A new design for sampling with adaptive sample plots

Adaptive cluster sampling (ACS) is a sampling technique for sampling rare and geographically clustered populations. Aiming to enhance the practicability of ACS while maintaining some of its major characteristics, an adaptive sample plot design is introduced in this study which facilitates field work compared to “standard” ACS. The plot design is based on a conditional plot expansion: a larger plot (by a pre-defined plot size factor) is installed at a sample point instead of the smaller initial plot if a pre-defined condition is fulfilled. This study provides insight to the statistical performance of the proposed adaptive plot design. A design-unbiased estimator is presented and used on six artificial and one real tree position maps to estimate density (number of objects per ha). The performance in terms of coefficient of variation is compared to the non-adaptive alternative without a conditional expansion of plot size. The adaptive plot design was superior in all cases but the improvement depends on (1) the structure of the sampled population, (2) the plot size factor and (3) the critical value (the minimum number of objects triggering an expansion). For some spatial arrangements the improvement is relatively small. The adaptive design may be particularly attractive for sampling in rare and compactly clustered populations with an appropriately chosen plot size factor.     

建造能源-效率的城市网络：欧洲和巴西的一些实践经验

今天的能源政策不得不把面向能源供应和能源需求两个主动性结合起来 .鉴于油价危机以来逐渐增加的环境限制的压力和节能行为,一个基于能源消耗管理和增加利用地方（可更新的）能源的新能源政策,已变得十分必要 .在这一研究里,地方和区域一级是合作伙伴 .能源效率项目的发展和市政府之间有关最佳实践信息的交换和传播,正在由节能机构的网络在世界范围组织起来 .下面就是这样的网络发展的几个实例 .……     

沿海和海洋生态系统与人类人口系统间的相互作用:关于消费如何调解这种相互作用的看法

人口、环境及可持续发展的困境 20世纪的80和90年代,环境工作者和普通公众普遍认为,不加控制的人口增长是造成各类环境退化的根本原因.这种新马尔萨斯人口论的观点最初出现在20世纪60年代Ehrlich所著的<人口炸弹>的文章中,该文以危言耸听的语气解释了那十年空前高的人口增长率[1～3].     

The range fraction: an applied method to characterize regional groundwater responses to climate inputs

An important component of ongoing water-resource investigations in the eastern Great Basin, USA, has been to ascertain the impact of future predicted climate change on groundwater availability. As a first step in that analysis, it was hypothesized that potentiometric fluctuations at certain wells would reflect annual-scale precipitation variation. Potentiometric behavior at a well depends on local hydrologic conditions, well construction, and human activities, in addition to natural recharge and regional water levels. Moreover, measurement data are limited for many wells. After preliminarily screening, a large body of well and climate station data, short-term potentiometric responses to annual-scale climate inputs, were identified at 18 wells using a simple visualization methodology developed during the study. For water levels displaying multi-annual trends, the signals were measured as deviations from a linear trendline. Groundwater responses lagged precipitation signals by less than 1 year to as much as 3 years, with most wells showing at most a 1- to 2-year delay. Response amplitude was variable and strongly depended on the hydrologic setting of each well.     

建造能源-效率的城市网络：欧洲和巴西的一些实践经验

今天的能源政策不得不把面向能源供应和能源需求两个主动性结合起来 .鉴于油价危机以来逐渐增加的环境限制的压力和节能行为,一个基于能源消耗管理和增加利用地方（可更新的）能源的新能源政策,已变得十分必要 .在这一研究里,地方和区域一级是合作伙伴 .能源效率项目的发展和市政府之间有关最佳实践信息的交换和传播,正在由节能机构的网络在世界范围组织起来 .下面就是这样的网络发展的几个实例 .     

On the translation of uncertainty from toxicokinetic to toxicodynamic models--the TCDD example

When estimating human health risks from exposure to TCDD using toxicokinetic and toxicodynamic models, it is important to understand how model choice and assumptions necessary for modeling add to the uncertainty of risk estimates. Several toxicokinetic models have been proposed for the risk assessment of dioxins, in particular the elimination kinetics in humans has been a matter of constant debate. For a long time, a simple linear elimination kinetics has been common choice. Thus, it was used for the statistical analysis of the largest occupationally exposed cohort, the German Boehringer cohort. We challenge this assumption by considering, amongst others, a nonlinear modified Michaelis-Menten-type elimination kinetics, the so-called Carrier kinetics. Using the area under the lipid TCDD concentration time curve as dose metrics, we model the time to cancer-related death using the Cox proportional hazards model as toxicodynamic model. This risk assessment set-up was simulated in order to quantify uncertainty of both the dose (TCDD body burden) and the risk estimates, depending on the use of the kinetic model, variations of carcinogenic effect of TCDD and variations of latency period (lag time). If past exposure is estimated assuming a linear elimination kinetics although a Carrier kinetics actually holds, then high exposures in reality will be underestimated through statistical analysis and low exposures will be overestimated, respectively. This bias will carry over on the estimated individual concentration-time curves and the therefrom derived TCDD dose metric values. Using biased dose values when estimating a dose-response relationship will finally lead to biased risk estimates. The extent of bias and the decrease of precision are quantified in selected scenarios through this simulation approach. Our findings are in concordance with recent results in the field of dioxin risk assessment. They also reinforce the general demand for the scheduled uncertainty assessments in risk analyses.     

Evolution of habitat use by deep-sea mussels

Previous phylogenetic studies proposed that symbiont-bearing mussels of the subfamily Bathymodiolinae (Bivalvia: Mytilidae) invaded progressively deeper marine environments and evolved from lineages that decomposed wood and bone to specialized lineages that invaded cold-water hydrocarbon seeps and finally deep-sea hydrothermal vents. To assess the validity of the hypotheses, we examined two nuclear (18S and 28S rRNA) and two mitochondrial genes (COI and ND4) from a broad array of bathymodiolin species that included several recently discovered species from shallow hydrothermal seamounts. Bayesian phylogenetic analysis and maximum-likelihood estimates of ancestral character states revealed that vent species evolved multiple times, and that reversals in vent and seep habitat use occurred within the sampled taxa. Previous hypotheses regarding evolution from wood/bone-to-seeps/vents are supported in that mid-ocean hydrothermal vent species may represent a monophyletic group with one noticeable reversal. Earlier hypotheses about progressive evolution from shallow-to-deep habitats appear to hold with a few instances of habitat reversals.     

Temporal trends of polyfluoroalkyl compounds (PFCs) in liver tissue of grey seals (Halichoerus grypus) from the Baltic Sea, 1974-2008

Temporal trends of polyfluoroalkyl compounds (PFCs) were examined in grey seal (Halichoerus grypus) liver from the Baltic Sea over a period of 35 years (1974-2008). In total, 17 of 43 PFCs were found, including the perfluoroalkyl sulfonates (C₄-C₁₀ PFSAs), perfluorooctanesulfinate (PFOSi), long chain perfluoroalkyl carboxylates (C₇-C₁₄ PFCAs), and perfluoroalkyl sulfonamides (i.e., perfluorooctane sulfonamide (FOSA) and N-ethyl perfluorooctane sulfonamide (EtFOSA)), whereas saturated and unsaturated fluorotelomer carboxylates, shorter chain PFCAs and perfluoroalkyl phosphonic acids were not detected. Perfluorooctane sulfonate (PFOS) was the predominant compound (9.57-1444 ng g⁻¹ wet weight (ww)), followed by perfluorononanoate (PFNA, 0.47-109 ng g⁻¹ ww). C₆-C₈ PFSAs, PFOSi and C₇-C₁₃ PFCAs showed statistically significant increasing concentrations between 1974 and 1997, with a peak in 1997 and then decreased or levelled off (except for C₁₂ and C₁₃ PFCAs). FOSA had a different temporal trend with a maximum in 1989 followed by significant decreasing concentrations until 2008. Toxicological implications for grey seals are limited, but the maximal PFOS concentration found in this study was about 40 times lower than the predicted lowest observed effect concentrations (LOEC). The statistically significant decreasing concentrations or levelling off for several PFCs in the relative closed marine ecosystem of the Baltic Sea indicate a rapidly responding to reduced emissions to the marine environment. However, the high concentrations of PFOS and continuing increasing concentrations of the longer chain PFCAs (C₁₂-C₁₄) shows that further work on the reduction of environmental emissions of PFCs are necessary.