Estimating preferences for outdoor recreation:: a comparison of continuous and count data demand system frameworks

Continuous and count data demand system models have emerged as attractive alternatives to the discrete choice random utility maximization models (RUMs) that currently dominate the seasonal, multi-site recreation demand literature. This paper compares the frameworks conceptually and investigates their empirical performance with a common data set. Although the two modeling approaches employ substantially different behavioral and econometric assumptions, results from a recreation application based on the 1997 Iowa Wetlands Survey suggest that qualitatively similar policy inferences arise from the competing structures.     

帮助小的和不那么小的企业提高他们的三重底线成绩

要维持其市场地位,中小企业就必须提高他们的效率.然而,他们往往因为缺少时间、金钱和信息而难以对他们自己的活动、制定目标以及因此不断提高产品和服务(经济上、社会上和环境上)做出正确估价.现有的复杂的国际环境管理方案,对于中小企业常常不适用.不同级别信息"门童"间的合作,对于提高中小企业的环境与社会健康生产方式意识、教给他们日常业务中一体化关注环境与社会的方法、确立经济地位以及奖励这些努力,都是十分必要的.     

The natural food of the rabbitfish Siganus oramin and S. striolata

Specimens of juvenile and mature rabbitfish, Siganus oramin and S. striolata, were submitted to stomach analyses. Agarophytes of the genera Gracilaria, Hypnea and Laurencia proved to be the most preferred diet. Small invertebrates were ingested accidentally.     

Vertical distribution of euthecosomatous pteropods in the upper 100m of the Hilutangan Channel,Cebu, The Philippines

The vertical distribution of euthecosomatous pteropods in the upper 100 m of the Hilutangan Channel, Cebu, The Philippines was studied, based on 126 samples, comprising 47, 282 individuals. Thirty-min horizontal plankton tows were performed at depths of 1, 20, 50, 70 and 100 m in January and February 1972. Thirteen species —including 3 subspecies — of juvenile and adult euthecosomes were identified. In decreasing order of abundance the species are: Creseis acicula (20.4%), Limacina trochiformis (19.9%), Creseis virgula constricta (14.6%), L. inflata (10.5%), Clio pyramidata (9.9%), Creseis virgula conica (8.9%), L. bulimoides (7.3%), Diacria quadridentata (5.3%), Cavolinia longirostris (1.9%), Creseis virgula virgula (1.0%), Hyalocylix striata (0.1%), Cuvierina columella (0.08%), Cavolinia uncinata (0.002%). In 3 species, a large percentage were juveniles; for 1 species, Clio pyramidata, only juveniles were caught. The Vertical species distribution was similar to the distribution of the respective species in Caribbean and Bermuda waters. Temperature, salinity and dissolved oxygen influence vertical distribution little, if at all.     

Studies on the pathways and effects of cadmium in controlled ecosystem encolosures

Two experiments were performed during 1975 and 1976, in which cadmium was added to seawater and its plankton enclosed in plastic containers moored in Saanich Inlet (Vancouver Island, Canada), as part of the CEPEX project. In both experiments, two enclosures (ca. 68 m³ each) were used; one was spiked with about 1.3 g l^-1 cadmium, while the other served as a control, to assess the fate of the added metal and its effect on marine phytoplankton. In both experiments, the pattern of biological events was found to be very similar for the cadmium-treated bag and for the control. Furthermore, there were no marked differences in the phytoplankton species composition, thus indicating that at this concentration level cadmium did not affect the ecosystem. The rate of removal of cadmium by biological processes was relatively slow. The fraction of metal accumulated (for 2 and 4 weeks, respectively) in the settling material was less than 1% for the cadmium-treated bags. Experiments on the mechanism of cadmium binding indicated that the major part of the particulate metla is loosely bound to the outer cell membranes.