Simple elimination models: Theoretical estimates of the effect of variations in elimination rates

This paper analyses the effect of variations in the elimination rates of four elimination models. Three types of variations are studied: (1) a periodic change between two elimination rates; (2) changes between two elimination rates at random times; and (3), an elimination rate varying smoothly in time, generated by having the elimination rate vary exponentially with temperature and a sinusoidally varying temperature. The elimination process is described by four different models: (1) a single compartment; (2) two compartments in parallel; (3) two compartments in series; and (4) the Goldstein-Elwood model. It is shown that for all 12 cases, the solutions can be given the same form as with constant elimination rates through reinterpretation of the parameters. As a special case, the use of elimination methods to estimate respiration is discussed and a possible source of error is pointed out.     

Population respiration: A theoretical approach

It is shown that the error in an estimate of the population respiration should generally not exceed 10% if the mean body weight is used instead of the full weight distribution. A convenient mathematical formulation of the Krogh-curve is given such that the commonly used exponential temperature dependence (Q₁₀ law) of the respiration rate is only a special case. A formula is derived which expresses the effect of a cyclic temperature relative to a constant temperature on the respiration of an animal, the respiration rate of which follows a Krogh-curve. This formula is shown to provide good estimates of annual population respiration both for cases where the population biomass can be considered as constant over the year and when its variation can be approximated with a sinusfunction. Our methods of estimating population respiration are shown to compare favourably with earlier shortcut methods.     

燃煤重金属污染抑制的研究进展

介绍了煤燃烧产物中重金属的存在情况 ,对重金属治理进行了分类讨论 ,着重评述了国内外在煤燃烧产物中重金属抑制方面取得的进展。     

Options for Emission Allowance Allocation Under the Eu Emissions Trading Directive

The article investigates four alternative allocation schemes for emission allowances. The investigated schemes are emission-based allocation, production-based allocation with actor-specific emission factors, production-based allocation with benchmarking and production-based allocation based on data on best available technology (BAT). All the examined schemes apply free allocation based on historical activities. The allocation schemes are evaluated against the criteria for a National Allocation Plan, listed in the Annex III of the EU ETS Directive, and regarding their conformity with the criteria put forward by the Swedish Parliamentary Delegation on Flexible Mechanisms, The FlexMex 2 Commission. No allocation scheme unambiguously meets all criteria. Each has its advantages and disadvantages. Emission-based allocation schemes are most straightforward, transparent and are the easiest to implement. Production-based allocation schemes meet more of the criteria, but are more costly to implement and require more data. Data on BAT will not be available to the extent necessary in order to base an allocation scheme implemented for the trading starting 2005 on BAT. It is unlikely that any given allocation scheme will be perceived as fair by all concerned parties, no matter how sophisticated it is. The overall characteristics of the studied allocation schemes are summarised in the paper. Due to the lack of abatement cost curves, it is not possible to accurately model capital flows between the trading sectors. Data availability will most probably limit the options available to the authorities designing the allocation schemes. An erratum to this article is available at .     

中国湖泊水资源问题与优化调控战略

湖泊水资源在国民经济和社会可持续发展中占有重要的位置,实施优化调控战略是中国湖泊水资源可持续开发利用的重要途径。文中扼要综述了中国湖泊水资源特点和开发利用中存在水资源短缺、湖泊水资源污染和相关问题,指出湖泊资源优化调控的思路是进行湖泊流域系统的综合调控,目前针对中国湖泊水资源问题的优化战略措施包括:实施湖泊水资源流域管理战略、建立流域节约型国民经济体系、增加科技投入并因地制宜实施环境整治、流域污染的全过程与全方位控制、实施环境教育战略。     

Impacts of land cover change on plant and bird species diversity in Hainan Island,China

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露天煤矿复垦土地的植物群落多样性与稳定性

随着科学技术的不断发展和进步,人类对自然的干扰越来越强,引发了许多环境问题,使生态系统在不断的退化。“生物多样性”已成为近年来生态学中最为集中的研究热点之一。本文以平朔安太堡露天煤矿为例,讨论了露天煤矿复垦区的植物群落多样性与稳定性,旨在对矿区土地复垦与生态重建中的重合生态系统,提供了一定的理论依据。     

Antigenic specificity of the sea urchin sperm surface

The antigenic composition of the sperm surface in Paracentrotus lividus Lam. and Sphaerechinus granularis Lam. was studied using the sperm agglutination test with homologous and heterologous antisera. The results indicated that sperm of both species have at least one antigenic determinant located on their surface and shared by both species. In addition, Paracentrotus sperm bear at least one species specific determinant on their surface. The existence of antigenic determinants common to gametes of both species was demonstrated.     

A new structure-affinity relationship for TCDD receptor binding

We have investigated the capacity of various indoles to inhibit specific binding of [1,6-³H]2,3,7,8-tetrachlorodibenzo- -dioxin ([³H]TCDD) in rat liver cytosol, as analyzed by electrofocusing in polyacrylamide gels. Of these indoles, indolo[3,2- ]carbazole was the most active. The IC₅₀ value for TCDD receptor binding of indolo[3,2- ]carbazole as well as for 2,3,7,8-tetrachlorodibenzofuran was 3.6 nM. We have also studied the influence on binding exerted by introduction of some substituents on indolo[3,2- ]carbazole. Substitution with methyl groups at the 5 and 11 positions resulted in an increased affinity (IC₅₀ 1.2 nM) for the TCDD receptor as compared to the parent compound. Computer-supported molecular structure studies indicated that if the van der Waals radii of atoms are included, a rectangle of 6.8 × 13.7 Å may account for the binding of high-affinity ligands to the TCDD receptor.