@phdthesis{Zoeller2005, author = {Z{\"o}ller, Gert}, title = {Critical states of seismicity : modeling and data analysis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-7427}, school = {Universit{\"a}t Potsdam}, year = {2005}, abstract = {The occurrence of earthquakes is characterized by a high degree of spatiotemporal complexity. Although numerous patterns, e.g. fore- and aftershock sequences, are well-known, the underlying mechanisms are not observable and thus not understood. Because the recurrence times of large earthquakes are usually decades or centuries, the number of such events in corresponding data sets is too small to draw conclusions with reasonable statistical significance. Therefore, the present study combines both, numerical modeling and analysis of real data in order to unveil the relationships between physical mechanisms and observational quantities. The key hypothesis is the validity of the so-called "critical point concept" for earthquakes, which assumes large earthquakes to occur as phase transitions in a spatially extended many-particle system, similar to percolation models. New concepts are developed to detect critical states in simulated and in natural data sets. The results indicate that important features of seismicity like the frequency-size distribution and the temporal clustering of earthquakes depend on frictional and structural fault parameters. In particular, the degree of quenched spatial disorder (the "roughness") of a fault zone determines whether large earthquakes occur quasiperiodically or more clustered. This illustrates the power of numerical models in order to identify regions in parameter space, which are relevant for natural seismicity. The critical point concept is verified for both, synthetic and natural seismicity, in terms of a critical state which precedes a large earthquake: a gradual roughening of the (unobservable) stress field leads to a scale-free (observable) frequency-size distribution. Furthermore, the growth of the spatial correlation length and the acceleration of the seismic energy release prior to large events is found. The predictive power of these precursors is, however, limited. Instead of forecasting time, location, and magnitude of individual events, a contribution to a broad multiparameter approach is encouraging.}, subject = {Seismizit{\"a}t}, language = {en} } @article{Zaehle2005, author = {Z{\"a}hle, Henryk}, title = {Space-time regularity of catalytic super-Brownian motion}, year = {2005}, abstract = {The paper studies catalytic super-Brownian motion on the real line, where the branching rate is controlled by a catalyst. D. A. Dawson, K. Fleischmann and S. Roelly showed, for a broad class of catalysts, that, as for constant branching, the processes are absolutely continuous measures. This paper considers a class of catalysts, called moderate, which must satisfy a uniform boundedness condition and a condition controlling the degree of singularity---essentially that the mass of catalyst in small balls should (uniformly) be of order r^a, where a>0. The main result of this paper shows that for this class of catalysts there is a continuous density field for the process. Moreover the density is the unique solution (in law) of an appropriate SPDE.}, language = {en} } @incollection{Zollna2005, author = {Zollna, Isabel}, title = {Ohr und Hand : die Taquigraf{\´i}a castellana o arte de escribir con tanta velocidad como se habla (1803) von Francisco de Paula Mart{\´i}}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-9886}, publisher = {Universit{\"a}t Potsdam}, year = {2005}, language = {de} } @article{ZollerBethBinosietal.2005, author = {Zoller, Peter and Beth, Thomas and Binosi, D. and Blatt, Rainer and Briegel, Hans J. and Bruss, D. and Calarco, Tommaso and Cirac, Juan Ignacio and Deutsch, David and Eisert, Jens and Ekert, Artur and Fabre, Claude and Gisin, Nicolas and Grangiere, P. and Grassl, Markus and Haroche, Serge and Imamoglu, Atac and Karlson, A. and Kempe, Julia and Kouwenhoven, Leo P. and Kr{\"o}ll, S. and Leuchs, Gerd and Lewenstein, Maciej and Loss, Daniel and L{\"u}tkenhaus, Norbert and Massar, Serge and Mooij, J. E. and Plenio, Martin Bodo and Polzik, Eugene and Popescu, Sandu and Rempe, Gerhard and Sergienko, Alexander and Suter, David and Twamley, John and Wendin, G{\"o}ran and Werner, Reinhard F. and Winter, Andreas and Wrachtrup, J{\"o}rg and Zeilinger, Anton}, title = {Quantum information processing and communication : Strategic report on current status, visions and goals for research in Europe}, issn = {1434-6060}, year = {2005}, abstract = {We present an excerpt of the document "Quantum Information Processing and Communication: Strategic report on current status, visions and goals for research in Europe", which has been recently published in electronic form at the website of FET (the Future and Emerging Technologies Unit of the Directorate General Information Society of the European Commission, http://www.cordis.lu/ist/fet/qipc-sr.htm). This document has been elaborated, following a former suggestion by FET, by a committee of QIPC scientists to provide input towards the European Commission for the preparation of the Seventh Framework Program. Besides being a document addressed to policy makers and funding agencies (both at the European and national level), the document contains a detailed scientific assessment of the state-of-the-art, main research goals, challenges, strengths, weaknesses, visions and perspectives of all the most relevant QIPC sub-fields, that we report here}, language = {en} } @article{ZollerHolschneiderBenZion2005, author = {Zoller, Gert and Holschneider, Matthias and Ben-Zion, Yehuda}, title = {The role of heterogeneities as a tuning parameter of earthquake dynamics}, issn = {0033-4553}, year = {2005}, abstract = {We investigate the influence of spatial heterogeneities on various aspects of brittle failure and seismicity in a model of a large strike-slip fault. The model dynamics is governed by realistic boundary conditions consisting of constant velocity motion of regions around the fault, static/kinetic friction laws, creep with depth-dependent coefficients, and 3-D elastic stress transfer. The dynamic rupture is approximated on a continuous time scale using a finite stress propagation velocity ("quasidynamic model''). The model produces a "brittle- ductile'' transition at a depth of about 12.5 km, realistic hypocenter distributions, and other features of seismicity compatible with observations. Previous work suggested that the range of size scales in the distribution of strength-stress heterogeneities acts as a tuning parameter of the dynamics. Here we test this hypothesis by performing a systematic parameter-space study with different forms of heterogeneities. In particular, we analyze spatial heterogeneities that can be tuned by a single parameter in two distributions: ( 1) high stress drop barriers in near- vertical directions and ( 2) spatial heterogeneities with fractal properties and variable fractal dimension. The results indicate that the first form of heterogeneities provides an effective means of tuning the behavior while the second does not. In relatively homogeneous cases, the fault self-organizes to large-scale patches and big events are associated with inward failure of individual patches and sequential failures of different patches. The frequency-size event statistics in such cases are compatible with the characteristic earthquake distribution and large events are quasi-periodic in time. In strongly heterogeneous or near-critical cases, the rupture histories are highly discontinuous and consist of complex migration patterns of slip on the fault. In such cases, the frequency-size and temporal statistics follow approximately power-law relations}, language = {en} } @article{ZollerHainzlHolschneideretal.2005, author = {Zoller, Gert and Hainzl, Sebastian and Holschneider, Matthias and Ben-Zion, Yehuda}, title = {Aftershocks resulting from creeping sections in a heterogeneous fault}, issn = {0094-8276}, year = {2005}, abstract = {We show that realistic aftershock sequences with space-time characteristics compatible with observations are generated by a model consisting of brittle fault segments separated by creeping zones. The dynamics of the brittle regions is governed by static/kinetic friction, 3D elastic stress transfer and small creep deformation. The creeping parts are characterized by high ongoing creep velocities. These regions store stress during earthquake failures and then release it in the interseismic periods. The resulting postseismic deformation leads to aftershock sequences following the modified Omori law. The ratio of creep coefficients in the brittle and creeping sections determines the duration of the postseismic transients and the exponent p of the modified Omori law}, language = {en} } @phdthesis{Zobel2005, author = {Zobel, Alexander}, title = {Agilit{\"a}t im dynamischen Wettbewerb : Basisf{\"a}higkeit zur Bew{\"a}ltigung {\"o}konomischer Turbulenzen}, publisher = {Deutscher Universit{\"a}tsverlag}, address = {Wiesbaden, s.l.}, isbn = {3-8244-0846-5}, doi = {10.1007/978-3-322-81216-2}, pages = {XVI, 304 S. : graph. Darst.}, year = {2005}, language = {de} } @phdthesis{Zippel2005, author = {Zippel, Barbara}, title = {Einfluss von Intraguild Predation auf die Dynamik der Planktonsukzession in einem sauren Bergbausee}, address = {Potsdam}, pages = {82 S. : graph. Darst.}, year = {2005}, language = {de} } @misc{Zimmering2005, author = {Zimmering, Raina}, title = {Das mexikanische Milit{\"a}r : von der Revolutionsarmee zur Polizeikraft}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-48258}, year = {2005}, abstract = {The military in Mexico started out as a revolutionary army that secured the regime of the governmental party PRI. The article discusses the change of this army into a national and hemispheric police force under the influence of the USA. Today, the functions of the Mexican army are a mix of fighting against drugs, organized delinquency, terrorism and counterinsurgency and cooperating with US as well as other Latin American forces.}, language = {de} } @article{ZillmerPikovskij2005, author = {Zillmer, R{\"u}diger and Pikovskij, Arkadij}, title = {Continuous approach for the random-field Ising chain}, year = {2005}, abstract = {We study the random-field Ising chain in the limit of strong exchange coupling. In order to calculate the free energy we apply a continuous Langevin-type approach. This continuous model can be solved exactly, whereupon we are able to locate the crossover between an exponential and a power-law decay of the free energy with increasing coupling strength. In terms of magnetization, this crossover restricts the validity of the linear scaling. The known analytical results for the free energy are recovered in the corresponding limits. The outcomes of numerical computations for the free energy are presented, which confirm the results of the continuous approach. We also discuss the validity of the replica method which we then utilize to investigate the sample-to-sample fluctuations of the finite size free energy}, language = {en} }