How do microorganisms reach the stratosphere?

A number of studies have demonstrated that bacteria and fungi are present in the stratosphere. Since the tropopause is generally regarded as a barrier to the upward movement of particles it is difficult to see how such microorganisms can reach heights above 17 km. Volcanoes provide an obvious means by which this could be achieved, but these occur infrequently and any microorganisms entering the stratosphere from this source will rapidly fall out of the stratosphere. Here, we suggest mechanisms by which microorganisms might reach the stratosphere on a more regular basis; such mechanisms are, however, likely only to explain how micrometre to submicrometre particles could be elevated into the stratosphere. Intriguingly, clumps of bacteria of size in excess of 10 μm have been found in stratospheric samples. It is difficult to understand how such clumps could be ejected from the Earth to this height, suggesting that such bacterial masses may be incoming to Earth. We suggest that the stratospheric microflora is made up of two components: (a) a mixed population of bacteria and fungi derived from Earth, which can occasionally be cultured; and (b) a population made up of clumps of, viable but non-culturable, bacteria which are too large to have originated from Earth; these, we suggest, have arrived in the stratosphere from space. Finally, we speculate on the possibility that the transfer of bacteria from the Earth to the highly mutagenic stratosphere may have played a role in bacterial evolution

Level correlations in integrable systems

We derive a simple analytical expression for the level correlation function of an integrable system. It accounts for both the lack of correlations at smaller energy scales and for global rigidity (level number conservation) at larger scales. We apply our results to a rectangle with incommensurate sides and show that they are in excellent agreement with the limiting cases established in the semiclassical theory of level rigidity.Comment: 5 page

Membrane distillation for treating hydraulic fracturing produced waters

The reuse of wastewater for beneficial uses has become increasingly important in recent years. There is an urgent need to develop innovative and more effective technologies for treatment of wastewaters. Many of these wastewaters such as hydraulic fracturing produced waters, contain very high total dissolved solids (TDS). Treatment of hydraulic fracturing produced waters can be very challenging as not only can they exhibit very high TDS, in excess of 200,000 ppm, they also contain surfactants and small organic compounds. Pressure driven membrane processes such as reverse osmosis are impractical for treating very high salinity wastewaters due to the high osmotic back pressure that must be overcome. Membrane distillation has been proposed as a new unit operation for treatment of very high TDS wastewaters. Vapor pressure is the driving force for water recovery in membrane distillation. An advantages of membrane distillation is the fact that low grade waste heat may be used. Here we have screened a number of commercially available microporous hydrophobic membranes. We have characterized membrane surface as well as bulk properties. Using bulk membrane properties, we calculate a structural parameter that indicates membranes that display high permeate flux. Next these membranes were challenged with feed streams containing 100,000 ppm (1.7 M) NaCl. The feeds stream was concentrated until breakthrough of the feed liquid into the permeate. Breakthrough occurred when the permeate flux rose rapidly while the conductivity of the permeate increased above 50 mS cm-1. Finally, these membranes were tested with real produced waters. Membranes that enabled the greatest concentration of TDS were selected for testing. While membrane distillation could be used to concentrate the feed to the solubility limit of the dissolved species present, leakage of feed water through the membrane pores into the distillate often occurs well before this level of water recovery. Leakage occurs due the presence of oil and suspended solids in the feed which can adsorb on the membrane surface. Thus pretreatment of the feed is essential. Here we have investigated the use of electrocoagulation as a pretreatment step for membrane distillation. Suspended solids and oil can be effectively coagulated followed by sedimentation prior to membrane distillation. A laboratory scale electrocoagulation system containing aluminum electrodes was designed, optimized and employed successfully to pretreat the feed. Please click Additional Files below to see the full abstract

Enabling superior m-health project success: a tricountry validation

The healthcare industry is facing increasing pressures to embrace new technologies that support greater patient access to, and higher quality of (but at the same time offer cost-effective), healthcare delivery. This pressure has spawned a plethora of initiatives to embrace the possibilities and potentials of technologies to develop and then diffuse new devices, new pharmaceutical products and support minimal invasive surgical techniques that will facilitate superior healthcare delivery

“Tell me what I should watch”: A customer value perspective of YouTube metadata

YouTube is increasingly being considered a lucrative means of earning money in addition to becoming popular among viewers. To gain these benefits YouTube content creators (YouTubers) need to first attract viewers’ attention to their videos and then persuade them to watch. YouTube metadata, such as the title, thumbnail, description, and keywords, can assist in achieving both objectives. This has been established in the current literature which shows, for example, that metadata optimizing can increase view counts. While these studies have demonstrated the end result of metadata optimization, they do not indicate why viewers respond to different characteristics of metadata in different ways. We contribute to the literature on marketing and consuming YouTube videos by examining, using Holbrook’s (1999) value typology for theorisation, how viewers experience the metadata and how these experiences contribute to the overall value creation process of watching YouTube videos. We employed an interpretive, qualitative research design in conducting the study, using focus group discussions with 21 young YouTube viewers as the data collection method. Data were analysed using thematic analysis. Key findings were that metadata can both deliver value (efficiency) and provide signals about values delivered through the video (excellence and aesthetics). Further, the play value viewers get from interacting with the video is indirectly influenced by the metadata. We also identified that although viewers commonly expect some characteristics in the title and thumbnail, irrespective of their purpose of using YouTube, the importance of each differs when they seek information or entertainment gratification. Further, when value promises made by the metadata are not delivered through the videos, viewers respond negatively. Keywords: Entertainment gratification, Information gratification, Metadata optimization, Value, YouTub