A stage-structured, Aedes albopictus population model

Aedes albopictus has been the fastest spreading invasive animal species in the world from the mid-1980s until the mid-2000s. In areas it infests, it disrupts native mosquito ecology and can potentially vector up to 21 viruses. To better understand the population dynamics of this species, we created a temperature dependent population model. A stage-structured model was chosen to allow each life-stage to have different temperature dependent mortality and development rates, and each stage was modeled with an ordinary differential equation. Model parameters and distributions were based upon literature values. Initially, a basic model was constructed. This model then had parameters that were forced based upon daily average temperatures. Several criteria were used to evaluate the model, including a comparison to field data from Lubbock, TX. In a stochastic version of the model, a 95% confidence limit contained 70.7% of the field data points. Based upon these results, we feel reasonably confident that we have captured the role of temperature in driving the population dynamics of Ae. albopictus.     

俯采工作面采空区“三带”分布研究

为了防治采空区煤炭自燃,采用热电偶测温和束管气体监测方法对五沟矿1021俯采工作面观测,得到采空区温度及氧浓度的变化情况。通过对温度和氧浓度实测结果的分析,并利用MIN-MAX方法优化,最终确定了采空区"三带"的范围。结合五沟矿煤的自然发火期,可以推算出工作面的临界推进速度,以此有效指导工作面的防灭火工作。     

Ethical Consumption, Values Convergence/Divergence and Community Development

Ethical consumption is on the rise, however little is known about the degree and the implications of the sometime conflicting sets of values held by the broad category of consumers who report consuming ethically. This paper explores convergence and divergence of ethical consumption values through a study of organic, fair trade, and local food consumers in Colorado. Using survey and focus group results, we first examine demographic and attitudinal correlates of ethical consumption. We then report evidence that while many organic, fair trade, and local food consumers converge around similar values, some Colorado consumers support only local food, while opposing the consumption of organic and fair trade products. Next, we investigate how ethical consumers who converge and diverge frame their commitment to consuming ethically. The discussion and conclusion suggest that community development planners of projects that focus on ethical consumption will need to successfully traverse issues stemming from convergence and divergence to enjoy long-term sustained success.     

A~2/O工艺在低温低浓度条件下处理效果及节能减耗研究

研究在低水温条件下,进厂污水中有机物浓度较低时(污水平均BOD5为45 mg/L左右),漳扎污水处理厂生化系统较优的运行工况。研究结果表明,在上述情况下,较优的连续运行工况为:污泥回流比为75%左右,MLSS为3 200~3 500 mg/L,生化池处的溶解氧在0.7~1.3 mg/L之间;较优的间歇运行工况为:以曝气3 h停曝3 h的方式运行,生化池处的溶解氧在3~5 mg/L之间,污泥回流比为75%左右,MLSS为3 200~3 500 mg/L。上述两种运行工况对污水中的污染物质都有较高的去除率,能成功避免污泥解絮的发生,使系统中的微生物平稳过冬;其中间歇曝气方式能达到节能减耗的目的,建议在旅游淡季时采用该方式运行。     

Natural recovery of different areas of a deserted quarry in South China

A quarry is a surface mining operated place, which produces enormous quantities of gravel, limestone, and other materials for industrial and construction applications. Restoration and revegetation of deserted quarries are becoming increasingly important. Three areas of a typical quarry in South China: terrace for crushed materials (terrace), spoiled mound, and remaining side slope, were investigated, to compare the existing plant species and to study the relationship between environmental factors and revegetation. The plant species composition of these three areas was found to differ significantly after eight years of natural recovery. The typical plant communities found over them were composed of gramineous herbs, fems, and shrubs. Soil organic matter, soil moisture, and soil bulk density were considered to be the major determining factors for vegetation succession. There existed abiotic and biotic thresholds during quarrying restoration. Suggestions had been presented that could have accelerated the process of natural recovery in quarries.     

Research on Tourism Competitiveness of Chinese Island Counties: Based on Factor and Cluster Analysis

Abstract

From the perspective of tourism competitiveness, the paper takes 12 island counties of China as the research object, and applies the method of factor analysis to study their competitiveness. The result shows that Putuo and Dinghai are more competitive while Pingtan and Nan’ao are less competitive. Finally, the 12 island counties are divided into four styles: first-class competitive county (Putuo), seond-class competitive counties (Dinghai,Yuhuan), third-class competitive counties (Chongming, Daishan, Changdao, Changhai and Shengsi), fourth-class competitive counties (Dongshan, Dongtou, Pingtan and Nan’ao) by cluster analysis. The classification of island counties is to clear their relative position, then to promote their development.     

Invasive Microstegium populations consistently outperform native range populations across diverse environments

Plant species introduced into novel ranges may become invasive due to evolutionary change, phenotypic plasticity, or other biotic or abiotic mechanisms. Evolution of introduced populations could be the result of founder effects, drift, hybridization, or adaptation to local conditions, which could enhance the invasiveness of introduced species. However, understanding whether the success of invading populations is due to genetic differences between native and introduced populations may be obscured by origin x environment interactions. That is, studies conducted under a limited set of environmental conditions may show inconsistent results if native or introduced populations are differentially adapted to specific conditions. We tested for genetic differences between native and introduced populations, and for origin x environment interactions, between native (China) and introduced (U.S.) populations of the invasive annual grass Microstegium vimineum (stiltgrass) across 22 common gardens spanning a wide range of habitats and environmental conditions. On average, introduced populations produced 46% greater biomass and had 7.4% greater survival, and outperformed native range populations in every common garden. However, we found no evidence that introduced Microstegium exhibited greater phenotypic plasticity than native populations. Biomass of Microstegium was positively correlated with light and resident community richness and biomass across the common gardens. However, these relationships were equivalent for native and introduced populations, suggesting that the greater mean performance of introduced populations is not due to unequal responses to specific environmental parameters. Our data on performance of invasive and native populations suggest that post-introduction evolutionary changes may have enhanced the invasive potential of this species. Further, the ability of Microstegium to survive and grow across the wide variety of environmental conditions demonstrates that few habitats are immune to invasion.     

Forecasting population trend from the scaling pattern of occupancy

Forecasting the temporal trend of a focal species, its range expansion or retraction, provides crucial information regarding population viability. To this end, we require the accumulation of temporal records which is evidently time consuming. Progress in spatial data capturing has enabled rapid and accurate assessment of species distribution across large scales. Therefore, it would be appealing to infer the temporal trends of populations from the spatial structure of their distributions. Based on a combination of models from the fields of range dynamics, occupancy scaling and spatial autocorrelation, here I present a model for forecasting the population trend solely from its spatial distribution. Numerical tests using cellular automata confirm a positive correlation, as inferred from the model, between the temporal change in species range sizes and the exponent of the power-law scaling pattern of occupancy. The model is thus recommended for rapid estimation of species range dynamics from a single snapshot of its current distribution. Further applications in biodiversity conservation could provide a swift risk assessment, especially, for endangered and invasive species.