@phdthesis{Topaj2001,
  author    = {Topaj, Dmitri},
  title     = {Synchronization transitions in complex systems},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0000367},
  school      = {Universit{\"a}t Potsdam},
  year      = {2001},
  abstract  = {Gegenstand dieser Arbeit ist die Untersuchung generischer Synchronisierungsph{\"a}nomene in interagierenden komplexen Systemen. Diese Ph{\"a}nomene werden u.a. in gekoppelten deterministischen chaotischen Systemen beobachtet. Bei sehr schwachen Interaktionen zwischen individuellen Systemen kann ein {\"U}bergang zum schwach koh{\"a}renten Verhalten der Systeme stattfinden. In gekoppelten zeitkontinuierlichen chaotischen Systemen manifestiert sich dieser {\"U}bergang durch den Effekt der Phasensynchronisierung, in gekoppelten chaotischen zeitdiskreten Systemen durch den Effekt eines nichtverschwindenden makroskopischen Feldes. Der {\"U}bergang zur Koh{\"a}renz in einer Kette lokal gekoppelter Oszillatoren, beschrieben durch Phasengleichungen, wird im Bezug auf die Symmetrien des Systems untersucht. Es wird gezeigt, daß die durch die Symmetrien verursachte Reversibilit{\"a}t des Systems nichttriviale topologische Eigenschaften der Trajektorien bedingt, so daß das als dissipativ konstruierte System in einem ganzen Parameterbereich quasi-Hamiltonische Z{\"u}ge aufweist, d.h. das Phasenvolumen ist im Schnitt erhalten, und die Lyapunov-Exponenten sind paarweise symmetrisch. Der {\"U}bergang zur Koh{\"a}renz in einem Ensemble global gekoppelter chaotischer Abbildungen wird durch den Verlust der Stabilit{\"a}t des entkoppelten Zustandes beschrieben. Die entwickelte Methode besteht darin, die Selbstkonsistenz des makroskopischen Feldes aufzuheben, und das Ensemble in Analogie mit einem Verst{\"a}rkerschaltkreis mit R{\"u}ckkopplung durch eine komplexe lineare {\"U}bertragungssfunktion zu charakterisieren. Diese Theorie wird anschließend f{\"u}r einige theoretisch interessanten F{\"a}lle verallgemeinert.},
  language  = {en}
}
@misc{JackischAngermannAllroggenetal.2017,
  author    = {Jackisch, Conrad and Angermann, Lisa and Allroggen, Niklas and Sprenger, Matthias and Blume, Theresa and Tronicke, Jens and Zehe, Erwin},
  title     = {Form and function in hillslope hydrology},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {665},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-41918},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419188},
  pages     = {27},
  year      = {2017},
  abstract  = {The study deals with the identification and characterization of rapid subsurface flow structures through pedo- and geo-physical measurements and irrigation experiments at the point, plot and hillslope scale. Our investigation of flow-relevant structures and hydrological responses refers to the general interplay of form and function, respectively. To obtain a holistic picture of the subsurface, a large set of different laboratory, exploratory and experimental methods was used at the different scales. For exploration these methods included drilled soil core profiles, in situ measurements of infiltration capacity and saturated hydraulic conductivity, and laboratory analyses of soil water retention and saturated hydraulic conductivity. The irrigation experiments at the plot scale were monitored through a combination of dye tracer, salt tracer, soil moisture dynamics, and 3-D time-lapse ground penetrating radar (GPR) methods. At the hillslope scale the subsurface was explored by a 3-D GPR survey. A natural storm event and an irrigation experiment were monitored by a dense network of soil moisture observations and a cascade of 2-D time-lapse GPR "trenches". We show that the shift between activated and non-activated state of the flow paths is needed to distinguish structures from overall heterogeneity. Pedo-physical analyses of point-scale samples are the basis for sub-scale structure inference. At the plot and hillslope scale 3-D and 2-D time-lapse GPR applications are successfully employed as non-invasive means to image subsurface response patterns and to identify flow-relevant paths. Tracer recovery and soil water responses from irrigation experiments deliver a consistent estimate of response velocities. The combined observation of form and function under active conditions provides the means to localize and characterize the structures (this study) and the hydrological processes (companion study Angermann et al., 2017, this issue).},
  language  = {en}
}
@misc{SchroenKoehliScheiffeleetal.2017,
  author    = {Schr{\"o}n, Martin and K{\"o}hli, Markus and Scheiffele, Lena and Iwema, Joost and Bogena, Heye R. and Lv, Ling and Martini, Edoardo and Baroni, Gabriele and Rosolem, Rafael and Weimar, Jannis and Mai, Juliane and Cuntz, Matthias and Rebmann, Corinna and Oswald, Sascha Eric and Dietrich, Peter and Schmidt, Ulrich and Zacharias, Steffen},
  title     = {Improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {636},
  doi       = {10.25932/publishup-41913},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419134},
  pages     = {5009 -- 5030},
  year      = {2017},
  abstract  = {In the last few years the method of cosmic-ray neutron sensing (CRNS) has gained popularity among hydrologists, physicists, and land-surface modelers. The sensor provides continuous soil moisture data, averaged over several hectares and tens of decimeters in depth. However, the signal still may contain unidentified features of hydrological processes, and many calibration datasets are often required in order to find reliable relations between neutron intensity and water dynamics. Recent insights into environmental neutrons accurately described the spatial sensitivity of the sensor and thus allowed one to quantify the contribution of individual sample locations to the CRNS signal. Consequently, data points of calibration and validation datasets are suggested to be averaged using a more physically based weighting approach. In this work, a revised sensitivity function is used to calculate weighted averages of point data. The function is different from the simple exponential convention by the extraordinary sensitivity to the first few meters around the probe, and by dependencies on air pressure, air humidity, soil moisture, and vegetation. The approach is extensively tested at six distinct monitoring sites: two sites with multiple calibration datasets and four sites with continuous time series datasets. In all cases, the revised averaging method improved the performance of the CRNS products. The revised approach further helped to reveal hidden hydrological processes which otherwise remained unexplained in the data or were lost in the process of overcalibration. The presented weighting approach increases the overall accuracy of CRNS products and will have an impact on all their applications in agriculture, hydrology, and modeling.},
  language  = {en}
}
@misc{SchmidtWellenburgLebaron2018,
  author    = {Schmidt-Wellenburg, Christian and Lebaron, Frederic},
  title     = {There is no such thing as "the Economy"},
  series = {Historical Social Research},
  volume    = {43},
  journal   = {Historical Social Research},
  number    = {3},
  publisher = {GESIS, Leibniz Institute for the Social Sciences},
  address   = {Cologne},
  issn      = {0172-6404},
  doi       = {10.12759/hsr.43.2018.3.7-38},
  pages     = {7 -- 38},
  year      = {2018},
  abstract  = {This introductory essay to the HSR Special Issue "Economists, Politics, and Society" argues for a strong field-theoretical programme inspired by Pierre Bourdieu to research economic life as an integral part of different social forms. Its main aim is threefold. First, we spell out the very distinct Durkheimian legacy in Bourdieu's thinking and the way he applies it in researching economic phenomena. Without this background, much of what is actually part of how Bourdieu analysed economic aspects of social life would be overlooked or reduced to mere economic sociology. Second, we sketch the main theoretical concepts and heuristics used to analyse economic life from a field perspective. Third, we focus on practical methodological issues of field-analytical research into economic phenomena. We conclude with a short summary of the basic characteristics of this approach and discuss the main insights provided by the contributions to this special issue.},
  language  = {en}
}
@article{SchmidtWellenburg2018,
  author    = {Schmidt-Wellenburg, Christian},
  title     = {Struggling over crisis},
  series = {Historical Social Research},
  volume    = {43},
  journal   = {Historical Social Research},
  number    = {3},
  publisher = {GESIS, Leibniz Institute for the Social Sciences},
  address   = {Cologne},
  issn      = {0172-6404},
  doi       = {10.12759/hsr.43.2018.3.147-188},
  pages     = {147 -- 188},
  year      = {2018},
  abstract  = {If you put two economists in a room, you get two opinions, unless one of them is Lord Keynes, in which case you get three opinions." Following the premise of this quotation attributed to Winston Churchill, varying perceptions of the European crisis by academic economists and their structural homology to economists' positions in the field of economics are examined. The dataset analysed using specific multiple correspondence analysis (MCA) and hierarchical agglomerative clustering (HAC) comprises information on the careers of 480 German-speaking economists and on statements they made concerning crisis-related issues. It can be shown that the main structural differences in the composition and amount of scientific and academic capital held by economists as well as their age and degree of transnationalisation are linked to how they see the crisis: as a national sovereign debt crisis, as a European banking crisis, or as a crisis of European integration and institutions.},
  language  = {en}
}