Measurement of Turbulence Power Spectra in Agitated Vessels of Different Size with a Laser-Doppler Velocimeter

We have used the laser-Doppler velocimeter with a new noise reduction technique for measurements in water-filled, turbine-agitated vessels of several sizes, but of the same geometry. Mean velocities, turbulence intensities and turbulence power spectra were obtained in the impeller stream region. With these results we hope, in the future, to put scaling rules for mixing vessels on a sounder basis

Predators marked with chemical cues from one prey have increased attack success on another prey species

1. To reduce the risk of being eaten by predators, prey alter their morphology or behaviour. This response can be tuned to the current danger if chemical or other cues associated with predators inform the prey about the risks involved. 2. It is well known that various prey species discriminate between chemical cues from predators that fed on conspecific prey and those that fed on heterospecific prey, and react stronger to the first. It is therefore expected that generalist predators are more successful in capturing a given prey species when they are contaminated with chemical cues from another prey species instead of cues from the same prey species. 3. Here, a generalist predatory mite was studied that feeds on thrips larvae as well as on whitefly eggs and crawlers. Mites were marked with cues (i.e. body fluids) of one of these two prey species and were subsequently offered thrips larva. 4. Predators marked with thrips cues killed significantly fewer thrips than predators marked with whitefly cues, even though the predator's tendency to attack was the same. In addition, more thrips larvae sought refuge in the presence of a predatory mite marked with thrips cues instead of whitefly cues. 5. This suggests that generalist predators may experience improved attack success when switching prey species.R.v.M. received a scholarship of the Technology Foundation (STW Project 7180). G.B. received a fellowship from the OECD. E.A.F. received a fellowship from Fundació Caixa Castelló-Bancaixa (E-2011-09

Near Vertical Incidence Skywave (NVIS) Antenna and Propagation Research in The Netherlands

Near Vertical Incidence Skywave (NVIS) propagation can be used to realize radio communication without the need for an intermediate network. NVIS uses the ionosphere as a reflector to cover a large area (200 × 200 km) around the transmitter, on frequencies ranging from 3 to 10 MHz. NVIS is therefore used for telecommunication in areas that lack a telecommunication infrastructure, or in areas where the existing infrastructure is destroyed by a large scale disaster, such as the 2005 flooding of New Orleans. We will give an overview of the NVIS research performed in The Netherlands

Confidentiality and public protection: ethical dilemmas in qualitative research with adult male sex offenders

This paper considers the ethical tensions present when engaging in in-depth interviews with convicted sex offenders. Many of the issues described below are similar to those found in other sensitive areas of research. However, confidentiality and public protection are matters that require detailed consideration when the desire to know more about men who have committed serious and harmful offences is set against the possibility of a researcher not disclosing previously unknown sensitive information that relates to the risk of someone being harmed.</p

Circulation of four Anaplasma phagocytophilum ecotypes in Europe.

BACKGROUND Anaplasma phagocytophilum is the etiological agent of granulocytic anaplasmosis in humans and animals. Wild animals and ticks play key roles in the enzootic cycles of the pathogen. Potential ecotypes of A. phagocytophilum have been characterized genetically, but their host range, zoonotic potential and transmission dynamics has only incompletely been resolved. METHODS The presence of A. phagocytophilum DNA was determined in more than 6000 ixodid ticks collected from the vegetation and wildlife, in 289 tissue samples from wild and domestic animals, and 69 keds collected from deer, originating from various geographic locations in The Netherlands and Belgium. From the qPCR-positive lysates, a fragment of the groEL-gene was amplified and sequenced. Additional groEL sequences from ticks and animals from Europe were obtained from GenBank, and sequences from human cases were obtained through literature searches. Statistical analyses were performed to identify A. phagocytophilum ecotypes, to assess their host range and their zoonotic potential. The population dynamics of A. phagocytophilum ecotypes was investigated using population genetic analyses. RESULTS DNA of A. phagocytophilum was present in all stages of questing and feeding Ixodes ricinus, feeding I. hexagonus, I. frontalis, I. trianguliceps, and deer keds, but was absent in questing I. arboricola and Dermacentor reticulatus. DNA of A. phagocytophilum was present in feeding ticks and tissues from many vertebrates, including roe deer, mouflon, red foxes, wild boar, sheep and hedgehogs but was rarely found in rodents and birds and was absent in badgers and lizards. Four geographically dispersed A. phagocytophilum ecotypes were identified, that had significantly different host ranges. All sequences from human cases belonged to only one of these ecotypes. Based on population genetic parameters, the potentially zoonotic ecotype showed significant expansion. CONCLUSION Four ecotypes of A. phagocytophilum with differential enzootic cycles were identified. So far, all human cases clustered in only one of these ecotypes. The zoonotic ecotype has the broadest range of wildlife hosts. The expansion of the zoonotic A. phagocytophilum ecotype indicates a recent increase of the acarological risk of exposure of humans and animals

Human behaviour and economic growth: a psychocultural perspective on local and regional development

A renewed emphasis on behavioural traits has emerged as a means of explaining regional and local differences in economic performance and development. Given this, the aim of this study is to identify distinct local psychocultural behavioural profiles and to examine the extent to which these are associated with economic growth. Combining theories of community culture and personality psychology into a holistic spatially-oriented perspective, the paper argues that the types of human behaviour found across local places emerges from the co-evolution of cultural and personality factors. An empirical analysis of localities in Great Britain identifies and explores three underlying psychocultural profiles: Diverse Extraversion; Inclusive Amenability and Individual Commitment. It is found that inclusive amenable and individually committed psychocultural behaviour generally appear to hold back local economic growth, with the exception of recessionary periods. The reverse relationship is somewhat the case for diverse extravert behaviour. It is concluded that a better understanding of the holistic relationship and co-evolution of the cultural and psychological behavioural make-up of localities and regions has the potential to provide new insights into expected development outcomes as well as the forms of policy intervention that are required within regions and localities, each of which has its own individual psychocultural character