@phdthesis{Vapenka2011,
  author    = {V{\´a}penka, Aleš},
  title     = {Geschlechterstereotype und Geschlechtsidentit{\"a}t von M{\"a}nnern mit unterschiedlichem Verlauf der psychosexuellen Entwicklung},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53175},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Im Rahmen eines explorativen Vergleichsuntersuchungsplans wurde untersucht, inwieweit sich die durch biologische Faktoren bedingte unterschiedliche Lebenserfahrung sowie die Sozialisationsbedingungen in der psychosexuellen Entwicklung bei hetero-, homo- und postoperativen transsexuellen M{\"a}nnern (N = 191) auf die Integration der Geschlechterstereotypen in die kognitiven (Selbst-, Fremdwahrnehmung), emotionalen (Selbst- und Fremdbewertung) und verhaltensm{\"a}ßigen Aspekte (Normen der geschlechtsspezifischen Verhaltens) der Geschlechtsidentit{\"a}t auswirken und ob sich Identifikationsmuster der Entwicklung des geschlechtlichen Selbstkonzepts ableiten lassen. Die Messung der kognitiven Aspekte des geschlechtlichen Selbstkonzepts (Maskulinit{\"a}t und Femininit{\"a}t) erfolgte mittels der GERO-Skala von Brengelmann und Hendrich (1990). Zur Erfassung der emotionalen Aspekte und Identifikationsmuster der Entwicklung des geschlechtlichen Selbstkonzepts wurden die Werte f{\"u}r die Variablen Maskulinit{\"a}t und Femininit{\"a}t zuerst mittels der computergesteuerten Methodik IDEXMONO und IDEXIDIO, die auf der Identit{\"a}tsstrukturanalyse (Identity Structure Analysis) von Weinreich (2003) basiert, aufgearbeitet und weiter interferenzstatistisch ausgewertet. Weiterhin wurden der Fragebogen zur Messung normativer Geschlechtsrollenorientierung (NGRO) von Athenstaedt (2000) sowie ein ad hoc entworfener demographischer Fragebogen eingesetzt. Die Ergebnisse zeigen, dass der Verlauf der psychosexuellen Entwicklung einen starken Einfluss auf die Integration der Geschlechterstereotypen in die geschlechtliche Selbst- und Fremdwahrnehmung hat. Im kognitiven Bereich, bezogen auf die pers{\"o}nliche Identit{\"a}t (Grad der Selbstzuschreibung m{\"a}nnlicher und weiblicher Merkmale), stellt die Maskulinit{\"a}t eine stabile und erstrebenswerte Variable zur Herausbildung des geschlechtlichen Selbstkonzepts bei allen Gruppen dar. Die Femininit{\"a}t tr{\"a}gt am meisten zur Differenzierung zwischen den Hetero-, Homo- und Transsexuellen bei. Sie wird, je nach der Entwicklungsphase, unterschiedlich in das geschlechtliche Selbstkonzept integriert. Hinsichtlich der sozialen Identit{\"a}t (Zugeh{\"o}rigkeitsgef{\"u}hl) lassen sich die Gruppen bez{\"u}glich der wahrgenommenen {\"A}hnlichkeiten sowohl mit m{\"a}nnlichen als auch weiblichen Personen, je nach der Entwicklungsphase, unterscheiden. Die soziale Wahrnehmung von M{\"a}nnern und Frauen (Fremdwahrnehmung), ist bei Transsexuellen traditioneller als die der Hetero- und Homosexuellen. Bei der Selbst- und Fremdbewertung ergaben sich keine signifikanten Unterschiede. Bei der Internalisierung der sozialen Normen des geschlechtsspezifischen Verhaltens zeigt sich, dass Heterosexuelle der Aus{\"u}bung der Geschlechterrollen gegen{\"u}ber egalit{\"a}rer eingestellt sind als Trans- und Homosexuelle. Bei den Sozialisationsfaktoren ist hervorzuheben, dass generell weibliche Identifikationspersonen einen st{\"a}rkeren Einfluss auf die Herausbildung des geschlechtlichen Selbstkonzeptes hatten als m{\"a}nnliche Identifikationspersonen. Es scheint jedoch, dass Homosexuelle bei der Entwicklung ihres geschlechtlichen Selbstkonzepts st{\"a}rker unter dem Einfluss der Frauen stehen als die anderen zwei erforschten Gruppen. Zur Beantwortung der Frage, welche selbstkonzeptbezogenen Variablen und Entwicklungsfaktoren die gr{\"o}ßte statistische Bedeutung f{\"u}r die Trennung und Pr{\"a}diktion der einzelnen untersuchten Gruppen haben, wurde eine Diskriminanzanalyse berechnet. Die gr{\"o}ßte diskriminatorische Bedeutung besitzen die Variablen „Stereotypische Wahrnehmung der m{\"a}nnlichen Personen" und „Ego-Involvement mit weiblichen Personen" f{\"u}r die Diskriminanzfunktion 1 (Trennung der Transsexuellen von Hetero- und Homosexuellen) und die Variablen „Empathische Identifikation mit m{\"a}nnlichen Personen in der Vergangenheit" und „Zuwachs an empathischer Identifikation mit weiblichen Personen" f{\"u}r die Diskriminanzfunktion 2 (Trennung der Hetero- von Homosexuellen).},
  language  = {de}
}
@phdthesis{FloresSuarez2011,
  author    = {Flores Su{\´a}rez, Rosaura},
  title     = {Three-dimensional polarization probing in polymer ferroelectrics, polymer-dispersed liquid crystals, and polymer ferroelectrets},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-60173},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {A key non-destructive technique for analysis, optimization and developing of new functional materials such as sensors, transducers, electro-optical and memory devices is presented. The Thermal-Pulse Tomography (TPT) provides high-resolution three-dimensional images of electric field and polarization distribution in a material. This thermal technique use a pulsed heating by means of focused laser light which is absorbed by opaque electrodes. The diffusion of the heat causes changes in the sample geometry, generating a short-circuit current or change in surface potential, which contains information about the spatial distribution of electric dipoles or space charges. Afterwards, a reconstruction of the internal electric field and polarization distribution in the material is possible via Scale Transformation or Regularization methods. In this way, the TPT was used for the first time to image the inhomogeneous ferroelectric switching in polymer ferroelectric films (candidates to memory devices). The results shows the typical pinning of electric dipoles in the ferroelectric polymer under study and support the previous hypotheses of a ferroelectric reversal at a grain level via nucleation and growth. In order to obtain more information about the impact of the lateral and depth resolution of the thermal techniques, the TPT and its counterpart called Focused Laser Intensity Modulation Method (FLIMM) were implemented in ferroelectric films with grid-shaped electrodes. The results from both techniques, after the data analysis with different regularization and scale methods, are in total agreement. It was also revealed a possible overestimated lateral resolution of the FLIMM and highlights the TPT method as the most efficient and reliable thermal technique. After an improvement in the optics, the Thermal-Pulse Tomography method was implemented in polymer-dispersed liquid crystals (PDLCs) films, which are used in electro-optical applications. The results indicated a possible electrostatic interaction between the COH group in the liquid crystals and the fluorinate atoms of the used ferroelectric matrix. The geometrical parameters of the LC droplets were partially reproduced as they were compared with Scanning Electron Microscopy (SEM) images. For further applications, it is suggested the use of a non-strong-ferroelectric polymer matrix. In an effort to develop new polymerferroelectrets and for optimizing their properties, new multilayer systems were inspected. The results of the TPT method showed the non-uniformity of the internal electric-field distribution in the shaped-macrodipoles and thus suggested the instability of the sample. Further investigation on multilayers ferroelectrets was suggested and the implementation of less conductive polymers layers too.},
  language  = {en}
}
@phdthesis{Stoyanov2011,
  author    = {Stoyanov, Hristiyan},
  title     = {Soft nanocomposites with enhanced electromechanical response for dielectric elastomer actuators},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51194},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Electromechanical transducers based on elastomer capacitors are presently considered for many soft actuation applications, due to their large reversible deformation in response to electric field induced electrostatic pressure. The high operating voltage of such devices is currently a large drawback, hindering their use in applications such as biomedical devices and biomimetic robots, however, they could be improved with a careful design of their material properties. The main targets for improving their properties are increasing the relative permittivity of the active material, while maintaining high electric breakdown strength and low stiffness, which would lead to enhanced electrostatic storage ability and hence, reduced operating voltage. Improvement of the functional properties is possible through the use of nanocomposites. These exploit the high surface-to-volume ratio of the nanoscale filler, resulting in large effects on macroscale properties. This thesis explores several strategies for nanomaterials design. The resulting nanocomposites are fully characterized with respect to their electrical and mechanical properties, by use of dielectric spectroscopy, tensile mechanical analysis, and electric breakdown tests. First, nanocomposites consisting of high permittivity rutile TiO2 nanoparticles dispersed in thermoplastic block copolymer SEBS (poly-styrene-coethylene-co-butylene-co-styrene) are shown to exhibit permittivity increases of up to 3.7 times, leading to 5.6 times improvement in electrostatic energy density, but with a trade-off in mechanical properties (an 8-fold increase in stiffness). The variation in both electrical and mechanical properties still allows for electromechanical improvement, such that a 27 \% reduction of the electric field is found compared to the pure elastomer. Second, it is shown that the use of nanofiller conductive particles (carbon black (CB)) can lead to a strong increase of relative permittivity through percolation, however, with detrimental side effects. These are due to localized enhancement of the electric field within the composite, which leads to sharp reductions in electric field strength. Hence, the increase in permittivity does not make up for the reduction in breakdown strength in relation to stored electrical energy, which may prohibit their practical use. Third, a completely new approach for increasing the relative permittivity and electrostatic energy density of a polymer based on 'molecular composites' is presented, relying on chemically grafting soft π-conjugated macromolecules to a flexible elastomer backbone. Polarization caused by charge displacement along the conjugated backbone is found to induce a large and controlled permittivity enhancement (470 \% over the elastomer matrix), while chemical bonding, encapsulates the PANI chains manifesting in hardly any reduction in electric breakdown strength, and hence resulting in a large increase in stored electrostatic energy. This is shown to lead to an improvement in the sensitivity of the measured electromechanical response (83 \% reduction of the driving electric field) as well as in the maximum actuation strain (250 \%). These results represent a large step forward in the understanding of the strategies which can be employed to obtain high permittivity polymer materials with practical use for electro-elastomer actuation.},
  language  = {en}
}
@phdthesis{Kalbitz2011,
  author    = {Kalbitz, Ren{\´e}},
  title     = {Stability of polarization in organic ferroelectric metal-insulator-semiconductor structures},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57276},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Organic thin film transistors (TFT) are an attractive option for low cost electronic applications and may be used for active matrix displays and for RFID applications. To extend the range of applications there is a need to develop and optimise the performance of non-volatile memory devices that are compatible with the solution-processing fabrication procedures used in plastic electronics. A possible candidate is an organic TFT incorporating the ferroelectric co-polymer poly(vinylidenefluoride-trifluoroethylene)(P(VDF-TrFE)) as the gate insulator. Dielectric measurements have been carried out on all-organic metal-insulator-semiconductor structures with the ferroelectric polymer poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) as the gate insu-lator. The capacitance spectra of MIS devices, were measured under different biases, showing the effect of charge accumulation and depletion on the Maxwell-Wagner peak. The position and height of this peak clearly indicates the lack of stable depletion behavior and the decrease of mobility when increasing the depletion zone width, i.e. upon moving into the P3HT bulk. The lack of stable depletion was further investigated with capacitance-voltage (C-V) measurements. When the structure was driven into depletion, C-V plots showed a positive flat-band voltage shift, arising from the change in polarization state of the ferroelectric insulator. When biased into accumulation, the polarization was reversed. It is shown that the two polarization states are stable i.e. no depolarization occurs below the coercive field. However, negative charge trapped at the semiconductor-insulator interface during the depletion cycle masks the negative shift in flat-band voltage expected during the sweep to accumulation voltages. The measured output characteristics of the studied ferroelectric-field-effect transistors confirmed the results of the C-V plots. Furthermore, the results indicated a trapping of electrons at the positively charged surfaces of the ferroelectrically polarized P(VDF-TrFE) crystallites near the insulator/semiconductor in-terface during the first poling cycles. The study of the MIS structure by means of thermally stimulated current (TSC) revealed further evidence for the stability of the polarization under depletion voltages. It was shown, that the lack of stable depletion behavior is caused by the compensation of the orientational polarization by fixed electrons at the interface and not by the depolarization of the insulator, as proposed in several publications. The above results suggest a performance improvement of non-volatile memory devices by the optimization of the interface.},
  language  = {en}
}
@phdthesis{Menzel2011,
  author    = {Menzel, Michael},
  title     = {Model-driven security in service-oriented architectures : leveraging security patterns to transform high-level security requirements to technical policies},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-59058},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Service-oriented Architectures (SOA) facilitate the provision and orchestration of business services to enable a faster adoption to changing business demands. Web Services provide a technical foundation to implement this paradigm on the basis of XML-messaging. However, the enhanced flexibility of message-based systems comes along with new threats and risks. To face these issues, a variety of security mechanisms and approaches is supported by the Web Service specifications. The usage of these security mechanisms and protocols is configured by stating security requirements in security policies. However, security policy languages for SOA are complex and difficult to create due to the expressiveness of these languages. To facilitate and simplify the creation of security policies, this thesis presents a model-driven approach that enables the generation of complex security policies on the basis of simple security intentions. SOA architects can specify these intentions in system design models and are not required to deal with complex technical security concepts. The approach introduced in this thesis enables the enhancement of any system design modelling languages - for example FMC or BPMN - with security modelling elements. The syntax, semantics, and notion of these elements is defined by our security modelling language SecureSOA. The metamodel of this language provides extension points to enable the integration into system design modelling languages. In particular, this thesis demonstrates the enhancement of FMC block diagrams with SecureSOA. To enable the model-driven generation of security policies, a domain-independent policy model is introduced in this thesis. This model provides an abstraction layer for security policies. Mappings are used to perform the transformation from our model to security policy languages. However, expert knowledge is required to generate instances of this model on the basis of simple security intentions. Appropriate security mechanisms, protocols and options must be chosen and combined to fulfil these security intentions. In this thesis, a formalised system of security patterns is used to represent this knowledge and to enable an automated transformation process. Moreover, a domain-specific language is introduced to state security patterns in an accessible way. On the basis of this language, a system of security configuration patterns is provided to transform security intentions related to data protection and identity management. The formal semantics of the security pattern language enable the verification of the transformation process introduced in this thesis and prove the correctness of the pattern application. Finally, our SOA Security LAB is presented that demonstrates the application of our model-driven approach to facilitate a dynamic creation, configuration, and execution of secure Web Service-based composed applications.},
  language  = {en}
}
@phdthesis{Mohamed2011,
  author    = {Mohamed, Rasha},
  title     = {Das Programm "Gesunde D{\"o}rfer" in Syrien : eine empirische Analyse},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-55545},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Der Begriff Gesundheit wurde von der WHO definiert als „nicht nur die Abwesenheit von Krankheit, sondern, positiv als Naturrecht formuliert, vollst{\"a}ndiges k{\"o}rperliches, seelisches und soziales Wohlbefinden". Deswegen hat die WHO mit dem Gesundheitsministerium in Syrien das Programm „Gesunde D{\"o}rfer" seit 1996 gestaltet. Es zielt darauf, den wirtschaftlichen, sozialen und gesundheitlichen Zustand der Landbev{\"o}lkerung zu verbessern, insbesondere soll es den großen Unterschied zwischen Stadt und Land vermindern. Das Projekt stellt sich die Aufgabe, den Einfluss des Programms auf Wirtschafts- und Gesundheitsparameter im Vergleich mit anderen Kontrolled{\"o}rfern zu analysieren. Hierzu werden Umfragedaten in Syrien ausgewertet. Die Auswertung der Befragung in der vorliegenden Arbeit zeigte, dass das Programm seine Ziele bez{\"u}glich der Verbesserung der Gesundheits- und Lebensqualit{\"a}t erreicht Erfolgreich war das Programm „Gesunde D{\"o}rfer" auch, mit Ausnahme der n{\"o}rdlichen und {\"o}stlichen Region, in der Verringerung der Anzahl arbeitender Kinder, in der F{\"o}rderung der Frauen eine Besch{\"a}ftigung aufzunehmen bzw. ein Studium zu absolvieren sowie in der Reduzierung der Analphabetenrate.},
  language  = {de}
}
@phdthesis{Robinson2011,
  author    = {Robinson, Alexander},
  title     = {Modeling the Greenland Ice Sheet response to climate change in the past and future},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-50430},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {The Greenland Ice Sheet (GIS) contains enough water volume to raise global sea level by over 7 meters. It is a relic of past glacial climates that could be strongly affected by a warming world. Several studies have been performed to investigate the sensitivity of the ice sheet to changes in climate, but large uncertainties in its long-term response still exist. In this thesis, a new approach has been developed and applied to modeling the GIS response to climate change. The advantages compared to previous approaches are (i) that it can be applied over a wide range of climatic scenarios (both in the deep past and the future), (ii) that it includes the relevant feedback processes between the climate and the ice sheet and (iii) that it is highly computationally efficient, allowing simulations over very long timescales. The new regional energy-moisture balance model (REMBO) has been developed to model the climate and surface mass balance over Greenland and it represents an improvement compared to conventional approaches in modeling present-day conditions. Furthermore, the evolution of the GIS has been simulated over the last glacial cycle using an ensemble of model versions. The model performance has been validated against field observations of the present-day climate and surface mass balance, as well as paleo information from ice cores. The GIS contribution to sea level rise during the last interglacial is estimated to be between 0.5-4.1 m, consistent with previous estimates. The ensemble of model versions has been constrained to those that are consistent with the data, and a range of valid parameter values has been defined, allowing quantification of the uncertainty and sensitivity of the modeling approach. Using the constrained model ensemble, the sensitivity of the GIS to long-term climate change was investigated. It was found that the GIS exhibits hysteresis behavior (i.e., it is multi-stable under certain conditions), and that a temperature threshold exists above which the ice sheet transitions to an essentially ice-free state. The threshold in the global temperature is estimated to be in the range of 1.3-2.3°C above preindustrial conditions, significantly lower than previously believed. The timescale of total melt scales non-linearly with the overshoot above the temperature threshold, such that a 2°C anomaly causes the ice sheet to melt in ca. 50,000 years, but an anomaly of 6°C will melt the ice sheet in less than 4,000 years. The meltback of the ice sheet was found to become irreversible after a fraction of the ice sheet is already lost - but this level of irreversibility also depends on the temperature anomaly.},
  language  = {en}
}
@phdthesis{Andorf2011,
  author    = {Andorf, Sandra},
  title     = {A systems biological approach towards the molecular basis of heterosis in Arabidopsis thaliana},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51173},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Heterosis is defined as the superiority in performance of heterozygous genotypes compared to their corresponding genetically different homozygous parents. This phenomenon is already known since the beginning of the last century and it has been widely used in plant breeding, but the underlying genetic and molecular mechanisms are not well understood. In this work, a systems biological approach based on molecular network structures is proposed to contribute to the understanding of heterosis. Hybrids are likely to contain additional regulatory possibilities compared to their homozygous parents and, therefore, they may be able to correctly respond to a higher number of environmental challenges, which leads to a higher adaptability and, thus, the heterosis phenomenon. In the network hypothesis for heterosis, presented in this work, more regulatory interactions are expected in the molecular networks of the hybrids compared to the homozygous parents. Partial correlations were used to assess this difference in the global interaction structure of regulatory networks between the hybrids and the homozygous genotypes. This network hypothesis for heterosis was tested on metabolite profiles as well as gene expression data of the two parental Arabidopsis thaliana accessions C24 and Col-0 and their reciprocal crosses. These plants are known to show a heterosis effect in their biomass phenotype. The hypothesis was confirmed for mid-parent and best-parent heterosis for either hybrid of our experimental metabolite as well as gene expression data. It was shown that this result is influenced by the used cutoffs during the analyses. Too strict filtering resulted in sets of metabolites and genes for which the network hypothesis for heterosis does not hold true for either hybrid regarding mid-parent as well as best-parent heterosis. In an over-representation analysis, the genes that show the largest heterosis effects according to our network hypothesis were compared to genes of heterotic quantitative trait loci (QTL) regions. Separately for either hybrid regarding mid-parent as well as best-parent heterosis, a significantly larger overlap between the resulting gene lists of the two different approaches towards biomass heterosis was detected than expected by chance. This suggests that each heterotic QTL region contains many genes influencing biomass heterosis in the early development of Arabidopsis thaliana. Furthermore, this integrative analysis led to a confinement and an increased confidence in the group of candidate genes for biomass heterosis in Arabidopsis thaliana identified by both approaches.},
  language  = {en}
}
@phdthesis{Reusser2011,
  author    = {Reusser, Dominik Edwin},
  title     = {Combining smart model diagnostics and effective data collection for snow catchments},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52574},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Complete protection against flood risks by structural measures is impossible. Therefore flood prediction is important for flood risk management. Good explanatory power of flood models requires a meaningful representation of bio-physical processes. Therefore great interest exists to improve the process representation. Progress in hydrological process understanding is achieved through a learning cycle including critical assessment of an existing model for a given catchment as a first step. The assessment will highlight deficiencies of the model, from which useful additional data requirements are derived, giving a guideline for new measurements. These new measurements may in turn lead to improved process concepts. The improved process concepts are finally summarized in an updated hydrological model. In this thesis I demonstrate such a learning cycle, focusing on the advancement of model evaluation methods and more cost effective measurements. For a successful model evaluation, I propose that three questions should be answered: 1) when is a model reproducing observations in a satisfactory way? 2) If model results deviate, of what nature is the difference? And 3) what are most likely the relevant model components affecting these differences? To answer the first two questions, I developed a new method to assess the temporal dynamics of model performance (or TIGER - TIme series of Grouped Errors). This method is powerful in highlighting recurrent patterns of insufficient model behaviour for long simulation periods. I answered the third question with the analysis of the temporal dynamics of parameter sensitivity (TEDPAS). For calculating TEDPAS, an efficient method for sensitivity analysis is necessary. I used such an efficient method called Fourier Amplitude Sensitivity Test, which has a smart sampling scheme. Combining the two methods TIGER and TEDPAS provided a powerful tool for model assessment. With WaSiM-ETH applied to the Weisseritz catchment as a case study, I found insufficient process descriptions for the snow dynamics and for the recession during dry periods in late summer and fall. Focusing on snow dynamics, reasons for poor model performance can either be a poor representation of snow processes in the model, or poor data on snow cover, or both. To obtain an improved data set on snow cover, time series of snow height and temperatures were collected with a cost efficient method based on temperature measurements on multiple levels at each location. An algorithm was developed to simultaneously estimate snow height and cold content from these measurements. Both, snow height and cold content are relevant quantities for spring flood forecasting. Spatial variability was observed at the local and the catchment scale with an adjusted sampling design. At the local scale, samples were collected on two perpendicular transects of 60 m length and analysed with geostatistical methods. The range determined from fitted theoretical variograms was within the range of the sampling design for 80\% of the plots. No patterns were found, that would explain the random variability and spatial correlation at the local scale. At the watershed scale, locations of the extensive field campaign were selected according to a stratified sample design to capture the combined effects of elevation, aspect and land use. The snow height is mainly affected by the plot elevation. The expected influence of aspect and land use was not observed. To better understand the deficiencies of the snow module in WaSiM-ETH, the same approach, a simple degree day model was checked for its capability to reproduce the data. The degree day model was capable to explain the temporal variability for plots with a continuous snow pack over the entire snow season, if parameters were estimated for single plots. However, processes described in the simple model are not sufficient to represent multiple accumulation-melt-cycles, as observed for the lower catchment. Thus, the combined spatio-temporal variability at the watershed scale is not captured by the model. Further tests on improved concepts for the representation of snow dynamics at the Weißeritz are required. From the data I suggest to include at least rain on snow and redistribution by wind as additional processes to better describe spatio-temporal variability. Alternatively an energy balance snow model could be tested. Overall, the proposed learning cycle is a useful framework for targeted model improvement. The advanced model diagnostics is valuable to identify model deficiencies and to guide field measurements. The additional data collected throughout this work helps to get a deepened understanding of the processes in the Weisseritz catchment.},
  language  = {en}
}
@phdthesis{Naaf2011,
  author    = {Naaf, Tobias},
  title     = {Floristic homogenization and impoverishment : herb layer changes over two decades in deciduous forest patches of the Weser-Elbe region (NW Germany)},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52446},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Human-induced alterations of the environment are causing biotic changes worldwide, including the extinction of species and a mixing of once disparate floras and faunas. One type of biological communities that is expected to be particularly affected by environmental alterations are herb layer plant communities of fragmented forests such as those in the west European lowlands. However, our knowledge about current changes in species diversity and composition in these communities is limited due to a lack of adequate long-term studies. In this thesis, I resurveyed the herb layer communities of ancient forest patches in the Weser-Elbe region (NW Germany) after two decades using 175 semi-permanent plots. The general objectives were (i) to quantify changes in plant species diversity considering also between-community (β) and functional diversity, (ii) to determine shifts in species composition in terms of species' niche breadth and functional traits and (iii) to find indications on the most likely environmental drivers for the observed changes. These objectives were pursued with four independent research papers (Chapters 1-4) whose results were brought together in a General Discussion. Alpha diversity (species richness) increased by almost four species on average, whereas β diversity tended to decrease (Chapter 1). The latter is interpreted as a beginning floristic homogenization. The observed changes were primarily the result of a spread of native habitat generalists that are able to tolerate broad pH and moisture ranges. The changes in α and β diversity were only significant when species abundances were neglected (Chapters 1 and 2), demonstrating that the diversity changes resulted mainly from gains and losses of low-abundance species. This study is one of the first studies in temperate Europe that demonstrates floristic homogenization of forest plant communities at a larger than local scale. The diversity changes found at the taxonomic level did not result in similar changes at the functional level (Chapter 2). The likely reason is that these communities are functionally "buffered". Single communities involve most of the functional diversity of the regional pool, i.e., they are already functionally rich, while they are functionally redundant among each other, i.e., they are already homogeneous. Independent of taxonomic homogenization, the abundance of 30 species decreased significantly (Chapter 4). These species included 12 ancient forest species (i.e., species closely tied to forest patches with a habitat continuity > 200 years) and seven species listed on the Red List of endangered plant species in NW Germany. If these decreases continue over the next decades, local extinctions may result. This biotic impoverishment would seriously conflict with regional conservation goals. Community assembly mechanisms changed at the local level particularly at sites that experienced disturbance by forest management activities between the sampling periods (Chapter 3). Disturbance altered community assembly mechanisms in two ways: (i) it relaxed environmental filters and allowed the coexistence of different reproduction strategies, as reflected by a higher diversity of reproductive traits at the time of the resurvey, and (ii) it enhanced light availability and tightened competitive filters. These limited the functional diversity with respect to canopy height and selected for taller species. Thirty-one winner and 30 loser species, which had significantly increased or decreased in abundance, respectively, were characterized by various functional traits and ecological performances to find indications on the most likely environmental drivers for the observed floristic changes (Chapter 4). Winner species had higher seed longevity, flowered later in the season and had more often an oceanic distribution compared to loser species. Loser species tended to have a higher specific leaf area, to be more susceptible to deer browsing and to have a performance optimum at higher soil pH values compared to winner species. Multiple logistic regression analyses indicated that disturbances due to forest management interventions were the primary cause of the species shifts. As one of the first European resurvey studies, this study provides indications that an enhanced browsing pressure due to increased deer densities and increasingly warmer winters are important drivers. The study failed to demonstrate that eutrophication and acidification due to atmospheric deposition substantially drive herb layer changes. The restriction of the sample to the most base-rich sites in the region is discussed as a likely reason. Furthermore, the decline of several ancient forest species is discussed as an indication that the forest patches are still paying off their "extinction debt", i.e., exhibit a delayed response to forest fragmentation.},
  language  = {en}
}
@phdthesis{CastroPrieto2011,
  author    = {Castro Prieto, Aines del Carmen},
  title     = {Immunogenetics of free-ranging felids on Namibian farmlands},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-55505},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Genetic variation is crucial for the long-term survival of the species as it provides the potential for adaptive responses to environmental changes such as emerging diseases. The Major Histocompatibility Complex (MHC) is a gene family that plays a central role in the vertebrate's immune system by triggering the adaptive immune response after exposure to pathogens. MHC genes have become highly suitable molecular markers of adaptive significance. They synthesize two primary cell surface molecules namely MHC class I and class II that recognize short fragments of proteins derived respectively from intracellular (e.g. viruses) and extracellular (e.g. bacteria, protozoa, arthropods) origins and present them to immune cells. High levels of MHC polymorphism frequently observed in natural populations are interpreted as an adaptation to detect and present a wide array of rapidly evolving pathogens. This variation appears to be largely maintained by positive selection driven mainly by pathogenic selective pressures. For my doctoral research I focused on MHC I and II variation in free-ranging cheetahs (Acinonyx jubatus) and leopards (Panthera pardus) on Namibian farmlands. Both felid species are sympatric thus subject to similar pathogenic pressures but differ in their evolutionary and demographic histories. The main aims were to investigate 1) the extent and patterns of MHC variation at the population level in both felids, 2) the association between levels of MHC variation and disease resistance in free-ranging cheetahs, and 3) the role of selection at different time scales in shaping MHC variation in both felids. Cheetahs and leopards represent the largest free-ranging carnivores in Namibia. They concentrate in unprotected areas on privately owned farmlands where domestic and other wild animals also occur and the risk of pathogen transmission is increased. Thus, knowledge on adaptive genetic variation involved in disease resistance may be pertinent to both felid species' conservation. The cheetah has been used as a classic example in conservation genetics textbooks due to overall low levels of genetic variation. Reduced variation at MHC genes has been associated with high susceptibility to infectious diseases in cheetahs. However, increased disease susceptibility has only been observed in captive cheetahs whereas recent studies in free-ranging Namibian cheetahs revealed a good health status. This raised the question whether the diversity at MHC I and II genes in free-ranging cheetahs is higher than previously reported. In this study, a total of 10 MHC I alleles and four MHC II alleles were observed in 149 individuals throughout Namibia. All alleles but one likely belong to functional MHC genes as their expression was confirmed. The observed alleles belong to four MHC I and three MHC II genes in the species as revealed by phylogenetic analyses. Signatures of historical positive selection acting on specific sites that interact directly with pathogen-derived proteins were detected in both MHC classes. Furthermore, a high genetic differentiation at MHC I was observed between Namibian cheetahs from east-central and north-central regions known to differ substantially in exposure to feline-specific viral pathogens. This suggests that the patterns of MHC I variation in the current population mirrors different pathogenic selective pressure imposed by viruses. Cheetahs showed low levels of MHC diversity compared with other mammalian species including felids, but this does not seem to influence the current immunocompetence of free-ranging cheetahs in Namibia and contradicts the previous conclusion that the cheetah is a paradigm species of disease susceptibility. However, it cannot be ruled out that the low MHC variation might limit a prosperous immunocompetence in the case of an emerging disease scenario because none of the remaining alleles might be able to recognize a novel pathogen. In contrast to cheetahs, leopards occur in most parts of Africa being perhaps the most abundant big cat in the continent. Leopards seem to have escaped from large-scale declines due to epizootics in the past in contrast to some free-ranging large carnivore populations in Africa that have been afflicted by epizootics. Currently, no information about the MHC sequence variation and constitution in African leopards exists. In this study, I characterized genetic variation at MHC I and MHC II genes in free-ranging leopards from Namibia. A total of six MHC I and six MHC II sequences were detected in 25 individuals from the east-central region. The maximum number of sequences observed per individual suggests that they likely correspond to at least three MHC I and three MHC II genes. Hallmarks of MHC evolution were confirmed such as historical positive selection, recombination and trans-species polymorphism. The low MHC variation detected in Namibian leopards is not conclusive and further research is required to assess the extent of MHC variation in different areas of its geographic range. Results from this thesis will contribute to better understanding the evolutionary significance of MHC and conservation implications in free-ranging felids. Translocation of wildlife is an increasingly used management tool for conservation purposes that should be conducted carefully as it may affect the ability of the translocated animals to cope with different pathogenic selective pressures.},
  language  = {en}
}
@phdthesis{Junginger2011,
  author    = {Junginger, Annett},
  title     = {East African climate variability on different time scales : the Suguta Valley in the African-Asian Monsoon Domain},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56834},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Motivation | Societal and economic needs of East Africa rely entirely on the availability of water, which is governed by the regular onset and retreat of the rainy seasons. Fluctuations in the amounts of rainfall has tremendous impact causing widespread famine, disease outbreaks and human migrations. Efforts towards high resolution forecasting of seasonal precipitation and hydrological systems are therefore needed, which requires high frequency short to long-term analyses of available climate data that I am going to present in this doctoral thesis by three different studies. 15,000 years - Suguta Valley | The main study of this thesis concentrated on the understanding of humidity changes within the last African Humid Period (AHP, 14.8-5.5 ka BP). The nature and causes of intensity variations of the West-African (WAM) and Indian Summer monsoons (ISM) during the AHP, especially their exact influence on regional climate relative to each other, is currently intensely debated. Here, I present a high-resolution multiproxy lake-level record spanning the AHP from the remote Suguta Valley in the northern Kenya Rift, located between the WAM and ISM domains. The presently desiccated valley was during the AHP filled by a 300 m deep and 2200 km2 large palaeo-lake due to an increase in precipitation of only 26\%. The record explains the synchronous onset of large lakes in the East African Rift System (EARS) with the longitudinal shift of the Congo Air Boundary (CAB) over the East African and Ethiopian Plateaus, as the direct consequence of an enhanced atmospheric pressure gradient between East-Africa and India due to a precessional-forced northern hemisphere insolation maximum. Pronounced, and abrupt lake level fluctuations during the generally wet AHP are explained by small-scale solar irradiation changes weakening this pressure gradient atmospheric moisture availability preventing the CAB from reaching the study area. Instead, the termination of the AHP occurred, in a non-linear manner due to a change towards an equatorial insolation maximum ca. 6.5 ka ago extending the AHP over Ethiopia and West-Africa. 200 years - Lake Naivasha | The second part of the thesis focused on the analysis of a 200 year-old sediment core from Lake Naivasha in the Central Kenya Rift, one of the very few present freshwater lakes in East Africa. The results revealed and confirmed, that the appliance of proxy records for palaeo-climate reconstruction for the last 100 years within a time of increasing industrialisation and therefore human impact to the proxy-record containing sites are broadly limited. Since the middle of the 20th century, intense anthropogenic activity around Lake Naivasha has led to cultural eutrophication, which has overprinted the influence of natural climate variation to the lake usually inferred from proxy records such as diatoms, transfer-functions, geochemical and sedimentological analysis as used in this study. The results clarify the need for proxy records from remote unsettled areas to contribute with pristine data sets to current debates about anthropologic induced global warming since the past 100 years. 14 years - East African Rift | In order to avoid human influenced data sets and validate spatial and temporal heterogeneities of proxy-records from East Africa, the third part of the thesis therefore concentrated on the most recent past 14 years (1996-2010) detecting climate variability by using remotely sensed rainfall data. The advancement in the spatial coverage and temporal resolutions of rainfall data allow a better understanding of influencing climate mechanisms and help to better interpret proxy-records from the EARS in order to reconstruct past climate conditions. The study focuses on the dynamics of intraseasonal rainfall distribution within catchments of eleven lake basins in the EARS that are often used for palaeo-climate studies. We discovered that rainfall in adjacent basins exhibits high complexities in the magnitudes of intraseasonal variability, biennial to triennial precipitation patterns and even are not necessarily correlated often showing opposite trends. The variability among the watersheds is driven by the complex interaction of topography, in particular the shape, length and elevation of the catchment and its relative location to the East African Rift System and predominant influence of the ITCZ or CAB, whose locations and intensities are dependent on the strength of low pressure cells over India, SST variations in the Atlantic, Pacific or Indian Ocean, QBO phases and the 11-year solar cycle. Among all seasons we observed, January-September is the season of highest and most complex rainfall variability, especially for the East African Plateau basins, most likely due to the irregular penetration and sensitivity of the CAB.},
  language  = {en}
}
@phdthesis{Ruge2011,
  author    = {Ruge, Marcus},
  title     = {Stimmungen und Erwartungen im System der M{\"a}rkte : eine Analyse mit DPLS-Modellen},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-86956-142-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52900},
  school      = {Universit{\"a}t Potsdam},
  pages     = {XIV, 254},
  year      = {2011},
  abstract  = {Diese Forschungsarbeit widmet sich der Analyse von Stimmungen und Erwartungen im System der M{\"a}rkte mit Dynamic Partial Least Squares (DPLS) Modellen. Die Analyse komplexer Systeme mit umfangreichen Datens{\"a}tzen und die Erkennung relevanter Muster erfordern die Verwendung moderner statistischer Verfahren. DPLS-Modelle, eine Variante der Strukturgleichungs-modelle mit Latenten Variablen, werden methodisch erweitert, um mehrere zeitliche Verz{\"o}gerungsstufen gleichzeitig modellieren zu k{\"o}nnen. Die {\"o}konometrischen Modelle versuchen, zahlreiche latente Einflussfaktoren und ihre verdeckten Beziehungen zu identifizieren. Als Daten werden rund 80 Indikatoren verwendet von Januar 1991 bis Juni 2010, um Stimmungen, Erwartungen und wirtschaftlich relevanten Gr{\"o}ßen zu operationalisieren und die Zusammenh{\"a}nge detailliert zu untersuchen. Die Modellergebnisse zeigen, dass Stimmungen, also die Einsch{\"a}tzung der aktuellen wirtschaftlichen Lage, deutlich mit wirtschaftlichen Gr{\"o}ßen zusammenh{\"a}ngen, unter anderem mit Investitionen, Auftragseing{\"a}ngen oder Aktienmarktentwicklungen. Die Erwartungen, also die Einsch{\"a}tzung der zuk{\"u}nftigen Entwicklung, bieten eine mittlere bis schwache Prognosekraft f{\"u}r sechs bis maximal achtzehn Monate in die Zukunft. F{\"u}r k{\"u}rzere Zeitr{\"a}ume von sechs Monaten sind Stimmungen und Erwartungen die besten verf{\"u}gbaren Prognosevariablen. Die Analyse der Modellabweichungen erlaubt R{\"u}ckschl{\"u}sse auf wirtschaftstheoretische Konzepte, wie Rationalit{\"a}t der Erwartungen. Auff{\"a}llig sind scheinbare Phasen der systematischen {\"U}ber- und Unterbewertungen der aktuellen Situation oder zuk{\"u}nftigen Entwicklung, insbesondere vor und nach Krisensituationen. Die Ergebnisse dieser Arbeit geben somit einen erweiterten Einblick in die empirischen Zusammenh{\"a}nge subjektiver Einsch{\"a}tzungen mit realen wirtschaftlichen Gr{\"o}ßen.},
  language  = {de}
}
@phdthesis{Kristen2011,
  author    = {Kristen, Juliane Ute},
  title     = {Amphiphilic BAB-triblock copolymers bearing fluorocarbon groups : synthesis and self-organization in aqueous media},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-61782},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {In this work new fluorinated and non-fluorinated mono- and bifunctional trithiocarbonates of the structure Z-C(=S)-S-R and Z-C(=S)-S-R-S-C(=S)-Z were synthesized for the use as chain transfer agents (CTAs) in the RAFT-process. All newly synthesized CTAs were tested for their efficiency to moderate the free radical polymerization process by polymerizing styrene (M3). Besides characterization of the homopolymers by GPC measurements, end- group analysis of the synthesized block copolymers via 1H-, 19F-NMR, and in some cases also UV-vis spectroscopy, were performed attaching suitable fluorinated moieties to the Z- and/or R-groups of the CTAs. Symmetric triblock copolymers of type BAB and non-symmetric fluorine end- capped polymers were accessible using the RAFT process in just two or one polymerization step. In particular, the RAFT-process enabled the controlled polymerization of hydrophilic monomers such as N-isopropylacrylamide (NIPAM) (M1) as well as N-acryloylpyrrolidine (NAP) (M2) for the A-blocks and of the hydrophobic monomers styrene (M3), 2-fluorostyrene (M4), 3-fluorostyrene (M5), 4-fluorostyrene (M6) and 2,3,4,5,6-pentafluorostyrene (M7) for the B-blocks. The properties of the BAB-triblock copolymers were investigated in dilute, concentrated and highly concentrated aqueous solutions using DLS, turbidimetry, 1H- and 19F-NMR, rheology, determination of the CMC, foam height- and surface tension measurements and microscopy. Furthermore, their ability to stabilize emulsions and microemulsions and the wetting behaviour of their aqueous solutions on different substrates was investigated. The behaviour of the fluorine end-functionalized polymers to form micelles was studied applying DLS measurements in diluted organic solution. All investigated BAB-triblock copolymers were able to form micelles and show surface activity at room temperature in dilute aqueous solution. The aqueous solutions displayed moderate foam formation. With different types and concentrations of oils, the formation of emulsions could be detected using a light microscope. A boosting effect in microemulsions could not be found adding BAB-triblock copolymers. At elevated polymer concentrations, the formation of hydrogels was proved applying rheology measurements.},
  language  = {en}
}
@phdthesis{Hoehne2011,
  author    = {H{\"o}hne, Janet},
  title     = {Aktivit{\"a}ts- und Herzfrequenz-Monitoring zur Erfassung der Bewegungszeit und der Bewegungsintensit{\"a}t im schulischen und außerschulischen Kontext von Grundsch{\"u}lern im Land Brandenburg},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57937},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {"Kinderwelt ist Bewegungswelt" (Schmidt, 1997, S. 156, zitiert nach Schmidt, Hartmann-Tews \& Brettschneider, 2003, S. 31). Das kindliche Bewegungsverhalten hat sich bereits im Grundschulalter ver{\"a}ndert, so dass sich Bewegungsaktivit{\"a}ten von Kindern erheblich unterscheiden und keineswegs mehr verallgemeinert werden k{\"o}nnen. Richtet man den Fokus auf die Frage „Wie bewegt sind unsere Kinder?" so scheint diese von den Medien bereits beantwortet zu sein, da dort von ansteigendem Bewegungsmangel der heutigen Kinder gegen{\"u}ber fr{\"u}heren Generationen berichtet wird. Wenn es in den Diskussionen um den Gesundheitszustand unserer Kinder geht, nimmt die k{\"o}rperlich-sportliche Aktivit{\"a}t eine entscheidende Rolle ein. Bewegungsmangel ist hierbei ein zentraler Begriff der in der {\"O}ffentlichkeit diskutiert wird. Bei der Betrachtung der einzelnen Studien f{\"a}llt auf, dass deutliche Defizite in der Messung der k{\"o}rperlich-sportlichen Aktivit{\"a}t bestehen. Zentraler Kritikpunkt in den meisten Studien ist die subjektive Erfassung der k{\"o}rperlich-sportlichen Aktivit{\"a}t. Ein Großteil bisheriger Untersuchungen zum Bewegungsverhalten basiert auf Beobachtungen, Befragungen oder Bewegungstageb{\"u}chern. Diese liefern ausschließlich zum Teil subjektive Einsch{\"a}tzungen der Kinder oder Eltern {\"u}ber die tats{\"a}chliche Bewegungszeit und -intensit{\"a}t. Das objektive Erfassen der Aktivit{\"a}t bzw. Inaktivit{\"a}t ist zwar seit einigen Jahren zentraler Gegenstand vieler Studien, dennoch gilt es, dieses noch sachkundiger zu l{\"o}sen, um subjektive und objektive Daten zu vergleichen. Um dem Bewegungsmangel der heutigen Kinder entgegenzuwirken, sind empirisch abgesicherte Erkenntnisse {\"u}ber die Bedingungsfaktoren und die Folgen des ver{\"a}nderten Bewegungsverhaltens dringend n{\"o}tig. Die Quer- und L{\"a}ngsschnittuntersuchung umfasst die Bereiche Anthropometrie, die Erfassung der k{\"o}rperlich-sportlichen Aktivit{\"a}t und die Herzfrequenzmessung {\"u}ber 24h. F{\"u}r die Studie konnten 106 Jungen und M{\"a}dchen im Zeitraum von Januar 2007 bis April 2009 rekrutiert und {\"u}berpr{\"u}ft werden. Die physiologischen Parameter wurden mit Hilfe des ACTIHEART-Messsytems aufgezeichnet und berechnet. Die Ergebnisse zur k{\"o}rperlich-sportlichen Aktivit{\"a}t wurden in die Untersuchungsabschnitte Schulzeit gesamt, Pause, Sportunterricht, Nachmittag und 24h unterteilt. Durch das Messsystem werden die Bewegungsaktivit{\"a}t und die Herzfrequenz synchron aufgezeichnet. Das System nimmt die Beschleunigungswerte des K{\"o}rpers auf und speichert sie im frei w{\"a}hlbaren Zeitintervall, Short oder Long Term, in Form von „activity counts" ab. Das Messsytem berechnet weiterhin die Intensit{\"a}t k{\"o}rperlicher Aktivit{\"a}t.},
  language  = {de}
}
@phdthesis{Vosloh2011,
  author    = {Vosloh, Daniel},
  title     = {Subcellular compartmentation of primary carbon metabolism in mesophyll cells of Arabidopsis thaliana},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-55534},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Metabolismus in Pflanzenzellen ist stark kompartimentiert. Viele Stoffwechselwege haben Reaktionen in mehr als einem Kompartiment. Zum Beispiel wird w{\"a}hrend der Photosynthese in pflanzlichen Mesophyllzellen Kohlenstoff in Form von St{\"a}rke in den Chloroplasten synthetisiert, w{\"a}hrend es im Zytosol in Form von Sacharose gebildet und in der Vakuole gespeichert wird. Diese Reaktionen sind strikt reguliert um ein Gleichgewicht der Kohlenstoffpools der verschiedenen Kompartimente aufrecht zu erhalten und die Energieversorgung aller Teile der Zelle f{\"u}r anabolische Reaktionen sicher zu stellen. Ich wende eine Methode an, bei der die Zellen unter nicht-w{\"a}ssrigen Bedingungen fraktioniert werden und daher der metabolische Status der w{\"a}hrend der Ernte herrschte {\"u}ber den ganzen Zeitraum der Auftrennung beibehalten wird. Durch die Kombination von nichtw{\"a}ssriger Fraktionierung und verschiedener Massenspektrometrietechniken (Fl{\"u}ssigchromotagraphie- und Gaschromotagraphie basierende Massenspekrometrie) ist es m{\"o}glich die intrazellul{\"a}re Verteilung der meisten Intermediate des photosynthetischen Kohlenstoffstoffwechsels und der Produkte der nachgelagerten metabolischen Reaktionen zu bestimmen. Das Wissen {\"u}ber die in vivo Konzentrationen dieser Metabolite wurde genutzt um die {\"A}nderung der freien Gibbs Energie in vivo zu bestimmen. Mit Hilfe dessen kann bestimmt werden, welche Reaktion sich in einem Gleichgewichtszustand befinden und welche davon entfernt sind. Die Konzentration der Enzyme und der Km Werte wurden mit den Konzentrationen der Metabolite in vivo verglichen, um festzustellen, welche Enzyme substratlimitiert sind und somit sensitiv gegen{\"u}ber {\"A}nderungen der Substratkonzentration sind. Verschiedene Intermediate des Calvin-Benson Zyklus sind gleichzeitig Substrate f{\"u}r andere Stoffwechselwege, als da w{\"a}ren Dihyroxyaceton-phosphat (DHAP, Saccharosesynthese), Fructose 6-phosphat (Fru6P, St{\"a}rkesynthese), Erythrose 4-phosphat (E4P, Shikimat Stoffwechselweg) und Ribose 5-phosphat (R5P, Nukleotidbiosynthese). Die Enzyme, die diese Intermediate verstoffwechseln, liegen an den Abzweigungspunkten zu diesen Stoffwechselwegen. Diese sind Trisose phosphat isomerase (DHAP), Transketolase (E4P), Sedoheptulose-1,7 biphosphat aldolase (E4P) und Ribose-5-phosphat isomerase (R5P), welche nicht mit ihren Substraten ges{\"a}ttigt sind, da die jeweilige Substratkonzentration geringer als der zugeh{\"o}rige Km Wert ist. F{\"u}r metabolische Kontrolle bedeutet dies, dass diese Schritte am sensitivsten gegen{\"u}ber {\"A}nderungen der Substratkonzentrationen sind. Im Gegensatz dazu sind die regulierten irreversiblen Schritte von Fructose-1,6.biphosphatase und Sedoheptulose-1,7-biphosphatase relativ insensitiv gegen{\"u}ber {\"A}nderungen der Substratkonzentration. F{\"u}r den Stoffwechselweg der Saccharosesynthese konnte gezeigt werden, dass die zytosolische Aldolase eine geringer Bindeseitenkonzentration als Substratkonzentration (DHAP) aufweist, und dass die Konzentration von Saccharose-6-phosphat geringer als der Km Wert des synthetisierenden Enzyms Saccharose-phosphatase ist. Sowohl die Saccharose-phosphat-synthase, also auch die Saccharose-phosphatase sind in vivo weit von einem Gleichgewichtszustand entfernt. In Wildtyp Arabidopsis thaliana Columbia-0 Bl{\"a}ttern wurde der gesamte Pool von ADPGlc im Chloroplasten gefunden. Das Enzyme ADPGlc pyrophosphorylase ist im Chloroplasten lokalisiert und synthetisiert ADPGlc aus ATP und Glc1P. Dieses Verteilungsmuster spricht eindeutig gegen die Hypothese von Pozueta-Romero und Kollegen, dass ADPGlc im Zytosol durch ADP vermittelte Spaltung von Saccharose durch die Saccharose Synthase erzeugt wird. Basierend auf dieser Beobachtung und anderen ver{\"o}ffentlichten Ergebnissen wurde geschlußfolgert, dass der generell akzeptierte Stoffwechselweg der St{\"a}rkesynthese durch ADPGlc Produktion via ADPGlc pyrophosphorylase in den Chloroplasten korrekt ist, und die Hypothese des alternativen Stoffwechselweges unhaltbar ist. Innerhalb des Stoffwechselweges der Saccharosesynthsese wurde festgestellt, dass die Konzentration von ADPGlc geringer als der Km Wert des St{\"a}rkesynthase ist, was darauf hindeutet, dass das Enzym substratlimitiert ist. Eine generelle Beobachtung ist, dass viele Enzmye des Calvin-Benson Zyklus {\"a}hnliche Bindeseitenkonzentrationen wie Metabolitkonzentrationen aufweisen, wohingegen in den Synthesewegen von Saccharose und St{\"a}rke die Bindeseitenkonzentrationen der Enzyme viel geringer als die Metabolitkonzentrationen sind.},
  language  = {en}
}
@phdthesis{Zurell2011,
  author    = {Zurell, Damaris},
  title     = {Integrating dynamic and statistical modelling approaches in order to improve predictions for scenarios of environmental change},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56845},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Species respond to environmental change by dynamically adjusting their geographical ranges. Robust predictions of these changes are prerequisites to inform dynamic and sustainable conservation strategies. Correlative species distribution models (SDMs) relate species' occurrence records to prevailing environmental factors to describe the environmental niche. They have been widely applied in global change context as they have comparably low data requirements and allow for rapid assessments of potential future species' distributions. However, due to their static nature, transient responses to environmental change are essentially ignored in SDMs. Furthermore, neither dispersal nor demographic processes and biotic interactions are explicitly incorporated. Therefore, it has often been suggested to link statistical and mechanistic modelling approaches in order to make more realistic predictions of species' distributions for scenarios of environmental change. In this thesis, I present two different ways of such linkage. (i) Mechanistic modelling can act as virtual playground for testing statistical models and allows extensive exploration of specific questions. I promote this 'virtual ecologist' approach as a powerful evaluation framework for testing sampling protocols, analyses and modelling tools. Also, I employ such an approach to systematically assess the effects of transient dynamics and ecological properties and processes on the prediction accuracy of SDMs for climate change projections. That way, relevant mechanisms are identified that shape the species' response to altered environmental conditions and which should hence be considered when trying to project species' distribution through time. (ii) I supplement SDM projections of potential future habitat for black grouse in Switzerland with an individual-based population model. By explicitly considering complex interactions between habitat availability and demographic processes, this allows for a more direct assessment of expected population response to environmental change and associated extinction risks. However, predictions were highly variable across simulations emphasising the need for principal evaluation tools like sensitivity analysis to assess uncertainty and robustness in dynamic range predictions. Furthermore, I identify data coverage of the environmental niche as a likely cause for contrasted range predictions between SDM algorithms. SDMs may fail to make reliable predictions for truncated and edge niches, meaning that portions of the niche are not represented in the data or niche edges coincide with data limits. Overall, my thesis contributes to an improved understanding of uncertainty factors in predictions of range dynamics and presents ways how to deal with these. Finally I provide preliminary guidelines for predictive modelling of dynamic species' response to environmental change, identify key challenges for future research and discuss emerging developments.},
  language  = {en}
}
@phdthesis{Pourteau2011,
  author    = {Pourteau, Amaury},
  title     = {Closure of the Neotethys Ocean in Anatolia : structural, petrologic and geochronologic insights from low-grade high-pressure metasediments, Afyon Zone},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57803},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {The complete consumption of the oceanic domain of a tectonic plate by subduction into the upper mantle results in continent subduction, although continental crust is typically of lower density than the upper mantle. Thus, the sites of former oceanic domains (named suture zones) are generally decorated with stratigraphic sequences deposited along continental passive margins that were metamorphosed under low-grade, high-pressure conditions, i.e., low temperature/depth ratios (< 15°C/km) with respect to geothermal gradients in tectonically stable regions. Throughout the Mesozoic and Cenozoic (i.e., since ca. 250 Ma), the Mediterranean realm was shaped by the closure of the Tethyan Ocean, which likely consisted in numerous oceanic domains and microcontinents. However, the exact number and position of Tethyan oceans and continents (i.e., the Tethyan palaeogeography) remains debated. This is particularly the case of Western and Central Anatolia, where a continental fragment was accreted to the southern composite margin of the Eurasia sometime between the Late Cretaceous and the early Cenozoic. The most frontal part of this microcontinent experienced subduction-related metamorphism around 85-80 Ma, and collision-related metamorphism affected more external parts around 35 Ma. This unsually-long period between subduction- and collision-related metamorphisms (ca. 50 Ma) in units ascribed to the same continental edge constitutes a crucial issue to address in order to unravel how Anatolia was assembled. The Afyon Zone is a tectono-sedimentary unit exposed south and structurally below the front high-pressure belt. It is composed of a Mesozoic sedimentary sequence deposited on top of a Precambrian to Palaeozoic continental substratum, which can be traced from Northwestern to southern Central Anatolia, along a possible Tethyan suture. Whereas the Afyon Zone was defined as a low-pressure metamorphic unit, high-pressure minerals (mainly Fe-Mg-carpholite in metasediments) were recently reported from its central part. These findings shattered previous conceptions on the tectono-metamorphic evolution of the Afyon Zone in particular, and of the entire region in general, and shed light on the necessity to revise the regional extent of subduction-related metamorphism by re-inspecting the petrology of poorly-studied metasediments. In this purpose, I re-evaluated the metamorphic evolution of the entire Afyon Zone starting from field observations. Low-grade, high-pressure mineral assemblages (Fe-Mg-carpholite and glaucophane) are reported throughout the unit. Well-preserved carpholite-chloritoid assemblages are useful to improve our understanding of mineral relations and transitions in the FeO-MgO-Al2O3-SiO2-H2O system during rocks' travel down to depth (prograde metamorphism). Inspection of petrographic textures, minute variations in mineral composition and Mg-Fe distribution among carpholite-chloritoid assemblages documents multistage mineral growth, accompanied by a progressive enrichment in Mg, and strong element partitioning. Using an updated database of mineral thermodynamic properties, I modelled the pressure and temperature conditions that are consistent with textural and chemical observations. Carpholite-bearing assemblages in the Afyon Zone account for a temperature increase from 280 to 380°C between 0.9 and 1.1 GPa (equivalent to a depth of 30-35 km). In order to further constrain regional geodynamics, first radiometric ages were determined in close association with pressure-temperature estimates for the Afyon Zone, as well as two other tectono-sedimentary units from the same continental passive margin (the {\"O}ren and Kurudere-Nebiler Units from SW Anatolia). For age determination, I employed 40Ar-39Ar geochronology on white mica in carpholite-bearing rocks. For thermobarometry, a multi-equilibrium approach was used based on quartz-chlorite-mica and quartz-chlorite-chloritoid associations formed at the expense of carpholite-bearing assemblages, i.e., during the exhumation from the subduction zone. This combination allows deciphering the significance of the calculated radiometric ages in terms of metamorphic conditions. Results show that the Afyon Zone and the {\"O}ren Unit represent a latest Cretaceous high-pressure metamorphic belt, and the Kurudere-Nebiler Unit was affected by subduction-related metamorphism around 45 Ma and cooled down after collision-related metamorphism around 26 Ma. The results provided in the present thesis and from the literature allow better understanding continental amalgamation in Western Anatolia. It is shown that at least two distinct oceanic branches, whereas only one was previously considered, have closed during continuous north-dipping subduction between 92 and 45 Ma. Between 85-80 and 70-65 Ma, a narrow continental domain (including the Afyon Zone) was buried into a subduction zone within the northern oceanic strand. Parts of the subducted continent crust were exhumed while the upper oceanic plate was transported southwards. Subduction of underlying lithosphere persisted, leading to the closure of the southern oceanic branch and to subduct the front of a second continental domain (including the Kurudere-Nebiler Unit). This followed by a continental collisional stage characterized by the cease of subduction, crustal thicknening and the detachment of the subducting oceanic slab from the accreted continent lithosphere. The present study supports that in the late Mesozoic the East Mediterranean realm had a complex tectonic configuration similar to present Southeast Asia or the Caribbean, with multiple, coexisting oceanic basins, microcontinents and subduction zones.},
  language  = {en}
}
@phdthesis{Jurish2011,
  author    = {Jurish, Bryan},
  title     = {Finite-state canonicalization techniques for historical German},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-55789},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {This work addresses issues in the automatic preprocessing of historical German input text for use by conventional natural language processing techniques. Conventional techniques cannot adequately account for historical input text due to conventional tools' reliance on a fixed application-specific lexicon keyed by contemporary orthographic surface form on the one hand, and the lack of consistent orthographic conventions in historical input text on the other. Historical spelling variation is treated here as an error-correction problem or "canonicalization" task: an attempt to automatically assign each (historical) input word a unique extant canonical cognate, thus allowing direct application-specific processing (tagging, parsing, etc.) of the returned canonical forms without need for any additional application-specific modifications. In the course of the work, various methods for automatic canonicalization are investigated and empirically evaluated, including conflation by phonetic identity, conflation by lemma instantiation heuristics, canonicalization by weighted finite-state rewrite cascade, and token-wise disambiguation by a dynamic Hidden Markov Model.},
  language  = {en}
}
@phdthesis{BarbosaPfannes2011,
  author    = {Barbosa Pfannes, Eva Katharina},
  title     = {Probing the regulatory mechanisms of the actomyosin system in motile cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57812},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Actin-based directional motility is important for embryonic development, wound healing, immune responses, and development of tissues. Actin and myosin are essential players in this process that can be subdivided into protrusion, adhesion, and traction. Protrusion is the forward movement of the membrane at the leading edge of the cell. Adhesion is required to enable movement along a substrate, and traction finally leads to the forward movement of the entire cell body, including its organelles. While actin polymerization is the main driving force in cell protrusions, myosin motors lead to the contraction of the cell body. The goal of this work was to study the regulatory mechanisms of the motile machinery by selecting a representative key player for each stage of the signaling process: the regulation of Arp2/3 activity by WASP (actin system), the role of cGMP in myosin II assembly (myosin system), and the influence of phosphoinositide signaling (upstream receptor pathway). The model organism chosen for this work was the social ameba Dictyostelium discoideum, due to the well-established knowledge of its cytoskeletal machinery, the easy handling, and the high motility of its vegetative and starvation developed cells. First, I focused on the dynamics of the actin cytoskeleton by modulating the activity of one of its key players, the Arp2/3 complex. This was achieved using the carbazole derivative Wiskostatin, an inhibitor of the Arp2/3 activator WASP. Cells treated with Wiskostatin adopted a round shape, with no of few pseudopodia. With the help of a microfluidic cell squeezer device, I could show that Wiskostatin treated cells display a reduced mechanical stability, comparable to cells treated with the actin disrupting agent Latrunculin A. Furthermore, the WASP inhibited cells adhere stronger to a surface and show a reduced motility and chemotactic performance. However, the overall F-actin content in the cells was not changed. Confocal microscopy and TIRF microscopy imaging showed that the cells maintained an intact actin cortex. Localized dynamic patches of increased actin polymerization were observed that, however, did not lead to membrane deformation. This indicated that the mechanisms of actin-driven force generation were impaired in Wiskostatin treated cells. It is concluded that in these cells, an altered architecture of the cortical network leads to a reduced overall stiffness of the cell, which is insufficient to support the force generation required for membrane deformation and pseudopod formation. Second, the role of cGMP in myosin II dynamics was investigated. Cyclic GMP is known to regulate the association of myosin II with the cytoskeleton. In Dictyostelium, intracellular cGMP levels increase when cells are exposed to chemoattractants, but also in response to osmotic stress. To study the influence of cyclic GMP on actin and myosin II dynamics, I used the laser-induced photoactivation of a DMACM-caged-Br-cGMP to locally release cGMP inside the cell. My results show that cGMP directly activates the myosin II machinery, but is also able to induce an actin response independently of cAMP receptor activation and signaling. The actin response was observed in both vegetative and developed cells. Possible explanations include cGMP-induced actin polymerization through VASP (vasodilator-stimulated phosphoprotein) or through binding of cGMP to cyclic nucleotide-dependent kinases. Finally, I investigated the role of phosphoinositide signaling using the Polyphosphoinositide-Binding Peptide (PBP10) that binds preferentially to PIP2. Phosphoinositides can recruit actin-binding proteins to defined subcellular sites and alter their activity. Neutrophils, as well as developed Dictyostelium cells produce PIP3 in the plasma membrane at their leading edge in response to an external chemotactic gradient. Although not essential for chemotaxis, phosphoinositides are proposed to act as an internal compass in the cell. When treated with the peptide PBP10, cells became round, with fewer or no pseudopods. PH-CRAC translocation to the membrane still occurs, even at low cAMP stimuli, but cell motility (random and directional) was reduced. My data revealed that the decrease in the pool of available PIP2 in the cell is sufficient to impair cell motility, but enough PIP2 remains so that PIP3 is formed in response to chemoattractant stimuli. My data thus highlights how sensitive cell motility and morphology are to changes in the phosphoinositide signaling. In summary, I have analyzed representative regulatory mechanisms that govern key parts of the motile machinery and characterized their impact on cellular properties including mechanical stability, adhesion and chemotaxis.},
  language  = {en}
}
@phdthesis{Wolff2011,
  author    = {Wolff, Christian Michael},
  title     = {East African monsoon variability since the last glacial},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-58079},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {The impact of global warming on human water resources is attracting increasing attention. No other region in this world is so strongly affected by changes in water supply than the tropics. Especially in Africa, the availability and access to water is more crucial to existence (basic livelihoods and economic growth) than anywhere else on Earth. In East Africa, rainfall is mainly influenced by the migration of the Inter-Tropical Convergence Zone (ITCZ) and by the El Ni{\~n}o Southern Oscillation (ENSO) with more rain and floods during El Ni{\~n}o and severe droughts during La Ni{\~n}a. The forecasting of East African rainfall in a warming world requires a better understanding of the response of ENSO-driven variability to mean climate. Unfortunately, existing meteorological data sets are too short or incomplete to establish a precise evaluation of future climate. From Lake Challa near Mount Kilimanjaro, we report records from a laminated lake sediment core spanning the last 25,000 years. Analyzing a monthly cleared sediment trap confirms the annual origin of the laminations and demonstrates that the varve-thicknesses are strongly linked to the duration and strength of the windy season. Given the modern control of seasonal ITCZ location on wind and rain in this region and the inverse relation between the two, thicker varves represent windier and thus drier years. El Ni{\~n}o (La Ni{\~n}a) events are associated with wetter (drier) conditions in east Africa and decreased (increased) surface wind speeds. Based on this fact, the thickness of the varves can be used as a tool to reconstruct a) annual rainfall b) wind season strength, and c) ENSO variability. Within this thesis, I found evidence for centennialscale changes in ENSO-related rainfall variability during the last three millennia, abrupt changes in variability during the Medieval Climate Anomaly and the Little Ice Age, and an overall reduction in East African rainfall and its variability during the Last Glacial period. Climate model simulations support forward extrapolation from these lake-sediment data, indicating that a future Indian Ocean warming will enhance East Africa's hydrological cycle and its interannual variability in rainfall. Furthermore, I compared geochemical analyses from the sediment trap samples with a broad range of limnological, meteorological, and geological parameters to characterize the impact of sedimentation processes from the in-situ rocks to the deposited sediments. As a result an excellent calibration for existing μXRF data from Lake Challa over the entire 25,000 year long profile was provided. The climate development during the last 25,000 years as reconstructed from the Lake Challa sediments is in good agreement with other studies and highlights the complex interactions between long-term orbital forcing, atmosphere, ocean and land surface conditions. My findings help to understand how abrupt climate changes occur and how these changes correlate with climate changes elsewhere on Earth.},
  language  = {en}
}
@phdthesis{Massie2011,
  author    = {Massie, Thomas Michael},
  title     = {Dynamic behavior of phytoplankton populations far from steady state : chemostat experiments and mathematical modeling},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-58102},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Nature changes continuously and is only seemingly at equilibrium. Environmental parameters like temperature, humidity or insolation may strongly fluctuate on scales ranging from seconds to millions of years. Being part of an ecosystem, species have to cope with these environmental changes. For ecologists, it is of special interest how individual responses to environmental changes affect the dynamics of an entire population - and, if this behavior is predictable. In this context, the demographic structure of a population plays a decisive role since it originates from processes of growth and mortality. These processes are fundamentally influenced by the environment. But, how exactly does the environment influence the behavior of populations? And what does the transient behavior look like? As a result from environmental influences on demography, so called cohorts form. They are age or size classes that are disproportionally represented in the demographic distribution of a population. For instance, if most old and young individuals die due to a cold spell, the population finally consists of mainly middle-aged individuals. Hence, the population got synchronized. Such a population tends to show regular fluctuations in numbers (denoted as oscillations) since the alternating phases of individual growth and population growth (due to reproduction) are now performed synchronously by the majority of the population.That is, one time the population growths, and the other time it declines due to mortality. Synchronous behavior is one of the most pervasive phenomena in nature. Gravitational synchrony in the solar system; fireflies flashing in unison; coordinate firing of pacemaker cells in the heart; electrons in a superconductor marching in lockstep. Whatever scale one looks at, in animate as well as inanimate systems, one is likely to encounter synchrony. In experiments with phytoplankton populations, I could show that this principle of synchrony (as used by physicists) could well-explain the oscillations observed in the experiments, too. The size of the fluctuations depended on the strength by which environmental parameters changed as well as on the demographic state of a population prior to this change. That is, two population living in different habitats can be equally influenced by an environmental change, however, the resulting population dynamics may be significantly different when both populations differed in their demographic state before. Moreover, specific mechanisms relevant for the dynamic behavior of populations, appear only when the environmental conditions change. In my experiments, the population density declined by 50\% after ressource supply was doubled. This counter-intuitive behavior can be explained by increasing ressource consumption. The phytoplankton cells grew larger and enhanced their individual constitution. But at the same time, reproduction was delayed and the population density declined due to the losses by mortality. Environmental influences can also synchronize two or more populations over large distances, which is denoted as Moran effect. Assume two populations living on two distant islands. Although there is no exchange of individuals between them, both populations show a high similarity when comparing their time series. This is because the globally acting climate synchronizes the regionally acting weather on both island. Since the weather fluctuations influence the population dynamics, the Moran effect states that the synchrony between the environment equals the one between the populations. My experiments support this theory and also explain deviations arising when accounting for differences in the populations and the habitats they are living in. Moreover, model simulations and experiments astonishingly show that the synchrony between the populations can be higher than between the environment, when accounting for differences in the environmental fluctuations ("noise color").},
  language  = {de}
}
@phdthesis{Lauterbach2011,
  author    = {Lauterbach, Stefan},
  title     = {Lateglacial to Holocene climatic and environmental changes in Europe : multi-proxy studies on lake sediments along a transect from northern Italy to northeastern Poland},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-58157},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Sediment records of three European lakes were investigated in order to reconstruct the regional climate development during the Lateglacial and Holocene, to investigate the response of local ecosystems to climatic fluctuations and human impact and to relate regional peculiarities of past climate development to climatic changes on a larger spatial scale. The Lake Hańcza (NE Poland) sediment record was studied with a focus on reconstructing the early Holocene climate development and identifying possible differences to Western Europe. Following the initial Holocene climatic improvement, a further climatic improvement occurred between 10 000 and 9000 cal. a BP. Apparently, relatively cold and dry climate conditions persisted in NE Poland during the first ca. 1500 years of the Holocene, most likely due to a specific regional atmospheric circulation pattern. Prevailing anticyclonic circulation linked to a high-pressure cell above the remaining Scandinavian Ice Sheet (SIS) might have blocked the eastward propagation of warm and moist Westerlies and thus attenuated the early Holocene climatic amelioration in this region until the final decay of the SIS, a pattern different from climate development in Western Europe. The Lateglacial sediment record of Lake Mondsee (Upper Austria) was investigated in order to study the regional climate development and the environmental response to rapid climatic fluctuations. While the temperature rise and environmental response at the onset of the Holocene took place quasi-synchronously, major leads and lags in proxy responses characterize the onset of the Lateglacial Interstadial. In particular, the spread of coniferous woodlands and the reduction of detrital flux lagged the initial Lateglacial warming by ca. 500-750 years. Major cooling at the onset of the Younger Dryas took place synchronously with a change in vegetation, while the increase of detrital matter flux was delayed by about 150-300 years. Complex proxy responses are also detected for short-term Lateglacial climatic fluctuations. In summary, periods of abrupt climatic changes are characterized by complex and temporally variable proxy responses, mainly controlled by ecosystem inertia and the environmental preconditions. A second study on the Lake Mondsee sediment record focused on two small-scale climate deteriorations around 8200 and 9100 cal. a BP, which have been triggered by freshwater discharges to the North Atlantic, causing a shutdown of the Atlantic meridional overturning circulation (MOC). Combining microscopic varve counting and AMS 14C dating yielded a precise duration estimate (ca. 150 years) and absolute dating of the 8.2 ka cold event, both being in good agreement with results from other palaeoclimate records. Moreover, a sudden temperature overshoot after the 8.2 ka cold event was identified, also seen in other proxy records around the North Atlantic. This was most likely caused by enhanced resumption of the MOC, which also initiated substantial shifts of oceanic and atmospheric front systems. Although there is also evidence from other proxy records for pronounced recovery of the MOC and atmospheric circulation changes after the 9.1 ka cold event, no temperature overshoot is seen in the Lake Mondsee record, indicating the complex behaviour of the global climate system. The Holocene sediment record of Lake Iseo (northern Italy) was studied to shed light on regional earthquake activity and the influence of climate variability and anthropogenic impact on catchment erosion and detrital flux into the lake. Frequent small-scale detrital layers within the sediments reflect allochthonous sediment supply by extreme surface runoff events. During the early to mid-Holocene, increased detrital flux coincides with periods of cold and wet climate conditions, thus apparently being mainly controlled by climate variability. In contrast, intervals of high detrital flux during the late Holocene partly also correlate with phases of increased human impact, reflecting the complex influences on catchment erosion processes. Five large-scale event layers within the sediments, which are composed of mass-wasting deposits and turbidites, are supposed to have been triggered by strong local earthquakes. While the uppermost of these event layers is assigned to a documented adjacent earthquake in AD 1222, the four other layers are supposed to be related to previously undocumented prehistorical earthquakes.},
  language  = {en}
}
@phdthesis{Schaal2011,
  author    = {Schaal, Janina},
  title     = {Synthese und Photochemie von photoaktivierbaren Biomolek{\"u}len},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57929},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Mechanistische und kinetische Untersuchungen von komplexen zellul{\"a}ren Prozessen in situ sind in den vergangenen Jahren durch den Einsatz photoaktivierbarer Biomolek{\"u}le, sogenannter caged Verbindungen, m{\"o}glich geworden. Bei den caged Verbindungen handelt es sich um photolabile inaktive Derivate von biologisch aktiven Molek{\"u}len, aus denen durch ultraviolettes Licht mit Hilfe einer photochemischen Reaktion die nat{\"u}rliche, biologisch aktive Substanz schnell freigesetzt werden kann. Im Rahmen der vorliegenden Arbeit wurden caged Verbindungen von den Neurotransmittern Octopamin und Dopamin, dem Octopamin-Antagonist Epinastin, den Proteinsyntheseinhibitoren Emetin und Anisomycin, dem Protonophor CCCP und dem Riechstoff Bourgeonal hergestellt. Zur Synthese dieser caged Verbindungen wurden sowohl bekannte als auch verschiedene im Rahmen dieser Arbeit neu entwickelte photolabile Schutzgruppen mit einem (Cumarin-4-yl)methyl- bzw. einem 2-Nitrobenzyl-Ger{\"u}st eingesetzt. Entsprechende Syntheseverfahren wurden erarbeitet. Anschließend erfolgte eine umfassende physikalisch-chemische sowie photochemische Charakterisierung der erhaltenen caged Verbindungen. Dabei wurde besonders auf gute L{\"o}slichkeit in Wasser bei physiologischer Ionenst{\"a}rke, schnelle und effiziente Photoreaktivit{\"a}t, hohe Extinktion bei Wellenl{\"a}ngen von 350-430 nm und gute solvolytische Stabilit{\"a}t bei geringer Toxizit{\"a}t der freigesetzten Schutzgruppe geachtet. Ein Schwerpunkt bei der photochemischen Charakterisierung bildeten die Untersuchungen zur Quantifizierung der 2-Photonen-Anregung, uncaging action cross-sections, der Cumarinylmethyl-caged Verbindungen, aufgrund ihrer Bedeutung f{\"u}r die Photofreisetzung von Biomolek{\"u}len, da die gleichzeitige Absorption von 2 IR-Photonen eine h{\"o}here dreidimensionale Aufl{\"o}sung und eine wesentlich tiefere Gewebepenetration erlaubt. Mit Hilfe von Kooperationspartnern wurden zeitaufgel{\"o}sten Fluoreszenz- und IR-Messungen an verschiedenen (Cumarin-4-yl)methoxycarbonyl-caged Modellverbindungen durchgef{\"u}hrt, mit denen die Geschwindigkeitskonstanten k1 und kdecarb des Photolysemechanismus ermittelt wurde. Am Ende folgten die Anwendungserprobungen ausgew{\"a}hlter caged Verbindungen in einem Translationsassay bzw. in Zelluntersuchungen.},
  language  = {de}
}
@phdthesis{Sietz2011,
  author    = {Sietz, Diana},
  title     = {Dryland vulnerability : typical patterns and dynamics in support of vulnerability reduction efforts},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-58097},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {The pronounced constraints on ecosystem functioning and human livelihoods in drylands are frequently exacerbated by natural and socio-economic stresses, including weather extremes and inequitable trade conditions. Therefore, a better understanding of the relation between these stresses and the socio-ecological systems is important for advancing dryland development. The concept of vulnerability as applied in this dissertation describes this relation as encompassing the exposure to climate, market and other stresses as well as the sensitivity of the systems to these stresses and their capacity to adapt. With regard to the interest in improving environmental and living conditions in drylands, this dissertation aims at a meaningful generalisation of heterogeneous vulnerability situations. A pattern recognition approach based on clustering revealed typical vulnerability-creating mechanisms at global and local scales. One study presents the first analysis of dryland vulnerability with global coverage at a sub-national resolution. The cluster analysis resulted in seven typical patterns of vulnerability according to quantitative indication of poverty, water stress, soil degradation, natural agro-constraints and isolation. Independent case studies served to validate the identified patterns and to prove the transferability of vulnerability-reducing approaches. Due to their worldwide coverage, the global results allow the evaluation of a specific system's vulnerability in its wider context, even in poorly-documented areas. Moreover, climate vulnerability of smallholders was investigated with regard to their food security in the Peruvian Altiplano. Four typical groups of households were identified in this local dryland context using indicators for harvest failure risk, agricultural resources, education and non-agricultural income. An elaborate validation relying on independently acquired information demonstrated the clear correlation between weather-related damages and the identified clusters. It also showed that household-specific causes of vulnerability were consistent with the mechanisms implied by the corresponding patterns. The synthesis of the local study provides valuable insights into the tailoring of interventions that reflect the heterogeneity within the social group of smallholders. The conditions necessary to identify typical vulnerability patterns were summarised in five methodological steps. They aim to motivate and to facilitate the application of the selected pattern recognition approach in future vulnerability analyses. The five steps outline the elicitation of relevant cause-effect hypotheses and the quantitative indication of mechanisms as well as an evaluation of robustness, a validation and a ranking of the identified patterns. The precise definition of the hypotheses is essential to appropriately quantify the basic processes as well as to consistently interpret, validate and rank the clusters. In particular, the five steps reflect scale-dependent opportunities, such as the outcome-oriented aspect of validation in the local study. Furthermore, the clusters identified in Northeast Brazil were assessed in the light of important endogenous processes in the smallholder systems which dominate this region. In order to capture these processes, a qualitative dynamic model was developed using generalised rules of labour allocation, yield extraction, budget constitution and the dynamics of natural and technological resources. The model resulted in a cyclic trajectory encompassing four states with differing degree of criticality. The joint assessment revealed aggravating conditions in major parts of the study region due to the overuse of natural resources and the potential for impoverishment. The changes in vulnerability-creating mechanisms identified in Northeast Brazil are well-suited to informing local adjustments to large-scale intervention programmes, such as "Avan{\c{c}}a Brasil". Overall, the categorisation of a limited number of typical patterns and dynamics presents an efficient approach to improving our understanding of dryland vulnerability. Appropriate decision-making for sustainable dryland development through vulnerability reduction can be significantly enhanced by pattern-specific entry points combined with insights into changing hotspots of vulnerability and the transferability of successful adaptation strategies.},
  language  = {en}
}
@phdthesis{Nada2011,
  author    = {Nada, Wael Mohamed Abdel-Rahman},
  title     = {Wood compost process engineering, properties and its impact on extreme soil characteristics},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51046},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {The landfilling of biodegradable waste is proven to contribute to environmental degradation. Much wood and lumber is discharged as waste from the cleared fields. These woody wastes are subsequently disposed of by burning. However, it would be preferable to dispose of them without combustion to avoid the release of carbon dioxide, one of the critical greenhouse gases. Instead of burning these woody wastes, we should recycle them as future resources. One solution to this problem is to make compost from the waste. Compost use in agriculture is increasing as both an alternative to landfilling for the management of biodegradable waste, as well as means of increasing or preserving soil organic matter. This research aimed to contribute to the identification of a system for managing the production and utilization of wood waste (Quercus rubra and Pinus sylvestris) compost for sustainable agriculture, with particular regards to carbon dioxide produced from both compost and combustion of wood. Compost of wood was implemented in two consecutive trials. The first was carried out in greenhouse experiment in 4 liter pot of Quercus rubra and Pinus sylvestris (QR and PS) moisted by compost and tap water and infected by tiger worm (Eisenia fetida, EF) and European night crawlers (Dendrobaena veneta, DV) at different mixed ratios with lake mud (LM). The second was conducted in greenhouse experiment in 40 liter pot of the successful wood and worm from the first compost trial (QR and EF respectively). The tested wood (QR) was mixed separately by lake mud and horse manure and irrigated by compost and tap water. The final product, successful wood compost (QR) produced from the first trial (4 liter pot) was utilized in different mixed ratios with coal mine tailings (tertiary sand) in greenhouse pot trial to study his effects on improving soil physical and chemical properties and some plant growth parameters of RSM 7.2.1 grass. The wood compost produced from the second compost experiment (40 liter pot) and other artificial component named Arkadolith® were used as soil amelioration in field experiments of different selected sites with extremely unsuitable characteristics (tertiary and quaternary sand in Lusatia lignite region, Germany). The soil in each site was sowed by RSM 7.2.1 and autochthonous grasses. Also, some vermicompost samples were selected to study its thermal stability which compared with a soil sample (Niedermoorgleys) by using thermogravimetric analysis technique. Further investigation was achieved to evaluate the effect of charcoal as a source of carbon on vermicompost stability. Moreover some selected vermicompost samples were used to examine its microstructure under scanning electron microscope which compared also with the same soil used in thermal analysis. The obtained results under all studied experiments can be arranged as follow: First compost trial, Cumulative amount of carbon dioxide produced during composting period was lower than that evolved by combustion of wood. The results showed composting of wood can reduce the emitted CO2 up to 50 \% when compared with the amount of CO2 produced from combustion of wood. The effect of different studied factors on different studied parameters show that, QR wood compost have more responsive to decomposition processes and humification rate in comparison with PS wood compost. Under different infection worms, Eisenia fetida (EF) was better than Dendrobaena veneta (DV) in biodegradation rate. Compost water has had a better impact of tap water in all studied decomposition parameters. For example, The compost content of OM and total OC was decreased with the increase of the decomposition period in the treatments of compost water and EF worm, where this decrease was higher at mixed ratio of 1:3 (wood: mud, w/w). The total content of N in the final products takes reversible trend regarding to OM and C content. The high content of N was found in QR wood compost moisted by compost water and infected by EF worm. The content of both macro-and micro-nutrients was clearly positive affected by the studied factors. The content of these nutrients in QR wood compost was higher than that found in the compost of PS wood. Second compost trial, The observed data show that, the amount of CO2 produced by composting was lower than that evolved by combustion of wood. Composting of wood reduced CO2 emission up to 40 \% of the combustion wood CO2. Cumulative amount of CO2 produced from wood compost treated by horse manure was higher than that fount in the other treated by LM. The compost of wood treated by horse manure has had a high decomposition rate in comparison with that treated by lake mud. The treatments left without worms during all composting period and moisted by compost water have a responsive effects but it was lower than that infected by worms. Total and available contents of N, P, K, Mg, Zn, and Cu in the compost treated by HM were higher than that found in compost treated by LM. The other nutrients (Ca, Fe, Cu, and Mn) take reversible trend, which it was higher in LM than HM treatments. Thermal and microstructure analysis, The selected vermicompost samples from both first and second compost experiments showed, up to 200° C temperature the mass loss was due to free water and bound water (It was in vermicompost samples higher than soil sample). Mass loss from 200 to 550° C is due to easily oxidizable organic forms and it was higher in vermicompost than soil. In this stage the soil OM seems to be more stable than vermicompost which can be explained by a more intensive bond between the organic and inorganic components. At higher temperatures (T> 550° C) no significant detectable was appeared of soil organic matter. In contrast, the vermicompost treatments showed a high proportion of stable groups, especially aromatic compounds. These statements seem to be importance particularly for the practical application of the wood compost in terms of their long-term effect in the soil. The application of charcoal, showed no additional stabilizing effect of vermicompost. Also, the data show that, vermicompost structure characterized with high homogeneity and ratio of surface area to volume compared to those in soil structure. First plant trials (greenhouse), Different compost mixed ratios had positive impact on different extreme soil physiochemical properties. At the end of experiment (42 days) compost increased soil water holding capacity, decreased soil bulk and particle density and increased total porosity. The used wood compost modified soil buffering capacity and soil acidity. The availability of soil macro and micro nutrients were increased after adding wood compost. The wood compost had a positive effect in some growth parameters like fresh and dry matter yield of the selected grass. High dry matter yield and nutrients uptake was achieved with higher rates of compost application (25.0\% > 12.5\% > 3.0\% > 0.0 \%, w/w). Second plant trials (field experiment), Regarding to the effect of wood compost (QR) and Arkadolith® component on tertiary and quaternary sand, at the end of grown season (6 month) most soil and plant characteristics of tertiary sand were improved and it was better than that in quaternary sand. This trend reveals to, physical and chemical properties of tertiary sand was better than that in quaternary sand, like organic matter content, CEC, WHC, TOC, available nutrients. In the both sites, the effects of different type of soil conditioners arranged as follow: the treatments treated with wood compost is the better followed by the other treated with both wood compost and Arkadolith. Wood compost increased soil pH, CEC, soil buffering capacity, OM content, and soil WHC in comparison with Arkadolith which make a small improvement of these properties in both sites. Finally, Different growth parameters (height, covering, fresh and dry matter yield) of the used grasses were clearly positive affected by wood compost, with the highest production inherent to the treatments treated by the high amount of wood compost.},
  language  = {de}
}
@phdthesis{AndradeLinares2011,
  author    = {Andrade Linares, Diana Roc{\´i}o},
  title     = {Characterization of tomato root-endophytic fungi and analysis of their effects on plant development, on fruit yield and quality and on interaction with the pathogen Verticillium dahliae},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51375},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Non-mycorrhizal fungal endophytes are able to colonize internally roots without causing visible disease symptoms establishing neutral or mutualistic associations with plants. These fungi known as non-clavicipitaceous endophytes have a broad host range of monocot and eudicot plants and are highly diverse. Some of them promote plant growth and confer increased abiotic-stress tolerance and disease resistance. According to such possible effects on host plants, it was aimed to isolate and to characterize native fungal root endophytes from tomato (Lycopersicon esculentum Mill.) and to analyze their effects on plant development, plant resistance and fruit yield and quality together with the model endophyte Piriformospora indica. Fifty one new fungal strains were isolated from desinfected tomato roots of four different crop sites in Colombia. These isolates were roughly characterized and fourteen potential endophytes were further analyzed concerning their taxonomy, their root colonization capacity and their impact on plant growth. Sequencing of the ITS region from the ribosomal RNA gene cluster and in-depth morphological characterisation revealed that they correspond to different phylogenetic groups among the phylum Ascomycota. Nine different morphotypes were described including six dark septate endophytes (DSE) that did not correspond to the Phialocephala group. Detailed confocal microscopy analysis showed various colonization patterns of the endophytes inside the roots ranging from epidermal penetration to hyphal growth through the cortex. Tomato pot experiments under glass house conditions showed that they differentially affect plant growth depending on colonization time and inoculum concentration. Three new isolates (two unknown fungal endophyte DSE48, DSE49 and one identified as Leptodontidium orchidicola) with neutral or positiv effects were selected and tested in several experiments for their influence on vegetative growth, fruit yield and quality and their ability to diminish the impact of the pathogen Verticillium dahliae on tomato plants. Although plant growth promotion by all three fungi was observed in young plants, vegetative growth parameters were not affected after 22 weeks of cultivation except a reproducible increase of root diameter by the endophyte DSE49. Additionally, L. orchidicola increased biomass and glucose content of tomato fruits, but only at an early date of harvest and at a certain level of root colonization. Concerning bioprotective effects, the endophytes DSE49 and L. orchidicola decreased significantly disease symptoms caused by the pathogen V. dahliae, but only at a low dosis of the pathogen. In order to analyze, if the model root endophytic fungus Piriformospora indica could be suitable for application in production systems, its impact on tomato was evaluated. Similarly to the new fungal isolates, significant differences for vegetative growth parameters were only observable in young plants and, but protection against V. dahliae could be seen in one experiment also at high dosage of the pathogen. As the DSE L. orchidicola, P. indica increased the number and biomass of marketable tomatoes only at the beginning of fruit setting, but this did not lead to a significant higher total yield. If the effects on growth are due to a better nutrition of the plant with mineral element was analyzed in barley in comparison to the arbuscular mycorrhizal fungus Glomus mosseae. While the mycorrhizal fungus increased nitrogen and phosphate uptake of the plant, no such effect was observed for P. indica. In summary this work shows that many different fungal endophytes can be also isolated from roots of crops and, that these isolates can have positive effects on early plant development. This does, however, not lead to an increase in total yield or in improvement of fruit quality of tomatoes under greenhouse conditions.},
  language  = {en}
}
@phdthesis{Flotyńska2011,
  author    = {Flotyńska, Anna},
  title     = {Besteuerung von Unternehmensgewinnen im Licht des Konzepts der konsumorientierten Einkommensteuer},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-86956-138-7},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52493},
  school      = {Universit{\"a}t Potsdam},
  pages     = {iii, 222},
  year      = {2011},
  abstract  = {Die Dissertation widmet sich dem Problem der fiskalischen Konsequenzen der konsumorientierten Steuern, die die unternehmerischen Gewinne unabh{\"a}ngig von der Rechtsform belasten. Im empirischen Teil der Arbeit wird der Untersuchungsgegenstand auf die zinsbereinigte Gewinnsteuer (allowance for corporate equity) eingegrenzt. Die Untersuchung beruht auf theoretischen {\"U}berlegungen sowie einer eigenen Simulationsanalyse. Den Schwerpunkt bilden dabei zwei Kategorien, zwischen denen ein kausaler Zusammenhang vorliegt: die Gestaltung der Bemessungsgrundlage einerseits und die Erf{\"u}llung der Fiskalfunktion andererseits. Das Hauptziel der Arbeit ist es, die fiskalischen Konsequenzen einer nach dem Konzept der Konsumorientierung modifizierten Bemessungsgrundlage der Gewinnsteuern zu {\"u}berpr{\"u}fen. Die Absch{\"a}tzung der fiskalischen Konsequenzen wird aufgrund der vier folgenden Bereiche vorgenommen: (1) theoretische Konzepte der konsumorientierten Einkommensteuer, (2) bisherige Umsetzungen der Konzepte der konsumorientierten Gewinnsteuer, (3) bisherige Untersuchungen der konsumorientierten Gewinnsteuer, (4) eine eigene Simulation der fiskalischen Konsequenzen der konsumorientierten Gewinnsteuer. Um das Hauptziel der Arbeit zu erreichen, werden acht in Form von Teilfragen ausformulierte Untersuchungsprobleme gel{\"o}st. Sie betreffen sowohl die theoretischen Ausf{\"u}hrungen, als auch die empirische Untersuchung. Dabei entsprechen sie den einzelnen Untersuchungsschritten, die in den aufeinander folgenden Kapiteln der Arbeit durchgef{\"u}hrt werden. Anhand der Analyse der bisherigen wissenschaftlichen Erkenntnisse und der praktischen Umsetzungen des Konzepts der konsumorientierten Steuern wurde die folgende Haupthypothese aufgestellt: Der Ausfall des Steueraufkommens, der ein direkter Effekt der Gestaltung der Bemessungsgrundlage nach dem Konzept der Konsumorientierung ist, schließt die Fiskalfunktion der Gewinnsteuern nicht aus. Das Verfahren, das eine Verifizierung der Haupthypothese zum Ziel hat, erfolgt durch eine Untersuchung von drei Teilhypothesen: der Hypothese {\"u}ber die Nullsteuer, der Hypothese {\"u}ber den differenzierten Aufkommensausfall und der Hypothese {\"u}ber die Konzentration der Steuerschuld. In der Dissertation werden empirische Daten aus drei Quellen benutzt. Sie umfassen einen Teil der in Polen in den Jahren 2004-2008 t{\"a}tigen Unternehmen und erm{\"o}glichen es, eine Simulationsanalyse des Aufkommensausfalls durchzuf{\"u}hren. Diese bedient sich der Methodik der Mikro- und Gruppensimulation, was in den bisherigen Untersuchungen zur Unternehmensbesteuerung ein eher selten anzutreffender Ansatz ist. Die gewonnenen Ergebnisse zeigen, dass die Steuereinnahmen aus der Einkommensteuer und der K{\"o}rperschaftsteuer durch die Modifizierung der Bemessungsgrundlage deutlich reduziert werden. Die relativ große fiskalische Bedeutung der beiden Steuern bleibt jedoch erhalten und der Ausfall des Steueraufkommens, der direkt nach der Einf{\"u}hrung einer konsumorientierten Steuerreform eintreten w{\"u}rde, w{\"a}re der „Preis" f{\"u}r eine bessere, weniger verzerrende Bemessungsgrundlage. Die Dissertation liefert Ergebnisse, die f{\"u}r die Gestaltung der Steuerpolitik in Polen wie auch in anderen L{\"a}ndern relevant sind. Dies scheint insbesondere im Kontext des h{\"a}ufig diskutierten Umbaus des Systems der Einkommen- und Gewinnbesteuerung bedeutsam. Dar{\"u}ber hinaus bildet die Arbeit einen Ausgangspunkt f{\"u}r weitere, vertiefte Untersuchungen zu den m{\"o}glichen Gestaltungsformen der Einkommen- und Gewinnsteuern wie auch zu deren Folgen. Die Methode der Steuersimulation kann weiterentwickelt werden und in anderen Analysen der potenziellen Konsequenzen von Steuerreformen Anwendung finden.},
  language  = {de}
}
@phdthesis{Schumacher2011,
  author    = {Schumacher, Soeren},
  title     = {Saccharide recognition : boronic acids as receptors in polymeric networks},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52869},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {In this thesis entitled "Saccharide Recognition - Boronic acids as Receptors in Polymeric Networks" different aspects of boronic acid synthesis, their analysis and incorporation or attachment to different polymeric networks and characterisation thereof were investigated. The following key aspects were considered: • Provision of a variety of different characterised arylboronic acids and benzoboroxoles • Attachment of certain derivatives to nanoparticles and the characterisation of saccharide binding by means of isothermal titration calorimetry and displacement assay (ARS) to enhance the association constant to saccharides at pH 7.4 • Enhancement of selectivity in polymeric systems by means of molecular imprinting using fructose as template and a polymerisable benzoboroxole as functional monomer for the recognition at pH 7.4 (Joined by a diploma thesis of F. Gr{\"u}neberger) • Development of biomimetic saccharide structures and the development of saccharide (especially glucose and fructose) binding MIPs by using these structures as template molecules. In the first part of the thesis different arylboronic acid derivatives were synthesised and their binding to glucose or fructose was investigated by means of isothermal titration calorimetry (ITC). It could be derived, which is in parallel to the literature, that derivatives bearing a methylhydroxyl-group in ortho-position to the boron (benzoboroxole) exhibit in most cases a two-fold higher association constant compared to the corresponding phenylboronic acid derivative. To gain a deeper understanding NMR spectroscopy and mass spectrometry with the benzoboroxole and glucose or fructose was performed. It could be shown that the exchange rate in terms of NMR time scale is quite slow since in titration experiments new peaks appeared. Via mass spectrometry of a mixture between benzoboroxole and glucose or fructose, different binding stoichiometries could be detected showing that the binding of saccharides is comparable with their binding to phenylboronic acid. In addition, the use of Alizarin Red S as an electrochemical reporter was described for the first time to monitor the saccharide binding to arylboronic acids not only with spectroscopy. Here, the redox behaviour and the displacement were recorded by cyclic voltammograms. In the second part different applications of boronic acids in polymeric networks were investigated. The attachment of benzoboroxoles to nanoparticles was investigated and monitored by means of isothermal titration calorimetry and a colourimetric assay with Alizarin Red S as the report dye. The investigations by isothermal titration calorimetry compared the fructose binding of arylboronic acids and benzoboroxoles coupled to these nanoparticles and "free" in solution. It could be shown that the attached derivatives showed a higher binding constant due to an increasing entropy term. This states for possible multivalent binding combined with a higher water release. Since ITC could not characterise the binding of glucose to these nanoparticles due to experimental restrictions the glucose binding at pH 7.4 was shown with ARS. Here, the displacement of ARS by fructose and also glucose could be followed and consequently these nanoparticles can be used for saccharide determination. Within this investigation also the temperature stability of these nanoparticles was examined and after normal sterilisation procedures (121°C, 20 min.) the binding behaviour was still unchanged. To target the selectivity of the used polymeric networks, molecular imprinting was used as a technique for creating artificial binding pockets on a molecular scale. As functional monomer 3-methacrylamidobenzoboroxole was introduced for the recognition of fructose. In comparison to polymers prepared with vinylphenylboronic acid the benzoboroxole containing polymer had a stronger binding at pH 7.4 which was shown for the first time. In addition, another imprinted polymer was synthesised especially for the recognition of glucose and fructose employing biomimetic saccharide analogues as template molecule. The advantage to use the saccharide analogues is the defined template-functional monomer complex during the polymerisation which is not the case, for example, for glucose-boronic acid interaction. The biomimetic character was proven through structural superimposition of crystal structures of the analogues with already described crystal structures of boronic acid esters of glucose and fructose. A molecularly imprinted polymer was synthesised with vinylphenylboronic acid as the functional monomer to show that both glucose and fructose are able to bind to the polymer which was predicted by the structural similarity of the analogues. The major scientific contributions of this thesis are • the determination of binding constants for some, not yet reported saccharide - boronic acid / benzoboroxole pairs, • the use of ARS as electrochemical reporter for saccharide detection, • the thermodynamic characterisation of a saccharide binding nanoparticle system containing benzoboroxole and functioning at pH 7.4, • the use of a polymerisable benzoboroxole as functional monomer for saccharide recognition in neutral, aqueous environments • and the synthesis and utilisation of biomimetic saccharide analogues as template molecules especially for the development of a glucose binding MIP.},
  language  = {en}
}
@phdthesis{Ehrke2011,
  author    = {Ehrke, J{\"u}rgen},
  title     = {Zur Stabilisierung fragmentierter Staaten},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  isbn      = {978-3-86956-155-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53975},
  school      = {Universit{\"a}t Potsdam},
  pages     = {366},
  year      = {2011},
  abstract  = {Die internationale Staatengemeinschaft steht Sezessionsbestrebungen zur Aufspaltung bestehender Staaten gew{\"o}hnlich ablehnend gegen{\"u}ber. Gleichzeitig wendet sie in vielen L{\"a}ndern Instrumente der Entwicklungspolitik an und greift so auch in den dortigen politischen Prozess ein. Untersucht wird, inwiefern Entwicklungspolitik so gestaltet werden kann, dass sie nicht, quasi als Nebenwirkung, einer Sezessionsbewegung zum Durchbruch verhilft. Betrachtet wird dabei neben der gezielten F{\"o}rderung wirtschaftlichen Wachstums auch das Instrument der Dezentralisierung, das oft als Mittel zur „Beruhigung" separatistischer Bestrebungen vorgeschlagen wird. Zuvor jedoch wird aufgewiesen, dass eine Politik, die Sezessionen verhindern will, zumindest in vielen F{\"a}llen auch moralphilosophisch schl{\"u}ssig begr{\"u}ndet werden kann. Den Abschluss der Arbeit bilden drei Fallstudien zu Sezessionen auf dem Gebiet der ehemaligen Sowjetunion.},
  language  = {de}
}
@phdthesis{Yustus2011,
  author    = {Yustus, Ekaterina},
  title     = {Verfassungsgerichtsbarkeit in Russland und Deutschland},
  series = {Europ{\"a}ische Hochschulschriften : Reihe 2, Rechtswissenschaften},
  volume    = {5205},
  journal   = {Europ{\"a}ische Hochschulschriften : Reihe 2, Rechtswissenschaften},
  publisher = {Lang},
  address   = {Frankfurt am Main},
  isbn      = {978-3-631-60741-1},
  issn      = {0531-7312},
  pages     = {244 S.},
  year      = {2011},
  language  = {de}
}
@phdthesis{Kittner2011,
  author    = {Kittner, Madeleine},
  title     = {Folding and aggregation of amyloid peptides},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53570},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Aggregation of the Amyloid β (Aβ) peptide to amyloid fibrils is associated with the outbreak of Alzheimer's disease. Early aggregation intermediates in form of soluble oligomers are of special interest as they are believed to be the major toxic components in the process. These oligomers are of disordered and transient nature. Therefore, their detailed molecular structure is difficult to access experimentally and often remains unknown. In the present work extensive, fully atomistic replica exchange molecular dynamics simulations were performed to study the preaggregated, monomer states and early aggregation intermediates (dimers, trimers) of Aβ(25-35) and Aβ(10-35)-NH2 in aqueous solution. The folding and aggregation of Aβ(25-35) were studied at neutral pH and 293 K. Aβ(25-35) monomers mainly adopt β-hairpin conformations characterized by a β-turn formed by residues G29 and A30, and a β-sheet between residues N27-K28 and I31-I32 in equilibrium with coiled conformations. The β-hairpin conformations served as initial configurations to model spontaneous aggregation of Aβ(25-35). As expected, within the Aβ(25-35) dimer and trimer ensembles many different poorly populated conformations appear. Nevertheless, we were able to distinguish between disordered and fibril-like oligomers. Whereas disordered oligomers are rather compact with few intermolecular hydrogen bonds (HBs), fibril-like oligomers are characterized by the formation of large intermolecular β-sheets. In most of the fibril-like dimers and trimers individual peptides are fully extended forming in- or out-of-register antiparallel β-sheets. A small amount of fibril-like trimers contained V-shaped peptides forming parallel β-sheets. The dimensions of extended and V-shaped oligomers correspond well to the diameters of two distinct morphologies found for Aβ(25-35) fibrils. The transition from disordered to fibril-like Aβ(25-35) dimers is unfavorable but driven by energy. The lower energy of fibril-like dimers arises from favorable intermolecular HBs and other electrostatic interactions which compete with a loss in entropy. Approximately 25 \% of the entropic cost correspond to configurational entropy. The rest relates to solvent entropy, presumably caused by hydrophobic and electrostatic effects. In contrast to the transition towards fibril-like dimers the first step of aggregation is driven by entropy. Here, we compared structural and thermodynamic properties of the individual monomer, dimer and trimer ensembles to gain qualitative information about the aggregation process. The β-hairpin conformation observed for monomers is successively dissolved in dimer and trimer ensembles while instead intermolecular β-sheets are formed. As expected upon aggregation the configurational entropy decreases. Additionally, the solvent accessible surface area (SASA), especially the hydrophobic SASA, decreases yielding a favorable solvation free energy which overcompensates the loss in configurational entropy. In summary, the hydrophobic effect, possibly combined with electrostatic effects, yields an increase in solvent entropy which is believed to be one major driving force towards aggregation. Spontaneous folding of the Aβ(10-35)-NH2 monomer was modeled using two force fields, GROMOS96 43a1 and OPLS/AA, and compared to primary NMR data collected at pH 5.6 and 283 K taken from the literature. Unexpectedly, the two force fields yielded significantly different main conformations. Comparison between experimental and calculated nuclear Overhauser effect (NOE) distances is not sufficient to distinguish between the different force fields. Additionally, the comparison with scalar coupling constants suggest that the chosen protonation in both simulations corresponds to a pH lower than in the experiment. Based on this analysis we were unable to determine which force field yields a better description of this system. Dimerization of Aβ(10-35)-NH2 was studied at neutral pH and 300 K. Dimer conformations arrange in many distinct, poorly populated and rather complex alignments or interlocking patterns which are rather stabilized by side chain interactions than by specific intermolecular hydrogen bonds. Similar to Aβ(25-35) dimers, transition towards β-sheet-rich, fibril-like Aβ(10-35) dimers is driven by energy competing with a loss in entropy. Here, transition is mediated by favorable peptide-solvent and solvent-solvent interactions mainly arising from electrostatic interactions.},
  language  = {en}
}
@phdthesis{Stockhorst2011,
  author    = {Stockhorst, Stefanie},
  title     = {Einf{\"u}hrung in das Werk Gotthold Ephraim Lessings},
  series = {Einf{\"u}hrungen Germanistik},
  journal   = {Einf{\"u}hrungen Germanistik},
  publisher = {WBG},
  address   = {Darmstadt},
  isbn      = {978-3-534-22984-0},
  pages     = {143 S.},
  year      = {2011},
  language  = {de}
}
@phdthesis{Wang2011,
  author    = {Wang, Long},
  title     = {X-tracking the usage interest on web sites},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51077},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {The exponential expanding of the numbers of web sites and Internet users makes WWW the most important global information resource. From information publishing and electronic commerce to entertainment and social networking, the Web allows an inexpensive and efficient access to the services provided by individuals and institutions. The basic units for distributing these services are the web sites scattered throughout the world. However, the extreme fragility of web services and content, the high competence between similar services supplied by different sites, and the wide geographic distributions of the web users drive the urgent requirement from the web managers to track and understand the usage interest of their web customers. This thesis, "X-tracking the Usage Interest on Web Sites", aims to fulfill this requirement. "X" stands two meanings: one is that the usage interest differs from various web sites, and the other is that usage interest is depicted from multi aspects: internal and external, structural and conceptual, objective and subjective. "Tracking" shows that our concentration is on locating and measuring the differences and changes among usage patterns. This thesis presents the methodologies on discovering usage interest on three kinds of web sites: the public information portal site, e-learning site that provides kinds of streaming lectures and social site that supplies the public discussions on IT issues. On different sites, we concentrate on different issues related with mining usage interest. The educational information portal sites were the first implementation scenarios on discovering usage patterns and optimizing the organization of web services. In such cases, the usage patterns are modeled as frequent page sets, navigation paths, navigation structures or graphs. However, a necessary requirement is to rebuild the individual behaviors from usage history. We give a systematic study on how to rebuild individual behaviors. Besides, this thesis shows a new strategy on building content clusters based on pair browsing retrieved from usage logs. The difference between such clusters and the original web structure displays the distance between the destinations from usage side and the expectations from design side. Moreover, we study the problem on tracking the changes of usage patterns in their life cycles. The changes are described from internal side integrating conceptual and structure features, and from external side for the physical features; and described from local side measuring the difference between two time spans, and global side showing the change tendency along the life cycle. A platform, Web-Cares, is developed to discover the usage interest, to measure the difference between usage interest and site expectation and to track the changes of usage patterns. E-learning site provides the teaching materials such as slides, recorded lecture videos and exercise sheets. We focus on discovering the learning interest on streaming lectures, such as real medias, mp4 and flash clips. Compared to the information portal site, the usage on streaming lectures encapsulates the variables such as viewing time and actions during learning processes. The learning interest is discovered in the form of answering 6 questions, which covers finding the relations between pieces of lectures and the preference among different forms of lectures. We prefer on detecting the changes of learning interest on the same course from different semesters. The differences on the content and structure between two courses leverage the changes on the learning interest. We give an algorithm on measuring the difference on learning interest integrated with similarity comparison between courses. A search engine, TASK-Moniminer, is created to help the teacher query the learning interest on their streaming lectures on tele-TASK site. Social site acts as an online community attracting web users to discuss the common topics and share their interesting information. Compared to the public information portal site and e-learning web site, the rich interactions among users and web content bring the wider range of content quality, on the other hand, provide more possibilities to express and model usage interest. We propose a framework on finding and recommending high reputation articles in a social site. We observed that the reputation is classified into global and local categories; the quality of the articles having high reputation is related with the content features. Based on these observations, our framework is implemented firstly by finding the articles having global or local reputation, and secondly clustering articles based on their content relations, and then the articles are selected and recommended from each cluster based on their reputation ranks.},
  language  = {en}
}
@phdthesis{Wang2011,
  author    = {Wang, Yongbo},
  title     = {Late glacial to Holocene climate and vegetation changes on the Tibetan Plateau inferred from fossil pollen records in lacustrine sediments},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-63155},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {The past climate in central Asia, and especially on the Tibetan Plateau (TP), is of great importance for an understanding of global climate processes and for predicting the future climate. As a major influence on the climate in this region, the Asian Summer Monsoon (ASM) and its evolutionary history are of vital importance for accurate predictions. However, neither the evolutionary pattern of the summer monsoon nor the driving mechanisms behind it are yet clearly understood. For this research, I first synthesized previously published Late Glacial to Holocene climatic records from monsoonal central Asia in order to extract the general climate signals and the associated summer monsoon intensities. New climate and vegetation sequences were then established using improved quantitative methods, focusing on fossil pollen records recovered from Tibetan lakes and also incorporating new modern datasets. The pollen-vegetation and vegetation-climate relationships on the TP were also evaluated in order to achieve a better understanding of fossil pollen records. The synthesis of previously published moisture-related palaeoclimate records in monsoonal central Asia revealed generally different temporal patterns for the two monsoonal subsystems, i.e. the Indian Summer Monsoon (ISM) and East Asian Summer Monsoon (EASM). The ISM appears to have experienced maximum wet conditions during the early Holocene, while many records from the area affected by the EASM indicate relatively dry conditions at that time, particularly in north-central China where the maximum moisture levels occurred during the middle Holocene. A detailed consideration of possible driving factors affecting the summer monsoon, including summer solar insolation and sea surface temperatures, revealed that the ISM was primarily driven by variations in northern hemisphere solar insolation, and that the EASM may have been constrained by the ISM resulting in asynchronous patterns of evolution for these two subsystems. This hypothesis is further supported by modern monsoon indices estimated using the NCEP/NCAR Reanalysis data from the last 50 years, which indicate a significant negative correlation between the two summer monsoon subsystems. By analogy with the early Holocene, intensification of the ISM during coming decades could lead to increased aridification elsewhere as a result of the asynchronous nature of the monsoon subsystems, as can already be observed in the meteorological data from the last 15 years. A quantitative climate reconstruction using fossil pollen records was achieved through analysis of sediment core recovered from Lake Donggi Cona (in the north-eastern part of the TP) which has been dated back to the Last Glacial Maximum (LGM). A new data-set of modern pollen collected from large lakes in arid to semi-arid regions of central Asia is also presented herein. The concept of "pollen source area" was introduced to modern climate calibration based on pollen from large lakes, and was applied to the fossil pollen sequence from Lake Donggi Cona. Extremely dry conditions were found to have dominated the LGM, and a subsequent gradually increasing trend in moisture during the Late Glacial period was terminated by an abrupt reversion to a dry phase that lasted for about 1000 years and coincided with the first Heinrich Event of the northern Atlantic region. Subsequent periods corresponding to the warm B{\o}lling-Aller{\o}d period and the Younger Dryas cold event were followed by moist conditions during the early Holocene, with annual precipitation of up to about 400 mm. A slightly drier trend after 9 cal ka BP was then followed by a second wet phase during the middle Holocene that lasted until 4.5 cal ka BP. Relatively steady conditions with only slight fluctuations then dominated the late Holocene, resulting in the present climatic conditions. In order to investigate the relationship between vegetation and climate, temporal variations in the possible driving factors for vegetation change on the northern TP were examined using a high resolution late Holocene pollen record from Lake Kusai. Moving-window Redundancy Analyses (RDAs) were used to evaluate the correlations between pollen assemblages and individual sedimentary proxies. These analyses have revealed frequent fluctuations in the relative abundances of alpine steppe and alpine desert components, and in particular a decrease in the total vegetation cover at around 1500 cal a BP. The climate was found to have had an important influence on vegetation changes when conditions were relatively wet and stable. However, after the 1500 cal a BP threshold in vegetation cover was crossed the vegetation appears to have been affected more by extreme events such as dust storms or fluvial erosion than by the general climatic trends. In addition, pollen spectra over the last 600 years have been revealed by Procrustes analysis to be significantly different from those recovered from older samples, which is attributed to an increased human impact that resulted in unprecedented changes to the composition of the vegetation. Theoretical models that have been developed and widely applied to the European area (i.e. the Extended R-Value (ERV) model and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model) have been applied to the high alpine TP ecosystems in order to investigate the pollen-vegetation relationships, as well as for quantitative reconstructions of vegetation abundance. The modern pollen-vegetation relationships for four common pollen species on the TP have been investigated using Poaceae as the reference taxa. The ERV Submodel 2 yielded relatively high PPEs for the steppe and desert taxa (Artemisia Chenopodiaceae), and low PPEs for the Cyperaceae that are characteristic of the alpine Kobresia meadows. The plant abundances on the central and north-eastern TP were quantified by applying these PPEs to four post-Late Glacial fossil pollen sequences. The reconstructed vegetation assemblages for the four pollen sequences always yielded smaller compositional species turnovers than suggested by the pollen spectra, indicating that the strength of the previously-reported vegetation changes may therefore have been overestimated. In summary, the key findings of this thesis are that (a) the two ASM subsystems show asynchronous patterns during both the Holocene and modern time periods, (b) fossil pollen records from large lakes reflect regional signals for which the pollen source areas need to be taken into account, (c) climate is not always the main driver for vegetation change, and (d) previously reported vegetation changes on the TP may have been overestimated because they ignored inter-species variations in pollen productivity.},
  language  = {en}
}
@phdthesis{Wischnewski2011,
  author    = {Wischnewski, Juliane},
  title     = {Reconstructing climate variability on the Tibetan Plateau : comparing aquatic and terrestrial signals},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52453},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Spatial and temporal temperature and moisture patterns across the Tibetan Plateau are very complex. The onset and magnitude of the Holocene climate optimum in the Asian monsoon realm, in particular, is a subject of considerable debate as this time period is often used as an analogue for recent global warming. In the light of contradictory inferences regarding past climate and environmental change on the Tibetan Plateau, I have attempted to explain mismatches in the timing and magnitude of change. Therefore, I analysed the temporal variation of fossil pollen and diatom spectra and the geochemical record from palaeo-ecological records covering different time scales (late Quaternary and the last 200 years) from two core regions in the NE and SE Tibetan Plateau. For interpretation purposes I combined my data with other available palaeo-ecological data to set up corresponding aquatic and terrestrial proxy data sets of two lake pairs and two sets of sites. I focused on the direct comparison of proxies representing lacustrine response to climate signals (e.g., diatoms, ostracods, geochemical record) and proxies representing changes in the terrestrial environment (i.e., terrestrial pollen), in order to asses whether the lake and its catchments respond at similar times and magnitudes to environmental changes. Therefore, I introduced the established numerical technique procrustes rotation as a new approach in palaeoecology to quantitatively compare raw data of any two sedimentary records of interest in order to assess their degree of concordance. Focusing on the late Quaternary, sediment cores from two lakes (Kuhai Lake 35.3°N; 99.2°E; 4150 m asl; and Koucha Lake 34.0°N; 97.2°E; 4540 m asl) on the semi-arid northeastern Tibetan Plateau were analysed to identify post-glacial vegetation and environmental changes, and to investigate the responses of lake ecosystems to such changes. Based on the pollen record, five major vegetation and climate changes could be identified: (1) A shift from alpine desert to alpine steppe indicates a change from cold, dry conditions to warmer and more moist conditions at 14.8 cal. ka BP, (2) alpine steppe with tundra elements points to conditions of higher effective moisture and a stepwise warming climate at 13.6 cal. ka BP, (3) the appearance of high-alpine meadow vegetation indicates a further change towards increased moisture, but with colder temperatures, at 7.0 cal. ka BP, (4) the reoccurrence of alpine steppe with desert elements suggests a return to a significantly colder and drier phase at 6.3 cal. ka BP, and (5) the establishment of alpine steppe-meadow vegetation indicates a change back to relatively moist conditions at 2.2 cal. ka BP. To place the reconstructed climate inferences from the NE Tibetan Plateau into the context of Holocene moisture evolution across the Tibetan Plateau, I applied a five-scale moisture index and average link clustering to all available continuous pollen and non-pollen palaeoclimate records from the Tibetan Plateau, in an attempt to detect coherent regional and temporal patterns of moisture evolution on the Plateau. However, no common temporal or spatial pattern of moisture evolution during the Holocene could be detected, which can be assigned to the complex responses of different proxies to environmental changes in an already very heterogeneous mountain landscape, where minor differences in elevation can result in marked variations in microenvironments. Focusing on the past 200 years, I analysed the sedimentary records (LC6 Lake 29.5°N, 94.3°E, 4132 m asl; and Wuxu Lake 29.9°N, 101.1°E, 3705 m asl) from the southeastern Tibetan Plateau. I found that despite presumed significant temperature increases over that period, pollen and diatom records from the SE Tibetan Plateau reveal only very subtle changes throughout their profiles. The compositional species turnover investigated over the last 200 years appears relatively low in comparison to the species reorganisations during the Holocene. The results indicate that climatically induced ecological thresholds are not yet crossed, but that human activity has an increasing influence, particularly on the terrestrial ecosystem. Forest clearances and reforestation have not caused forest decline in our study area, but a conversion of natural forests to semi-natural secondary forests. The results from the numerical proxy comparison of the two sets of two pairs of Tibetan lakes indicate that the use of different proxies and the work with palaeo-ecological records from different lake types can cause deviant stories of inferred change. Irrespective of the timescale (Holocene or last 200 years) or region (SE or NE Tibetan Plateau) analysed, the agreement in terms of the direction, timing, and magnitude of change between the corresponding terrestrial data sets is generally better than the match between the corresponding lacustrine data sets, suggesting that lacustrine proxies may partly be influenced by in-lake or local catchment processes whereas the terrestrial proxy reflects a more regional climatic signal. The current disaccord on coherent temporal and spatial climate patterns on the Tibetan Plateau can partly be ascribed to the complexity of proxy response and lake systems on the Tibetan Plateau. Therefore, a multi-proxy, multi-site approach is important in order to gain a reliable climate interpretation for the complex mountain landscape of the Tibetan Plateau.},
  language  = {en}
}
@phdthesis{Risse2011,
  author    = {Risse, Sarah},
  title     = {Processing in the perceptual span : investigations with the n+2-boundary paradigm},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-60414},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Cognitive psychology is traditionally interested in the interaction of perception, cognition, and behavioral control. Investigating eye movements in reading constitutes a field of research in which the processes and interactions of these subsystems can be studied in a well-defined environment. Thereby, the following questions are pursued: How much information is visually perceived during a fixation, how is processing achieved and temporally coordinated from visual letter encoding to final sentence comprehension, and how do such processes reflect on behavior such as the control of the eyes' movements during reading. Various theoretical models have been proposed to account for the specific eye-movement behavior in reading (for a review see Reichle, Rayner, \& Pollatsek, 2003). Some models are based on the idea of shifting attention serially from one word to the next within the sentence whereas others propose distributed attention allocating processing resources to more than one word at a time. As attention is assumed to drive word recognition processes one major difference between these models is that word processing must either occur in strict serial order, or that word processing is achieved in parallel. In spite of this crucial difference in the time course of word processing, both model classes perform well on explaining many of the benchmark effects in reading. In fact, there seems to be not much empirical evidence that challenges the models to a point at which their basic assumptions could be falsified. One issue often perceived as being decisive in the debate on serial and parallel word processing is how not-yet-fixated words to the right of fixation affect eye movements. Specifically, evidence is discussed as to what spatial extent such parafoveal words are previewed and how this influences current and subsequent word processing. Four experiments investigated parafoveal processing close to the spatial limits of the perceptual span. The present work aims to go beyond mere existence proofs of previewing words at such spatial distances. Introducing a manipulation that dissociates the sources of long-range preview effects, benefits and costs of parafoveal processing can be investigated in a single analysis and the differing impact is tracked across a three-word target region. In addition, the same manipulation evaluates the role of oculomotor error as the cause of non-local distributed effects. In this respect, the results contribute to a better understanding of the time course of word processing inside the perceptual span and attention allocation during reading.},
  language  = {en}
}
@phdthesis{Gendt2011,
  author    = {Gendt, Anja},
  title     = {Eye movements under the control of working memory : the challenge of a reading-span task},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69224},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {During reading oculomotor processes guide the eyes over the text. The visual information recorded is accessed, evaluated and processed. Only by retrieving the meaning of a word from the long-term memory, as well as through the connection and storage of the information about each individual word, is it possible to access the semantic meaning of a sentence. Therefore memory, and here in particular working memory, plays a pivotal role in the basic processes of reading. The following dissertation investigates to what extent different demands on memory and memory capacity have an effect on eye movement behavior while reading. The frequently used paradigm of the reading span task, in which test subjects read and evaluate individual sentences, was used for the experimental review of the research questions. The results speak for the fact that working memory processes have a direct effect on various eye movement measurements. Thus a high working memory load, for example, reduced the perceptual span while reading. The lower the individual working memory capacity of the reader was, the stronger was the influence of the working memory load on the processing of the sentence.},
  language  = {en}
}
@phdthesis{Giesewetter2011,
  author    = {Giesewetter, Stefan},
  title     = {Resolute readings of later Wittgenstein and the challenge of avoiding hierarchies in philosophy},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57021},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {This dissertation addresses the question: How did later Wittgenstein aim to achieve his goal of putting forward a way of dissolving philosophical problems which centered on asking ourselves what we mean by our words - yet which did not entail any claims about the essence of language and meaning? This question is discussed with reference to "resolute" readings of Wittgenstein. I discuss the readings of James Conant, Oskari Kuusela, and Martin Gustafsson. I follow Oskari Kuusela's claim that in order to fully appreciate how later Wittgenstein meant to achieve his goal, we need to clearly see how he aimed to do away with hierarchies in philosophy: Not only is the dissolution of philosophical problems via the method of clarifying the grammar of expressions to be taken as independent from any theses about what meaning must be - but furthermore, it is to be taken as independent from the dissolution of any particular problem via this method. As Kuusela stresses, this also holds for the problems involving rule-following and meaning: the clarification of the grammar of "rule" and "meaning" has no foundational status - it is nothing on which the method of clarifying the grammar of expressions as such were meant to in any way rely on. The lead question of this dissertation then is: What does it mean to come to see that the method of dissolving philosophical problems by asking "How is this word actually used?" does not in any way rely on the results of our having investigated the grammar of the particular concepts "rule" and "meaning"? What is the relation of such results - results such as "To follow a rule, [...], to obey an order, [...] are customs (uses, institutions)" or "The meaning of a word is its use in the language" - to this method? From this vantage point, I concern myself with two aspects of the readings of Gustafsson and Kuusela. In Gustafsson, I concern myself with his idea that the dissolution of philosophical problems in general "relies on" the very agreement which - during the dissolution of the rule-following problem - comes out as a presupposition for our talk of "meaning" in terms of rules. In Kuusela, I concern myself with his idea that Wittgenstein, in adopting a way of philosophical clarification which investigates the actual use of expressions, is following the model of "meaning as use" - which model he had previously introduced in order to perspicuously present an aspect of the actual use of the word "meaning". This dissertation aims to show how these two aspects of Gustafsson's and Kuusela's readings still fail to live up to the vision of Wittgenstein as a philosopher who aimed to do away with any hierarchies in philosophy. I base this conclusion on a detailed analysis of which of the occasions where Wittgenstein invokes the notions of "use" and "application" (as also "agreement") have to do with the dissolution of a specific problem only, and which have to do with the dissolution of philosophical problems in general. I discuss Wittgenstein's remarks on rule-following, showing how in the dissolution of the rule-following paradox, notions such as "use", "application", and "practice" figure on two distinct logical levels. I then discuss an example of what happens when this distinction is not duly heeded: Gordon Baker and Peter Hacker's idea that the rule-following remarks have a special significance for his project of dissolving philosophical problems as such. I furnish an argument to the effect that their idea that the clarification of the rules of grammar of the particular expression "following a rule" could answer a question about rules of grammar in general rests on a conflation of the two logical levels on which "use" occurs in the rule-following remarks, and that it leads into a regress. I then show that Gustafsson's view - despite its decisive advance over Baker and Hacker - contains a version of that same idea, and that it likewise leads into a regress. Finally, I show that Kuusela's idea of a special significance of the model "meaning as use" for the whole of the method of stating rules for the use of words is open to a regress argument of a similar kind as that he himself advances against Baker and Hacker. I conclude that in order to avoid such a regress, we need to reject the idea that the grammatical remark "The meaning of a word is its use in the language" - because of the occurrence of "use" in it - stood in any special relation to the method of dissolving philosophical problems by describing the use of words. Rather, we need to take this method as independent from this outcome of the investigation of the use of the particular word "meaning".},
  language  = {en}
}