@phdthesis{Jehannin2015,
  author    = {Jehannin, Marie},
  title     = {About the role of physico-chemical properties and hydrodynamics on the progress of a precipitation reaction},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-88364},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xii, 130},
  year      = {2015},
  abstract  = {The size and morphology control of precipitated solid particles is a major economic issue for numerous industries. For instance, it is interesting for the nuclear industry, concerning the recovery of radioactive species from used nuclear fuel. The precipitates features, which are a key parameter from the post-precipitate processing, depend on the process local mixing conditions. So far, the relationship between precipitation features and hydrodynamic conditions have not been investigated. In this study, a new experimental configuration consisting of coalescing drops is set to investigate the link between reactive crystallization and hydrodynamics. Two configurations of aqueous drops are examined. The first one corresponds to high contact angle drops (>90°) in oil, as a model system for flowing drops, the second one correspond to sessile drops in air with low contact angle (<25°). In both cases, one reactive is dissolved in each drop, namely oxalic acid and cerium nitrate. When both drops get into contact, they may coalesce; the dissolved species mix and react to produce insoluble cerium oxalate. The precipitates features and effect on hydrodynamics are investigated depending on the solvent. In the case of sessile drops in air, the surface tension difference between the drops generates a gradient which induces a Marangoni flow from the low surface tension drop over the high surface tension drop. By setting the surface tension difference between the two drops and thus the Marangoni flow, the hydrodynamics conditions during the drop coalescence could be modified. Diols/water mixtures are used as solvent, in order to fix the surface tension difference between the liquids of both drops regardless from the reactant concentration. More precisely, the used diols, 1,2-propanediol and 1,3-propanediol, are isomer with identical density and close viscosity. By keeping the water volume fraction constant and playing with the 1,2-propanediol and 1,3-propanediol volume fractions of the solvents, the mixtures surface tensions differ up to 10 mN/m for identical/constant reactant concentration, density and viscosity. 3 precipitation behaviors were identified for the coalescence of water/diols/recatants drops depending on the oxalic excess. The corresponding precipitates patterns are visualized by optical microscopy and the precipitates are characterized by confocal microscopy SEM, XRD and SAXS measurements. In the intermediate oxalic excess regime, formation of periodic patterns can be observed. These patterns consist in alternating cerium oxalate precipitates with distinct morphologies, namely needles and "microflowers". Such periodic fringes can be explained by a feedback mechanism between convection, reaction and the diffusion.},
  language  = {en}
}
@phdthesis{Schirmack2015,
  author    = {Schirmack, Janosch},
  title     = {Activity of methanogenic archaea under simulated Mars analog conditions},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-73010},
  school      = {Universit{\"a}t Potsdam},
  pages     = {VI, 108},
  year      = {2015},
  abstract  = {Assumed comparable environmental conditions of early Mars and early Earth in 3.7 Ga ago - at a time when first fossil records of life on Earth could be found - suggest the possibility of life emerging on both planets in parallel. As conditions changed, the hypothetical life on Mars either became extinct or was able to adapt and might still exist in biological niches. The controversial discussed detection of methane on Mars led to the assumption, that it must have a recent origin - either abiotic through active volcanism or chemical processes, or through biogenic production. Spatial and seasonal variations in the detected methane concentrations and correlations between the presence of water vapor and geological features such as subsurface hydrogen, which are occurring together with locally increased detected concentrations of methane, gave fuel to the hypothesis of a possible biological source of the methane on Mars. Therefore the phylogenetically old methanogenic archaea, which have evolved under early Earth conditions, are often used as model-organisms in astrobiological studies to investigate the potential of life to exist in possible extraterrestrial habitats on our neighboring planet. In this thesis methanogenic archaea originating from two extreme environments on Earth were investigated to test their ability to be active under simulated Mars analog conditions. These extreme environments - the Siberian permafrost-affected soil and the chemoautotrophically based terrestrial ecosystem of Movile cave, Romania - are regarded as analogs for possible Martian (subsurface) habitats. Two novel species of methanogenic archaea isolated from these environments were described within the frame of this thesis. It could be shown that concentrations up to 1 wt\% of Mars regolith analogs added to the growth media had a positive influence on the methane production rates of the tested methanogenic archaea, whereas higher concentrations resulted in decreasing rates. Nevertheless it was possible for the organisms to metabolize when incubated on water-saturated soil matrixes made of Mars regolith analogs without any additional nutrients. Long-term desiccation resistance of more than 400 days was proven with reincubation and indirect counting of viable cells through a combined treatment with propidium monoazide (to inactivate DNA of destroyed cells) and quantitative PCR. Phyllosilicate rich regolith analogs seem to be the best soil mixtures for the tested methanogenic archaea to be active under Mars analog conditions. Furthermore, in a simulation chamber experiment the activity of the permafrost methanogen strain Methanosarcina soligelidi SMA-21 under Mars subsurface analog conditions could be proven. Through real-time wavelength modulation spectroscopy measurements the increase in the methane concentration at temperatures down to -5 °C could be detected. The results presented in this thesis contribute to the understanding of the activity potential of methanogenic archaea under Mars analog conditions and therefore provide insights to the possible habitability of present-day Mars (near) subsurface environments. Thus, it contributes also to the data interpretation of future life detection missions on that planet. For example the ExoMars mission of the European Space Agency (ESA) and Roscosmos which is planned to be launched in 2018 and is aiming to drill in the Martian subsurface.},
  language  = {en}
}
@phdthesis{Lamanna2015,
  author    = {Lamanna, Francesco},
  title     = {Adaptive radiation and speciation in African weakly-electric fish},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-80097},
  school      = {Universit{\"a}t Potsdam},
  pages     = {114},
  year      = {2015},
  abstract  = {The rise of evolutionary novelties is one of the major drivers of evolutionary diversification. African weakly-electric fishes (Teleostei, Mormyridae) have undergone an outstanding adaptive radiation, putatively owing to their ability to communicate through species-specific Electric Organ Discharges (EODs) produced by a novel, muscle-derived electric organ. Indeed, such EODs might have acted as effective pre-zygotic isolation mechanisms, hence favoring ecological speciation in this group of fishes. Despite the evolutionary importance of this organ, genetic investigations regarding its origin and function have remained limited. The ultimate aim of this study is to better understand the genetic basis of EOD production by exploring the transcriptomic profiles of the electric organ and of its ancestral counterpart, the skeletal muscle, in the genus Campylomormyrus. After having established a set of reference transcriptomes using "Next-Generation Sequencing" (NGS) technologies, I performed in silico analyses of differential expression, in order to identify sets of genes that might be responsible for the functional differences observed between these two kinds of tissues. The results of such analyses indicate that: i) the loss of contractile activity and the decoupling of the excitation-contraction processes are reflected by the down-regulation of the corresponding genes in the electric organ; ii) the metabolic activity of the electric organ might be specialized towards the production and turnover of membrane structures; iii) several ion channels are highly expressed in the electric organ in order to increase excitability, and iv) several myogenic factors might be down-regulated by transcription repressors in the EO. A secondary task of this study is to improve the genus level phylogeny of Campylomormyrus by applying new methods of inference based on the multispecies coalescent model, in order to reduce the conflict among gene trees and to reconstruct a phylogenetic tree as closest as possible to the actual species-tree. By using 1 mitochondrial and 4 nuclear markers, I was able to resolve the phylogenetic relationships among most of the currently described Campylomormyrus species. Additionally, I applied several coalescent-based species delimitation methods, in order to test the hypothesis that putatively cryptic species, which are distinguishable only from their EOD, belong to independently evolving lineages. The results of this analysis were additionally validated by investigating patterns of diversification at 16 microsatellite loci. The results suggest the presence of a new, yet undescribed species of Campylomormyrus.},
  language  = {en}
}
@phdthesis{Zakharova2015,
  author    = {Zakharova, Olga},
  title     = {Analysis and modeling of transient earthquake patterns and their dependence on local stress regimes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-86455},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XVI, 94},
  year      = {2015},
  abstract  = {Investigations in the field of earthquake triggering and associated interactions, which includes aftershock triggering as well as induced seismicity, is important for seismic hazard assessment due to earthquakes destructive power. One of the approaches to study earthquake triggering and their interactions is the use of statistical earthquake models, which are based on knowledge of the basic seismicity properties, in particular, the magnitude distribution and spatiotemporal properties of the triggered events. In my PhD thesis I focus on some specific aspects of aftershock properties, namely, the relative seismic moment release of the aftershocks with respect to the mainshocks; the spatial correlation between aftershock occurrence and fault deformation; and on the influence of aseismic transients on the aftershock parameter estimation. For the analysis of aftershock sequences I choose a statistical approach, in particular, the well known Epidemic Type Aftershock Sequence (ETAS) model, which accounts for the input of background and triggered seismicity. For my specific purposes, I develop two ETAS model modifications in collaboration with Sebastian Hainzl. By means of this approach, I estimate the statistical aftershock parameters and performed simulations of aftershock sequences as well. In the case of seismic moment release of aftershocks, I focus on the ratio of cumulative seismic moment release with respect to the mainshocks. Specifically, I investigate the ratio with respect to the focal mechanism of the mainshock and estimate an effective magnitude, which represents the cumulative aftershock energy (similar to Bath's law, which defines the average difference between mainshock and the largest aftershock magnitudes). Furthermore, I compare the observed seismic moment ratios with the results of the ETAS simulations. In particular, I test a restricted ETAS (RETAS) model which is based on results of a clock advanced model and static stress triggering. To analyze spatial variations of triggering parameters I focus in my second approach on the aftershock occurrence triggered by large mainshocks and the study of the aftershock parameter distribution and their spatial correlation with the coseismic/postseismic slip and interseismic locking. To invert the aftershock parameters I improve the modified ETAS (m-ETAS) model, which is able to take the extension of the mainshock rupture into account. I compare the results obtained by the classical approach with the output of the m-ETAS model. My third approach is concerned with the temporal clustering of seismicity, which might not only be related to earthquake-earthquake interactions, but also to a time-dependent background rate, potentially biasing the parameter estimations. Thus, my coauthors and I also applied a modification of the ETAS model, which is able to take into account time-dependent background activity. It can be applicable for two different cases: when an aftershock catalog has a temporal incompleteness or when the background seismicity rate changes with time, due to presence of aseismic forces. An essential part of any research is the testing of the developed models using observational data sets, which are appropriate for the particular study case. Therefore, in the case of seismic moment release I use the global seismicity catalog. For the spatial distribution of triggering parameters I exploit two aftershock sequences of the Mw8.8 2010 Maule (Chile) and Mw 9.0 2011 Tohoku (Japan) mainshocks. In addition, I use published geodetic slip models of different authors. To test our ability to detect aseismic transients my coauthors and I use the data sets from Western Bohemia (Central Europe) and California. Our results indicate that: (1) the seismic moment of aftershocks with respect to mainshocks depends on the static stress changes and is maximal for the normal, intermediate for thrust and minimal for strike-slip stress regimes, where the RETAS model shows a good correspondence with the results; (2) The spatial distribution of aftershock parameters, obtained by the m-ETAS model, shows anomalous values in areas of reactivated crustal fault systems. In addition, the aftershock density is found to be correlated with coseismic slip gradient, afterslip, interseismic coupling and b-values. Aftershock seismic moment is positively correlated with the areas of maximum coseismic slip and interseismically locked areas. These correlations might be related to the stress level or to material properties variations in space; (3) Ignoring aseismic transient forcing or temporal catalog incompleteness can lead to the significant under- or overestimation of the underlying trigger parameters. In the case when a catalog is complete, this method helps to identify aseismic sources.},
  language  = {en}
}
@phdthesis{EidSabbagh2015,
  author    = {Eid-Sabbagh, Rami-Habib},
  title     = {Business process architectures},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-79719},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xvii, 256},
  year      = {2015},
  abstract  = {Business Process Management has become an integral part of modern organizations in the private and public sector for improving their operations. In the course of Business Process Management efforts, companies and organizations assemble large process model repositories with many hundreds and thousands of business process models bearing a large amount of information. With the advent of large business process model collections, new challenges arise as structuring and managing a large amount of process models, their maintenance, and their quality assurance. This is covered by business process architectures that have been introduced for organizing and structuring business process model collections. A variety of business process architecture approaches have been proposed that align business processes along aspects of interest, e. g., goals, functions, or objects. They provide a high level categorization of single processes ignoring their interdependencies, thus hiding valuable information. The production of goods or the delivery of services are often realized by a complex system of interdependent business processes. Hence, taking a holistic view at business processes interdependencies becomes a major necessity to organize, analyze, and assess the impact of their re-/design. Visualizing business processes interdependencies reveals hidden and implicit information from a process model collection. In this thesis, we present a novel Business Process Architecture approach for representing and analyzing business process interdependencies on an abstract level. We propose a formal definition of our Business Process Architecture approach, design correctness criteria, and develop analysis techniques for assessing their quality. We describe a methodology for applying our Business Process Architecture approach top-down and bottom-up. This includes techniques for Business Process Architecture extraction from, and decomposition to process models while considering consistency issues between business process architecture and process model level. Using our extraction algorithm, we present a novel technique to identify and visualize data interdependencies in Business Process Data Architectures. Our Business Process Architecture approach provides business process experts,managers, and other users of a process model collection with an overview that allows reasoning about a large set of process models, understanding, and analyzing their interdependencies in a facilitated way. In this regard we evaluated our Business Process Architecture approach in an experiment and provide implementations of selected techniques.},
  language  = {en}
}
@phdthesis{Boettle2015,
  author    = {B{\"o}ttle, Markus},
  title     = {Coastal floods in view of sea level rise},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-91074},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xiii, 111},
  year      = {2015},
  abstract  = {The sea level rise induced intensification of coastal floods is a serious threat to many regions in proximity to the ocean. Although severe flood events are rare they can entail enormous damage costs, especially when built-up areas are inundated. Fortunately, the mean sea level advances slowly and there is enough time for society to adapt to the changing environment. Most commonly, this is achieved by the construction or reinforcement of flood defence measures such as dykes or sea walls but also land use and disaster management are widely discussed options. Overall, albeit the projection of sea level rise impacts and the elaboration of adequate response strategies is amongst the most prominent topics in climate impact research, global damage estimates are vague and mostly rely on the same assessment models. The thesis at hand contributes to this issue by presenting a distinctive approach which facilitates large scale assessments as well as the comparability of results across regions. Moreover, we aim to improve the general understanding of the interplay between mean sea level rise, adaptation, and coastal flood damage. Our undertaking is based on two basic building blocks. Firstly, we make use of macroscopic flood-damage functions, i.e. damage functions that provide the total monetary damage within a delineated region (e.g. a city) caused by a flood of certain magnitude. After introducing a systematic methodology for the automatised derivation of such functions, we apply it to a total of 140 European cities and obtain a large set of damage curves utilisable for individual as well as comparative damage assessments. By scrutinising the resulting curves, we are further able to characterise the slope of the damage functions by means of a functional model. The proposed function has in general a sigmoidal shape but exhibits a power law increase for the relevant range of flood levels and we detect an average exponent of 3.4 for the considered cities. This finding represents an essential input for subsequent elaborations on the general interrelations of involved quantities. The second basic element of this work is extreme value theory which is employed to characterise the occurrence of flood events and in conjunction with a damage function provides the probability distribution of the annual damage in the area under study. The resulting approach is highly flexible as it assumes non-stationarity in all relevant parameters and can be easily applied to arbitrary regions, sea level, and adaptation scenarios. For instance, we find a doubling of expected flood damage in the city of Copenhagen for a rise in mean sea levels of only 11 cm. By following more general considerations, we succeed in deducing surprisingly simple functional expressions to describe the damage behaviour in a given region for varying mean sea levels, changing storm intensities, and supposed protection levels. We are thus able to project future flood damage by means of a reduced set of parameters, namely the aforementioned damage function exponent and the extreme value parameters. Similar examinations are carried out to quantify the aleatory uncertainty involved in these projections. In this regard, a decrease of (relative) uncertainty with rising mean sea levels is detected. Beyond that, we demonstrate how potential adaptation measures can be assessed in terms of a Cost-Benefit Analysis. This is exemplified by the Danish case study of Kalundborg, where amortisation times for a planned investment are estimated for several sea level scenarios and discount rates.},
  language  = {en}
}
@phdthesis{Kniepert2015,
  author    = {Kniepert, Juliane},
  title     = {Correlation between dynamic parameters and device performance of organic solar cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-90087},
  school      = {Universit{\"a}t Potsdam},
  pages     = {129},
  year      = {2015},
  abstract  = {Organic bulk heterojunction (BHJ) solar cells based on polymer:fullerene blends are a promising alternative for a low-cost solar energy conversion. Despite significant improvements of the power conversion efficiency in recent years, the fundamental working principles of these devices are yet not fully understood. In general, the current output of organic solar cells is determined by the generation of free charge carriers upon light absorption and their transport to the electrodes in competition to the loss of charge carriers due to recombination. The object of this thesis is to provide a comprehensive understanding of the dynamic processes and physical parameters determining the performance. A new approach for analyzing the characteristic current-voltage output was developed comprising the experimental determination of the efficiencies of charge carrier generation, recombination and transport, combined with numerical device simulations. Central issues at the beginning of this work were the influence of an electric field on the free carrier generation process and the contribution of generation, recombination and transport to the current-voltage characteristics. An elegant way to directly measure the field dependence of the free carrier generation is the Time Delayed Collection Field (TDCF) method. In TDCF charge carriers are generated by a short laser pulse and subsequently extracted by a defined rectangular voltage pulse. A new setup was established with an improved time resolution compared to former reports in literature. It was found that charge generation is in general independent of the electric field, in contrast to the current view in literature and opposed to the expectations of the Braun-Onsager model that was commonly used to describe the charge generation process. Even in cases where the charge generation was found to be field-dependend, numerical modelling showed that this field-dependence is in general not capable to account for the voltage dependence of the photocurrent. This highlights the importance of efficient charge extraction in competition to non-geminate recombination, which is the second objective of the thesis. Therefore, two different techniques were combined to characterize the dynamics and efficiency of non-geminate recombination under device-relevant conditions. One new approach is to perform TDCF measurements with increasing delay between generation and extraction of charges. Thus, TDCF was used for the first time to measure charge carrier generation, recombination and transport with the same experimental setup. This excludes experimental errors due to different measurement and preparation conditions and demonstrates the strength of this technique. An analytic model for the description of TDCF transients was developed and revealed the experimental conditions for which reliable results can be obtained. In particular, it turned out that the \$RC\$ time of the setup which is mainly given by the sample geometry has a significant influence on the shape of the transients which has to be considered for correct data analysis. Secondly, a complementary method was applied to characterize charge carrier recombination under steady state bias and illumination, i.e. under realistic operating conditions. This approach relies on the precise determination of the steady state carrier densities established in the active layer. It turned out that current techniques were not sufficient to measure carrier densities with the necessary accuracy. Therefore, a new technique {Bias Assisted Charge Extraction} (BACE) was developed. Here, the charge carriers photogenerated under steady state illumination are extracted by applying a high reverse bias. The accelerated extraction compared to conventional charge extraction minimizes losses through non-geminate recombination and trapping during extraction. By performing numerical device simulations under steady state, conditions were established under which quantitative information on the dynamics can be retrieved from BACE measurements. The applied experimental techniques allowed to sensitively analyse and quantify geminate and non-geminate recombination losses along with charge transport in organic solar cells. A full analysis was exemplarily demonstrated for two prominent polymer-fullerene blends. The model system P3HT:PCBM spincast from chloroform (as prepared) exhibits poor power conversion efficiencies (PCE) on the order of 0.5\%, mainly caused by low fill factors (FF) and currents. It could be shown that the performance of these devices is limited by the hole transport and large bimolecular recombination (BMR) losses, while geminate recombination losses are insignificant. The low polymer crystallinity and poor interconnection between the polymer and fullerene domains leads to a hole mobility of the order of 10^-7 cm^2/Vs which is several orders of magnitude lower than the electron mobility in these devices. The concomitant build up of space charge hinders extraction of both electrons and holes and promotes bimolecular recombination losses. Thermal annealing of P3HT:PCBM blends directly after spin coating improves crystallinity and interconnection of the polymer and the fullerene phase and results in comparatively high electron and hole mobilities in the order of 10^-3 cm^2/Vs and 10^-4 cm^2/Vs, respectively. In addition, a coarsening of the domain sizes leads to a reduction of the BMR by one order of magnitude. High charge carrier mobilities and low recombination losses result in comparatively high FF (>65\%) and short circuit current (J_SC ≈ 10 mA/cm^2). The overall device performance (PCE ≈ 4\%) is only limited by a rather low spectral overlap of absorption and solar emission and a small V_OC, given by the energetics of the P3HT. From this point of view the combination of the low bandgap polymer PTB7 with PCBM is a promising approach. In BHJ solar cells, this polymer leads to a higher V_OC due to optimized energetics with PCBM. However, the J_SC in these (unoptimized) devices is similar to the J_SC in the optimized blend with P3HT and the FF is rather low (≈ 50\%). It turned out that the unoptimized PTB7:PCBM blends suffer from high BMR, a low electron mobility of the order of 10^-5 cm^2/Vs and geminate recombination losses due to field dependent charge carrier generation. The use of the solvent additive DIO optimizes the blend morphology, mainly by suppressing the formation of very large fullerene domains and by forming a more uniform structure of well interconnected donor and acceptor domains of the order of a few nanometers. Our analysis shows that this results in an increase of the electron mobility by about one order of magnitude (3 x 10^-4 cm^2/Vs), while BMR and geminate recombination losses are significantly reduced. In total these effects improve the J_SC (≈ 17 mA/cm^2) and the FF (> 70\%). In 2012 this polymer/fullerene combination resulted in a record PCE for a single junction OSC of 9.2\%. Remarkably, the numerical device simulations revealed that the specific shape of the J-V characteristics depends very sensitively to the variation of not only one, but all dynamic parameters. On the one hand this proves that the experimentally determined parameters, if leading to a good match between simulated and measured J-V curves, are realistic and reliable. On the other hand it also emphasizes the importance to consider all involved dynamic quantities, namely charge carrier generation, geminate and non-geminate recombination as well as electron and hole mobilities. The measurement or investigation of only a subset of these parameters as frequently found in literature will lead to an incomplete picture and possibly to misleading conclusions. Importantly, the comparison of the numerical device simulation employing the measured parameters and the experimental \$J-V\$ characteristics allows to identify loss channels and limitations of OSC. For example, it turned out that inefficient extraction of charge carriers is a criticical limitation factor that is often disobeyed. However, efficient and fast transport of charges becomes more and more important with the development of new low bandgap materials with very high internal quantum efficiencies. Likewise, due to moderate charge carrier mobilities, the active layer thicknesses of current high-performance devices are usually limited to around 100 nm. However, larger layer thicknesses would be more favourable with respect to higher current output and robustness of production. Newly designed donor materials should therefore at best show a high tendency to form crystalline structures, as observed in P3HT, combined with the optimized energetics and quantum efficiency of, for example, PTB7.},
  language  = {en}
}
@phdthesis{Wettstein2015,
  author    = {Wettstein, Christoph},
  title     = {Cytochrome c-DNA and cytochrome c-enzyme interactions for the construction of analytical signal chains},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-78367},
  school      = {Universit{\"a}t Potsdam},
  pages     = {120},
  year      = {2015},
  abstract  = {Electron transfer (ET) reactions play a crucial role in the metabolic pathways of all organisms. In biotechnological approaches, the redox properties of the protein cytochrome c (cyt c), which acts as an electron shuttle in the respiratory chain, was utilized to engineer ET chains on electrode surfaces. With the help of the biopolymer DNA, the redox protein assembles into electro active multilayer (ML) systems, providing a biocompatible matrix for the entrapment of proteins. In this study the characteristics of the cyt c and DNA interaction were defined on the molecular level for the first time and the binding sites of DNA on cyt c were identified. Persistent cyt c/DNA complexes were formed in solution under the assembly conditions of ML architectures, i.e. pH 5.0 and low ionic strength. At pH 7.0, no agglomerates were formed, permitting the characterization of the NMR spectroscopy. Using transverse relaxation-optimized spectroscopy (TROSY)-heteronuclear single quantum coherence (HSQC) experiments, DNAs' binding sites on the protein were identified. In particular, negatively charged AA residues, which are known interaction sites in cyt c/protein binding were identified as the main contact points of cyt c and DNA. Moreover, the sophisticated task of arranging proteins on electrode surfaces to create functional ET chains was addressed. Therefore, two different enzyme types, the flavin dependent fructose dehydrogenase (FDH) and the pyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH), were tested as reaction partners of freely diffusing cyt c and cyt c immobilized on electrodes in mono- and MLs. The characterisation of the ET processes was performed by means of electrochemistry and the protein deposition was monitored by microgravimetric measurements. FDH and PQQ-GDH were found to be generally suitable for combination with the cyt c/DNA ML system, since both enzymes interact with cyt c in solution and in the immobilized state. The immobilization of FDH and cyt c was achieved with the enzyme on top of a cyt c monolayer electrode without the help of a polyelectrolyte. Combining FDH with the cyt c/DNA ML system did not succeed, yet. However, the basic conditions for this protein-protein interaction were defined. PQQ-GDH was successfully coupled with the ML system, demonstrating that that the cyt c/DNA ML system provides a suitable interface for enzymes and that the creation of signal chains, based on the idea of co-immobilized proteins is feasible. Future work may be directed to the investigation of cyt c/DNA interaction under the precise conditions of ML assembly. Therefore, solid state NMR or X-ray crystallography may be required. Based on the results of this study, the combination of FDH with the ML system should be addressed. Moreover, alternative types of enzymes may be tested as catalytic component of the ML assembly, aiming on the development of innovative biosensor applications.},
  language  = {en}
}
@phdthesis{Meyer2015,
  author    = {Meyer, Andreas},
  title     = {Data perspective in business process management},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-84806},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xxi, 362},
  year      = {2015},
  abstract  = {Gesch{\"a}ftsprozessmanagement ist ein strukturierter Ansatz zur Modellierung, Analyse, Steuerung und Ausf{\"u}hrung von Gesch{\"a}ftsprozessen, um Gesch{\"a}ftsziele zu erreichen. Es st{\"u}tzt sich dabei auf konzeptionelle Modelle, von denen Prozessmodelle am weitesten verbreitet sind. Prozessmodelle beschreiben wer welche Aufgabe auszuf{\"u}hren hat, um das Gesch{\"a}ftsziel zu erreichen, und welche Informationen daf{\"u}r ben{\"o}tigt werden. Damit beinhalten Prozessmodelle Informationen {\"u}ber den Kontrollfluss, die Zuweisung von Verantwortlichkeiten, den Datenfluss und Informationssysteme. Die Automatisierung von Gesch{\"a}ftsprozessen erh{\"o}ht die Effizienz der Arbeitserledigung und wird durch Process Engines unterst{\"u}tzt. Daf{\"u}r werden jedoch Informationen {\"u}ber den Kontrollfluss, die Zuweisung von Verantwortlichkeiten f{\"u}r Aufgaben und den Datenfluss ben{\"o}tigt. W{\"a}hrend aktuelle Process Engines die ersten beiden Informationen weitgehend automatisiert verarbeiten k{\"o}nnen, m{\"u}ssen Daten manuell implementiert und gewartet werden. Dem entgegen verspricht ein modell-getriebenes Behandeln von Daten eine vereinfachte Implementation in der Process Engine und verringert gleichzeitig die Fehleranf{\"a}lligkeit dank einer graphischen Visualisierung und reduziert den Entwicklungsaufwand durch Codegenerierung. Die vorliegende Dissertation besch{\"a}ftigt sich mit der Modellierung, der Analyse und der Ausf{\"u}hrung von Daten in Gesch{\"a}ftsprozessen. Als formale Basis f{\"u}r die Prozessausf{\"u}hrung wird ein konzeptuelles Framework f{\"u}r die Integration von Prozessen und Daten eingef{\"u}hrt. Dieses Framework wird durch operationelle Semantik erg{\"a}nzt, die mittels einem um Daten erweiterten Petrinetz-Mapping vorgestellt wird. Die modellgetriebene Ausf{\"u}hrung von Daten muss komplexe Datenabh{\"a}ngigkeiten, Prozessdaten und den Datenaustausch ber{\"u}cksichtigen. Letzterer tritt bei der Kommunikation zwischen mehreren Prozessteilnehmern auf. Diese Arbeit nutzt Konzepte aus dem Bereich der Datenbanken und {\"u}berf{\"u}hrt diese ins Gesch{\"a}ftsprozessmanagement, um Datenoperationen zu unterscheiden, um Abh{\"a}ngigkeiten zwischen Datenobjekten des gleichen und verschiedenen Typs zu spezifizieren, um modellierte Datenknoten sowie empfangene Nachrichten zur richtigen laufenden Prozessinstanz zu korrelieren und um Nachrichten f{\"u}r die Prozess{\"u}bergreifende Kommunikation zu generieren. Der entsprechende Ansatz ist nicht auf eine bestimmte Prozessbeschreibungssprache begrenzt und wurde prototypisch implementiert. Die Automatisierung der Datenbehandlung in Gesch{\"a}ftsprozessen erfordert entsprechend annotierte und korrekte Prozessmodelle. Als Unterst{\"u}tzung zur Datenannotierung f{\"u}hrt diese Arbeit einen Algorithmus ein, welcher Informationen {\"u}ber Datenknoten, deren Zust{\"a}nde und Datenabh{\"a}ngigkeiten aus Kontrollflussinformationen extrahiert und die Prozessmodelle entsprechend annotiert. Allerdings k{\"o}nnen gew{\"o}hnlich nicht alle erforderlichen Informationen aus Kontrollflussinformationen extrahiert werden, da detaillierte Angaben {\"u}ber m{\"o}gliche Datenmanipulationen fehlen. Deshalb sind weitere Prozessmodellverfeinerungen notwendig. Basierend auf einer Menge von Objektlebenszyklen kann ein Prozessmodell derart verfeinert werden, dass die in den Objektlebenszyklen spezifizierten Datenmanipulationen automatisiert in ein Prozessmodell {\"u}berf{\"u}hrt werden k{\"o}nnen. Prozessmodelle stellen eine Abstraktion dar. Somit fokussieren sie auf verschiedene Teilbereiche und stellen diese im Detail dar. Solche Detailbereiche sind beispielsweise die Kontrollflusssicht und die Datenflusssicht, welche oft durch Aktivit{\"a}ts-zentrierte beziehungsweise Objekt-zentrierte Prozessmodelle abgebildet werden. In der vorliegenden Arbeit werden Algorithmen zur Transformation zwischen diesen Sichten beschrieben. Zur Sicherstellung der Modellkorrektheit wird das Konzept der „weak conformance" zur {\"U}berpr{\"u}fung der Konsistenz zwischen Objektlebenszyklen und dem Prozessmodell eingef{\"u}hrt. Dabei darf das Prozessmodell nur Datenmanipulationen enthalten, die auch in einem Objektlebenszyklus spezifiziert sind. Die Korrektheit wird mittels Soundness-{\"U}berpr{\"u}fung einer hybriden Darstellung ermittelt, so dass Kontrollfluss- und Datenkorrektheit integriert {\"u}berpr{\"u}ft werden. Um eine korrekte Ausf{\"u}hrung des Prozessmodells zu gew{\"a}hrleisten, m{\"u}ssen gefundene Inkonsistenzen korrigiert werden. Daf{\"u}r werden f{\"u}r jede Inkonsistenz alternative Vorschl{\"a}ge zur Modelladaption identifiziert und vorgeschlagen. Zusammengefasst, unter Einsatz der Ergebnisse dieser Dissertation k{\"o}nnen Gesch{\"a}ftsprozesse modellgetrieben ausgef{\"u}hrt werden unter Ber{\"u}cksichtigung sowohl von Daten als auch den zuvor bereits unterst{\"u}tzten Perspektiven bez{\"u}glich Kontrollfluss und Verantwortlichkeiten. Dabei wird die Modellerstellung teilweise mit automatisierten Algorithmen unterst{\"u}tzt und die Modellkonsistenz durch Datenkorrektheits{\"u}berpr{\"u}fungen gew{\"a}hrleistet.},
  language  = {en}
}
@phdthesis{TorresAcosta2015,
  author    = {Torres Acosta, Ver{\´o}nica},
  title     = {Denudation processes in a tectonically active rift on different time scales},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-84534},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xv, ix, 183},
  year      = {2015},
  abstract  = {Continental rifts are excellent regions where the interplay between extension, the build-up of topography, erosion and sedimentation can be evaluated in the context of landscape evolution. Rift basins also constitute important archives that potentially record the evolution and migration of species and the change of sedimentary conditions as a result of climatic change. Finally, rifts have increasingly become targets of resource exploration, such as hydrocarbons or geothermal systems. The study of extensional processes and the factors that further modify the mainly climate-driven surface process regime helps to identify changes in past and present tectonic and geomorphic processes that are ultimately recorded in rift landscapes. The Cenozoic East African Rift System (EARS) is an exemplary continental rift system and ideal natural laboratory to observe such interactions. The eastern and western branches of the EARS constitute first-order tectonic and topographic features in East Africa, which exert a profound influence on the evolution of topography, the distribution and amount of rainfall, and thus the efficiency of surface processes. The Kenya Rift is an integral part of the eastern branch of the EARS and is characterized by high-relief rift escarpments bounded by normal faults, gently tilted rift shoulders, and volcanic centers along the rift axis. Considering the Cenozoic tectonic processes in the Kenya Rift, the tectonically controlled cooling history of rift shoulders, the subsidence history of rift basins, and the sedimentation along and across the rift, may help to elucidate the morphotectonic evolution of this extensional province. While tectonic forcing of surface processes may play a minor role in the low-strain rift on centennial to millennial timescales, it may be hypothesized that erosion and sedimentation processes impacted by climate shifts associated with pronounced changes in the availability in moisture may have left important imprints in the landscape. In this thesis I combined thermochronological, geomorphic field observations, and morphometry of digital elevation models to reconstruct exhumation processes and erosion rates, as well as the effects of climate on the erosion processes in different sectors of the rift. I present three sets of results: (1) new thermochronological data from the northern and central parts of the rift to quantitatively constrain the Tertiary exhumation and thermal evolution of the Kenya Rift. (2) 10Be-derived catchment-wide mean denudation rates from the northern, central and southern rift that characterize erosional processes on millennial to present-day timescales; and (3) paleo-denudation rates in the northern rift to constrain climatically controlled shifts in paleoenvironmental conditions during the early Holocene (African Humid Period). Taken together, my studies show that time-temperature histories derived from apatite fission track (AFT) analysis, zircon (U-Th)/He dating, and thermal modeling bracket the onset of rifting in the Kenya Rift between 65-50 Ma and about 15 Ma to the present. These two episodes are marked by rapid exhumation and, uplift of the rift shoulders. Between 45 and 15 Ma the margins of the rift experienced very slow erosion/exhumation, with the accommodation of sediments in the rift basin. In addition, I determined that present-day denudation rates in sparsely vegetated parts of the Kenya Rift amount to 0.13 mm/yr, whereas denudation rates in humid and more densely vegetated sectors of the rift flanks reach a maximum of 0.08 mm/yr, despite steeper hillslopes. I inferred that hillslope gradient and vegetation cover control most of the variation in denudation rates across the Kenya Rift today. Importantly, my results support the notion that vegetation cover plays a fundamental role in determining the voracity of erosion of hillslopes through its stabilizing effects on the land surface. Finally, in a pilot study I highlighted how paleo-denudation rates in climatic threshold areas changed significantly during times of transient hydrologic conditions and involved a sixfold increase in erosion rates during increased humidity. This assessment is based on cosmogenic nuclide (10Be) dating of quartzitic deltaic sands that were deposited in the northern Kenya Rift during a highstand of Lake Suguta, which was associated with the Holocene African Humid Period. Taken together, my new results document the role of climate variability in erosion processes that impact climatic threshold environments, which may provide a template for potential future impacts of climate-driven changes in surface processes in the course of Global Change.},
  language  = {en}
}