正度拟齐次Toeplitz算子的乘积

在Bergman空间上讨论了以拟齐次函数为符号的Toeplitz算子的乘积问题.使用Mellin变换作为工具,得出了当拟齐次函数的度都为正度时两个Toeplitz算子乘积仍是Toeplitz算子的充分必要条件,完善了以往文献中的有关结果.     

Estimation of Agricultural Production Functfons on a World-Wide Basis

Agricultural production is becoming increasingly capital and research intensive. Hayami and Ruttan, along with others, have developed and applied the metaproduction functional approach to the examination of this phenomenon on a worldwide basis. Limitations to the approach derive from a restrictive functional form chosen for estimation, and from a restrictive specification of agricultural capital and land. This study addresses those difficulties by use of the flexible translog functional form for estimation and by specifying an overall agricultural capital index and a land measure incorporating differences in the quality of land (agricultural natural resource) endowments. Estimation results indicate that agricultural comparative advantage in production is likely shifting to developed countries relative to LDC's due to capital constraints in the latter. Also agricultural potential (i.e., land endowments) do not serve to differentiate nations on the basis of agricultural production. Investment in agriculture, including land improvement, is key to the determination of comparative advantage. La production agricole fait appelle de plus en plus a beaucoup de re-cherches et de capitaux. Hayami et Ruttan, avec d'autres, ont developpe et appliqué l'approche fonctionnelle métaproduction pour examiner ce phénomena à l‘échelle du monde. Les limitations de cette approache provienneent de la forme fonctionnelle restrictive choisie pour l'estimation, et de la spécification restrictive de capitaux et terres agricoles. Cette étude traite ces difficultés en utilisant la formule “translog’ fonctionnelle adaptable pour l'estimation et en spécificant un indice du capital agricole global et une mesure de terre qui incorpore les différences du qualité des terres agricoles (ressources agricoles naturelles). Tous les résultats estimatifs indiquent que l'avantage comparatif agricole de production s'incline vers les pays développés parraport aux PMD dû aux constraintes de capitaux dans ces derniers. Aussi la capacité agricole (c'est à dire la richesse des sols) ne sert pas à différencier les nations sur le plan de production agricole. L'investissement dans l'agriculte, notamment l'amélioration de terre, est la cief pour déterminer l'avantage comparatif.     

我国资本市场存在的制度功能缺陷与对策

我国资本市场是在新旧体制转换中建立起来的，先天就存在着制度和市场功能方面的缺陷，亟需要采取有效应对策略以弥补，使我国资本市场的发展走上正常轨道。     

Economic analysis of the impact of adopting herd health control programs on smallholder dairy farms in Central Thailand

The economic impact of adopting herd health programs for mastitis and reproduction by small-scale dairy producers of Central Thailand was assessed using a policy analysis matrix (PAM). Following a reduction in the incidence of bovine disease on adopter farms, an increase in private net profits is observed. More importantly the social costs of supporting dairy farmers is reduced; the PAM effective protection coefficient was reduced by 35% for mastitis program adopters and by 44% for reproductive program adopters, indicating improved social efficiency of dairy policy. Other indicators of efficiency and policy implications are discussed.     

Likelihood-based specification analysis of continuous-time models of the short-term interest rate

An extensive collection of continuous-time models of the short-term interest rate is evaluated over data sets that have appeared previously in the literature. The analysis, which uses the simulated maximum likelihood procedure proposed by Durham and Gallant (2002), provides new insights regarding several previously unresolved questions. For single factor models, I find that the volatility, not the drift, is the critical component in model specification. Allowing for additional flexibility beyond a constant term in the drift provides negligible benefit. While constant drift would appear to imply that the short rate is nonstationary, in fact, stationarity is volatility-induced. The simple constant elasticity of volatility model fits weekly observations of the three-month Treasury bill rate remarkably well but is easily rejected when compared with more flexible volatility specifications over daily data. The methodology of Durham and Gallant can also be used to estimate stochastic volatility models. While adding the latent volatility component provides a large improvement in the likelihood for the physical process, it does little to improve bond-pricing performance.     

现代配送中心经营定位的思考

从分析和研究现代物流配送中心的基本功能出发，提出了不同经济功能下配送中心的不同类型，并在此基础上探讨了不同功能的配送中心在市场竞争中的基本经营定位。     

Simpler Probabilistic Population Forecasts: Making Scenarios Work

The traditional high-low-medium scenario approach to quantifying uncertainty in population forecasts has been criticized as lacking probabilistic meaning and consistency. This paper shows, under certain assumptions, how appropriately calibrated scenarios can be used to approximate the uncertainty intervals on future population size and age structure obtained with fully stochastic forecasts. As many forecasting organizations already produce scenarios and because dealing with them is familiar territory, the methods presented here offer an attractive intermediate position between probabilistically inconsistent scenario analysis and fully stochastic forecasts.     

The risk-return trade-off in human capital investment

In this paper, we analyze investments in human capital in a way which is standard for financial assets, but not (yet) for human capital assets. We study mean-variance plots of human capital assets. We compare the properties of human capital returns using a performance measure and by using tests for mean-variance spanning. Fields differ strongly not only in common rates of return, but also in return per unit of risk. We identify a range of educations that are efficient in terms of investment goods, and a range of educations that may be chosen for consumption purposes.     

建立健全内部审计制度的思考

本文从建立健全企业内部控制制度入手，分析了内控与内审的关系；其次，从分析我国内审现状着手，陈述了内审现状不容乐观；最后，在具体如何强化方面，主要涉及内审的职能转变、结构模式的转变、人员素质的提高及多元化、与外部审计的结合，事后审计向事前事中审计的转变及向行业管理转变建立内审职业规范等措施。     

对我国生态环境保护的初步探讨

中国是世界上最大的发展中国家,由于现代工农业生产而造成了严重的环境污染,尤其是大量使用农用化学品所导致的生态失调与环境破坏,已严重威胁到人类生存环境及生活健康。今后社会发展必须大力提倡与推广无公害、无污染的清洁生产,全面实现生产的"零污染"与废物的"零排放"、保护环境与追求生态和谐的发展目标。