GLOBAL ANALYSIS OF AN EBENMAN＇S MODEL OF POPULATION WITH TWO COMPETING AGE CLASSES

ＧＬＯＢＡＬＡＮＡＬＹＳＩＳＯＦＡＮＥＢＥＮＭＡＮ＇ＳＭＯＤＥＬＯＦＰＯＰＵＬＡＴＩＯＮＷＩＴＨＴＷＯＣＯＭＰＥＴＩＮＧＡＧＥＣＬＡＳＳＥＳＬＩＵＷＥＩＭＩＮ（刘为民）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃａｌＳｃｉｅｎｃｅｓ，Ｉｎｄｉａｎａ...     

高维市场结构与创新

以往的创新研究局限于一维市场结构：所有企业的创新能力都一样，谁也不占有优势。实际上应根据企业不同的创新能力特征，分成若干种类型，形成高维市场结构，在此结构下研究创新竞争。本首先证明在高维市场结构下均衡点唯一；其次指出何种类型企业具有竞争优势，分析企业合资研究对竞争优势的影响；最后讨论竞争企业数量增加时均衡状态的变化，并将市场的结果与社会最优结果作比较。     

企业集团与科研机构的融合机制

随着科技经济一体化的发展，作为其中重要方面的企业集团与科研机构的融合便受到了关注．本文首先论述了双方融合的必要性和必然性，同时对市场经济中出现和未出现的可行性融合模式分类进行了论述．最后，本文从科技经济一体化发展的趋势，得到结论：企业集团与科研机构必将从“融合”为主流走向“结合”为主流．     

银胶体系中吖啶橙、吡啶共吸附竞争的研究

本文利用光学多道分析仪,着重研究了吖啶橙—银胶—吡啶体系;观察了吖啶橙荧光的两次瞬间增强的时间效应荧光谱;分析了吖啶橙与吡啶在银表面上共吸附竞争以及氯化钾在这一竞争中所起的作用。对于表面与分子间相互作用的这一规律作了初步探讨。     

A UNIFIED APPROACH TO MULTISPECIES MODELING

Ordinary differential equation (ODE) population models have been pivotal in the development of ecological theory. Here I propose an ODE formulation that is biologically more consistent than previous formulations and applies equally well to modeling predation, competition, mutualism, and combinations of all three in complex food webs. The formulation is based on two principles: I. The rate at which a population consumes resources is determined by a functional response that includes the effects of both consumer satiation and intraspecific interference competition; II. The intrinsic growth rate of a population, independent of trophic level, is a saturating function of resources consumed and approaches minus infinity as the rate of resources consumption approaches zero. After deriving a general model, I consider specific forms for the consumption and growth functions associated with Principles I and II. I use these functions to derive a generalized logistic growth model, in the process expressing the logistic growth and carrying capacity parameters in terms of the biologically more intuitive consumption and intrinsic growth function parameters. I then go on to consider specific prey-predator, trophic stack, consumer-resource, competition, and mutualism models and, where appropriate, contrast them with models that have been obtained by direct modification of the Lotka-Volterra approach to multispecies analysis.     

1.3μm InGaAsP／InP脊形波导激光器偏振输出的测量

本文对发射波长为１．３μｍ，具有不同脊形波导宽度ＩｎＧａＡｓＰ激光器的ＴＥ，ＴＭ模偏振输出特性进行了测量，实验观察到脊形波导比较窄的器件具有ＴＥ，ＴＭ模竞争现象，而脊形波导比较宽的器件在阈值电流以上，只有ＴＥ模激射，没有模式竞争。利用偏振度概念计算了阈值电流以上和阈值电流以下的偏振度，并对其进行了讨论。本文指出，只要严格选择激光器的参数，并控制环境温度，合理使用器件，就可获得稳定的偏振输出，而不必     

Analysis of a parabolic cross-diffusion population model without self-diffusion

The global existence of non-negative weak solutions to a strongly coupled parabolic system arising in population dynamics is shown. The cross-diffusion terms are allowed to be arbitrarily large, whereas the self-diffusion terms are assumed to disappear. The last assumption complicates the analysis since these terms usually provide H¹ estimates of the solutions. The existence proof is based on a positivity-preserving backward Euler-Galerkin approximation, discrete entropy estimates, and L¹ weak compactness arguments. Furthermore, employing the entropy-entropy production method, we show for special stationary solutions that the transient solution converges exponentially fast to its steady state. As a by-product, we prove that only constant steady states exist if the inter-specific competition parameters disappear no matter how strong the cross-diffusion constants are.     

中介企业的服务定价研究

定价问题是中介企业的核心问题之一。本主要目的是探讨中介企业如何对自己提供的中介服务进行定价。定性研究表明：中介对买卖双方收取的服务费用与以下三个因素有关1．双方在选择中介交易方式下节约的交易成本；2．中介企业自身的成本；3．买卖双方面临的风险成本。并在此基础上，给出了中介企业定价的基本模型。     

Immunization procedures forE. coli proteins

Three immunization procedures were compared for the production of antibodies to the minor components of a complex E. coli protein (ECP) mixture: a conventional protocol and two methods that allow for the selective in vitro (cascade) or in vivo (passive) depletion of highly immunogenic proteins. An indirect ELISA showed that a maximum ELISA antibody titer was obtained with all the procedures 60 d after immunization. Analysis of these antisera by two-dimensional SDS-PAGE immunoblots, however, demonstrated that antibody reactivity to minor components in the mixture was not achieved until 112 d. This analysis also showed that a marked improvement in antibody response to minor components was obtained with the cascade immunization procedure. The mean titer and spectrum of antibody reactivity was similar for each group, and suggested that, although some individual variation was noted, the improvements observed were the result of the protocol used. Thus, for these ECPs, and multiple antigen mixtures in general, the preferred immunization protocol should employ at least three hosts and utilize the cascade immunization of Thalhamer and Freund. Characterization of the resulting antisera is best performed by use of silver stained two-dimensional SDS-PAGE and immunoblotting.     

Extinction in nonautonomous competitive Lotka-Volterra systems

It is well known that for the two species autonomous competitive Lotka-Volterra model with no fixed point in the open positive quadrant, one of the species is driven to extinction, whilst the other population stabilises at its own carrying capacity. In this paper we prove a generalisation of this result to nonautonomous systems of arbitrary finite dimension. That is, for the species nonautonomous competitive Lotka-Volterra model, we exhibit simple algebraic criteria on the parameters which guarantee that all but one of the species is driven to extinction. The restriction of the system to the remaining axis is a nonautonomous logistic equation, which has a unique solution that is strictly positive and bounded for all time; see Coleman (Math. Biosci. 45 (1979), 159-173) and Ahmad (Proc. Amer. Math. Soc. 117 (1993), 199-205). We prove in addition that all solutions of the -dimensional system with strictly positive initial conditions are asymptotic to .