Geologic vs. geographic constraints on cement resources

This study evaluates the importance of geologic and geographic factors in constraining the location of limestone mining operations for the production of cement in the Great Lakes region of the United States. Cities and their infrastructure require abundant cement, which is manufactured from limestone and other quarry products, but expansion of cities limits the locations of these operations. Possible locations of limestone and cement operations are controlled by geologic factors including distribution and mineralogy of geologic formations as well as depth of overburden, and geographic factors including location of wetlands, cities, and other surface features that preclude development of quarries and manufacturing operations. Overlay analysis was used to evaluate the importance of these factors. Results show that, although limestone underlies about a third of the region, almost 50 percent of this limestone is unavailable for quarrying due to coverage by the built environment, protected natural areas, or excessive overburden thickness. When characteristics such as limestone quality are also accounted for, accessible resources shrink to as little as 2 percent of the total land area. Although the remaining 2 percent of land area may supply local needs for some years, geologic factors clearly must be included in long-term regional land use planning.     

青蒿试管苗开花及用花器官为外植体诱导丛生芽生产青蒿素

将培养于MS培养基上5wk的青蒿试管苗置于光周期13,光强6000lx,温度为26℃（昼）和22℃（夜）的条件下,成功地诱导其开花,利用不同发育阶段的花蕾和花器官为外植体诱导丛生芽,发现不同浓度（ρ）的6－BA对丛生芽的诱导率和青蒿素的生物合成有重要影响。结果表明：以花蕾为外植体诱导丛生芽的最佳培养基是：MS附加4.0mg L^-1的6－BA和0.05mg L^-1的NAA;但当ρ（6－BA）在0－0.5mg L^-1之间时,有利于青蒿素的合成ρ（6－BA）=0.5-4mg L^-1时抑制青蒿素的生命合成,丛生芽中促进青蒿素合成的最佳ρ（6－BA）为0.5mg L^-1,用HPLC法测定发现用此法得到的丛生芽青蒿素的含量比直接利用叶片诱导的丛生芽青蒿素含量高1倍。     

乙草胺对小麦生理机能的影响与生物标记物识别

对乙草胺胁迫下小麦幼苗叶片的超氧化物歧化酶（SOD）、过氧化物酶（POD）活性、可溶性蛋白含量、丙二醛（MDA）以及叶片中叶绿素含量的变化进行了研究.结果表明,乙草胺处理小麦幼苗1 d后,叶片MDA含量显著增加,说明了乙草胺处理诱导有毒活性氧（AOS）生成,但随着处理时间的延长,不同浓度处理与对照的差异逐渐减小.对小麦叶片中POD活性变化的研究表明,在乙草胺胁迫的开始阶段,植物有能力抵抗低浓度乙草胺污染所产生的氧化胁迫,但是,随着暴露时间的延长和污染物浓度的增加,这种抵抗能力将会消失.对小麦SOD活性的研究表明,小麦叶片中POD酶活的上升可能与其它途径而不是SOD诱导产生的H₂O₂有关.小麦叶片中MDA含量和POD活性不能作为土壤乙草胺污染的生物标记物.小麦叶片中SOD酶活性有着作为乙草胺污染土壤生物标记物的潜力,但还需要进一步研究.小麦叶片叶绿素含量和可溶性蛋白含量可以作为乙草胺污染胁迫的生物标记物,并且小麦幼苗叶片可溶性蛋白含量与土壤乙草胺浓度之间具有较好的剂量-效应关系.     

On technical change in the elasticities of resource inputs

This article analyses growth of an economy where the substitutability between non-renewable and renewable resource inputs changes over time. We allow for exogenous technical change in the elasticity of substitution (EoS) between these two types of resources as well as for biased factor-augmenting technical change. Our main results are: (1) sustained technical change in the EoS is enough to overcome resource constraints; (2) productivity-enhancing technical change is most beneficial when directed to the resource which is currently most important for production; (3) the speed of productivity-enhancing technical change is crucial for its usefulness to overcome resource constraints; (4) sustainability depends critically on the type of technical change.     

Sea Otters (Enhydra lutris L.) of Bering Island, the Commander Islands: Age and Sex Composition of Dead Animals and Spatial Distribution

Animal censuses and assessment of mortality in the sea otter subpopulation of Bering Island (the Commander Islands) have shown that indices of seasonal mortality may be used as a criterion for estimating well-being of this animal group. In 1999, the subpopulation of Bering Island entered a phase of stabilization of its spatial, age, and sex structure, with the stabilization process proper taking approximately three years after a peak of mortality. Mortality in the course of this process proved to be relatively high in age groups older than eight years but insignificant among middle-aged reproductive animals. As the age and sex structure of the insular group varies during the year and in different coastal areas, the data obtained by collecting dead animals cannot be used for estimating the structure of the whole population.     

Mining and corruption

This study examines the links between mineral dependency and corruption. Specifically, it develops a cross-section econometric model that estimates the effects of per capita income, fuel exports, non-fuel exports, and average per unit value of mineral exports on corruption.     

重庆獐牙菜属药用植物资源及其开发利用

经调查鉴定，重庆獐牙菜属药用植物有9种，其中西南獐牙菜、北方獐牙菜为重庆分布新记录。重点介绍了它们的医疗用途、地理分布、资源现状及其开发前景，为正确鉴别使用，编制了其分种检索表。     

Journalism and Science: How to Erode the Idea of Knowledge

This paper discusses aspects of the relationship between the scientific community and the public at large. Inspired by the European public debate on genetically modified crops and food, ethical challenges to the scientific community are highlighted. This is done by a discussion of changes that are likely to occur to journalistic attitudes – mirroring changing attitudes in the wider society – towards science and scientific researchers. Two journalistic conventions – those of science transmission and of investigative journalism – are presented and discussed in relation to the present drive towards commercialization within the world of science: how are journalists from these different schools of thought likely to respond to the trend of commercialization? Likely journalistic reactions could, while maintaining the authority of the scientific method, be expected to undermine public trust in scientists. In the long term, this may lead to an erosion of the idea of knowledge as something that cannot simply be reduced to the outcome of negotiation between stakeholders. It is argued that science is likely to be depicted as a fallen angel. This may be countered, it is posited, by science turning human, by recognizing its membership of society, and by recognizing that such membership entails more than just commercial relations. To rethink its relationship with the public at large – and, in particular, to rethink the ideal of disinterested science – is an ethical challenge facing the scientific community.     

多效唑在重瓣丝石竹组织培养中的作用

多效唑能增加重瓣丝石竹组织培养苗的节数,缩短节间距,使试管苗健壮,其最适浓度为1．0mg/L。经多效唑（0．05ml/L-0.2ml/L)壮苗培养,显著地促进了组织培养苗生根。较高浓度的多效唑（0．20mg/L-1.0mg/L)对茎尖外植体不定芽分化有明显的增殖作用,同时抑制了试管苗玻璃化。