Toward harmonizing prospective effectiveness assessment for road safety: Comparing tools in standard test case simulations

Abstract

Objective: With the overall goal to harmonize prospective effectiveness assessment of active safety systems, the specific objective of this study is to identify and evaluate sources of variation in virtual precrash simulations and to suggest topics for harmonization resulting in increased comparability and thus trustworthiness of virtual simulation-based prospective effectiveness assessment.

Methods: A round-robin assessment of the effectiveness of advanced driver assistance systems was performed using an array of state-of-the-art virtual simulation tools on a set of standard test cases. The results were analyzed to examine reasons for deviations in order to identify and assess aspects that need to be harmonized and standardized. Deviations between results calculated by independent engineering teams using their own tools should be minimized if the research question is precisely formulated regarding input data, models, and postprocessing steps.

Results: Two groups of sources of variations were identified; one group (mostly related to the implementation of the system under test) can be eliminated by using a more accurately formulated research question, whereas the other group highlights further harmonization needs because it addresses specific differences in simulation tool setups. Time-to-collision calculations, vehicle dynamics, especially braking behavior, and hit-point position specification were found to be the main sources of variation.

Conclusions: The study identified variations that can arise from the use of different simulation setups in assessment of the effectiveness of active safety systems. The research presented is a first of its kind and provides significant input to the overall goal of harmonization by identifying specific items for standardization. Future activities aim at further specification of methods for prospective assessments of the effectiveness of active safety, which will enhance comparability and trustworthiness in this kind of studies and thus contribute to increased traffic safety.     

On the crucial importance of a small bird: The ecosystem services of the little auk (<Emphasis Type="Italic">Alle alle</Emphasis>) population in Northwest Greenland in a long-term perspective

The little auk is the most numerous seabird in the North Atlantic and its most important breeding area is the eastern shores of the North Water polynya. Here, a population of an estimated 33 million pairs breeds in huge colonies and significantly shapes the ecosystem. Archaeological remains in the colonies document that the little auk has been harvested over millennia. Anthropological research discloses how the little auk has a role both as social engineer and as a significant resource for the Inughuit today. The hunting can be practiced without costly equipment, and has no gender and age discrimination in contrast to the dominant hunt for marine mammals. Little auks are ecological engineers in the sense that they transport vast amounts of nutrients from sea to land, where the nutrients are deposited as guano. Here, the fertilized vegetation provides important foraging opportunities for hares, geese, fox, reindeer, and the introduced muskox. We estimate that the relative muskox density is ten times higher within 1 km of little auk fertilized vegetation hotspots.     

最近和未来欧洲气候变化的特征

为了从日温度和日降水变化的层次来研究欧洲未来的气候,进行了6个区域气候模型的试验,研究了上述变量概率分布的变化.研究发现,这些分布的非对称性随地点和季节的变化各不相同.夏季中欧、东欧、南欧极端最高温度的大幅度变化之后,通常会出现暖季高于平均的温度升高,与此类似,东欧和北欧寒冷日温度的升高也显著大于冬季平均温度的升高.将冬季温度的模型模拟值与历史观测资料值进行比较,结果表明模拟值与观测值在日变率方面是相似的.特别地,和历史上寒冷时期相比,观测到的温暖时期平均温度在增加,而较这种增加强烈得多的寒冷日温度增加也被模型模拟了出来.在欧洲绝大部分地区和所有季节,强降水事件在模拟中的作用增加.     

基于卫星图像的村庄真实形态评价:一种识别欧洲完整文化景观的方法

土地由中心到边缘呈现不同分布利用方式的村庄,构成了欧洲文化景观的基本单元.然而在许多的乡村景观中,那些拥有细致结构的耕地和有树木的草场的真正前工业时代的村庄正在不断失去其原有的结构,这种遗失威胁着文化的继承和生物多样性.因此,监测景观中这样的村庄真实形态的变化范围和速度是非常重要的.随着废弃时间的增加,村庄的真实形态不断丢失,我们所要研究的是怎样的丢失程度才能够通过卫星图像定量分析和目视解译进行评价.1999年,我们在波兰东南部的Bieszczady山脉开展本研究.使用1998年的陆地卫星TM数据,利用景观元素的粒度(田地大小)和土地覆盖组成(灌木和森林的扩侵)对代表真实村庄结构形态退化不同阶段的6种类型村庄进行定量描述.我们利用历史地图勾勒出村庄的边界,并测量从前森林和空地的范围.利用卫星数据,将当前的土地利用和表示成粒度及森林的扩侵状况的土地废弃程度绘制成图.退化沿着2条变化路径发生:被废弃并且最终变成森林,或者形成集约农业.为了验证这样的结果,我们通过对原始卫星影像的目视解译,将1000km2范围内的22个其他村庄分成了4类.而后,我们收集了过去60年人口变化的历史数据.村庄真实形态的分类与人口下降速度明显相关.我们希望验证和应用这种快速评估文化景观真实形态的方法能够得到重视,尤其是在随着欧盟的扩大正在经历或者将要发生巨大变化的欧洲区域.最后,我们论证了村庄具有成为一个融合自然与社会科学的景观尺度的可能性.     

Supportive Breeding and Variance Effective Population Size

The practice of supporting weak, wild populations through release of individuals bred in captivity is becoming an increasingly important conservation measure. A frequently recommended form of such breeding-release activity refers to supportive breeding: a fraction of the target population is brought into captivity for reproduction, and the resulting progeny are released to mix with the wild segment of the population. We derived an expression for the variance effective size of a population managed through supportive breeding and discuss its relationship to previously published equations that are based on the assumption of random mating. We show that the effect of supportive breeding may be quite different on the inbreeding and the variance effective sizes. Whereas supportive breeding always results in a reduction of the inbreeding effective number, the variance effective number may either decrease, increase, or remain unchanged. We discuss these observations in relation to conservation management and suggest some general guidelines for supportive breeding situations. Our recommendations include making a distinction between inbreeding and variance effective numbers; taking particular care when dealing with organisms with high reproductive potential; assuring that the amount of drift be no larger than it would be without supportive breeding; and focusing primarily on the variance effective size of a population-that is, on the effective number directly related to the rate of loss of gene diversity.     

The aggregation pheromone ofIps duplicatus and its role in competitive interactions withI. typographus (Coleoptera: Scolytidae)

Summary Ips duplicatus withI. typographus co-inhabiting Norway spruce (Picea abies (L.) Karst.) would benefit from a pheromone blend distinct from that of the larger competitorI. typographus. GC-MS analysis showed thatI. duplicatus males feeding in the host produced ipsdienol (Id),cis-verbenol (cV),trans-verbenol (tV), myrtenol (Mt), andE-myrcenol (EM) and traces of 2-methyl-3-buten-2-ol (MB).I. duplicatus produced Id in approximately racemic form (48.9-54.5% (+)-(S)-isomer). The amounts of Id and EM released over a 9 day period had a maximum of 250 and 5 ng/h/male, respectively, on day 2. Exposure ofI. duplicatus males to myrcene and -pinene resulted in the production of small amounts of Id, cV, tV, Mt, andtrans-pinocarveol, but not of EM. In laboratory bioassays with walking beetles, the pheromone component Id alone was weakly attractive while EM was inactive, but in binary combination with Id strongly synergized attraction. A combination of EM and Id at a release rate equivalent to 100–200 males was more attractive in the field than 70 unmated males in a spruce log. The addition of myrcene ( a suggested pheromone precursor of Id) to Id did not enhance trap caches, while addition of EM increased catches > 10-fold. Subtracting EM from a blend of Id, EM, cV and MB drastically reduced trap catches while subtraction of cV or MB or both had no significant effect. Addition of EM over a wide concentration range to the synthetic pheromone ofI. typographus did not reduce the attraction of females of this species in the laboratory. A two-species pheromone interaction field test releasingI. typographus pheromone components (MB + cV) at 10–1000 male equivalents (ME) andI. duplicatus pheromone (Id + EM) at 0, 10–1000 ME in all possible combinations showed both positive intraspecific dose-response effects and an interspecific inhibition. Higher release rates of EM appeared to inhibitI. typographus, especially males. In a tree colonization model, the response of the two competing species to their respective pheromones show a good separation during the mass-attack with a small initial cross-attraction. It remains to be shown whether either of the two pheromone systems have in fact evolved in the present sympatry, or if they are an incidental effect of ancestry of these phylogenetically distantIps.     

Diffusive sampling of methyl isocyanate using 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ) as derivatizing agent

A diffusive sampling method for the determination of methyl isocyanate (MIC) in air is introduced. MIC is collected using a glass fiber filter impregnated with 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ). The urea derivative formed is desorbed from the filter with acetonitrile and analyzed by means of high-performance liquid chromatography (HPLC) using fluorescence detection (FLD) with lambdaex = 471 nm and lambdaex = 540 nm. Additionally, a method was developed using tandem mass spectrometric (MS-MS) detection, which was performed as selected reaction monitoring (SRM) on the transition [MIC-NBDPZ + H]+ (m/z 307) to [NBDPZ + H]+ (m/z 250). The diffusive sampler was tested with MIC concentrations between 1 and 35 microg m(-3). The sampling periods varied from 15 min to 8 h, and the relative humidity (RH) was set from 20% up to 80%. The sampling rate for all 15 min experiments was determined to be 15.0 mL min(-1) (using HPLC-FLD) with a relative standard deviation of 9.9% for 56 experiments. At 80% RH, only 15 min sampling gave acceptable results. Further experiments revealed that humidity did not affect the MIC derivative but the reagent on the filter prior to and during sampling. The sampling rate for all experiments (including long term sampling) performed at 20% RH was found to be 15.0 mL min(-1) with a relative standard deviation of 6.3% (N = 42). The limit of quantification was 3 microg m(-3) (LC-MS-MS: 1.3 microg m(-3)) for 15 min sampling periods and 0.2 microg m(-3) (LC-MS-MS: 0.15 microg m(-3)) for 8 h sampling runs applying fluorescence detection.     

Development of a diffusive sampling method for determination of methyl isocyanate in air

A diffusive sampling method for determination of methyl isocyanate in air has been developed. A glass fibre filter impregnated with 1-(2-methoxyphenyl)piperazine in a commercially available diffusive sampling device was used to collect methyl isocyanate and the derivative formed was analysed with LC-MS/MS. The sampling rate was determined to be 15.6 ml min(-1), with a relative standard deviation of 7.3%. The sampler was validated for sampling periods from 15 min to 8 h, for relative humidities from 20% to 80% and for concentrations from I to 46 microg m(-3). A field validation was also made and the diffusive sampling results showed no difference compared to a pumped reference method. The impregnated filters have to be stored apart from the diffusive sampler housing and loaded into the sampler prior to each sampling.     

科学的挑战--重视成本效益,清洁波罗的海

波罗的海是世界上受人类活动影响最严重的海洋之一,虽然有减少向波罗的海排放营养物质的国际协议,但迄今为止采取的措施,既没有从根本上减少营养物质的排放,也没有促进环境的改善.部分原因可以归咎为缺少有关物理学、生物地球化学和生态特性之间大尺度关系和相互作用的知识,但是还缺少全流域范围的成本效益分析.错误的决策非常危险,例如,执行的减少排放的方案根本没有效果,或远远达不到成本效益.许多学科的研究者正面临着一个共同的挑战开发一个决策支持系统,作为整个波罗的海成本效益分析法的科学基础.研究项目海洋富营养化的研究(MARE)(http∥www.mare.su.se)正致力于这方面的研究.     

从富营养化状态中复原：减少对瑞典四大湖磷输入的经验

自20世纪60年代以来,人们一直在研究随着输入的减少韦特恩湖、维纳恩湖、梅拉伦湖以及哈马伦湖中磷(P)和氮(N)的浓度变化.在前两个水更新速度较慢的深水、贫营养湖中,自70年代以来磷输入的急剧减少只是造成较长一段时间内磷浓度的少量减小.同时在水团中出现了非有机氮的积累现象,本文对这一现象的可能原因进行了探讨.在后两个中等营养到高营养的湖中,哈马伦湖中的两个浅盆地由于沉积物释放的氮而显示出恢复较慢.这两个盆地以及梅拉伦湖中的两个盆地有氮缺乏现象,特别是在磷输入减少之前的数年中、而且表明存在固氮现象.在梅拉伦湖的两个盆地中,湖内磷浓度的恢复与用于湖泊从营养物污染中恢复的IMSA模型相比较预期的要好.在其他的5个湖泊/盆地中,20年之后的叶绿素浓度与那些模拟的情况相比类似.