来的发展方向：一是从个体农业到集团农业到产业化农业的发展，二是从种粮农业到经济作物农业和特色农业的发展；三是从农业到商业和工业的发展；四是从传统农业到信息农业和科学农业；五是政府和和农业科研院所联合体发展；六是政府 公司 定单 农户的经济一体化发展；七是生态农业和可持续农业发展。     

月球轨道器交会对接同波束VLBI测量差分相时延实时解算

同波束VLBI技术是解决月球轨道交会对接地面高精度引导的重要手段．传统的多频点同波束VLBI实时解算算法成功解算差分相位整周模糊度的概率较低,而事后统计修正求解整周模糊度的算法存在较大的时间滞后,从而直接影响月球轨道交会对接两个航天器地面定轨、定位的精度以及实时性．在此背景下,本文研究了应用于月球交会对接条件下的同波束VLBI差分相时延实时解算算法．首先给出了多频点同波束VLBI解算差分相时延及整周模糊度的原理,根据差分相关相位整周模糊和差分相时延实时及事后解算结果,对整周模糊度产生的原因进行分析通过求解精确差分群时延值、采用匹配搜索算法以及差分相位连接条件对传统实时解算算法进行改进,提出一种新的差分相时延实时解算算法．利用SELENE同波束VLBI观测数据进行实时解算．结果表明该算法成功解算模糊度的准确度达到95．49％,相对于传统解算算法准确度提高了5．45％．     

The accuracy of IMF and OECD forecasts for G7 countries

This paper analyses the size and nature of the errors in GDP forecasts in the G7 countries from 1971 to 1995. These GDP short‐term forecasts are produced by the Organization for Economic Cooperation and Development and by the International Monetary Fund, and published twice a year in the Economic Outlook and in the World Economic Outlook, respectively. The evaluation of the accuracy of the forecasts is based on the properties of the difference between the realization and the forecast. A forecast is considered to be accurate if it is unbiased and efficient. A forecast is unbiased if its average deviation from the outcome is zero, and it is efficient if it reflects all the information that is available at the time the forecast is made. Finally, we also examine tests of directional accuracy and offer a non‐parametric method of assessment. Copyright © 2000 John Wiley & Sons, Ltd.     

悬索桥几何非线性及主缆受力分析

利用离散、节点平衡求解、系统平衡协调迭代的方法求得具有确定长度的缆索在荷载作用下的曲线形式,详细分析了缆索在荷载作用下的挠度及变形。然后将悬索桥分为两大子结构,即主缆柔性结构,及加劲梁、塔柱等劲性结构。在两大子结构间的耦合点建立平衡方程,进行直接迭代求解。文中并对目前较为常用的结构几何非线性求解法进行了深入的探讨。通过算例证明本文方法不仅计算简单,迭代自由度少,而且计算结果完全可以与精确解媲美,完全克服了非线性方程求解中解的飘移现象。     

机器人的鲁棒控制

主要研究了机器人系统的鲁棒控制。介绍了机器人的鲁棒控制模型后,利用最优控制问题求解鲁棒控制,这种方法降低的构造Liapunov函数的难度。只需要求解一个代数的黎卡提方程,便可得到最优控制器,而且证明了这个最优控制器也是鲁棒控制器。但又由于基于这种方法得到的控制器较复杂而难以实现,而且能得到渐近稳定的定性结果,而不能得到其平衡点的衰减速率以及平衡点的吸引域的估计。因此在本文的第三部分中应用了算子非线性测废理论。基于非线性测度方法求解的鲁棒控制器,不仅简单易求,而且克服了压缩映像原理估计压缩常数的困难,在得到系统渐近稳定性的同时得到了系统平衡点的衰减速度和吸引域的估计。最后给出了两关节机器人鲁棒控制的的实例。由于控制器设计与f（X）无关,相关结果会比较保守,可为相关设计研究提供一些参考。