RESUMO
3D and 2D seismic data reveal the base-reflection of the Quaternary in the northwestern German North Sea locally at depths of more than 1000 m. This indicates extremely fast subsidence, with a rate of up to 480 m/Ma during the Quaternary, resulting in a NNW-SSE oriented sedimentary depocentre. Distinct iceberg scour marks, identified in 3D seismic data are used to calibrate quantitative subsidence analysis and to document shallow marine conditions during the Quaternary interglacials. Previously, a number of mechanisms have been proposed to explain the Quaternary subsidence. Here we show that compaction and load-induced subsidence alone explain about 75% of the observed Quaternary subsidence. However, a certain portion of the subsidence needs additional processes to be invoked. The extensive seismic dataset interpreted here makes it possible to exclude a phase of renewed tectonic activity as the origin of the subsidence anomaly. From the orientation and extent of the depocentre, lithosphere buckling and subsidence due to salt movement are considered unlikely. Possibly a post-glacial collapse after the retreat of glaciers in the North Sea Basin, local lower crustal flow, or dynamic topography or a combination of these processes contributed to the residual subsidence.
RESUMO
We prepared bicontinuous composite membranes comprising zeolite A particles. The particles form a monolayer which is embedded in a polymer sheet in such a way that each particle penetrates both surfaces of the polymer sheet. Preparation was done via "float casting"; a mixture of hydrophobized zeolite particles and an appropriate volume of a nonvolatile polymerizable organic liquid monomer was applied onto a water surface. The monomer was solidified via photopolymerization to form the above-mentioned membrane. In as-prepared state (without extensive drying), this membrane is permeable for water vapor (in case of zeolite 4A permeance = 8 × 10(-9) mol m(-2) s(-1) Pa(-1), permeability = 1.65 × 10(-14) mol m(-1) s(-1) Pa(-1) = 49 barrer) but impermeable for nitrogen (permeance below detection limit of 5 × 10(-12) mol m(-2) s(-1) Pa(-1), permeability below detection limit of 1 × 10(-17) mol m(-1) s(-1) Pa(-1) = 0.03 barrer). The permeance for water vapor increases with increasing pore size of the zeolite (in case of zeolite 5A, all other parameters being unchanged, permeance = 12 × 10(-9) mol m(-2) s(-1) Pa(-1), permeability = 2.4 × 10(-14) mol m(-1) s(-1) Pa(-1) = 72 barrer). These observations indicate that the water molecules are predominantly transported through the zeolite channels and at the same time block the passage of other molecules. The impermeability for nitrogen in as-prepared state indicates a low amount of defects that are not blocked by water. Furthermore, the composite nature of the membrane gives rise to a reduced brittleness; membranes can be handled manually without support structure and thus might be promising candidates for separation technology.
RESUMO
In this study self-organizing maps (SOM) were utilized for spatiotemporal analysis and classification of body surface potential mapping (BSPM) data. Altogether 86 cardiac depolarization (QRS) sequences paced by a catheter in 18 patients were included. Spatial BSPM distributions at every 5 ms over the QRS complex were first presented to an untrained SOM. The learning process of the SOM units organized the maps in such a way that similar BSPMs are represented in particular areas of the SOM network. Thereafter, time trajectories and distance maps were created on the trained SOM from sequential maps in a selected paced QRS. The trajectories and distance maps can be applied as such for the localization of abnormal ventricular activation, as well as quantitative input for statistical classification. The results indicate that the method has potential for locating endocardial sites of abnormal ventricular activation, despite the patient material being too limited to provide a reliable statistical evaluation of the source localization accuracy.
