Capillary focusing close to a topographic step: Shape and instability of confined liquid filaments

Step-emulsification is a microfluidic technique for droplet generation which relies on the abrupt decrease of confinement of a liquid filament surrounded by a continuous phase. A striking feature of this geometry is the transition between two distinct droplet breakup regimes, the "step-regime" and "jet-regime", at a critical capillary number. In the step-regime, small and monodisperse droplets break off from the filament directly at a topographic step, while in the jet-regime a jet protrudes into the larger channel region and large plug-like droplets are produced. We characterize the breakup behavior as a function of the filament geometry and the capillary number and present experimental results on the shape and evolution of the filament for a wide range of capillary numbers in the jet-regime. We compare the experimental results with numerical simulations. Assumptions based on the smallness of the depth of the microfluidic channel allow to reduce the governing equations to the Hele-Shaw problem with surface tension. The full nonlinear equations are then solved numerically using a volume-of-fluid based algorithm. The computational framework also captures the transition between both regimes, offering a deeper understanding of the underlying breakup mechanism

A digital simulation of message traffic for natural disaster warning communications satellite

Various types of weather communications are required to alert industries and the general public about the impending occurrence of tornados, hurricanes, snowstorms, floods, etc. A natural disaster warning satellite system has been proposed for meeting the communications requirements of the National Oceanic and Atmospheric Administration. Message traffic for a communications satellite was simulated with a digital computer in order to determine the number of communications channels to meet system requirements. Poisson inputs are used for arrivals and an exponential distribution is used for service

Investigations on alternative substances for control of apple scab - Results from Conidia germinating tests and experiments with plant extracts

The intention of this research project, which was supported within the "Bundesprogramm Ökologischer Landbau", was to find alternatives for the control of Venturia inaequalis for the organic fruitgrower. Beside the investigations on reducing the ascospore potential on fallen leaves, experiments were conducted in laboratory, greenhouses and in orchard to test direct control of scab with different plant extracts, concentrations and methods of extraction. Extracts from Inula viscosa, Quillaja saponaria-bark, citrus-species (AGROMIL) and Saponaria officinalis revealed a distinct efficacy against apple scab in greenhouse studies on apple seedlings. ELOT-VIS, CHITOPLANT, COMCAT, MOOSEXTRAKT, SILIOPLANT und FZB 24 did not show sufficient efficacy with the application schedule used for control of scab. Mixtures of Quillaja-saponine and sulphur reduced effectively apple scab incidence. In an experiment concerning rain stability Citrus-extract and Quillaja-saponine showed a lower efficacy against scab after a simulated rain of 5 mm. The screening of different supplements to Citrus-extract as surfactants and adhesives revealed GREEMAX and BIOPLUSS as promising additives. Both combinations showed an efficacy comparable to copperoxychloride corresponding to 400 g elementary copper per ha

On the uniqueness of community banks

To the public, all banks seem alike. But banking insiders make important distinctions between community banks and all other banks. Policymakers worry that community banks’ unique characteristics threaten their survival in the face of industry consolidation. However, despite dramatic regulatory and technological changes in the industry in the past two decades, community banks have not only survived but often prospered. ; This article explores the differences between community banks and larger banks to discover what makes community banks unique. Large banks engage primarily in transactional banking—the provision of highly standardized intermediation services, such as gathering deposits and extending loans, that require little human input to manage. Community banks, in contrast, typically focus on relationship banking, which requires more human input, more detailed credit evaluation, and localized decision making. ; Examining profit and risk measures for the 1998–2002 period for both community banks and large banking organizations, the authors find evidence that small banks were generally profitable. In all but the smallest size category, community banks have performed as well as, and often better than, large banks in managing net interest margins, aggregate profits, and credit risk. Also, community banks are more likely to adopt Subchapter S tax status, which allows them to avoid direct federal income taxation and pass tax benefits on to shareholders. These institutions typically have relatively higher returns on both equity and assets than larger banks do. Whether community banks will be able to sustain this good performance will depend, the authors conclude, on how well managers find valuable relationship lending niches, invest bank capital, and balance asset quality with growth.Community banks

Investigations on alternative substances for control of apple scab - results from sanitation trials

The intention of this research project, which was supported within the "Bundesprogramm Ökologischer Landbau", was to look for alternatives in organic fruit growing to control apple scab, Venturia inaequalis. One important part of the investigations was the application of different substances like microbiological nutrient media, enzymes usually used for production of fruit juices and organic fertilizers on their effect on the ascospore potential on depots of fallen leaves. Some substances like TRYPTIC SOY BROTH increased the decomposition of the leaves significantly, other like BACTOFIL B and HUMOFIX showed nearly no effect on the decomposition, but reduced the ascospore potential in early spring by 80 % compared to the untreated control

The design, implementation and evaluation of mass conferencing

There have been attempts to classify and analyse the approaches and techniques of using videoconferencing for teaching and learning. Most classifications include the use of videoconferencing techniques to support lecture‐style delivery to large audiences, or what might be referred to as ‘mass conferencing’. This is often dismissed by sceptics as another gimmick: the real thing is better, or it may be viewed as simply just another didactic approach with little to commend it either in the form of communication or in pedagogical terms. However, the key element in its use is the context within which the mass conferencing is being applied Whatever videoconferencing approaches are employed, it is our view that their successful implementation implies both a clearly defined structure and an operational template. Thus, this paper underlines some of the processes which we have used in mass conferencing. We then evaluate the outcomes, and identify, some themes to be incorporated in successful mass conferencing, including the key factors involved in successful delivery, namely in the preparation, activity, and evaluation stages. In operational terms, the introduction of an external element, beyond the control of course tutors, has highlighted many organizational, pedagogical and technical questions, some of which we address

Irreversibility line and low-field grain-boundary pinning in electron-doped superconducting thin films

AC magnetic susceptibilities of electron-doped Pr_{1.85}Ce_{0.15}CuO_4 (PCCO) and Sm_{1.85}Ce_{0.15}CuO_4 (SCCO) granular thin films have been measured as a function of temperature and magnetic-field strength. Depending on the level of homogeneity of our films, two different types of the irreversibility line (IL) defined as the intergrain-loss peak temperature in the imaginary part of susceptibility have been found. The obtained results are described via the critical-state model taking into account the low-field grain-boundary pinning. The extracted pinning-force densities in more granular SCCO films turn out to be four times larger than their counterparts in less granular PCCO films