Scaling dependence on the fluid viscosity ratio in the selective withdrawal transition

In the selective withdrawal experiment fluid is withdrawn through a tube with its tip suspended a distance S above a two-fluid interface. At sufficiently low withdrawal rates, Q, the interface forms a steady state hump and only the upper fluid is withdrawn. When Q is increased (or S decreased), the interface undergoes a transition so that the lower fluid is entrained with the upper one, forming a thin steady-state spout. Near this transition the hump curvature becomes very large and displays power-law scaling behavior. This scaling allows for steady-state hump profiles at different flow rates and tube heights to be scaled onto a single similarity profile. I show that the scaling behavior is independent of the viscosity ratio.Comment: 33 Pages, 61 figures, 1 tabl

Design of plasma shutters for improved heavy ion acceleration by ultra-intense laser pulses

In this work, we investigate the application of the plasma shutters for heavy ion acceleration driven by a high-intensity laser pulse. We use particle-in-cell (PIC) and hydrodynamic simulations. The laser pulse, transmitted through the opaque shutter, gains a steep-rising front and its peak intensity is locally increased at the cost of losing part of its energy. These effects have a direct influence on subsequent ion acceleration from the ultrathin target behind the shutter. In our 3D simulations of silicon nitride plasma shutter and a silver target, the maximal energy of high-Z ions increases significantly when the shutter is included for both linearly and circularly polarized laser pulses. Moreover, application of the plasma shutter for linearly polarized pulse results in focusing of ions towards the laser axis in the plane perpendicular to the laser polarization. The generated high energy ion beam has significantly lower divergence compared to the broad ion cloud, generated without the shutter. The effects of prepulses are also investigated assuming a double plasma shutter. The first shutter can withstand the assumed sub-ns prepulse (treatment of ns and ps prepulses by other techniques is assumed) and the pulse shaping occursvia interaction with the second shutter. On the basis of our theoretical findings, we formulated an approach towards designing a double plasma shutter for high-intensity and high-power laser pulses and built a prototype.Comment: 30 pages 13 figure

Seasonal variation of contaminant concentrations in wastewater treatment works effluents and river waters.

Results are presented for 170 wastewater treatment works sites (20 per substance in influent, effluent and 36 per substance in river water upstream and downstream of the WwTW discharge) over a period of two years between 2015 and 2017; this comprises data for approximately 3000 samples for effluent and 6000 for river samples taken downstream of effluent discharges. Seasonal trends in contaminant concentrations for several substances are reported. Two clear patterns of seasonal variation are proposed over and above all of the variables associated with environmental data including process technology, dilution and geography. Firstly, variation of riverine concentrations caused by seasonal fluctuations in river flow (sewage flow being relatively consistent) resulting in summer maxima and winter minima. Alternatively, variation is observed that is attributable to the improved performance of wastewater treatment processes under warmer conditions. This leads to the lowest concentrations in autumn when surface water/sewage treatment temperatures tend to peak. Seasonality for trace contaminants is more difficult to characterise than that of sanitary parameters owing to the higher variability in the concentration of the substances of interest. The data also provide an insight into the amplitude of such variations. This makes it possible to assess the likely effects of seasonality and its impact on aquatic life. For example, the existence of seasonality (perhaps due only to dilution effects) might be demonstrated, but the amplitude might be too small in relation to the potential ecotoxicological effects to be of any consequence

Hydraulic control of a highly stratified estuarine front

Author Posting. © American Meteorological Society, 2005. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 35 (2005): 374-387, doi:10.1175/JPO-2692.1.Observations at the mouth of the Fraser River (British Columbia, Canada) indicate an abrupt frontal transition between unstratified river outflow and a highly stratified river plume with differences in salinity greater than 25 psu across a few meters in the vertical direction and several hundred meters in the horizontal direction. The front roughly follows a natural break in the bathymetry, crossing the channel at an angle of approximately 45°, and is essentially stationary for a period of approximately 3.5 h centered on the low tide following the larger of two daily ebbs. The location of the front is coincident with observations of significantly supercritical internal Froude numbers at the front, based on velocities in the along-flow direction. This observation contradicts the one-dimensional theory, which indicates that the Froude number should be 1. However, because the front is oriented obliquely to the outflow, a coordinate system can be selected that is normal to the front and for which a critical Froude number of 1 is obtained. This indicates that a Froude angle, similar in application to a Mach angle for transonic flows, can be used to determine critical conditions when the front is oblique to the principal flow direction.This work was performed as a part of D. MacDonald’s Ph.D. thesis, and was funded by Office of Naval Research Grants N000-14-97-10134 and N000-14-97- 10566, National Science Foundation Grant OCE- 9906787, a National Science Foundation graduate fellowship, and support from the WHOI Academic Programs Office

Antimicrobial peptide omiganan enhances interferon responses to endosomal toll-like receptor ligands in human peripheral blood mononuclear cells

LL-37 is a cationic antimicrobial peptide and the sole human member of cathelicidins. Besides its bactericidal properties, LL-37 is known to have direct immunomodulatory effects, among which enhancement of antiviral responses via endosomal toll-like receptors (TLRs). Omiganan pentahydrochloride is a synthetic cationic peptide in clinical development. Previously, omiganan was primarily known for its direct bactericidal and antifungal properties. We investigated whether omiganan enhances endosomal TLR responses, similar to LL-37. Human peripheral blood mononuclear cells were treated with endosomal TLR3, -7, -8, and -9 ligands in the presence of omiganan. Omiganan enhanced TLR-mediated interferon-alpha release. Subsequent experiments with TLR9 ligands showed that plasmacytoid dendritic cells were main contributors to omiganan-enhanced IFN production. Based on this type I interferon-enhancing effect, omiganan may qualify as potential treatment modality for virus-driven diseases. The molecular mechanism by which omiganan enhances endosomal TLR responses remains to be elucidated.Drug Delivery Technolog

Internet of things

Manual of Digital Earth / Editors: Huadong Guo, Michael F. Goodchild, Alessandro Annoni .- Springer, 2020 .- ISBN: 978-981-32-9915-3Digital Earth was born with the aim of replicating the real world within the digital world. Many efforts have been made to observe and sense the Earth, both from space (remote sensing) and by using in situ sensors. Focusing on the latter, advances in Digital Earth have established vital bridges to exploit these sensors and their networks by taking location as a key element. The current era of connectivity envisions that everything is connected to everything. The concept of the Internet of Things(IoT)emergedasaholisticproposaltoenableanecosystemofvaried,heterogeneous networked objects and devices to speak to and interact with each other. To make the IoT ecosystem a reality, it is necessary to understand the electronic components, communication protocols, real-time analysis techniques, and the location of the objects and devices. The IoT ecosystem and the Digital Earth (DE) jointly form interrelated infrastructures for addressing today’s pressing issues and complex challenges. In this chapter, we explore the synergies and frictions in establishing an efficient and permanent collaboration between the two infrastructures, in order to adequately address multidisciplinary and increasingly complex real-world problems. Although there are still some pending issues, the identified synergies generate optimism for a true collaboration between the Internet of Things and the Digital Earth

Exchange flow between open water and floating vegetation

This study describes the exchange flow between a region with open water and a region with a partial-depth porous obstruction, which represents the thermally-driven exchange that occurs between open water and floating vegetation. The partial-depth porous obstruction represents the root layer, which does not penetrate to the bed. Initially, a vertical wall separates the two regions, with fluid of higher density in the obstructed region and fluid of lower density in the open region. This density difference represents the influence of differential solar heating due to shading by the vegetation. For a range of root density and root depths, the velocity distribution is measured in the lab using PIV. When the vertical wall is removed, the less dense water flows into the obstructed region at the surface. This surface flow bifurcates into two layers, one flowing directly through the root layer and one flowing beneath the root layer. A flow directed out of the vegetated region occurs at the bed. A model is developed that predicts the flow rates within each layer based on energy considerations. The experiments and model together suggest that at time- and length-scales relevant to the field, the flow structure for any root layer porosity approaches that of a fully blocked layer, for which the exchange flow occurs only beneath the root layer.National Science Foundation (U.S.) (grant EAR0509658