Aerosols: unexpected disequilibrium phenomena between airborne radio activities of lead-210 and its progenies bismuth-210 and polonium-210

For the first time, concentrations of the long lived radon progenies ²¹⁰Pb, ²¹⁰Bi and ²¹⁰Po were measured in the mine atmosphere of the so called "healing gallery" in Badgastein, Austria, a region famous for its radioactive springs. These investigations were performed in order to study the radioactive equilibrium between the ²¹⁰Pb-²¹⁰Bi and the ²¹⁰Pb-²¹⁰Po pairs so as to gain more information about the aerosol-forming processes in the mine. The particle size distribution of the aerosols was determined under different ventilation conditions. Six-stage and eight-stage cascade impactors with working ranges from 0.15 to5 µm and from 0.063 to 8 µm, respectively, were used to collect the mine aerosols. These samples were analysed in the laboratory and measured by liquid scintillation spectrometry. The most surprising results were found under full ventilation, when the total activity concentrations of ²¹⁰Pb, ²¹⁰Bi and ²¹⁰Po were 4.6, 2.0 and 16.5 mBq/m³, respectively. In this case ²¹⁰Po/²¹⁰Pb activity ratios ranged between 1.8ǂ.3 and 4.3ǂ.3. These unexpected results were confirmed by the eight-stage impactor samples. For the smallest particles, between 0.062 and 0.125 µm, an even higher value of 7.5 was observed. As outside sources could be excluded, such ²¹⁰Po enrichments must occur during the aerosol-forming process itself inside the mine.     

耕作农场决策的环境和经济影响:一种综合建模方法

本文研究了耕作农场中自然环境和人类起源系统的相互依赖关系.动态模拟模型的方法论起源于环境系统分析和微型模拟的建模传统.这个模型复制了自然流(例如能源、原料、排放、产品)、作为决策者的农场主以及影响农场的结构状况之间的相互连接.运行模型的目的是为了回答:价格、津贴、农场主的环境观及其生产配置选择的能力的差别对盈利和环境的影响(例如温室气体的影响、富营养化、酸化和能源消耗)是什么?模型模拟的结果说明,例如,就经济表现而言,农场主可以从两个相对可持续的战略中选择,或者专注于有机生产(从而从更高津贴和输出价格中受益),或者专注于常规的耕作并使用杀虫剂和化肥(从而通过大量生产获益).关于环境影响,由于分配肥料使用的困难,因此在有机农业和常规农业之间没有明确的区别.这个发现本质上是和系统边界的选择相关的,文章对于系统边界也作了彻底充分的讨论.     

Ring 19 mosaicism detected during prenatal diagnosis

A ring chromosome 19 was found in 14 of 20 metaphases (67 per cent) derived from amniotic fluid cell cultures following amniocentesis because of increased maternal age. Elective termination of the pregnancy revealed a hypotrophic female fetus with mild dysmorphic signs, but no congenital malformations. The case is discussed in relation to three reports in the literature of ring chromosome 19 mosaicism in a phenotypically normal girl, a mentally retarded man, and a boy with normal psychomotor development and minor dysmorphic features.     

Bestimmung von Mineralölkohlenwasserstoffen im Boden

The infra-red (IR) and the gas Chromatographic (GC) methods for the determination of mineral oil hydrocarbons in soils were examined in collaborative trials with regard to their accuracy and reproducibility. Natural, homogenized soils and soils spiked with mineral oil were used as standards. The soil matrix was composed relatively simply. The repeatability and reproducibility values obtained were about 5 % und 23 %, respectively. In contrast, the GC method revealed a considerably higher error range, especially by using the split/splitless technique. The degradation of mineral oil hydrocarbons in soils under different temperatures was investigated by IR throughout one year. The degradation rate at room temperature was about 25 %; at lower temperatures no degradation was detected. Thus, the spiked soils may be used as calibration standards for the mineral oil analysis.     

Correction to: Human behavior and Homo-mammal interactions at the first European peopling: new evidence from the Pirro Nord site (Apricena,Southern Italy)

The Science of Nature - Female-only colour polymorphism is rare in birds, but occurs in brood parasitic cuckoos (Cuculidae). Obligate brood parasites leave incubation and parental care to other...     

Benefits of kin association: related and familiar zebrafish larvae (<Emphasis Type="Italic">Danio rerio</Emphasis>) show improved growth

Zebrafish (Danio rerio) larvae prefer the olfactory cues of kin to non-kin. We examined the potential benefits of kin preference by comparing growth rate, shoaling, and aggressive behavior in juvenile zebrafish housed in groups of either familiar kin or unfamiliar non-kin. Over an observation period of 5 days, the animals grew 33% more in kin groups; however, neither shoaling nor the frequency of aggressive interactions was different in groups of related versus unrelated individuals. Shoaling behavior increased with increasing observation time and increasing age, while aggressive behavior remained the same. We conclude that associating with kin probably creates a less stressful environment that allows for higher growth rates, which can lead to higher direct fitness based on increased survival and earlier reproduction. Kin recognition leading to kin-structured groups may therefore be under positive selection.