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211.
I develop an innovative environmental new growth model driven by researchers striving for monopoly profits. Skilled labour is allocated between production vintages and two forms of research, ordinary and environmentally oriented. The intermediate sector includes fixed costs and decreasing returns, limiting the number of vintages used. I solve for planner's, laissez-faire, and regulator's solutions, and examine welfare implications and the various distortions in the model (monopoly power, knowledge spillovers, business stealing, environmental externalities). A regulator may wish: (i) to encourage environmentally oriented research; (ii) to concentrate production labour on recent (cleaner) vintages; (iii) to switch labour from production to research. An environmental sales tax may under some circumstances achieve all three—such taxes not only give incentives to reduce pollution, but also shift profits from old vintages to new, thus raising incentives to come up with newer (cleaner) vintages. An environmental tax may even lead to an increase in the rate of production growth.  相似文献   
212.
北极苔原带和北方森林(北部地区)因其分布广阔并远离农业土地利用变化及工业发展的影响,而一度被认为是地球上最后的净土.但如今这些地区如同地球上任何别的地区一样,也正经受着环境和社会变化的影响.本文总结了北部地区在全球系统中所起的作用,并提出方案以便对导致该地区对社会和环境变化敏感的那些因子进行评价.  相似文献   
213.
Choices have to be made to manage invasive species because eradication often is not possible. Both ecological and social factors have to be considered to improve the efficiency of management plans. We conducted a social study on Fallopia spp., a major invasive plant taxon in Europe, including (1) a survey on the perception of a landscape containing Fallopia spp. using a photoquestionnaire and (2) an analysis of the social representations of Fallopia spp. of managers and users in one highly invaded area and one less invaded area. The respondents to the photoquestionnaire survey appreciated the esthetics of the landscapes less when tall Fallopia spp. were present. Few people were able to identify and name the plant, and this knowledge negatively affected the appreciation of the photos containing Fallopia spp. The central core of the social representation of Fallopia spp. was composed of the invasive status of the plant, its density, and its ecological impacts. The peripheral elements of the representation depended on the people surveyed. The users highlighted the natural aspect whereas the managers identified the need for control. In the invaded area, the managers qualified the species as “unmanageable,” whereas the species was qualified as “foreign” in the less invaded area. Those results provide insights that have to be included when objectives of management plans of these species are selected.  相似文献   
214.
Human enteric viruses occur in high concentrations in wastewater and can contaminate receiving environmental waters. Due to the lack of data on the prevalence of enteric viruses in New Caledonia, the presence and the concentrations of enteric viruses in wastewater and seawater were determined. Untreated wastewater and seawater samples were collected monthly for 1 year from a wastewater treatment plant (WWTP) and from the WWTP’s outlet, located directly on a popular recreational beach. Samples were tested for norovirus genogroups I and II (NoV GI and GII), astroviruses (AsV), sapoviruses (SaV), enteroviruses (EV), hepatitis A viruses (HAV), rotaviruses (RoV), human adenoviruses (HAdV) and human polyomaviruses (HPyV). To support these data, faecal samples from cases of gastroenteritis were tested for the first time for NoV and detected in the population. NoV GI, NoV GII, EV, SaV, HAdV and HPyV were detected in all wastewaters, RoV in 75 % and AsV in 67 %. HAV were not detected in wastewater. Overall, 92 % of seawater samples were positive for at least one virus. HPyV were detected most frequently in 92 % of samples and at concentrations up to 7.7 × 103 genome copies/L. NoV GI, NoV GII, EV, SaV, RoV and HAdV were found in 33, 66, 41, 33, 16 and 66 % of seawater samples, respectively. AsV were not detected in seawater. This study reports for the first time the presence of NoV and other enteric viruses in New Caledonia and highlights the year-round presence of enteric viruses in the seawater of a popular beach.  相似文献   
215.
The bioconcentration potential of fluoxetine (FLX) and its biological effects were investigated in juvenile Pacific oyster exposed for 28 days to environmentally relevant concentrations of FLX (1 ng L?1, 100 ng L?1 and up to 10 μg L?1). FLX bioaccumulated in oyster flesh resulting in 28-day bioconcentration factors greater than 2,000 and 10,000 by referring to wet and dry weights, respectively. Nevertheless, FLX did not induce oyster mortality, delayed gametogenesis, or lead to adverse histopathological alterations. At the two highest concentrations, despite non-optimal trophic conditions, FLX stimulated shell growth but only in a transient manner, suggesting a role of serotonin in the regulation of feeding and metabolism in bivalves. Those high concentrations seemed to drive bell-shaped responses of catalase and glutathione S-transferase activities throughout the exposure period, which may indicate the activation of antioxidant enzyme synthesis and then an enhanced catabolic rate or direct inhibition of those enzymes. However, no clear oxidative stress was detected because no strong differences in thiobarbituric acid-reactive substance (TBARS) content (i.e. lipid peroxidation) were observed between oyster groups, suggesting that cellular defence mechanisms were effective. These results demonstrate the importance of considering additional biomarkers of oxidative stress to obtain a comprehensive overview of the FLX-induced changes in marine bivalves exposed under realistic conditions. Considering the battery of biomarkers used, FLX appears to induce little or no effects on oyster physiology even at a concentration of 10 μg L?1. These results do not confirm the lowest observed effect concentration (LOEC) values reported by some authors in other mollusc species.  相似文献   
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217.
Trisomy of the short arm of chromosome 4 is a well-known syndrome, and several observations have been made in the last 30 years. Herein, we report a new observation of trisomy 4p in a fetus with a semi-lobar holoprosencephaly (HPE), dysmorphic features and multiple malformations. The diagnosis of HPE was made, at 33 weeks' gestation, on the fetus of a healthy G1P0 woman. Amniocentesis was performed for chromosome analysis and additional material was found on a chromosome 22. The couple elected to terminate the pregnancy and fetal examination was realized. Conventional and molecular cytogenetic studies were performed on the fetus and the parents, which showed that the additional material found on one chromosome 22 corresponded to the short arm of chromosome 4 and therefore led us to establish a diagnosis of trisomy 4p inherited from the malsegregation of a paternal translocation t(4;22)(q12;q11.1). The etiology of HPE is very heterogeneous; it includes non-genetic factors such as maternal diabetes and genetic causes. HPE cases have been described in association with many chromosomal anomalies, trisomy 13 being the most frequent. However, to our knowledge, HPE has never been previously reported in association with a trisomy involving solely the short arm of chromosome 4. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
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Call rate can be a salient feature in animal communication. Depending on the species, different psychological variables appear to influence call rates but the exact nature of these relationships remains poorly explored. Here, we demonstrate for free-ranging Campbell’s monkeys that the call rates of four different alarm series (termed H, K, K+, and B series) vary systematically as a function of context, associated behaviour, and identity of the caller. K+ series were given more rapidly to predation than non-predation events, K+ and K series more rapidly to visual than auditory predator detection, and H series more rapidly while counterattacking an eagle than staying put. Finally, there were individual differences in B series, suggesting that call rate potentially provides listeners with cues about the caller’s anti-predator behaviour, event type experienced, and his identity.  相似文献   
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