湿地水环境可持续性概念辨析

20世纪60年代以来,随着全球性的生态与资源危机的不断出现,使得人们不得不开始检讨传统的经济发展观,寻求探索新的发展模式。20世纪80年代初期,由联合国环境与发展委员会提出的可持续发展理论,得到了世界各国的普遍认同。然而,从1992年的巴西里约热内卢到2002年的南非约翰内斯堡,可持续发展在这十年间遭遇到理论与实验的双重＂困境＂。2001年,23名世界著名学者在美国《科学》上发表了《可持续性科学》的论文,想用这样一个严格的科学定义来替代意义分歧的可持续发展,避免可持续发展走入歧途。从此,人们越来越频繁地使用＂可持续性＂一词,但怎么实现可持续性则众说不一。学术界对＂可持续性＂和＂可持续发展＂概念的讨论也非常活跃且一直没有间断过。在此,从＂可持续性＂的历史成因出发,分析其在生物学、生态学及环境学等方面的含义,探讨＂可持续性＂一词在湿地水环境这一具体领域的应用,提出＂湿地水环境可持续性＂这一概念,并深入分析其内涵和主要特征,为后续湿地水环境可持续性度量作理论铺垫。     

Asian Americans and workplace discrimination: The interplay between sex of evaluators and the perception of social skills

In two role‐playing scenarios, we investigate how White male and female evaluators perceive an Asian American versus White job candidate on the dimensions of competence and social skills and how these perceptions affect evaluators' decisions in hiring and promotion. Specifically, Study 1 examines how the perceptions of competence and social skills affect Asian (versus White) college graduates' chance of obtaining a non‐technical (versus technical) position, and Study 2 tests how these perceptions affect Asians' probability of promotion relative to Whites'. Our findings suggest that female evaluators were less likely to select Asian than White candidates into positions involving social skills and were less likely to promote Asian than White candidates into these types of positions. Furthermore, female evaluators' perception that Asians were less socially skilled than Whites mediated both of these decisions. This paper contributes to the understanding of workplace discrimination of Asian Americans. Copyright © 2012 John Wiley & Sons, Ltd.     

The higher price of cleaner fuels: Market power in the rail transport of fuel ethanol

This paper provides evidence of market power in the transportation of ethanol used in reformulated gasoline and alternative transportation fuels. I estimate a reduced form model for railroad route-level prices. My identification strategy instruments for railroad entry, controls for selection and explicitly models capacity constraints. A detailed understanding of this industry is important because U.S. environmental policies seek to substantially expand ethanol use. Evidence of market power may alter the types of policies pursued by lawmakers. I find that ethanol shipment prices are lower for more competitive routes. I also find evidence that railroads price discriminate based on environmental regulation at route destinations. Monopolist prices for shipments to carbon monoxide non-attainment areas are 3% higher than shipments to other destinations. This price premium falls sharply with increased competition. This suggests a perverse result where environmental regulation increases the price of a clean input.     

青山水库底泥磷释放与库区水体磷浓度的关系

通过对青山水库底泥磷释放特性的实验结果分析,对照库区水体浓度监测的数据,确定了库区各测点底磷释放量与水体浓度之间的关系,进而为库区环境总量控制与各支流的分配计算提供了依据。同时也为防止水库的进一步富营养化,进而改善水质提供了新的思路。     

Interpreting the relationship between pheromone component emission from commercial lures and captures of Helicoverpa zea (boddie) in bucket and cone traps

Abstract

Male corn earworm moths, Helicoverpa zea (Boddie), were captured in conical Texas pheromone traps (cone traps) and bucket traps baited with four different commercial lures manufactured by three different manufacturers. Because significant numbers were captured in bucket traps baited with some of the lures, and none with others, the volatile emissions from all of the lures were sampled and analyzed by gas Chromatographic methods. The numbers of males captured in two types of trap were compared with bait emissions in an endeavor to define a more effective lure for bucket traps. The lure from one manufacturer captured the same numbers of males in both trap types; one captured more in bucket traps than in cone traps, and another captured only a small number in bucket traps. The emission rate of all active compounds from each of the different lures was approximately linear for the duration of the assays. A gas‐liquid Chromatographic peak associated with a third compound, (Z)‐9‐tetradecenal, which reduces behavioral responses, was observed in the emissions from all lures evaluated. The effectiveness of the Hercon (Emmigsville, PA) lure in capturing males in both types of trap was associated with a lower emission of (Z)‐l 1‐hexadecenal, (Z)‐9‐hexadecenal and (Z)‐9‐tetradecenal than from the other lures.     

基于数字图像处理技术的金相分析研究

采用和改进了人际交互式图像分割算法Live-wire,对电气火灾中的典型火烧金相图和一次短路金相图进行处理,结合数字形态学操作,精确提取了两类金相图中的典型胞状晶和柱状晶结构;分析和讨论了多种结构描述子对晶格分类的作用,结果表明,离心率和晶格标记方差两个描述子能有效区分两类晶格结构;采用聚类分析和Fisher判别法,实现了对两类金相图的自动分类.     

Consequences of communal gall occupation and a test for kin discrimination in the aphid Tamalia coweni (Cockerell) (Homoptera: Aphididae)

This study investigated the consequences of communal gall induction on individual and group fitness in the aphid Tamaliacoweni. The possibilities that kin discrimination and foundress density are factors favoring communal gall occupation were examined. Clonally produced aphid foundresses were collected to create two treatments: clonal groups and groups of less closely related individuals. These were confined on suitable host plant tissue to compare their respective propensities towards communal behavior. There were no significant differences in the frequencies of communal gall occupation; therefore, active kin discrimination by T.coweni foundresses apparently does not play a role in their communal behavior, within the context of this experiment. In a second experiment, aphid foundress density on the host plant was manipulated in three treatments and was correlated with the frequency of communal gall occupation. Individual fitness was inversely related to the mean number of foundresses per gall. These results suggest that communal gall occupation does not necessarily represent mutual cooperation but may instead be the outcome of competition for limited gall sites on the host plant. However, natural selection at the clonal level may favor communal gall occupation under the conditions of resource limitation and high within-group relatedness. Received: 26 September 1997 / Accepted after revision: 28 March 1998     

Discrimination of different social companions in spectacled parrotlets (Forpus conspicillatus): evidence for individual vocal recognition

Individual recognition is generally assumed to be a prerequisite for establishing and maintaining a complex social system. Indeed, there is good evidence that highly social species have complex systems of vocal communication with individual recognition by acoustic cues. In this study, we provide experimental evidence that vocal class and individual recognition is present in a non-passerine bird, the spectacled parrotlet (Forpus conspicillatus). Spectacled parrotlets live in a complex system of social relationships. Soon after fledging, the young establish close sibling relationships which are important for successful socialization, pairing and reproduction. In a series of playback experiments we tested if spectacled parrotlets use contact calls for vocal recognition. The results showed that spectacled parrotlets discriminate between the contact calls of different social categories. Adult birds preferred to respond to the contact calls of their mates. Subadult individuals recognized the contact calls of their siblings. During the period of pair bond formation, the affiliative contacts to the siblings decrease, but the parrotlets continue to respond to the calls of their siblings. This is the first evidence that vocal sibling recognition might outlast the period of strong sibling interaction and extends into the period of pair bond formation. In cases of mate loss or divorce, the acoustic contact to their siblings might facilitate the re-establishment of close sibling relationships. Received: 29 October 1997 / Accepted after revision: 5 April 1998     

判别符合率递增法辅助酚类化合物构效关系研究

计算了酚类化合物的分子连接性指数及其在正辛醇和水之间的分配系数ｌｏｇＰ，运用新近提出的数学方法－判别符合率递增法，对酚类化合物的构效关系进行了研究，所得结果优于逐步判别法及穷举法。     

不同甘蔗基因型光合特性的数值分类

对30个甘蔗基因型光合性状进行数值分类、主成分、聚类和判别分析研究认为，甘蔗基因型间光合性状存在较大差异；利用主成分分析选出3个主成分，方差累计贡献率达到98．5％，蒸腾速率、气孔导度为第一主成分的主导因子，而净光合速率和气孔导度分别为二、三主成分的主导因子；经系统聚类将30个基因型分为三大类，在聚类分析基础上用判别分析选出对甘蔗光合性状数值分类有显著影响的4个光合参数，建立3个判别能力较高的判别模型．表5图1参22