Uniqueness of black holes with bubbles in minimal supergravity

We generalize uniqueness theorems for non-extremal black holes with three mutually independent Killing vector fields in five-dimensional minimal supergravity in order to account for the existence of non-trivial two-cycles in the domain of outer communication. The black hole space-times we consider may contain multiple disconnected horizons and be asymptotically flat or asymptotically Kaluza–Klein. We show that in order to uniquely specify the black hole space-time, besides providing its domain structure and a set of asymptotic and local charges, it is necessary to measure the magnetic fluxes that support the two-cycles as well as fluxes in the two semi-infinite rotation planes of the domain diagram.

Characterization and performance of carbonaceous materials obtained from exhausted sludges for the anaerobic biodecolorization of the azo dye Acid Orange II.

This work presents the preliminary study of new carbonaceous materials (CMs) obtained from exhausted sludge, their use in the heterogeneous anaerobic process of biodecolorization of azo dyes and the comparison of their performance with one commercial active carbon. The preparation of carbonaceous materials was conducted through chemical activation and carbonization. Chemical activation was carried out through impregnation of sludge-exhausted materials with ZnCl2 and the activation by means of carbonization at different temperatures (400, 600 and 800°C). Their physicochemical and surface characteristics were also investigated. Sludge based carbonaceous (SBC) materials SBC400, SBC600 and SBC800 present values of 13.0, 111.3 and 202.0m(2)/g of surface area. Biodecolorization levels of 76% were achieved for SBC600 and 86% for SBC800 at space time (τ) of 1.0min, similar to that obtained with commercial activated carbons in the continuous anaerobic up-flow packed bed reactor (UPBR). The experimental data fit well to the first order kinetic model and equilibrium data are well represented by the Langmuir isotherm model. Carbonaceous materials show high level of biodecolorization even at very short space times. Results indicate that carbonaceous materials prepared from sludge-exhausted materials have outstanding textural properties and significant degradation capacity for treating textile effluents.

Blackfolds, plane waves and minimal surfaces

Minimal surfaces in Euclidean space provide examples of possible non-compact horizon geometries and topologies in asymptotically flat space-time. On the other hand, the existence of limiting surfaces in the space-time provides a simple mechanism for making these configurations compact. Limiting surfaces appear naturally in a given space-time by making minimal surfaces rotate but they are also inherent to plane wave or de Sitter space-times in which case minimal surfaces can be static and compact. We use the blackfold approach in order to scan for possible black hole horizon geometries and topologies in asymptotically flat, plane wave and de Sitter space-times. In the process we uncover several new configurations, such as black helicoids and catenoids, some of which have an asymptotically flat counterpart. In particular, we find that the ultraspinning regime of singly-spinning Myers-Perry black holes, described in terms of the simplest minimal surface (the plane), can be obtained as a limit of a black helicoid, suggesting that these two families of black holes are connected. We also show that minimal surfaces embedded in spheres rather than Euclidean space can be used to construct static compact horizons in asymptotically de Sitter space-times.

Characterization of granite matrix porosity and pore-space geometry by in situ and laboratory methods

Most available studies of interconnected matrix porosity of crystalline rocks are based on laboratory investigations; that is, work on samples that have undergone stress relaxation and were affected by drilling and sample preparation. The extrapolation of the results to in situ conditions is therefore associated with considerable uncertainty, and this was the motivation to conduct the ‘in situ Connected Porosity’ experiment at the Grimsel Test Site (Central Swiss Alps). An acrylic resin doped with fluorescent agents was used to impregnate the microporous granitic matrix in situ around an injection borehole, and samples were obtained by overcoring. The 3-D structure of the porespace, represented by microcracks, was studied by U-stage fluorescence microscopy. Petrophysical methods, including the determination of porosity, permeability and P -wave velocity, were also applied. Investigations were conducted both on samples that were impregnated in situ and on non-impregnated samples, so that natural features could be distinguished from artefacts. The investigated deformed granites display complex microcrack populations representing a polyphase deformation at varying conditions. The crack population is dominated by open cleavage cracks in mica and grain boundary cracks. The porosity of non-impregnated samples lies slightly above 1 per cent, which is 2–2.5 times higher than the in situ porosity obtained for impregnated samples. Measurements of seismic velocities (Vp ) on spherical rock samples as a function of confining pressure, spatial direction and water saturation for both non-impregnated and impregnated samples provide further constraints on the distinction between natural and induced crack types. The main conclusions are that (1) an interconnected network of microcracks exists in the whole granitic matrix, irrespective of the distance to ductile and brittle shear zones, and (2) conventional laboratory methods overestimate the matrix porosity. Calculations of contaminant transport through fractured media often rely on matrix diffusion as a retardation mechanism.

Wetland-Archaeology in the Alpine Space. Overview and actual research issues.

First indications of prehistoric sites in lakes of Switzerland go back more than 200 years and in 1854 Ferdinand Keller (1800-1881) published his famous book The Celtic Pile Dwellings in Swiss Lakes. Since these times, large-scale rescue excavations as well as survey and research projects have extended our knowledge about Neolithic and Bronze Age settlements in lakes, bogs and rivers around the European Alps. In 2011 a representative choice of 111 sites out of nearly 1000 in six countries around the Alps (Austria, France, Germany, Italy, Slovenia and Switzerland) were recognized by the UNESCO World Heritage committee as serial World Heritage. The lecture will give a general overview on prehistoric lake dwellings around the Alps (distribution, types of lakes/bogs and environment of sites, chronology/cultural units in the time scale 5300 to 800 BC) and present examples of well-documented settlement structures. The intense use of dendrochronological dating allowed the building up of a well-fixed chronological framework. In some cases dendrochronology is the basis for year-by-year reconstructions of prehistoric village biographies and detailed insights in the life cycle of early agrarian settlements. Beside these local events the grouped repartition of lake dwelling remains on the time scale makes a more global correlation between Holocene lake levels and the preservation of archaeological layers likely.