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

Organizational sensegiving: Indicators and nonprofit signaling

Resource acquisition depends upon the agreement between an organization's sense of identity and the perceptions of organizational identity held by resource providers. To smooth the flow of resources and buffer against potential issues, organizations seek to manage external perceptions and, to the extent possible, control their organizational identity. Using exploratory factor analysis, we examine the data from 300 GuideStar profiles to develop a sense of how nonprofit organizations “give sense” to resource providers and attempt to manage their organizational identity. We find evidence of three sensegiving strategies. We then use a seemingly unrelated regression model to examine the relationship between these strategies and revenue outcomes, finding evidence that (a) nonprofit organizations demonstrate intentional sensegiving, and (b) different sensegiving approaches are related to different income streams

A systematic review and meta-analysis of diagnostic delay in pulmonary embolism

BACKGROUND: Diagnostic delay in patients with pulmonary embolism (PE) is typical, yet the proportion of patients with PE that experienced delay and for how many days is less well described, nor are determinants for such delay. OBJECTIVES: This study aimed to assess the prevalence and extent of delay in diagnosing PE. METHODS: A systematic literature search was performed to identify articles reporting delays in diagnosing PE. The primary outcome was mean delay (in days) or a percentage of patients with diagnostic delay (defined as PE diagnosis more than seven days after symptom onset). The secondary outcome was determinants of delay. Random-effect meta-analyses were applied to calculate a pooled estimate for mean delay and to explore heterogeneity in subgroups. RESULTS: The literature search yielded 10,933 studies, of which 24 were included in the final analysis. The pooled estimate of the mean diagnostic delay based on 12 studies was 6.3 days (95% prediction interval 2.5 to 15.8). The percentage of patients having more than seven days of delay varied between 18% and 38%. All studies assessing the determinants of coughing ( n  = 3), chronic lung disease ( n  = 6) and heart failure ( n  = 8) found a positive association with diagnostic delay. Similarly, all studies assessing recent surgery ( n  = 7) and hypotension ( n  = 6), as well as most studies assessing chest pain ( n  = 8), found a negative association with diagnostic delay of PE. CONCLUSION: Patients may have symptoms for almost one week before PE is diagnosed and in about a quarter of patients, the diagnostic delay is even longer

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