Passive water control at the surface of a superhydrophobic lichen

Some lichens have a super-hydrophobic upper surface, which repels water drops, keeping the surface dry but probably preventing water uptake. Spore ejection requires water and is most efficient just after rainfall. This study was carried out to investigate how super-hydrophobic lichens manage water uptake and repellence at their fruiting bodies, or podetia. Drops of water were placed onto separate podetia of Cladonia chlorophaea and observed using optical microscopy and cryo-scanning-electron microscopy (cryo-SEM) techniques to determine the structure of podetia and to visualise their interaction with water droplets. SEM and optical microscopy studies revealed that the surface of the podetia was constructed in a three-level structural hierarchy. By cryo-SEM of water-glycerol droplets placed on the upper part of the podetium, pinning of the droplet to specific, hydrophilic spots (pycnidia/apothecia) was observed. The results suggest a mechanism for water uptake, which is highly sophisticated, using surface wettability to generate a passive response to different types of precipitation in a manner similar to the Namib Desert beetle. This mechanism is likely to be found in other organisms as it offers passive but selective water control

Problems with Adaptation of Post-Accession Polish Migrants in Countries of the EU

Starting from 1st May, 2004 countries of European Fifteen have gradually opened their labour markets for the new EU members, including the Poles. The first to take this step was Great Britain, Ireland and Sweden, the last - Germany and Austria. For the new EU citizens, emerging opportunities were connected with benefits and wide possibilities, but also with limitations and adaptation difficulties. They had to deal with the language barrier as much as the different culture, accepted behaviours, traditions, work culture and model of spending leisure time. Mentality of migrants – whether they were able or not to immerse into the “new” – had impact on finding themselves in another environment. Most of those, who left Poland did not plan to settle, they were leaving “for some time”, temporarily. Mentally, they were still connected with previous place of residence, more interested in environment left behind than new one. Such behaviour was not conducive to adaptation; on the contrary, it made adaptation harder. Migrants through listening to Polish radio, watching Polish television stations, using the Polish Internet portals and reading national press, separated themselves from the new environment. All of these was due to the assumption that engaging in new place has no point since their stay is only temporary. Their attitude to the kind of work and workplace was similar. Majority of migrants from the EU-8 countries was taking up secondary employment, regardless of educational background. Wages comparable with Polish were supposed to compensate depreciation on the labour market. A wide spectrum of adaptation problems of Polish migrants is an issue raised in reports prepared by specialized research institutions, the Polish Ministry of Foreign Affairs and Polish Community organisations

Local mean-field study of capillary condensation in silica aerogels

We apply local mean-field (i.e. density functional) theory to a lattice model of a fluid in contact with a dilute, disordered gel network. The gel structure is described by a diffusion-limited cluster aggregation model. We focus on the influence of porosity on both the hysteretic and the equilibrium behavior of the fluid as one varies the chemical potential at low temperature. We show that the shape of the hysteresis loop changes from smooth to rectangular as the porosity increases and that this change is associated to disorder-induced out-of-equilibrium phase transitions that differ on adsorption and on desorption. Our results provide insight in the behavior of $^4$He in silica aerogels.Comment: 19 figure

No self-similar aggregates with sedimentation

Two-dimensional cluster-cluster aggregation is studied when clusters move both diffusively and sediment with a size dependent velocity. Sedimentation breaks the rotational symmetry and the ensuing clusters are not self-similar fractals: the mean cluster width perpendicular to the field direction grows faster than the height. The mean width exhibits power-law scaling with respect to the cluster size, ~ s^{l_x}, l_x = 0.61 +- 0.01, but the mean height does not. The clusters tend to become elongated in the sedimentation direction and the ratio of the single particle sedimentation velocity to single particle diffusivity controls the degree of orientation. These results are obtained using a simulation method, which becomes the more efficient the larger the moving clusters are.Comment: 10 pages, 10 figure

Block-Diagonalization and f-electron Effects in Tight-Binding Theory

We extend a tight-binding total energy method to include f-electrons, and apply it to the study of the structural and elastic properties of a range of elements from Be to U. We find that the tight-binding parameters are as accurate and transferable for f-electron systems as they are for d-electron systems. In both cases we have found it essential to take great care in constraining the fitting procedure by using a block-diagonalization procedure, which we describe in detail.Comment: 9 pages, 6 figure

Soccer or Football: The Level Playing Field Idea for the European Single Market in the Audiovisual Media Services

Article published in the Michigan State International Law Review

Weathering of Zinc-(Zn)-bearing Mine Wastes in a Neutral Mine Drainage Setting, Gunnerside Gill, Yorkshire

This is the final version of the article. Available from Elsevier via the DOI in this record.Numerous areas throughout the world are affected by circum-neutral pH, low iron (Fe) drainage with high concentrations of zinc (Zn) arising from discharges from, and weathering of, mine wastes. Gunnerside Gill, a small upland tributary in the headwaters of the River Swale in Yorkshire, is such a site affected by historic lead and zinc mining. The aim of the study is to assess the controls on Zn mobilisation from the mine tailings and floodplain sediments to the river water through a column leaching experiment. Sphalerite has been identified as the primary Zn mineral in the bedrock within Gunnerside Gill. However, there is more evidence of secondary phases of Zn were including Fe oxides and phosphates present within the samples and the BCR data suggests it is these phases that appear to be undergoing the majority of the Zn dissolution