Overcompensation and population cycles in an ungulate.

Although theoretical studies show that overcompensatory density-dependent mechanisms can potentially generate regular or chaotic fluctuations in animal numbers, the majority of realistic single-species models of invertebrate populations are not overcompensatory enough to cause sustained population cycles. The possibility that overcompensation may generate cycles or chaos in vertebrate populations has seldom been considered. Here we show that highly overcompensatng density-dependent mortality can generate recurrent population crashes consistent with those observed in a naturally limited population of Soay sheep. The observed interval of three or more years between crashes points to sharp 'focusing' of mortality over a narrow range of population density.     

Are you growing systems thinking managers? Use a systems model to teach and practice organizational analysis and planning,management policy,and organizational development

This paper discusses the use of the Kast and Rosenzweig systems and contingency model for teaching and practice in organizational analysis and planning, management policy, and organizational development. The need for an organizational model for graduate students and field-based managers and executives is identified. The model is presented beginning with the Kast and Rosenzweig work, with integration of research by Daft, Schein, Trist, Deal and Kennedy, Ackoff, Delbecq, and Mintzberg. The teaching and practice uses of the model in four areas are presented, including organizational analysis and planning, management policy making, and organizational development. In each area case examples of the use of the model in teaching and practice are presented. Needs for future research and implications for the use of the model are discussed.     

Tensile strength and chemical composition of the middle lamella of the flax fibre

Zusammenfassung Es wurde die Zugkraft nasser Flachsfasern nach Behandlung mit verschiedenen Chemikalien geprüft. Es wurde gefunden, daß die Mittellamelle der Flachsfaser verschiedene miteinander verbundene Systeme enthält, nämlich Pektin, Lignin und eine im Oxalat unlös iche alkaliempfindliche Komponente.     

生物序列分析

这次演讲将回顾近 1 0多年来应用某些随机模型于生物序列分析的研究工作 .这些模型本身有很长的历史 ,可追溯到 3 0多年以前 ,尽管从那时起 ,这些模型已经产生了很多新的变种 .在生物序列分析中模型的作用是归总那些涉及到在生物信息学中已知的模体 (motif)或域 (domain)的信息 ,并且提供一种工具在另一序列片段中寻找模体或域的实例 (instance) .我们将逐步介绍模体模型 ,从非常简单的 ,非随机情况开始 ,进而是更复杂的情况 ,直至近来的关于模体的剖面隐马氏模型 .第二个例子是来自利用一个或两个物种的序列数据进行基因发现 ,其中广义隐马氏模型或广义成对 (pair)隐马氏模型已被证实非常有效     

Indoxyl derivatives of drug metabolites

Summary Indoxyl derivatives were detected as minor products among the urinary metabolites of two trial drugs, a benzodiazepine (GP 55 129) and a benzophenone (CGP 11 952). Their structures were elucidated by NMR and mass spectroscopy. Presumably, metabolites containing potential aldehyde functions react spontaneously with endogenous indoxyl. Such derivatives have not hitherto been encountered in drug metabolism.     

地下感应式通信理论的研究

本文研究了地下矿井内,电波沿巷道内线缆传播的可行性及单线波模的传播与衰减规律,研究巷道内电小天线与线缆之间的耦合情况,从而为实际工作提供理论依据。     

Catecholamine metabolism in the vas deferens and the adrenal gland with special reference to the central catecholamine-depleted state

Experiments were carried out to elucidate the role of central catecholamines in regulating catecholamine metabolism in the vas deferens and adrenal gland of the rat. Rats were injected intracerebroventricularly (i.c.v.) with either vehicle or 6-hydroxydopamine (6-OHDA). Groups of animals pretreated with vehicle or 6-OHDA (i.c.v.) were injected intraperitoneally (i.p.) with alpha-methyl-para-tyrosine (AMT), a tyrosine hydroxylase inhibitor. Catecholamine turnover rates were estimated by determining norepinephrine or epinephrine content after administrating AMT.Central norepinephrine and dopamine contents decreased significantly (p<0.05) after treatment with 6-OHDA and AMT. The norepinephrine content of the vas deferens of rats pretreated with 6-OHDA was markedly reduced (p<0.001) after administration of AMT, whereas that of the vehicle-treated rats remained unchanged. Administration of 6-OHDA had no effect on the norepinephrine or epinephrine content of the adrenal gland.The present results indicate that central monoaminergic neurons have an inhibitory effect on the adrenergic neurons of the vas deferens. In contrast, this inhibitory regulation does not appear to be exerted on the adrenal glands.     

氧化物半导瓷中晶界势垒的起源

提出了一个关于氧化物半导瓷晶界势垒起源的新观点，认为晶界势垒起源于烧结过程中外界氧在晶界中的扩散，与材料的结构、化学缺陷、掺杂、外界气氛、烧结工艺、组成状态等有密切关系，并用此理论解释了许多实验现象。     

交织扩展Golay码编译码器实现方案的研究

论述了交织编码的工作原理，给出了一种交织扩展Ｇｏｌａｙ码的改进型软件设计方案，用ＴＭＳ３２０Ｃ２５实现了其编译码器并给出了模拟实验结果。实验结果表明，它能准确地纠正不大于７２比特位的差错；处理１２８×１２８×８比特位的一幅图像数据的运行时间为０．４１２ｓ．