Stability of a Chem ostatModelfor a Single Specieswith Delayed NutrientRecycling——Case ofWeak KernelFunction

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｃｏｍｍｏｎｃｈｅｍｏｓｔａｔｍｏｄｅｌｈａｓｂｅｅｎｃｏｎｓｉｄｅｒｅｄｂｙｍａｎｙｍａｔｈｅｍａｔｉａｎｓ（ｓｅｅ［１］）．Ｃｈｅｍｏｓｔａｔｍｏｄｅｌｓｉｎｃｏｒｐｏｒａｔｉｎｇｄｉｓｃｒｅｔｅｔｉｍｅｄｅｌａｙｈａｖｅｂｅｅｎｉｎｖｅｓｔｉｇａｔｅｄｉｎ［２］ａｎｄ［３］．Ｉｎ［４］ａｎｄ［５］，ｃｈｅｍｏｓｔａｔｍｏｄｅｌｓｗｉｔｈｃｏｎｔｉｎｕｏｕｓｔｉｍｅｄｅｌａｙｉｎｎｕｔｒｉｅｎｔｒｅｃｙｃｌｉｎｇｗｅｒｅｃｏｎｓｉｄ－ｅｒｅｄ．Ｉｎｔｈｉ…     

Generalized Quasi—Variational Inequalities on Paracompact Sets

Ｔｈｉｓｐａｐｅｒｉｓｃｏｎｔｉｎｕａｔｉｏｎｓｏｆ［１］，ｗｅｓｔｉｌｌｔｏｕｓｅｍａｒｋｓａｎｄｔｅｒｍｓｉｎ［１］ａｎｄｔｈｅｏｔｈｅｒｔｅｒｍｓａｇｒｅｅｗｉｔｈ［２］ａｎｄ［３］．ＬｅｔＥａｎｄＦｂｅｔｗｏＨａｕｓｄｏｒｆｆｔｏｐｏｌｏｇｉｃａｌｖｅｃｔｏｒｓｐａｃｅｓ，ＸＥ，ＹＦｂｅｔｗｏｎｏｎｅｍｐｔｙｓｅｔｓ，ＦｂｅｔｈｅｄｕａｌｓｐａｃｅｏｆＦ，Ａ：Ｘ→２ＹａｎｄＢ：Ｙ→２Ｆｂｅｔｗｏｓｅｔ－ｖａｌｕｅｄｍａｐｐｉｎｇ，Ｔ：Ｙ→Ｘｂｅｉｎｖｅｒｔｉｂｌｅ．Ｉｎｔｈｉｓｐ…     

A Duality Theorem Associated with the Smash Product of Graded Ring and G-set

ＬｅｔＲｂｅａＧ－ｇｒａｄｅｄｒｉｎｇｗｉｔｈｉｄｅｎｔｉｔｙ１；ｔｈａｔｉｓＲｇ∈ＧＲｇａｎｄＲｇＲｈＲｇｈｆｏｒａｌｌｇ，ｈ∈Ｇ．ＴｈｅａｓｓｏｃｉａｔｉｖｅｒｉｎｇＲ＃ＧｄｅｎｏｔｅｓｔｈｅｓｍａｓｈｐｒｏｄｕｃｔｆｏｒｔｈｅｇｒｏｕｐＧａｎｄｔｈｅｇｒａｄｅｄｒｉｎｇＲ（ｓｅｅ［３］ｏｒ［４］）．Ｉｎ［１］，ＣｏｈｅｎａｎｄＭｏｎｔｇｏｍｅｒｙｐｒｏｖｅｄｔｈｅｄｕａｌｉｔｙＴｈｅｏｒｅｍｓｆｏｒａｃｔｉｏｎｓａｎｄｃｏａｃｔｉｏｎｓｆｏｒｆｉｎｉｔｅｇｒｏｕｐＧ．Ｉｎ［２］，ａｆ…     

The Degree Theory of a New Operator

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｄｅｇｒｅｅｔｈｅｏｒｙｆｏｒａｋ－ｓｅｔ－ｃｏｎｔｒａｃｔｏｐｅｒａｔｏｒｈａｓｍａｎｙａｐｐｌｉｃａｔｉｏｎｓｏｎｔｈｅｅｘｉｓｔｅｎｃｅｏｆｔｈｅｓｏｌｕｔｉｏｎｓｏｆｓｏｍｅｅｑｕａｔｉｏｎｓ（ｓｅｅ［１］，［２］，［３］）．Ｈｏｗｅｖｅｒ，ｓｏｍｅｏｐｅｒａ－ｔｏｒｓａｒｅｎｏｔｋ－ｓｅｔ－ｃｏｎｔｒａｃｔｏｐｅｒａｔｏｒｓ．Ｉｔｉｓａｎｅｗｐｒｏｂｌｅｍｔｈａｔｗｅｅｓｔａｂｌｉｓｈａｄｅｇｒｅｅｔｈｅｏｒｙｆｏ…     

Quasi—uniformities on Lattice Implication Algebras

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｏｒｄｅｒｔｏｒｅｓｅａｒｃｈｔｈｅｌｏｇｉｃａｌｓｙｓｔｅｍｗｈｏｓｅｐｒｏｐｏｓｉｔｉｏｎａｌｖａｌｕｅｉｓｇｉｖｅｎｉｎａｌａｔｔｉｃｅ，ＸｕＹ．［Ｘｕ２］ｐｒｏｐｏｓｅｄｔｈｅｃｏｎｃｅｐｔｏｆｌａｔｔｉｃｅｉｍｐｌｉｃａｔｉｏｎａｌｇｅｂｒａａｎｄｄｉｓｃｕｓｓｅｄｉｔｓｓｏｍｅｐｒｏｐｅｒ－ｔｉｅｓｉｎ［Ｘｕ１］ａｎｄ［Ｘｕ２］．Ａｌｓｏ，ｉｎ［ＸＱ１］，ＸｕＹ．ｔｏｇｅｔｈｅｒｗｉｔｈＫ．Ｙ．Ｑｉｎｄｉｓｃｕｓｓｅｄｔｈｅｐｒｏｐ－ｅｒｔｉｅｓｏ…     

Variational Inclusions for Fuzzy Mappings

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｄｄｉｑｉａｎｄＡｎｓａｒｉ［４］ｄｅｖｅｌｏｐｅｄｉｔｅｒａｔｉｖｅａｌｇｏｒｉｔｈｍｓｆｏｒｆｉｎｄｉｎｇａｐｐｒｏｘｉｍａｔｅｓｏｌｕｔｉｏｎｔｏｎｅｗｃｌａｓｓｅｓｏｆｑｕａｓｉｖａｒｉａｔｉｏｎａｌｉｎｅｑｕａｌｉｔｉｅｓｉｎＨｉｌｂｅｒｔｓｐａｃｅｓ，ＨａｓｓｏｕｎｉａｎｄＭｏｕｄａｆｉ［１］ｅｘｔｅｎｄｔｈｅｍａｉｎｉｄｅａｓｏｆｐａｐｅｒ［４］ｔｏｍｏｒｅｇｅｎｅｒａｌｃａｓｅｓ，ｗｈｉｃｈｃｏｎｓｉｄｅｒｅｄａｃｌａｓｓｏｆｖａｒｉａｔｉｏｎ…     

D_∞-APPROXIMATION OF QUADRATIC VARIATIONS OF SMOOTH IT PROCESSES

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＩｎ［５］，ＭａｌｉａｖｉｎａｎｄＮｕａｌａｒｔｄｅｆｉｎｅｄｔｈｅｎｏｔｉｏｎｏｆ（ｒｅａｌ）ｓｍｏｏｔｈｍａｒｔｉｎｇａｌｅｓａｎｄｗｅｔｈｅｎｐｒｏｖｅｄｉｎ［６］ｔｈａｔｔｈｅｐｒｏｃｅｓｏｆｑｕａｓｉｓｕｒｅｑ...     

The Qualitative Study of Space Quadratic Systems with a First Integral

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｑｕａｌｉｔａｔｉｖｅｔｈｅｏｒｙｏｆｐｌａｎａｒｓｙｓｔｅｍｓｉｓｒａｔｈｅｒｃｏｍｐｌｅｔｅａｎｄｈａｓｗｉｄｅａｐｐｌｉｃａｔｉｏｎｓ（ｓｅｅ［１］,［２］）．Ｈｏｗｅｖｅｒ,ｔｈｅｔｈｅｏｒｙｏｆｔｈｒｅｅ...     

Minimum Ellipsiod and Optim alDesign

§０．　ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｈｅｐａｐｅｒ［１］，ＫｉｅｆｅｒａｎｄＷｏｌｆｏｗｉｔｚｓｏｌｖｅｄｔｈｅｅｑｕｉｖａｌｅｎｃｅｏｆＧ－ｏｐｔｉｍａｌｄｅｓｉｇｎａｎｄＤ－ｏｐｔｉｍａｌｄｅｓｉｇｎ．Ｉｎｔｈｅｐａｐｅｒ［２］，ＫａｉｌｉｎａｎｄＳｔｕｄｄｅｎｓｔｕｄｉｅｄｔｈｅａｌｇｅｂｒａｉｃｓｔｒｕｃｔｕｏｅｏｆｃｏｎｃｅｓ－ｓｉｏｎａｌｄｅｓｉｇｎ，Ｄ－ｏｐｔｉｍａｌａｎｄＣ－ｏｐｔｉｍａｌｄｅｓｉｇｎ．Ｉｎｔｈｅｐａｐｅｒ［３］，ＳｐｒｕｉｌｌｓｔｕｄｉｅｄｔｈｅＣ－ｏｐｔｉｍ…     

Asymptotic Behavior of Nodal Solutions for Semilinear Elliptic Equationsin R~n

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｃｅｎｔｌｙ，ｔｈｅｓｅｍｉｌｉｎｅａｒｅｌｌｉｐｔｉｃｅｑｕａｔｉｏｎｓ△ｕ＋ｆ（ｕ）＝０（１．１）ｕ（ｘ）→０ａｓ｜ｘ｜→∞（１．２）ｉｎＲｎｗｅｒｅｃｏｎｓｉｄｅｒｅｄｗｉｄｅｌｙ（ｓｅｅ［１］－［７］）．Ｉｎｔｈｅｎｉｃｅｐａｐｅｒｓ［１］ａｎｄ［２］，ｉｔｗａｓｐｒｏｖｅｄｔｈａｔａｎｙｐｏｓｉｔｉｖｅｓｏｌｕｔｉｏｎｏｆ（１．１）ｍｕｓｔｂｅｒａｄｉａｌｉｎｃａｓｅｆ（ｕ）∈Ｃ１＋δ（δ＞０）．Ｔｈｅｒｅｆｏｒｅ，ａｎｙｐｏｓｉｔｉｖｅｓｏｌｕｔｉ…     

USING RESERVES TO PROTECT FISH AND WILDLIFE SIMPLIFIED MODELING APPROACHES

ABSTRACT. This paper investigates theoretically to what extent a nature reserve may protect a uniformly distributed population of fish or wildlife against negative effects of harvesting. Two objectives of this protection are considered: avoidance of population extinction and maintenance of population, at or above a given precautionary population level. The pre‐reserve population is assumed to follow the logistic growth law and two models for post‐reserve population dynamics are formulated and discussed. For Model A by assumption the logistic growth law with a common carrying capacity is valid also for the post‐reserve population growth. In Model B, it is assumed that each sub‐population has its own carrying capacity proportionate to its distribution area. For both models, migration from the high‐density area to the low‐density area is proportional to the density difference. For both models there are two possible outcomes, either a unique globally stable equilibrium, or extinction. The latter may occur when the exploitation effort is above a threshold that is derived explicitly for both models. However, when the migration rate is less than the growth rate both models imply that the reserve can be chosen so that extinction cannot occur. For the opposite case, when migration is large compared to natural growth, a reserve as the only management tool cannot assure survival of the population, but the specific way it increases critical effort is discussed.     

Analysis of the power law logistic population model with slowly varying coefficients

We apply a multiscale method to construct general analytic approximations for the solution of a power law logistic model, where the model parameters vary slowly in time. Such approximations are a useful alternative to numerical solutions and are applicable to a range of parameter values. We consider two situations—positive growth rates, when the population tends to a slowly varying limiting state; and negative growth rates, where the population tends to zero in infinite time. The behavior of the population when a transition between these situations occurs is also considered. These approximations are shown to give excellent agreement with the numerical solutions of test cases. Copyright © 2012 John Wiley & Sons, Ltd.     

An allometric scaling relation based on logistic growth of cities

The relationships between urban area and population size have been empirically demonstrated to follow the scaling law of allometric growth. This allometric scaling is based on exponential growth of city size and can be termed “exponential allometry”, which is associated with the concepts of fractals. However, both city population and urban area comply with the course of logistic growth rather than exponential growth. In this paper, I will present a new allometric scaling based on logistic growth to solve the above mentioned problem. The logistic growth is a process of replacement dynamics. Defining a pair of replacement quotients as new measurements, which are functions of urban area and population, we can derive an allometric scaling relation from the logistic processes of urban growth, which can be termed “logistic allometry”. The exponential allometric relation between urban area and population is the approximate expression of the logistic allometric equation when the city size is not large enough. The proper range of the allometric scaling exponent value is reconsidered through the logistic process. Then, a medium-sized city of Henan Province, China, is employed as an example to validate the new allometric relation. The logistic allometry is helpful for further understanding the fractal property and self-organized process of urban evolution in the right perspective.     

经济增长转型与就业促进

创造就业机会,解决失业问题,已经成为中国政府亟待解决的首要经济发展目标。本文深入分析了改革开放以来经济增长与就业增长之间、资本增长与就业增长之间、工资增长与就业增长之间的关系,并进一步深讨了经济转轨各个阶段就业模式的变化,以及正规就业与非正规就业对就业增长的影响。在此基础上,作者明确指出,经济增长与投资增长对扩大就业的作用正逐渐削弱,宏观经济政策与就业政策的改革也不足以彻底缓解就业压力,解决失业问题的关键在于实现经济增长模式从"经济增长优先"向"就业增长优先"型的转变,正确处理和协调劳动力密集型产业与资本密集型产业之间、劳工利益与资本利益之间、扩大内需与创造就业之间的关系。     

A reaction-diffusion model with nonlinearity driven diffusion

In this paper, we deal with the model with a very general growth law and an M- driven diffusion For the general case of time dependent functions M and #, the existence and uniqueness for positive solution is obtained. If M and # are T0-periodic functions in t, then there is an attractive positive periodic solution. Furthermore, if M and # are time-independent, then the non-constant stationary solution M（x） is globally stable. Thus, we can easily formulate the conditions deriving the above behaviors for specific population models with the logistic growth law, Gilpin-Ayala growth law and Gompertz growth law, respectively. We answer an open problem proposed by L. Korobenko and E. Braverman in [Can. Appl. Math. Quart. 17（2009） 85-104].     

Mathematical models of urban growth

The article models the distribution of cities by population. Two approaches are considered to mathematical modeling of urban growth: a probability model in which the number of cities depends on the population and the rank model of distribution of cities by their population. Five population censuses are analyzed for Russia’s cities. The probability density function n(x, α) for the number of cities as a function of their population x is fitted to all the available censuses with a time-dependent coefficient α . The function α(t ) is approximated and a prediction for the nearest future is computed. In particular, it is shown that in 2010 compared with 2002 the number of large cities should increase, while the number of small town should decrease. A model is also proposed for the interaction of urban areas linked into a single hierarchical system. The model is based on a system of ordinary differential equations describing the change in urban population. Independently of the initial distribution, all the cities and town line up by the rank–size law and deviations from this law, as in real life, are observed only for some large and very small cities. Model parameters are fitted for Russia’s cities.     

Deterministic and stochastic analysis of a delayed allelopathic phytoplankton model within fluctuating environment

In this paper, we consider a two-dimensional model for two competitive phytoplankton species where one species is toxic phytoplankton and other is non-toxic species. The logistic growth of both the species follows the Hutchinson type growth law. First, we briefly discuss basic dynamical properties of non-delayed and delayed model system within deterministic environment. Next we formulate the stochastic delay differential equation model system to study the effect of environmental driving forces on the dynamical behavior. We calculate population fluctuation intensity (variance) for both species by Fourier transform method. Numerical simulations are carried out to substantiate the analytical findings. Significant results of our analytical findings and their interpretations from ecological point of view are provided in concluding section.     

On non-selective harvesting of a multispecies fishery

The present paper deals with the problem of non-selective harvesting of a prey-predator system in which both the prey and the predator species obey the law of logistic growth and each predators functional response to the prey approaches a constant as the prey population increases. Boundedness of the exploited system is examined. The existence of its steady states and their stability are studied using eigenvalue analysis. The existence of bionomic equilibria has been considered. The problem of determining the optimal harvest policy is then solved by using Pontryagin's maximal principle. Finally, some numerical examples are given to illustrate the results.     

The growth of solutions of differential equations with coefficients of small growth in the disc

In this paper, we classify the functions of small growth in the unit disc to different degree, and investigate the growth of solutions for certain linear differential equations with coefficients of small growth in the unit disc.     

Aggregation of economic growth rates and of its sources

In this paper we consider the question of measuring aggregate economic growth and its sources. We derive a theoretically justified solution for aggregating (across firms, industries, countries, etc.) growth rates and their sources within the framework of Solow’s (1957) growth accounting method. The resulting aggregation scheme turns out to be quite intuitive and, in fact, the one that is sometimes used in practice, but with theoretical justification missing and so the main value of our work is that our formal derivations show under what conditions this scheme has economic theory justification. We also provide a small empirical illustration of our method on the real data set and show how different the conclusions can be depending on the aggregation scheme used.