Time preference,the environment and the interests of future generations

The behavior of individuals currently living will generally have long-term consequences that affect the well-being of those who will come to live in the future. Intergenerational interdependencies of this nature raise difficult moral issues because only the current generation is in a position to decide on actions that will determine the nature of the world in which future generations will live. Although most are willing to attach some weight to the interests of future generations, many would argue that it is not necessary to treat these interests as equivalent to those of the current generation. A common approach in this context is to use a system of discounting to evaluate future benefits and harms. This paper assesses the logic of discounting drawing on the writings of economists and philosophers. Much of the economic literature concerns the choice of an appropriate social discount rate. The social discount rate can be taken to reflect beliefs about the rights of future generations, a subject that has been extensively debated in the phioosophic literature. The writings of both economists and philosophers concerned with the weight to attach to the interests of future generations are reviewed and evaluated in this paper and the implications for environmental policy are discussed.     

Applying knowledge-based methods to design and implement an air quality workshop

In response to protection needs in class I wilderness areas, forest land managers of the USDA Forest Service must provide input to regulatory agencies regarding air pollutant impacts on air quality-related values. Regional workshops have been convened for land managers and scientists to discuss the aspects and extent of wilderness protection needs. Previous experience with a national workshop indicated that a document summarizing workshop discussions will have little operational utility. An alternative is to create a knowledge-based analytical system, in addition to the document, to aid land managers in assessing effects of air pollutants on wilderness. Knowledge-based methods were used to design and conduct regional workshops in the western United States. Extracting knowledge from a large number of workshop participants required careful planning of workshop discussions. Knowledge elicitation methods helped with this task. This knowledge-based approach appears to be effective for focusing group discussions and collecting knowledge from large groups of specialists.     

Cross-shelf variation in calanoid copepod production during summer 1996 off the Oregon coast, USA

The fecundity of nine species of adult female calanoid copepods, and molting rates for copepodite stages of Calanus marshallae were measured in 24 h shipboard incubations from samples taken during the upwelling season off the Oregon coast. Hydrographic and chlorophyll measurements were made at approximately 300 stations, and living zooplankton were collected at 36 stations on the continental shelf (<150 m depth) and 37 stations offshore of the shelf (>150 m depth) for experimental work. In our experiments, maximum egg production rates (EPR) were observed only for Calanus pacificus and Pseudocalanus mimus, 65.7 and 3.9 eggs fem^-1 day^-1 respectively, about 95% of the maximum rates known from published laboratory observations. EPR of all other copepod species (e.g., C. marshallae, Acartia longiremis and Eucalanus californicus) ranged from 3% to 65% of maximum published rates. Fecundity was not significantly related to body weight or temperature, but was significantly correlated with chlorophyll a concentration for all species except Paracalanus parvus and A. longiremis. Copepod biomass and production in on-shelf waters was dominated by female P. mimus and C. marshallae, accounting for 93% of the adult biomass (3.1 mg C m^-3) and 81% of the adult production (0.19 mg C m^-3 day^-1). Biomass in the off-shelf environment was dominated by female E. californicus, P. mimus, and C. pacificus, accounting for 95% of the adult biomass (2.2 mg C m^-3) and 95% of the adult production (0.08 mg C m^-3 day^-1). Copepodite (C1-C5) production was estimated to be 2.1 mg C m^-3 day^-1 (on-shelf waters) and 1.2 mg C m^-3 day^-1 (off-shelf water). Total adult + juvenile production averaged 2.3 mg C m^-3 day^-1 (on-shelf waters) and 1.3 mg C m^-3 day^-1 (off-shelf waters). We compared our measured female weight-specific growth rates to those predicted from the empirical models of copepod growth rates of Huntley and Lopez [Am Nat (1992) 140:201-242] and Hirst and Lampitt [Mar Biol (1998) 132:247-257]. Most of our measured values were lower than those predicted from the equation of Huntley and Lopez. We found good agreement with Hirst and Lampitt for growth rates <0.10 day^-1 but found that their empirical equations underestimated growth at rates >0.10 day^-1. The mismatch with Hirst and Lampitt resulted because some of our species were growing at maximum rates whereas their composite empirical equations predict "global" averages that do not represent maximum growth rates.     

When r-selection may not predict introduced-species proliferation: predation of a nonnative oyster.

Predicting outcomes of species introductions may be enhanced by integrating life-history theory with results of contained experiments that compare ecological responses of exotic and analogue native species to dominant features of the recipient environment. An Asian oyster under consideration for introduction to the Chesapeake Bay, USA, the rapidly growing Suminoe oyster (Crassostrea ariakensis), may not be as successful an invader as its r-selected life history suggests if the trade-off for rapid growth and maturation is lower investment in defenses against blue crab (Callinectes sapidus) predation than the native Eastern oyster (Crassostrea virginica). In laboratory trials, blue crabs simultaneously offered equal numbers of Suminoe and Eastern oysters consumed more nonnatives, irrespective of whether the crabs had previous experience with Suminoe oysters as prey. Satiated blue crabs consumed nearly three times as many Suminoe oysters as Eastern oysters of 25-mm shell height, and eight times as many of 35-mm shell height. Despite blue crabs consuming small (30 mm) Suminoe oysters at twice the rate of large (40 mm) Suminoe oysters, when 40-mm Suminoe were paired with 30-mm Eastern oysters, seven times as many of the larger (Suminoe) oysters were consumed. The greater susceptibility of C. ariakensis than C. virginica to blue crab predation appears to be based upon the biomechanics of shell strength rather than active selection of a more attractive food. Much less force was required to crush shells of Suminoe than Eastern oysters of similar shell height. Tissue transplant experiments demonstrated greater predation on oyster tissues in weaker C. ariakensis shells independent of tissue identity, and duration of handling time before rejection of C. virginica exceeded the time to crush C. ariakensis. These results, coupled with the present importance of blue crab predation in limiting recovery of native Eastern oysters, imply a role for blue crabs in inhibiting Suminoe oysters, if introduced, from attaining high adult densities required to restore a fishery, provide appreciable reef habitat, and reduce turbidity through filtration. Thus, in high-predation environments, allocation of resources to rapid growth and development rather than to predation defenses reflects a life-history trade-off that may promote early stages of invasion, yet prevent attainment of dense adult populations.     

青岛理工大学安全工程专业课程体系设置模式

介绍了我国安全工程专业发展概况、存在的问题及青岛理工大学安全工程专业现状.重点介绍了青岛理工大学安全工程专业课程体系设置情况,提出了2006年安全工程专业课程体系设置调整的构想.     

Developing inventory and monitoring programs based on multiple objectives

Resource inventory and monitoring (I&M) programs in national parks combine multiple objectives in order to create a plan of action over a finite time horizon. Because all program activities are constrained by time and money, it is critical to plan I&M activities that make the best use of available agency resources. However, multiple objectives complicate a relatively straightforward allocation process. The analytic hierarchy process (AHP) offers a structure for multiobjective decision making so that decision-makers’ preferences can be formally incorporated in seeking potential solutions. Within the AHP, inventory and monitoring program objectives and decision criteria are organized into a hierarchy. Pairwise comparisons among decision elements at any level of the hierarchy provide a ratio scale ranking of those elements. The resulting priority values for all projects are used as each project’s contribution to the value of an overall I&M program. These priorities, along with budget and personnel constraints, are formulated as a zero/one integer programming problem that can be solved to select those projects that produce the best program. An extensive example illustrates how this approach is being applied to I&M projects in national parks in the Pacific Northwest region of the United States. The proposed planning process provides an analytical framework for multicriteria decisionmaking that is rational, consistent, explicit, and defensible.     

Demographic shifts around drinking water supply reservoirs in North Carolina,USA

Infrastructure intended to serve the public good frequently has implications for environmental justice and social sustainability. Drinking water supplies for sub/urban areas in North Carolina, USA, have regularly been secured by constructing dams to impound reservoirs. We used high-resolution, publicly available US Census data to explore whether 66 such reservoirs in North Carolina have induced demographic shifts in the communities that find themselves adjacent to the newly created lakeshores. Our principal findings include: (1) The ratio of white people to non-white people was significantly higher in communities within 0.5 miles of reservoir shorelines than in more distant communities; (2) even as North Carolina overall became less white from 1990 to 2010, the ratio of white people to non-white people within the 0.5 miles of the shoreline increased relative to the overall ratio in the State; and (3) similar, but less distinct, shifts in per capita income occurred during the period. Our results are consistent with the proposition that reservoirs have induced demographic shifts in communities adjacent to newly created lakeshores similar to the shifts associated with environmental gentrification and amenity migration, and may now be associated with perpetuating those shifts. These findings raise concerns about environmental justice and social sustainability that should be considered when planning and building infrastructure that creates environmental amenities. Where reservoirs are being planned, social costs, including the costs of demographic shifts associated with environmental gentrification or amenity migration, and disproportionate regulatory burdens, should be mitigated through innovative policy if possible.     

利用彗星实验检测丙烯酰胺对小鼠两种细胞的DNA损伤和修复

为了研究丙烯酰胺致小鼠睾丸细胞和外周血淋巴细胞DNA的损伤及修复情况,同时比较这两种细胞对丙烯酰胺的敏感性,将雄性昆明种小鼠一次性腹腔注射丙烯酰胺(50mg·kg-1(bw)),在暴露后第1、2、4、6、8、10、12d,分别对其睾丸组织细胞和外周血淋巴细胞DNA损伤进行彗星实验分析.结果表明,暴露结束后每个时间点小鼠睾丸组织细胞、外周血淋巴细胞DNA的迁移率均显著高于阴性对照组,随时间推移两种细胞DNA迁移距离逐渐降低,同一时间点睾丸组织细胞DNA损伤较外周血淋巴细胞DNA损伤更为严重,两者差异显著(p<0.05).以上结果表明,睾丸组织和外周血淋巴细胞可能是丙烯酰胺的作用位点;机体对丙烯酰胺造成的遗传损伤有一定的修复能力;与淋巴细胞相比,睾丸细胞对丙烯酰胺导致的遗传损伤更为敏感.