ALBERT

Description: Author(s): G. Tomaka, J. Grendysa, P. Śliż, C. R. Becker, J. Polit, R. Wojnarowska, A. Stadler, and E. M. Sheregii Experimental results of the magnetotransport measurements (longitudinal magnetoresistance R x x and the Hall resistance R x y ) are presented over a wide interval of temperatures for several samples of Hg 1 − x Cd x Te ( x ≈ 0.13 – 0.15 ) grown by MBE—thin layers (thickness about 100 nm) strained and not strained an… [Phys. Rev. B 93, 205419] Published Wed May 11, 2016

Description: Author(s): F. Deuretzbacher, D. Becker, J. Bjerlin, S. M. Reimann, and L. Santos We show that strongly interacting multicomponent gases in one dimension realize an effective spin chain, offering an alternative simple scenario for the study of one-dimensional (1D) quantum magnetism in cold gases in the absence of an optical lattice. The spin-chain model allows for an intuitive un... [Phys. Rev. A 90, 013611] Published Mon Jul 14, 2014

Description: Author(s): F. Deuretzbacher, D. Becker, J. Bjerlin, S. M. Reimann, and L. Santos Strongly interacting one-dimensional (1D) Bose–Fermi mixtures form a tunable X X Z spin chain. Within the spin-chain model developed here, all properties of these systems can be calculated from states representing the ordering of the bosons and fermions within the atom chain and from the ground-state … [Phys. Rev. A 95, 043630] Published Fri Apr 21, 2017

Description: Author(s): P. Scholz, A. Endres, A. Hennig, L. Netterdon, H. W. Becker, J. Endres, J. Mayer, U. Giesen, D. Rogalla, F. Schlüter, S. G. Pickstone, K. O. Zell, and A. Zilges Background: Uncertainties in adopted models of particle+nucleus optical-model potentials directly influence the accuracy in the theoretical predictions of reaction rates as they are needed for reaction-network calculations in, for instance, γ-process nucleosynthesis. The improvement of the α+nucleus... [Phys. Rev. C 90, 065807] Published Mon Dec 22, 2014

Description: The interaction between sea waves and a deformable sea-bed is studied with a simple two-layer model in which the upper-layer fluid is inviscid and the lower-layer fluid is bi-viscous to account for non-Newtonian behaviour of sand and sediments. The nonlinear response of the system to periodic forcing by an external surface pressure is determined. It is shown that a simple bi-viscous rheology allows small wavelength morphology in the lower layer to be generated from large wavelength surface waves in the upper inviscid layer, although the morphology is not permanent. For a bi-viscous rheology with a pressure-dependent yield stress (which accounts for the fact that sand yields less readily under loading than unloading), however, small wavelength and permanent features are formed in the seabed.

Description: The coupled interaction of long standing hydrodynamic waves with a deformable non-Newtonian seabed is examined using a two-layer model for which the upper layer fluid is inviscid and the lower layer is bi-viscous. The two-dimensional response of the system to forcing by a predominantly longitudinal (cross-shore) standing wave perturbed by a small transverse (along-shore) component is determined. With a constant yield stress in the bi-viscous lower layer, there is little amplification of these transverse per-turbations and the model response typically remains quasi-one-dimensional. However, for a bi-viscous layer with a pressure-dependent yield stress (which represents the effect that the seabed deforms less readily under compression and hence renders the rheology history dependent), the initially small transverse motions are amplified in some parameter regimes and two-dimensional, permanent bedforms are formed in the lower layer. This simple dynamical model is, therefore, able to explain the formation of permanent bedforms with significant cross- and along-shore features by predominantly cross-shore standing wave forcing.

Description: The Mw = 9.3 Sumatra earthquake of 26 December 2004 generated a tsunami that affected the entire Indian Ocean region and caused approximately 230 000 fatalities. In the response to this tragedy the German government funded the German Indonesian Tsunami Early Warning System (GITEWS) Project. The task of the GEOFON group of GFZ Potsdam was to develop and implement the seismological component. In this paper we describe the concept of the GITEWS earthquake monitoring system and report on its present status. The major challenge for earthquake monitoring within a tsunami warning system is to deliver rapid information about location, depth, size and possibly other source parameters. This is particularly true for coast lines adjacent to the potential source areas such as the Sunda trench where these parameters are required within a few minutes after the event in order to be able to warn the population before the potential tsunami hits the neighbouring coastal areas. Therefore, the key for a seismic monitoring system with short warning times adequate for Indonesia is a dense real-time seismic network across Indonesia with densifications close to the Sunda trench. A substantial number of supplementary stations in other Indian Ocean rim countries are added to strengthen the teleseismic monitoring capabilities. The installation of the new GITEWS seismic network – consisting of 31 combined broadband and strong motion stations – out of these 21 stations in Indonesia – is almost completed. The real-time data collection is using a private VSAT communication system with hubs in Jakarta and Vienna. In addition, all available seismic real-time data from the other seismic networks in Indonesia and other Indian Ocean rim countries are acquired also directly by VSAT or by Internet at the Indonesian Tsunami Warning Centre in Jakarta and the resulting "virtual" network of more than 230 stations can jointly be used for seismic data processing. The seismological processing software as part of the GITEWS tsunami control centre is an enhanced version of the widely used SeisComP software and the well established GEOFON earthquake information system operated at GFZ in Potsdam (http://geofon.gfz-potsdam.de/db/eqinfo.php). This recently developed software package (SeisComP3) is reliable, fast and can provide fully automatic earthquake location and magnitude estimates. It uses innovative visualization tools, offers the possibility for manual correction and re-calculation, flexible configuration, support for distributed processing and data and parameter exchange with external monitoring systems. SeisComP3 is not only used for tsunami warning in Indonesia but also in most other Tsunami Warning Centres in the Indian Ocean and Euro-Med regions and in many seismic services worldwide.

Description: Litterfall is one of the major pathways connecting above- and belowground processes. The effects of climate and land-use change on carbon (C) and nutrient inputs by litterfall are poorly known. We quantified and analyzed annual patterns of C and nutrient deposition via litterfall in natural forests and agroforestry systems along the unique elevation gradient of Mt. Kilimanjaro. Tree litter in three natural (lower montane, Ocotea and Podocarpus forests), two sustainably used (homegardens) and one intensively managed (shaded coffee plantation) was collected on a biweekly basis from May 2012 to July 2013. Leaves, branches and remaining residues were separated and analyzed for C and nutrient contents. The annual pattern of litterfall was closely related to rainfall seasonality, exhibiting a large peak towards the end of the dry season (August–October). This peak decreased at higher elevations with decreasing rainfall seasonality. Macronutrients (N, P, K) in leaf litter increased at mid elevation (2100 m a.s.l.) and with land-use intensity. Carbon content and micronutrients (Al, Fe, Mn, Na) however, were unaffected or decreased with land-use intensity. On the southern slope of Mt. Kilimanjaro, the annual pattern of litterfall depends on seasonal climatic conditions. While leaf litterfall decreased with elevation, total annual input was independent of climate. Compared to natural forests, the nutrient cycles in agroforestry ecosystems were accelerated by fertilization and the associated changes in dominant tree species.

Description: Litterfall is one of the major pathways connecting above- and below-ground processes. The effects of climate and land-use change on carbon (C) and nutrient inputs by litterfall are poorly known. We quantified and analyzed annual patterns of C and nutrient deposition via litterfall in natural forests and agroforestry systems along the unique elevation gradient of Mt. Kilimanjaro. Tree litter in three natural (lower montane, Ocotea and Podocarpus forests), two sustainably used (homegardens) and one intensively managed (shaded coffee plantation) ecosystems was collected on a biweekly basis from May 2012 to July 2013. Leaves, branches and remaining residues were separated and analyzed for C and nutrient contents. The annual pattern of litterfall was closely related to rainfall seasonality, exhibiting a large peak towards the end of the dry season (August–October). This peak decreased at higher elevations with decreasing rainfall seasonality. Macronutrients (N, P, K) in leaf litter increased at mid elevation (2100 m a.s.l.) and with land-use intensity. Carbon content and micronutrients (Al, Fe, Mn, Na) however, were unaffected or decreased with land-use intensity. While leaf litterfall decreased with elevation, total annual input was independent of climate. Compared to natural forests, the nutrient cycles in agroforestry ecosystems were accelerated by fertilization and the associated changes in dominant tree species.

Description: Im Folgenden wird eine neue Methodik von FPAAs (Field Programmable Analog Arrays) gezeigt, die speziell für die Instantiierung von zeitkontinuierlichen (continuous-time, CT) Analogfiltern in Hardware entwickelt wurde. Die Chiptopologie beinhaltet 17 digital konfigurierbare analoge Blöcke (configurable analog blocks, CABs), die durch ein hexagonales Netzwerk miteinander verbunden sind. Jeder CAB ist aus einstellbaren Gm-C Integratoren aufgebaut, welche das analoge Signal sowohl formen und seinen Weg durch die Matrix festlegen, gleichzeitig aber auch die Grundbausteine für zeitkontinuierliche Hochfrequenzfilter darstellen. Intelligente Pufferspeicher für die Ein-/Ausgänge (IO-buffer) garantieren die Rekonfigurierung der Matrix mit minimaler Störung des kontinuierlichen Analogsignals. Die Architektur wird als Hardwareplattform für beliebige Schaltungen, welche aus einer gegebenen Anzahl an Gm-C-Zellen bestehen, eingeführt und verifiziert bevor eine exemplarische Instantiierung eines Butterworth Filters 4. Ordnung in Biquad Anordnung gezeigt wird.