总大肠菌群测定中如何避免出现不定值

现行的环境监测分析方法与有关技术规范中总大肠菌群检数表里所列的几个不定值(“<”或“>”)给区域环境综合分析与评价工作带来一定的困难.为了避免在实测数据中出现不定值,实验分析人员应充分了解待检水样的环境因素以便确定合适的分析方法.对污染较重的水样要适当提高稀释倍数直至出现阴性反应.能否选择出正确的稀释度是实验成败的关键.     

The Effects of Discussion of Familiar or Non-Familiar Information on Opinions of Anthropogenic Climate Change

ABSTRACT

The study found that encountering new information in an online chat rather than information that participants already knew and were familiar with was more likely to reduce support for the view that climate change is due to anthropogenic causes, even though the majority of the presented information supported anthropogenic causes. Participants reported feeling more competent and knowledgeable about the topic and felt less ostracized from others in the chat when participants were already familiar with information others discussed than when information discussed by others in the chat was new information. However, they viewed other chat members as more competent and knowledgeable when those others mentioned new information. Results are discussed within knowledge deficit model of science communication and the bias for common information.     

利益、价值与认知视域下的环境冲突及其伦理调适

从利益、价值与认知三维视域出发,分析了环境冲突的形成原因,考察了环境伦理对环境冲突的调适机理.环境冲突是社会主体利益、价值、认知多元化背景下多种因素综合的结果.从彼此间独断性的对立和冲突转向建设性的生态与互动,是化解环境冲突的根本路径.对此,环境伦理学具有其独特的价值和意义.环境伦理通过对环境价值的辩护,将自然拉进道德关注的视野,塑造和影响人们的利益、价值和认知结构,调适人类社会中工业文明以来不断制度化的生态缺失,从而作为一种积极的要素,推进各主体的利益、价值和认知由对立和冲突走向彼此共存的生态互动.     

基于图像感兴趣区域融合特征的PM2.5浓度预测方法

通过图像预测PM_2.5浓度的准确性,在很大程度上取决于模型所选用的特征参数。为丰富特征参数的表达,设计了一种基于图像传统特征与深度特征充分融合的PM_2.5浓度预测方法。首先,根据不同PM_2.5浓度下的成像差异,选定图像感兴趣区域,解决图像尺寸过大导致的模型运算效率较低问题。然后,针对所选取的局部图像,利用传统图像处理方法手动设计并提取图像浅表视觉特征,同时利用卷积神经网络自动提取图像深层语义特征。最后,将两种特征融合,交由卷积神经网络的全连接层实现对PM_2.5浓度的回归预测。预测误差比对结果显示,相比使用单种特征,使用融合特征能够有效提高模型的预测性能。     

Property rights and grassland degradation: a study of the Xilingol pasture, Inner Mongolia, China

The semi-private property rights arrangement called the Household Production Responsibility System (HPRS) was started in the early 1980s in Xilingol pasture of Inner Mongolia (China), and stimulated the development of stockbreeding. The grassland has been degrading severely with increasing numbers of livestock. Based on a historical review of property rights regimes in Inner Mongolia and empirical surveys in Xilingol pasture during 2001-2003, this paper assesses the implementation of HPRS and its impacts on incomes of households as well as the environmental impact on the grassland. It was found that HPRS does not mitigate the "Tragedy of the Commons", instead it has exacerbated the situation. It was also found that co-management of grassland and livestock among a few households presents a sustainable use of grassland to develop livestock breeding. We conclude with the recommendation that small-scale collective property rights systems should be encouraged in Xilingol pasture of Inner Mongolia.     

Community action for environmental restoration: a case study on collective social capital in India

In southern India, tens of thousands of village-level irrigation systems (‘tanks’ and feeder channels) are in disrepair. This paper analyses the results of a local NGO effort that focused on awareness-raising and advice to bring about self-sustained community action for irrigation system restoration. After designing a model structure that contains both motivational and capacity (social capital) factors, it is found that (pre-existing) collective social capital, as measured through five simple indicators, strongly correlates with success of the NGO strategy. The intensity of the NGO’s effort shows a negative correlation with success, however. The discussion focuses on issues of social capital definition and measurement and the practical implications of the concept for environmental action, especially the difference between using existing social capital for environmental management versus the construction of social capital as a basis for later self-sustained environmental work. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.     

Environmental Constituent Interest, Green Electricity Policies, and Legislative Voting

Research in political economy has traditionally sought to disentangle the effects of legislative ideology and constituent interest in explaining policy decisions. Frequently, proxy variables are used to measure constituent interest. However, these measures do not adequately reflect true constituent interest, which is based upon the costs and benefits of the policies under consideration, incorporating the scope of the policies. Using Haiku, a detailed model of the US electricity sector, and TAF, an integrated assessment model of pollution pathways and valuation, I construct economic measures of constituent interest at the state level as well as for federal policy. I then use these measures to analyze state adoption of more stringent green electricity policies and congressional roll-call voting on federal environmental policy. Previous studies that use proxy measures of constituent interest typically find that the legislator ideology matters more, while my study shows that both ideology and constituent interest are significant factors.     

Should the redstart Phoenicurus phoenicurus accept or reject cuckoo Cuculus canorus eggs?

Hole-nesting habits of redstarts Phoenicurus phoenicurus make laying difficult for parasitic cuckoo Cuculus canorus females and eviction of host eggs difficult for the cuckoo hatchling, causing fitness costs of cuckoo parasitism to be lower than those reported for open nesting hosts. Redstarts have recognition problems when confronted with real cuckoo eggs showing a perfect mimicry with their own eggs since they never eject when parasitized with perfect mimetic cuckoo eggs but instead desert the nest. Here we use a cost-benefit model to assess the effects of parasitism costs and the probability of being parasitized to estimate the reproductive success of redstarts when accepting or rejecting in the presence or absence of parasitism. Baseline data for model calculations come from this and a previous study on a cuckoo parasitized redstart population in Finland. When desertion implies a loss of 50%, we found that below a threshold value of 20% parasitism redstarts should accept cuckoo eggs since the costs of rejection exceed the benefits, whereas above this threshold they should reject. Interestingly, as the cost of desertion increases the threshold value, it should pay the redstart to reject increasingly at an exponential rate. Our field observations on natural parasitism and experiments with artificial cuckoo eggs confirmed the predictions from the model when hatching failures of the cuckoo were taken into account. Therefore, the low cost imposed by cuckoo parasitism in the system, and the presumably high cost of desertion as a response to parasitism favours acceptance over rejection for a wide range of parasitism pressures. This finding could explain the low rejection rate of real cuckoo eggs found in the redstart despite the presumably long history of a coevolutionary relationship with the cuckoo in Finland.     

Potential Effects of Direct Transfer Payments on Farmland Habitat Diversity in a Marginal European Landscape

Farmland habitat diversity in marginal European landscapes changed significantly in the past decades. Further changes toward homogenization are expected, particularly in the course of European agricultural policy. Based on three alternative transfer payment schemes, we modeled spatially explicit potential effects on the farmland habitat diversity in a marginal European landscape. We defined (1) a scenario with direct transfer payments coupled to production, (2) a scenario with direct transfer payments decoupled from production, and (3) a scenario phasing out all direct transfer payments. We characterized habitat diversity with three indices: habitat richness, evenness, and rarity. The habitat pattern in 1995 served as reference for comparison. All scenarios predicted a general trend of homogenization of the farmland habitat pattern, yet to a differing extent. Transfer payments coupled to production (Scenario 1) favored the abandonment of agricultural production, particularly in low-productive areas and arable land use in more productive areas. Habitat richness and habitat evenness had intermediate values in this scenario. Decoupling transfer payments from production (Scenario 2) supported grassland as most profitable farming system. This led to a grassland-dominated landscape with low values of all habitat diversity indices. Phasing out transfer payments (Scenario 3) resulted in complete abandonment or afforestation of agricultural land and extremely low values in all habitat diversity indices. Scenario results indicate that transfer payments may prevent cessation of agricultural production, but may not counteract homogenization in marginal landscapes. Conserving high farmland habitat diversity in such landscapes may require support schemes, e.g., Pillar Two of EU Common Agricultural Policy.     

Is there a common metals demand curve?

Previous studies have identified a single, stable and strong correlation between the price of metals and their consumption, such that low priced metals are always used in large amounts and visa versa. Some have interpreted this as evidence that metals share a common demand curve so that a single price elasticity of demand exists. This paper reviews and tests this hypothesis against a number of other possible explanations, including the idea that the relationship is an empirical curiosity. Modifications to the demand curve were tested by allowing metals to have different intercepts and price elasticities. The results from this analysis suggest that metals do not share a common demand curve and that the correlation identified between the price of metals and their level of consumption is an empirical curiosity. As such, the singular price elasticities published in past papers should not be used for assessing future rates of metals substitution.