@inproceedings{Karvovskaya2013, author = {Karvovskaya, Lena}, title = {'Also' in Ishkashimi : additive particle and sentence connector}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66097}, year = {2013}, abstract = {The paper discusses the distribution and meaning of the additive particle -m@s in Ishkashimi. -m@s receives different semantic associations while staying in the same syntactic position. Thus, structurally combined with an object, it can semantically associate with the focused object or with the whole focused VP; similarly, combined with the subject it can semantically associate with the focused subject and with the whole focused sentence.}, language = {en} } @article{ErbilRoggeŞenetal.2013, author = {Erbil, Fethiye and Rogge, Lisa and Şen, Nazile and Siwick, Markus}, title = {Working in a multicultural group}, series = {Potsdamer geographische Praxis}, journal = {Potsdamer geographische Praxis}, number = {3}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2194-1599}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65973}, pages = {75 -- 81}, year = {2013}, abstract = {1. Motivation 2. Requirements 3. Positive sides of multicultural group work 4. Difficulties while Working in a Multicultural Group 5. Overall Judgement of the Project 6. Long-term Effects}, language = {en} } @article{AlSaffar2013, author = {Al-Saffar, Loay Talib Ahmed}, title = {Where girls take the role of boys in CS}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {5}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65034}, pages = {149 -- 154}, year = {2013}, abstract = {A survey has been carried out in the Computer Science (CS) department at the University of Baghdad to investigate the attitudes of CS students in a female dominant environment, showing the differences between male and female students in different academic years. We also compare the attitudes of the freshman students of two different cultures (University of Baghdad, Iraq, and the University of Potsdam).}, language = {en} } @article{BellettiniLonatiMalchiodietal.2013, author = {Bellettini, Carlo and Lonati, Violetta and Malchiodi, Dario and Monga, Mattia and Morpurgo, Anna and Torelli, Mauro}, title = {What you see is what you have in mind}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {6}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64612}, pages = {139 -- 147}, year = {2013}, abstract = {In this paper we report on our experiments in teaching computer science concepts with a mix of tangible and abstract object manipulations. The goal we set ourselves was to let pupils discover the challenges one has to meet to automatically manipulate formatted text. We worked with a group of 25 secondary school pupils (9-10th grade), and they were actually able to "invent" the concept of mark-up language. From this experiment we distilled a set of activities which will be replicated in other classes (6th grade) under the guidance of maths teachers.}, language = {en} } @phdthesis{Fuchs2013, author = {Fuchs, Sven}, title = {Well-log based determination of rock thermal conductivity in the North German Basin}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67801}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In sedimentary basins, rock thermal conductivity can vary both laterally and vertically, thus altering the basin's thermal structure locally and regionally. Knowledge of the thermal conductivity of geological formations and its spatial variations is essential, not only for quantifying basin evolution and hydrocarbon maturation processes, but also for understanding geothermal conditions in a geological setting. In conjunction with the temperature gradient, thermal conductivity represents the basic input parameter for the determination of the heat-flow density; which, in turn, is applied as a major input parameter in thermal modeling at different scales. Drill-core samples, which are necessary to determine thermal properties by laboratory measurements, are rarely available and often limited to previously explored reservoir formations. Thus, thermal conductivities of Mesozoic rocks in the North German Basin (NGB) are largely unknown. In contrast, geophysical borehole measurements are often available for the entire drilled sequence. Therefore, prediction equations to determine thermal conductivity based on well-log data are desirable. In this study rock thermal conductivity was investigated on different scales by (1) providing thermal-conductivity measurements on Mesozoic rocks, (2) evaluating and improving commonly applied mixing models which were used to estimate matrix and pore-filled rock thermal conductivities, and (3) developing new well-log based equations to predict thermal conductivity in boreholes without core control. Laboratory measurements are performed on sedimentary rock of major geothermal reservoirs in the Northeast German Basin (NEGB) (Aalenian, Rhaethian-Liassic, Stuttgart Fm., and Middle Buntsandstein). Samples are obtained from eight deep geothermal wells that approach depths of up to 2,500 m. Bulk thermal conductivities of Mesozoic sandstones range between 2.1 and 3.9 W/(m∙K), while matrix thermal conductivity ranges between 3.4 and 7.4 W/(m∙K). Local heat flow for the Stralsund location averages 76 mW/m², which is in good agreement to values reported previously for the NEGB. For the first time, in-situ bulk thermal conductivity is indirectly calculated for entire borehole profiles in the NEGB using the determined surface heat flow and measured temperature data. Average bulk thermal conductivity, derived for geological formations within the Mesozoic section, ranges between 1.5 and 3.1 W/(m∙K). The measurement of both dry- and water-saturated thermal conductivities allow further evaluation of different two-component mixing models which are often applied in geothermal calculations (e.g., arithmetic mean, geometric mean, harmonic mean, Hashin-Shtrikman mean, and effective-medium theory mean). It is found that the geometric-mean model shows the best correlation between calculated and measured bulk thermal conductivity. However, by applying new model-dependent correction, equations the quality of fit could be significantly improved and the error diffusion of each model reduced. The 'corrected' geometric mean provides the most satisfying results and constitutes a universally applicable model for sedimentary rocks. Furthermore, lithotype-specific and model-independent conversion equations are developed permitting a calculation of water-saturated thermal conductivity from dry-measured thermal conductivity and porosity within an error range of 5 to 10\%. The limited availability of core samples and the expensive core-based laboratory measurements make it worthwhile to use petrophysical well logs to determine thermal conductivity for sedimentary rocks. The approach followed in this study is based on the detailed analyses of the relationships between thermal conductivity of rock-forming minerals, which are most abundant in sedimentary rocks, and the properties measured by standard logging tools. By using multivariate statistics separately for clastic, carbonate and evaporite rocks, the findings from these analyses allow the development of prediction equations from large artificial data sets that predict matrix thermal conductivity within an error of 4 to 11\%. These equations are validated successfully on a comprehensive subsurface data set from the NGB. In comparison to the application of earlier published approaches formation-dependent developed for certain areas, the new developed equations show a significant error reduction of up to 50\%. These results are used to infer rock thermal conductivity for entire borehole profiles. By inversion of corrected in-situ thermal-conductivity profiles, temperature profiles are calculated and compared to measured high-precision temperature logs. The resulting uncertainty in temperature prediction averages < 5\%, which reveals the excellent temperature prediction capabilities using the presented approach. In conclusion, data and methods are provided to achieve a much more detailed parameterization of thermal models.}, language = {en} } @misc{ZaourarHamoudiMandeaetal.2013, author = {Zaourar, Naima and Hamoudi, Mohamed and Mandea, Mioara and Balasis, Georgios and Holschneider, Matthias}, title = {Wavelet-based multiscale analysis of geomagnetic disturbance}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, volume = {65}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {12}, issn = {1866-8372}, doi = {10.25932/publishup-43691}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436912}, pages = {1525 -- 1540}, year = {2013}, abstract = {The dynamics of external contributions to the geomagnetic field is investigated by applying time-frequency methods to magnetic observatory data. Fractal models and multiscale analysis enable obtaining maximum quantitative information related to the short-term dynamics of the geomagnetic field activity. The stochastic properties of the horizontal component of the transient external field are determined by searching for scaling laws in the power spectra. The spectrum fits a power law with a scaling exponent β, a typical characteristic of self-affine time-series. Local variations in the power-law exponent are investigated by applying wavelet analysis to the same time-series. These analyses highlight the self-affine properties of geomagnetic perturbations and their persistence. Moreover, they show that the main phases of sudden storm disturbances are uniquely characterized by a scaling exponent varying between 1 and 3, possibly related to the energy contained in the external field. These new findings suggest the existence of a long-range dependence, the scaling exponent being an efficient indicator of geomagnetic activity and singularity detection. These results show that by using magnetogram regularity to reflect the magnetosphere activity, a theoretical analysis of the external geomagnetic field based on local power-law exponents is possible.}, language = {en} } @phdthesis{Berg2013, author = {Berg, Gregor}, title = {Virtual prototypes for the model-based elicitation and validation of collaborative scenarios}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69729}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Requirements engineers have to elicit, document, and validate how stakeholders act and interact to achieve their common goals in collaborative scenarios. Only after gathering all information concerning who interacts with whom to do what and why, can a software system be designed and realized which supports the stakeholders to do their work. To capture and structure requirements of different (groups of) stakeholders, scenario-based approaches have been widely used and investigated. Still, the elicitation and validation of requirements covering collaborative scenarios remains complicated, since the required information is highly intertwined, fragmented, and distributed over several stakeholders. Hence, it can only be elicited and validated collaboratively. In times of globally distributed companies, scheduling and conducting workshops with groups of stakeholders is usually not feasible due to budget and time constraints. Talking to individual stakeholders, on the other hand, is feasible but leads to fragmented and incomplete stakeholder scenarios. Going back and forth between different individual stakeholders to resolve this fragmentation and explore uncovered alternatives is an error-prone, time-consuming, and expensive task for the requirements engineers. While formal modeling methods can be employed to automatically check and ensure consistency of stakeholder scenarios, such methods introduce additional overhead since their formal notations have to be explained in each interaction between stakeholders and requirements engineers. Tangible prototypes as they are used in other disciplines such as design, on the other hand, allow designers to feasibly validate and iterate concepts and requirements with stakeholders. This thesis proposes a model-based approach for prototyping formal behavioral specifications of stakeholders who are involved in collaborative scenarios. By simulating and animating such specifications in a remote domain-specific visualization, stakeholders can experience and validate the scenarios captured so far, i.e., how other stakeholders act and react. This interactive scenario simulation is referred to as a model-based virtual prototype. Moreover, through observing how stakeholders interact with a virtual prototype of their collaborative scenarios, formal behavioral specifications can be automatically derived which complete the otherwise fragmented scenarios. This, in turn, enables requirements engineers to elicit and validate collaborative scenarios in individual stakeholder sessions - decoupled, since stakeholders can participate remotely and are not forced to be available for a joint session at the same time. This thesis discusses and evaluates the feasibility, understandability, and modifiability of model-based virtual prototypes. Similarly to how physical prototypes are perceived, the presented approach brings behavioral models closer to being tangible for stakeholders and, moreover, combines the advantages of joint stakeholder sessions and decoupled sessions.}, language = {en} } @misc{BanerjeeSaalfrank2013, author = {Banerjee, Shiladitya and Saalfrank, Peter}, title = {Vibrationally resolved absorption, emission and resonance Raman spectra of diamondoids}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-94542}, pages = {144 -- 158}, year = {2013}, abstract = {The time-dependent approach to electronic spectroscopy, as popularized by Heller and coworkers in the 1980's, is applied here in conjunction with linear-response, time-dependent density functional theory to study vibronic absorption, emission and resonance Raman spectra of several diamondoids. Two-state models, the harmonic and the Condon approximations, are used for the calculations, making them easily applicable to larger molecules. The method is applied to nine pristine lower and higher diamondoids: adamantane, diamantane, triamantane, and three isomers each of tetramantane and pentamantane. We also consider a hybrid species "Dia = Dia" - a shorthand notation for a recently synthesized molecule comprising two diamantane units connected by a C[double bond, length as m-dash]C double bond. We resolve and interpret trends in optical and vibrational properties of these molecules as a function of their size, shape, and symmetry, as well as effects of "blending" with sp2-hybridized C-atoms. Time-dependent correlation functions facilitate the computations and shed light on the vibrational dynamics following electronic transitions.}, language = {en} } @misc{OttHoehle2013, author = {Ott, Susan and H{\"o}hle, Barbara}, title = {Verb inflection in German-learning children with typical and atypical language acquisition}, series = {Journal of Child Language}, journal = {Journal of Child Language}, number = {530}, issn = {1866-8364}, doi = {10.1017/S030500091200027X}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-416475}, pages = {24}, year = {2013}, abstract = {Previous research has shown that high phonotactic frequencies facilitate the production of regularly inflected verbs in English-learning children with specific language impairment (SLI) but not with typical development (TD). We asked whether this finding can be replicated for German, a language with a much more complex inflectional verb paradigm than English. Using an elicitation task, the production of inflected nonce verb forms (3 rd person singular with -t suffix) with either high- or low-frequency subsyllables was tested in sixteen German-learning children with SLI (ages 4;1-5 ;1), sixteen TD-children matched for chronological age (CA) and fourteen TD- children matched for verbal age (VA) (ages 3;0-3 ;11). The findings revealed that children with SLI, but not CA- or VA-children, showed differential performance between the two types of verbs, producing more inflectional errors when the verb forms resulted in low-frequency subsyllables than when they resulted in high-frequency subsyllables, replicating the results from English-learning children.}, language = {en} } @phdthesis{Schlolaut2013, author = {Schlolaut, Gordon}, title = {Varve and event layer chronology of Lake Suigetsu (Japan) back to 40 kyr BP and contribution to the international consensus atmospheric radiocarbon calibration curve}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69096}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The main intention of the PhD project was to create a varve chronology for the Suigetsu Varves 2006' (SG06) composite profile from Lake Suigetsu (Japan) by thin section microscopy. The chronology was not only to provide an age-scale for the various palaeo-environmental proxies analysed within the SG06 project, but also and foremost to contribute, in combination with the SG06 14C chronology, to the international atmospheric radiocarbon calibration curve (IntCal). The SG06 14C data are based on terrestrial leaf fossils and therefore record atmospheric 14C values directly, avoiding the corrections necessary for the reservoir ages of the marine datasets, which are currently used beyond the tree-ring limit in the IntCal09 dataset (Reimer et al., 2009). The SG06 project is a follow up of the SG93 project (Kitagawa \& van der Plicht, 2000), which aimed to produce an atmospheric calibration dataset, too, but suffered from incomplete core recovery and varve count uncertainties. For the SG06 project the complete Lake Suigetsu sediment sequence was recovered continuously, leaving the task to produce an improved varve count. Varve counting was carried out using a dual method approach utilizing thin section microscopy and micro X-Ray Fluorescence (µXRF). The latter was carried out by Dr. Michael Marshall in cooperation with the PhD candidate. The varve count covers 19 m of composite core, which corresponds to the time frame from ≈10 to ≈40 kyr BP. The count result showed that seasonal layers did not form in every year. Hence, the varve counts from either method were incomplete. This rather common problem in varve counting is usually solved by manual varve interpolation. But manual interpolation often suffers from subjectivity. Furthermore, sedimentation rate estimates (which are the basis for interpolation) are generally derived from neighbouring, well varved intervals. This assumes that the sedimentation rates in neighbouring intervals are identical to those in the incompletely varved section, which is not necessarily true. To overcome these problems a novel interpolation method was devised. It is computer based and automated (i.e. avoids subjectivity and ensures reproducibility) and derives the sedimentation rate estimate directly from the incompletely varved interval by statistically analysing distances between successive seasonal layers. Therefore, the interpolation approach is also suitable for sediments which do not contain well varved intervals. Another benefit of the novel method is that it provides objective interpolation error estimates. Interpolation results from the two counting methods were combined and the resulting chronology compared to the 14C chronology from Lake Suigetsu, calibrated with the tree-ring derived section of IntCal09 (which is considered accurate). The varve and 14C chronology showed a high degree of similarity, demonstrating that the novel interpolation method produces reliable results. In order to constrain the uncertainties of the varve chronology, especially the cumulative error estimates, U-Th dated speleothem data were used by linking the low frequency 14C signal of Lake Suigetsu and the speleothems, increasing the accuracy and precision of the Suigetsu calibration dataset. The resulting chronology also represents the age-scale for the various palaeo-environmental proxies analysed in the SG06 project. One proxy analysed within the PhD project was the distribution of event layers, which are often representatives of past floods or earthquakes. A detailed microfacies analysis revealed three different types of event layers, two of which are described here for the first time for the Suigetsu sediment. The types are: matrix supported layers produced as result of subaqueous slope failures, turbidites produced as result of landslides and turbidites produced as result of flood events. The former two are likely to have been triggered by earthquakes. The vast majority of event layers was related to floods (362 out of 369), which allowed the construction of a respective chronology for the last 40 kyr. Flood frequencies were highly variable, reaching their greatest values during the global sea level low-stand of the Glacial, their lowest values during Heinrich Event 1. Typhoons affecting the region represent the most likely control on the flood frequency, especially during the Glacial. However, also local, non-climatic controls are suggested by the data. In summary, the work presented here expands and revises knowledge on the Lake Suigetsu sediment and enabls the construction of a far more precise varve chronology. The 14C calibration dataset is the first such derived from lacustrine sediments to be included into the (next) IntCal dataset. References: Kitagawa \& van der Plicht, 2000, Radiocarbon, Vol 42(3), 370-381 Reimer et al., 2009, Radiocarbon, Vol 51(4), 1111-1150}, language = {en} } @article{BerryKusterer2013, author = {Berry, Carol and Kusterer, Peter}, title = {Using Teachers' TryScience to support educators and improve teaching}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {6}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64665}, pages = {161 -- 162}, year = {2013}, abstract = {The challenge is providing teachers with the resources they need to strengthen their instructions and better prepare students for the jobs of the 21st Century. Technology can help meet the challenge. Teachers' Tryscience is a noncommercial offer, developed by the New York Hall of Science, TeachEngineering, the National Board for Professional Teaching Standards and IBM Citizenship to provide teachers with such resources. The workshop provides deeper insight into this tool and discussion of how to support teaching of informatics in schools.}, language = {en} } @article{NylenDoerge2013, author = {Nyl{\´e}n, Aletta and D{\"o}rge, Christina}, title = {Using competencies to structure scientific writing education}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {5}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64851}, pages = {33 -- 44}, year = {2013}, abstract = {Scientific writing is an important skill for computer science and computer engineering professionals. In this paper we present a writing concept across the curriculum program directed towards scientific writing. The program is built around a hierarchy of learning outcomes. The hierarchy is constructed through analyzing the learning outcomes in relation to competencies that are needed to fulfill them.}, language = {en} } @article{Dolde2013, author = {Dolde, Walter}, title = {US Banks, Competitive Advantage, and the Volcker Rule}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68755}, pages = {155 -- 165}, year = {2013}, abstract = {1. Porter strategic competitive analysis 2. A Porter analysis of the competitive advantage of banks in business lending and proprietary trading 3. Summary, competitive advantage of banks in business lending and proprietary trading 4. JPMorgan's "London Whale" speculation 5. A common misapprehension about hedged positions in corporate debt 6. Conclusion}, language = {en} } @phdthesis{Uhlemann2013, author = {Uhlemann, Steffi}, title = {Understanding trans-basin floods in Germany : data, information and knowledge}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68868}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Large Central European flood events of the past have demonstrated that flooding can affect several river basins at the same time leading to catastrophic economic and humanitarian losses that can stretch emergency resources beyond planned levels of service. For Germany, the spatial coherence of flooding, the contributing processes and the role of trans-basin floods for a national risk assessment is largely unknown and analysis is limited by a lack of systematic data, information and knowledge on past events. This study investigates the frequency and intensity of trans-basin flood events in Germany. It evaluates the data and information basis on which knowledge about trans-basin floods can be generated in order to improve any future flood risk assessment. In particu-lar, the study assesses whether flood documentations and related reports can provide a valuable data source for understanding trans-basin floods. An adaptive algorithm was developed that systematically captures trans-basin floods using series of mean daily discharge at a large number of sites of even time series length (1952-2002). It identifies the simultaneous occurrence of flood peaks based on the exceedance of an initial threshold of a 10 year flood at one location and consecutively pools all causally related, spatially and temporally lagged peak recordings at the other locations. A weighted cumulative index was developed that accounts for the spatial extent and the individual flood magnitudes within an event and allows quantifying the overall event severity. The parameters of the method were tested in a sensitivity analysis. An intensive study on sources and ways of information dissemination of flood-relevant publications in Germany was conducted. Based on the method of systematic reviews a strategic search approach was developed to identify relevant documentations for each of the 40 strongest trans-basin flood events. A novel framework for assessing the quality of event specific flood reports from a user's perspective was developed and validated by independent peers. The framework was designed to be generally applicable for any natural hazard type and assesses the quality of a document addressing accessibility as well as representational, contextual, and intrinsic dimensions of quality. The analysis of time-series of mean daily discharge resulted in the identification of 80 trans-basin flood events within the period 1952-2002 in Germany. The set is dominated by events that were recorded in the hydrological winter (64\%); 36\% occurred during the summer months. The occurrence of floods is characterised by a distinct clustering in time. Dividing the study period into two sub-periods, we find an increase in the percentage of winter events from 58\% in the first to 70.5\% in the second sub-period. Accordingly, we find a significant increase in the number of extreme trans-basin floods in the second sub-period. A large body of 186 flood relevant documentations was identified. For 87.5\% of the 40 strongest trans-basin floods in Germany at least one report has been found and for the most severe floods a substantial amount of documentation could be obtained. 80\% of the material can be considered grey literature (i.e. literature not controlled by commercial publishers). The results of the quality assessment show that the majority of flood event specific reports are of a good quality, i.e. they are well enough drafted, largely accurate and objective, and contain a substantial amount of information on the sources, pathways and receptors/consequences of the floods. The inclusion of this information in the process of knowledge building for flood risk assessment is recommended. Both the results as well as the data produced in this study are openly accessible and can be used for further research. The results of this study contribute to an improved spatial risk assessment in Germany. The identified set of trans-basin floods provides the basis for an assessment of the chance that flooding occurs simultaneously at a number of sites. The information obtained from flood event documentation can usefully supplement the analysis of the processes that govern flood risk.}, language = {en} } @phdthesis{Gumienny2013, author = {Gumienny, Raja Carola}, title = {Understanding the adoption of digital whiteboard systems for collaborative design work}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72417}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {User-centered design processes are the first choice when new interactive systems or services are developed to address real customer needs and provide a good user experience. Common tools for collecting user research data, conducting brainstormings, or sketching ideas are whiteboards and sticky notes. They are ubiquitously available, and no technical or domain knowledge is necessary to use them. However, traditional pen and paper tools fall short when saving the content and sharing it with others unable to be in the same location. They are also missing further digital advantages such as searching or sorting content. Although research on digital whiteboard and sticky note applications has been conducted for over 20 years, these tools are not widely adopted in company contexts. While many research prototypes exist, they have not been used for an extended period of time in a real-world context. The goal of this thesis is to investigate what the enablers and obstacles for the adoption of digital whiteboard systems are. As an instrument for different studies, we developed the Tele-Board software system for collaborative creative work. Based on interviews, observations, and findings from former research, we tried to transfer the analog way of working to the digital world. Being a software system, Tele-Board can be used with a variety of hardware and does not depend on special devices. This feature became one of the main factors for adoption on a larger scale. In this thesis, I will present three studies on the use of Tele-Board with different user groups and foci. I will use a combination of research methods (laboratory case studies and data from field research) with the overall goal of finding out when a digital whiteboard system is used and in which cases not. Not surprisingly, the system is used and accepted if a user sees a main benefit that neither analog tools nor other applications can offer. However, I found that these perceived benefits are very different for each user and usage context. If a tool provides possibilities to use in different ways and with different equipment, the chances of its adoption by a larger group increase. Tele-Board has now been in use for over 1.5 years in a global IT company in at least five countries with a constantly growing user base. Its use, advantages, and disadvantages will be described based on 42 interviews and usage statistics from server logs. Through these insights and findings from laboratory case studies, I will present a detailed analysis of digital whiteboard use in different contexts with design implications for future systems.}, language = {en} } @phdthesis{Schick2013, author = {Schick, Daniel}, title = {Ultrafast lattice dynamics in photoexcited nanostructures : femtosecond X-ray diffraction with optimized evaluation schemes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68827}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Within the course of this thesis, I have investigated the complex interplay between electron and lattice dynamics in nanostructures of perovskite oxides. Femtosecond hard X-ray pulses were utilized to probe the evolution of atomic rearrangement directly, which is driven by ultrafast optical excitation of electrons. The physics of complex materials with a large number of degrees of freedom can be interpreted once the exact fingerprint of ultrafast lattice dynamics in time-resolved X-ray diffraction experiments for a simple model system is well known. The motion of atoms in a crystal can be probed directly and in real-time by femtosecond pulses of hard X-ray radiation in a pump-probe scheme. In order to provide such ultrashort X-ray pulses, I have built up a laser-driven plasma X-ray source. The setup was extended by a stable goniometer, a two-dimensional X-ray detector and a cryogen-free cryostat. The data acquisition routines of the diffractometer for these ultrafast X-ray diffraction experiments were further improved in terms of signal-to-noise ratio and angular resolution. The implementation of a high-speed reciprocal-space mapping technique allowed for a two-dimensional structural analysis with femtosecond temporal resolution. I have studied the ultrafast lattice dynamics, namely the excitation and propagation of coherent phonons, in photoexcited thin films and superlattice structures of the metallic perovskite SrRuO3. Due to the quasi-instantaneous coupling of the lattice to the optically excited electrons in this material a spatially and temporally well-defined thermal stress profile is generated in SrRuO3. This enables understanding the effect of the resulting coherent lattice dynamics in time-resolved X-ray diffraction data in great detail, e.g. the appearance of a transient Bragg peak splitting in both thin films and superlattice structures of SrRuO3. In addition, a comprehensive simulation toolbox to calculate the ultrafast lattice dynamics and the resulting X-ray diffraction response in photoexcited one-dimensional crystalline structures was developed in this thesis work. With the powerful experimental and theoretical framework at hand, I have studied the excitation and propagation of coherent phonons in more complex material systems. In particular, I have revealed strongly localized charge carriers after above-bandgap femtosecond photoexcitation of the prototypical multiferroic BiFeO3, which are the origin of a quasi-instantaneous and spatially inhomogeneous stress that drives coherent phonons in a thin film of the multiferroic. In a structurally imperfect thin film of the ferroelectric Pb(Zr0.2Ti0.8)O3, the ultrafast reciprocal-space mapping technique was applied to follow a purely strain-induced change of mosaicity on a picosecond time scale. These results point to a strong coupling of in- and out-of-plane atomic motion exclusively mediated by structural defects.}, language = {en} } @misc{SchatzOhlendorfBusseetal.2013, author = {Schatz, Juliane and Ohlendorf, Bernd and Busse, Peter and Pelz, Gerrit and Dolch, Dietrich and Teubner, Jens and Encarnacao, Jorge A. and M{\"u}hle, Ralf-Udo and Fischer, M. and Hoffmann, Bernd and Kwasnitschka, Linda and Balkema-Buschmann, Anne and Mettenleiter, Thomas Christoph and M{\"u}ller, T. and Freuling, Conrad M.}, title = {Twenty years of active bat rabies surveillance in Germany}, series = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Humanwissenschaftliche Reihe}, number = {533}, issn = {1866-8364}, doi = {10.25932/publishup-41514}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-415140}, pages = {12}, year = {2013}, abstract = {In Germany, active bat rabies surveillance was conducted between 1993 and 2012. A total of 4546 oropharyngeal swab samples from 18 bat species were screened for the presence of EBLV-1- , EBLV-2- and BBLV-specific RNA. Overall, 0 center dot 15\% of oropharyngeal swab samples tested EBLV-1 positive, with the majority originating from Eptesicus serotinus. Interestingly, out of seven RT-PCR-positive oropharyngeal swabs subjected to virus isolation, viable virus was isolated from a single serotine bat (E. serotinus). Additionally, about 1226 blood samples were tested serologically, and varying virus neutralizing antibody titres were found in at least eight different bat species. The detection of viral RNA and seroconversion in repeatedly sampled serotine bats indicates long-term circulation of the virus in a particular bat colony. The limitations of random-based active bat rabies surveillance over passive bat rabies surveillance and its possible application of targeted approaches for future research activities on bat lyssavirus dynamics and maintenance are discussed.}, language = {en} } @misc{VanBelProostVanNesteetal.2013, author = {Van Bel, Michiel and Proost, Sebastian and Van Neste, Christophe and Deforce, Dieter and Van de Peer, Yves and Vandepoele, Klaas}, title = {TRAPID}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {900}, issn = {1866-8372}, doi = {10.25932/publishup-43640}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436409}, pages = {12}, year = {2013}, abstract = {Transcriptome analysis through next-generation sequencing technologies allows the generation of detailed gene catalogs for non-model species, at the cost of new challenges with regards to computational requirements and bioinformatics expertise. Here, we present TRAPID, an online tool for the fast and efficient processing of assembled RNA-Seq transcriptome data, developed to mitigate these challenges. TRAPID offers high-throughput open reading frame detection, frameshift correction and includes a functional, comparative and phylogenetic toolbox, making use of 175 reference proteomes. Benchmarking and comparison against state-of-the-art transcript analysis tools reveals the efficiency and unique features of the TRAPID system. TRAPID is freely available at http://bioinformatics.psb.ugent.be/webtools/trapid/.}, language = {en} } @phdthesis{Duensing2013, author = {Duensing, Nina}, title = {Transport processes in the arbuscular mycorrhizal symbiosis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68210}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The nutrient exchange between plant and fungus is the key element of the arbuscular mycorrhizal (AM) symbiosis. The fungus improves the plant's uptake of mineral nutrients, mainly phosphate, and water, while the plant provides the fungus with photosynthetically assimilated carbohydrates. Still, the knowledge about the mechanisms of the nutrient exchange between the symbiotic partners is very limited. Therefore, transport processes of both, the plant and the fungal partner, are investigated in this study. In order to enhance the understanding of the molecular basis underlying this tight interaction between the roots of Medicago truncatula and the AM fungus Rhizophagus irregularis, genes involved in transport processes of both symbiotic partners are analysed here. The AM-specific regulation and cell-specific expression of potential transporter genes of M. truncatula that were found to be specifically regulated in arbuscule-containing cells and in non-arbusculated cells of mycorrhizal roots was confirmed. A model for the carbon allocation in mycorrhizal roots is suggested, in which carbohydrates are mobilized in non-arbusculated cells and symplastically provided to the arbuscule-containing cells. New insights into the mechanisms of the carbohydrate allocation were gained by the analysis of hexose/H+ symporter MtHxt1 which is regulated in distinct cells of mycorrhizal roots. Metabolite profiling of leaves and roots of a knock-out mutant, hxt1, showed that it indeed does have an impact on the carbohydrate balance in the course of the symbiosis throughout the whole plant, and on the interaction with the fungal partner. The primary metabolite profile of M. truncatula was shown to be altered significantly in response to mycorrhizal colonization. Additionally, molecular mechanisms determining the progress of the interaction in the fungal partner of the AM symbiosis were investigated. The R. irregularis transcriptome in planta and in extraradical tissues gave new insight into genes that are differentially expressed in these two fungal tissues. Over 3200 fungal transcripts with a significantly altered expression level in laser capture microdissection-collected arbuscules compared to extraradical tissues were identified. Among them, six previously unknown specifically regulated potential transporter genes were found. These are likely to play a role in the nutrient exchange between plant and fungus. While the substrates of three potential MFS transporters are as yet unknown, two potential sugar transporters are might play a role in the carbohydrate flow towards the fungal partner. In summary, this study provides new insights into transport processes between plant and fungus in the course of the AM symbiosis, analysing M. truncatula on the transcript and metabolite level, and provides a dataset of the R. irregularis transcriptome in planta, providing a high amount of new information for future works.}, language = {en} } @misc{ChmielewskiDumontTrautwein2013, author = {Chmielewski, Anna K. and Dumont, Hanna and Trautwein, Ulrich}, title = {Tracking effects depend on tracking type}, series = {American educational research journal}, volume = {50}, journal = {American educational research journal}, number = {5}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-404052}, pages = {33}, year = {2013}, abstract = {The aim of the present study was to examine how different types of tracking— between-school streaming, within-school streaming, and course-by-course tracking—shape students' mathematics self-concept. This was done in an internationally comparative framework using data from the Programme for International Student Assessment (PISA). After controlling for individual and track mean achievement, results indicated that generally for students in course-by-course tracking, high-track students had higher mathematics self-concepts and low-track students had lower mathematics self-concepts. For students in between-school and within-school streaming, the reverse pattern was found. These findings suggest a solution to the ongoing debate about the effects of tracking on students' academic self-concept and suggest that the reference groups to which students compare themselves differ according to the type of tracking.}, language = {en} } @misc{MolahajlooPirhayati2013, author = {Molahajloo, Shahla and Pirhayati, Mohammad}, title = {Traces of pseudo-differential operators on compact and Hausdorff groups}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, number = {893}, issn = {1866-8372}, doi = {10.25932/publishup-43637}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436371}, pages = {361 -- 369}, year = {2013}, abstract = {We give a characterization of and a trace formula for trace class pseudo-differential operators on compact Hausdorff groups.}, language = {en} } @phdthesis{Takey2013, author = {Takey, Ali Said Ahmed}, title = {The XMM-Newton/SDSS galaxy cluster survey}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71229}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Galaxy clusters are the largest known gravitationally bound objects, their study is important for both an intrinsic understanding of their systems and an investigation of the large scale structure of the universe. The multi- component nature of galaxy clusters offers multiple observable signals across the electromagnetic spectrum. At X-ray wavelengths, galaxy clusters are simply identified as X-ray luminous, spatially extended, and extragalactic sources. X-ray observations offer the most powerful technique for constructing cluster catalogues. The main advantages of the X-ray cluster surveys are their excellent purity and completeness and the X-ray observables are tightly correlated with mass, which is indeed the most fundamental parameter of clusters. In my thesis I have conducted the 2XMMi/SDSS galaxy cluster survey, which is a serendipitous search for galaxy clusters based on the X-ray extended sources in the XMM-Newton Serendipitous Source Catalogue (2XMMi-DR3). The main aims of the survey are to identify new X-ray galaxy clusters, investigate their X-ray scaling relations, identify distant cluster candidates, and study the correlation of the X-ray and optical properties. The survey is constrained to those extended sources that are in the footprint of the Sloan Digital Sky Survey (SDSS) in order to be able to identify the optical counterparts as well as to measure their redshifts that are mandatory to measure their physical properties. The overlap area be- tween the XMM-Newton fields and the SDSS-DR7 imaging, the latest SDSS data release at the starting of the survey, is 210 deg^2. The survey comprises 1180 X-ray cluster candidates with at least 80 background-subtracted photon counts, which passed the quality control process. To measure the optical redshifts of the X-ray cluster candidates, I used three procedures; (i) cross-matching these candidates with the recent and largest optically selected cluster catalogues in the literature, which yielded the photometric redshifts of about a quarter of the X-ray cluster candidates. (ii) I developed a finding algorithm to search for overdensities of galaxies at the positions of the X-ray cluster candidates in the photometric redshift space and to measure their redshifts from the SDSS-DR8 data, which provided the photometric redshifts of 530 groups/clusters. (iii) I developed an algorithm to identify the cluster candidates associated with spectroscopically targeted Luminous Red Galaxies (LRGs) in the SDSS-DR9 and to measure the cluster spectroscopic redshift, which provided 324 groups and clusters with spectroscopic confirmation based on spectroscopic redshift of at least one LRG. In total, the optically confirmed cluster sample comprises 574 groups and clusters with redshifts (0.03 ≤ z ≤ 0.77), which is the largest X-ray selected cluster catalogue to date based on observations from the current X-ray observatories (XMM-Newton, Chandra, Suzaku, and Swift/XRT). Among the cluster sample, about 75 percent are newly X-ray discovered groups/clusters and 40 percent are new systems to the literature. To determine the X-ray properties of the optically confirmed cluster sample, I reduced and analysed their X-ray data in an automated way following the standard pipelines of processing the XMM-Newton data. In this analysis, I extracted the cluster spectra from EPIC(PN, MOS1, MOS2) images within an optimal aperture chosen to maximise the signal-to-noise ratio. The spectral fitting procedure provided the X-ray temperatures kT (0.5 - 7.5 keV) for 345 systems that have good quality X-ray data. For all the optically confirmed cluster sample, I measured the physical properties L500 (0.5 x 10^42 - 1.2 x 10^45 erg s-1 ) and M500 (1.1 x 10^13 - 4.9 x 10^14 M⊙) from an iterative procedure using published scaling relations. The present X-ray detected groups and clusters are in the low and intermediate luminosity regimes apart from few luminous systems, thanks to the XMM-Newton sensitivity and the available XMM-Newton deep fields The optically confirmed cluster sample with measurements of redshift and X-ray properties can be used for various astrophysical applications. As a first application, I investigated the LX - T relation for the first time based on a large cluster sample of 345 systems with X-ray spectroscopic parameters drawn from a single survey. The current sample includes groups and clusters with wide ranges of redshifts, temperatures, and luminosities. The slope of the relation is consistent with the published ones of nearby clusters with higher temperatures and luminosities. The derived relation is still much steeper than that predicted by self-similar evolution. I also investigated the evolution of the slope and the scatter of the LX - T relation with the cluster redshift. After excluding the low luminosity groups, I found no significant changes of the slope and the intrinsic scatter of the relation with redshift when dividing the sample into three redshift bins. When including the low luminosity groups in the low redshift subsample, I found its LX - T relation becomes after than the relation of the intermediate and high redshift subsamples. As a second application of the optically confirmed cluster sample from our ongoing survey, I investigated the correlation between the cluster X-ray and the optical parameters that have been determined in a homogenous way. Firstly, I investigated the correlations between the BCG properties (absolute magnitude and optical luminosity) and the cluster global proper- ties (redshift and mass). Secondly, I computed the richness and the optical luminosity within R500 of a nearby subsample (z ≤ 0.42, with a complete membership detection from the SDSS data) with measured X-ray temperatures from our survey. The relation between the estimated optical luminosity and richness is also presented. Finally, the correlation between the cluster optical properties (richness and luminosity) and the cluster global properties (X-ray luminosity, temperature, mass) are investigated.}, language = {en} } @misc{ClahsenBalkhairSchutteretal.2013, author = {Clahsen, Harald and Balkhair, Loay and Schutter, John-Sebastian and Cunnings, Ian}, title = {The time course of morphological processing in a second language}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {379}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-403684}, pages = {25}, year = {2013}, abstract = {We report findings from psycholinguistic experiments investigating the detailed timing of processing morphologically complex words by proficient adult second (L2) language learners of English in comparison to adult native (L1) speakers of English. The first study employed the masked priming technique to investigate -ed forms with a group of advanced Arabic-speaking learners of English. The results replicate previously found L1/L2 differences in morphological priming, even though in the present experiment an extra temporal delay was offered after the presentation of the prime words. The second study examined the timing of constraints against inflected forms inside derived words in English using the eye-movement monitoring technique and an additional acceptability judgment task with highly advanced Dutch L2 learners of English in comparison to adult L1 English controls. Whilst offline the L2 learners performed native-like, the eye-movement data showed that their online processing was not affected by the morphological constraint against regular plurals inside derived words in the same way as in native speakers. Taken together, these findings indicate that L2 learners are not just slower than native speakers in processing morphologically complex words, but that the L2 comprehension system employs real-time grammatical analysis (in this case, morphological information) less than the L1 system.}, language = {en} } @article{Moreno2013, author = {Moreno, Aitor Garc{\´i}a}, title = {The spread of the German (?) calque ans{\´i} un... (Eng. such a...) in Judeo-Spanish}, series = {PaRDeS : Zeitschrift der Vereinigung f{\"u}r J{\"u}dische Studien e.V.}, journal = {PaRDeS : Zeitschrift der Vereinigung f{\"u}r J{\"u}dische Studien e.V.}, number = {19}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1614-6492}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67059}, pages = {57 -- 68}, year = {2013}, abstract = {In this article we analyze several examples of the syntactic structure ans{\´i} un...(Eng. such a...) apparently calqued from the German expression so ein... that can be found in different Judeo-Spanish texts since the second half of 19th Century. Although the eldest examples appeared in Judeo-Spanish translations of German novels, published in Vienna - what suggests that they could be mere cases derived from a kind of translation too attached to the original -, we can also find more examples in Sephardic texts produced outside the German speaking area (Bosnia, Bulgaria, etc.), not being necessarily translations of a German original. Dealing with all these cases, we will try to trace (and explain) the spread of the ans{\´i} un syntactic structure in modern Judeo-Spanish prose.}, language = {en} } @article{Rubtsov2013, author = {Rubtsov, Boris}, title = {The Russian Securities Market}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68720}, pages = {105 -- 118}, year = {2013}, abstract = {1. Introduction 2. Instruments 2.1 Stocks 2.2 Debt securities 3. Institutions 4. Conclusion}, language = {en} } @phdthesis{Patterson2013, author = {Patterson, Clare}, title = {The role of structural and discourse-level cues during pronoun resolution}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71280}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Pronoun resolution normally takes place without conscious effort or awareness, yet the processes behind it are far from straightforward. A large number of cues and constraints have previously been recognised as playing a role in the identification and integration of potential antecedents, yet there is considerable debate over how these operate within the resolution process. The aim of this thesis is to investigate how the parser handles multiple antecedents in order to understand more about how certain information sources play a role during pronoun resolution. I consider how both structural information and information provided by the prior discourse is used during online processing. This is investigated through several eye tracking during reading experiments that are complemented by a number of offline questionnaire experiments. I begin by considering how condition B of the Binding Theory (Chomsky 1981; 1986) has been captured in pronoun processing models; some researchers have claimed that processing is faithful to syntactic constraints from the beginning of the search (e.g. Nicol and Swinney 1989), while others have claimed that potential antecedents which are ruled out on structural grounds nonetheless affect processing, because the parser must also pay attention to a potential antecedent's features (e.g. Badecker and Straub 2002). My experimental findings demonstrate that the parser is sensitive to the subtle changes in syntactic configuration which either allow or disallow pronoun reference to a local antecedent, and indicate that the parser is normally faithful to condition B at all stages of processing. Secondly, I test the Primitives of Binding hypothesis proposed by Koornneef (2008) based on work by Reuland (2001), which is a modular approach to pronoun resolution in which variable binding (a semantic relationship between pronoun and antecedent) takes place before coreference. I demonstrate that a variable-binding (VB) antecedent is not systematically considered earlier than a coreference (CR) antecedent online. I then go on to explore whether these findings could be attributed to the linear order of the antecedents, and uncover a robust recency preference both online and offline. I consider what role the factor of recency plays in pronoun resolution and how it can be reconciled with the first-mention advantage (Gernsbacher and Hargreaves 1988; Arnold 2001; Arnold et al., 2007). Finally, I investigate how aspects of the prior discourse affect pronoun resolution. Prior discourse status clearly had an effect on pronoun resolution, but an antecedent's appearance in the previous context was not always facilitative; I propose that this is due to the number of topic switches that a reader must make, leading to a lack of discourse coherence which has a detrimental effect on pronoun resolution. The sensitivity of the parser to structural cues does not entail that cue types can be easily separated into distinct sequential stages, and I therefore propose that the parser is structurally sensitive but not modular. Aspects of pronoun resolution can be captured within a parallel constraints model of pronoun resolution, however, such a model should be sensitive to the activation of potential antecedents based on discourse factors, and structural cues should be strongly weighted.}, language = {en} } @phdthesis{RoncagliaDenissen2013, author = {Roncaglia-Denissen, Maria Paula}, title = {The role of first and second language speech rhythm in syntactic ambiguity processing and musical rhythmic aptitude}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-78256}, school = {Universit{\"a}t Potsdam}, pages = {vi, 157}, year = {2013}, abstract = {Rhythm is a temporal and systematic organization of acoustic events in terms of prominence, timing and grouping, helping to structure our most basic experiences, such as body movement, music and speech. In speech, rhythm groups auditory events, e.g., sounds and pauses, together into words, making their boundaries acoustically prominent and aiding word segmentation and recognition by the hearer. After word recognition, the hearer is able to retrieve word meaning form his mental lexicon, integrating it with information from other linguistic domains, such as semantics, syntax and pragmatics, until comprehension is achieved. The importance of speech rhythm, however, is not restricted to word segmentation and recognition only. Beyond the word level rhythm continues to operate as an organization device, interacting with different linguistic domains, such as syntax and semantics, and grouping words into larger prosodic constituents, organized in a prosodic hierarchy. This dissertation investigates the function of speech rhythm as a sentence segmentation device during syntactic ambiguity processing, possible limitations on its use, i.e., in the context of second language processing, and its transferability as cognitive skill to the music domain.}, language = {en} } @phdthesis{Hintersberger2013, author = {Hintersberger, Esther}, title = {The role of extension during the evolution of the NW Indian Himalaya}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66179}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The evolution of most orogens typically records cogenetic shortening and extension. Pervasive normal faulting in an orogen, however, has been related to late syn- and post-collisional stages of mountain building with shortening focused along the peripheral sectors of the orogen. While extensional processes constitute an integral part of orogenic evolution, the spatiotemporal characteristics and the kinematic linkage of structures related to shortening and extension in the core regions of the orogen are often not well known. Related to the India-Eurasia collision, the Himalaya forms the southern margin of the Tibetan Plateau and constitutes the most prominent Cenozoic type example of a collisional orogen. While thrusting is presently observed along the foothills of the orogen, several generations of extensional structures have been detected in the internal, high-elevation regions, both oriented either parallel or perpendicular to the strike of the orogen. In the NW Indian Himalaya, earthquake focal mechanisms, seismites and ubiquitous normal faulting in Quaternary deposits, and regional GPS measurements reveal ongoing E-W extension. In contrast to other extensional structures observed in the Himalaya, this extension direction is neither parallel nor perpendicular to the NE-SW regional shortening direction. In this study, I took advantage of this obliquity between the trend of the orogen and structures related to E-W oriented extension in order to address the question of the driving forces of different extension directions. Thus, extension might be triggered triggered by processes within the Tibetan Plateau or originates from the curvature of the Himalayan orogen. In order to elaborate on this topic, I present new fault-kinematic data based on systematic measurements of approximately 2000 outcrop-scale brittle fault planes with displacements of up to several centimeters that cover a large area of the NW Indian Himalaya. This new data set together with field observations relevant for relative chronology allows me to distinguish six different deformation styles. One of the main results are that the overall strain pattern derived from this data reflects the regionally important contractional deformation pattern very well, but also reveals significant extensional deformation. In total, I was able to identify six deformation styles, most of which are temporally and spatially linked and represent protracted shortening, but also significant extensional directions. For example, this is the first data set where a succession of both, arc-normal and E-W extension have been documented in the Himalaya. My observations also furnish the basis for a detailed overview of the younger extensional deformation history in the NW Indian Himalaya. Field and remote-sensing based geomorphic analyses, and geochronologic 40Ar/39Ar data on synkinematic muscovites along normal faults help elucidate widespread E-W extension in the NW Indian Himalaya which must have started at approximately 14-16 Ma, if not earlier. In addition, I documented and mapped fault scarps in Quaternary sedimentary deposits using satellite imagery and field inspection. Furthermore, I made field observations of regional normal faults, compiled structures from geological maps and put them in a regional context. Finally, I documented seismites in lake sediments close to the currently most active normal fault in the study area in order to extend the (paleo) seismic record of this particular fault. Taken together, this data sets document that E-W extension is the dominant active deformation style in the internal parts of the orogen. In addition, the combined field, geomorphic and remote-sensing data sets prove that E-W extension occurs in a much more larger region toward the south and west than the seismicity data have suggested. In conclusion, the data presented here reveal the importance of extension in a region, which is still dominated by ongoing collision and shortening. The regional fault distribution and cross-cutting relationships suggest that extension parallel and perpendicular to the strike of the orogen are an integral part of the southward propagation of the active thrust front and the associated lateral growth of the Himalayan arc. In the light of a wide range of models proposed for extension in the Himalaya and the Tibetan plateau, I propose that E-W extension in the NW Indian Himalaya is transferred from the Tibetan Plateau due the inability of the Karakorum fault (KF) to adequately accommodate ongoing E-W extension on the Tibetan Plateau. Furthermore, in line with other observations from Tibet, the onset of E-W normal faulting in the NW Himalaya may also reflect the attainment of high topography in this region, which generated crustal stresses conducive to spatially extensive extension.}, language = {en} } @article{Lessner2013, author = {Lessner, Daniel}, title = {The role of algorithm in general secondary education revisited}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {6}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64534}, pages = {99 -- 110}, year = {2013}, abstract = {The traditional purpose of algorithm in education is to prepare students for programming. In our effort to introduce the practically missing computing science into Czech general secondary education, we have revisited this purpose.We propose an approach, which is in better accordance with the goals of general secondary education in Czechia. The importance of programming is diminishing, while recognition of algorithmic procedures and precise (yet concise) communication of algorithms is gaining importance. This includes expressing algorithms in natural language, which is more useful for most of the students than programming. We propose criteria to evaluate such descriptions. Finally, an idea about the limitations is required (inefficient algorithms, unsolvable problems, Turing's test). We describe these adjusted educational goals and an outline of the resulting course. Our experience with carrying out the proposed intentions is satisfactory, although we did not accomplish all the defined goals.}, language = {en} } @misc{KrollVogel2013, author = {Kroll, Alexander and Vogel, Dominik}, title = {The PSM-leadership fit}, series = {Postprints der Universit{\"a}t Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe}, number = {77}, issn = {1867-5808}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-100853}, year = {2013}, abstract = {This article examines the use of performance information by public managers. It conceptualizes purposeful data use as a type of extra-role behaviour which requires additional effort on the part of the managers and which is not extrinsically rewarded. The article sheds light on one potential antecedent of performance information use - the motivation of the users. It argues that we can observe high levels of data use if managers driven by public service motivation (PSM) work under transformational leaders. Using a needs-supply perspective on supervisors and followers we suggest that there is a PSM-leadership fit which fosters the performance of this extra-role behaviour. The article is based on data from German local government and its findings contribute to the literatures on PSM as well as on performance management.}, language = {en} } @phdthesis{Macaulay2013, author = {Macaulay, Euan Angus}, title = {The orogenic evolution of the Central Kyrgyz Tien Shan}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68985}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Intra-continental mountain belts typically form as a result of tectonic forces associated with distant plate collisions. In general, each mountain belt has a distinctive morphology and orogenic evolution that is highly dependent on the unique distribution and geometries of inherited structures and other crustal weaknesses. In this thesis, I have investigated the complex and irregular Cenozoic orogenic evolution of the Central Kyrgyz Tien Shan in Central Asia, which is presently one of the most active intra-continental mountain belts in the world. This work involved combining a broad array of datasets, including thermochronologic, magnetostratigraphic, sediment provenance and stable isotope data, to identify and date various changes in tectonic deformation, climate and surface processes. Many of these changes are linked and can ultimately be related to regional-scale processes that altered the orogenic evolution of the Central Kyrgyz Tien Shan. The Central Kyrgyz Tien Shan contains a sub-parallel series of structures that were reactivated in the late Cenozoic in response to the tectonic forces associated with the distant India-Eurasia collision. Over time, slip on the various reactivated structures created the succession of mountain ranges and intermontane basins which characterises the modern morphology of the region. In this thesis, new quantitative constraints on the exhumation histories of several mountain ranges have been obtained by using low temperature thermochronological data from 95 samples (zircon (U-Th)/He, apatite fission track and (U-Th)/He). Time-temperature histories derived by modelling the thermochronologic data of individual samples identify at least two stages of Cenozoic cooling in most of the region's mountain ranges: (1) initially low cooling rates (<1°C/Myr) during the tectonic quiescent period and (2) increased cooling in the late Cenozoic, which occurred diachronously and with variable magnitude in different ranges. This second cooling stage is interpreted to represent increased erosion caused by active deformation, and in many of the sampled mountain ranges, provides the first available constraints on the timing of late Cenozoic deformation. New constraints on the timing of deformation have also been derived from the sedimentary record of intermontane basins. In the intermontane Issyk Kul basin, new magnetostratigraphic data from two sedimentary sections suggests that deposition of the first Cenozoic syn-tectonic sediments commenced at ~26 Ma. Zircon U-Pb provenance data, paleocurrent and conglomerate clast analysis reveals that these sediments were sourced from the Terskey Range to the south of the basin, suggesting that the onset of the late Cenozoic deformation occurred >26 Ma in that particular range. Elsewhere, growth strata relationships are used to identify syn-tecotnic deposition and constrain the timing of nearby deformation. Collectively, these new constraints obtained from thermochronologic and sedimentary data have allowed me to infer the spatiotemporal distribution of deformation in a transect through the Central Kyrgyz Tien Shan, and determine the order in which mountain ranges started deforming. These data suggest that deformation began in a few widely-spaced mountain ranges in the late Oligocene and early Miocene. Typically, these earlier mountain ranges are bounded on at least one side by a reactivated structure, which probably corresponds to the frictionally weakest and most suitably orientated inherited structures for accommodating the roughly north-south directed horizontal crustal shortening of the late Cenozoic. Moreover, tectonically-induced rock uplift in the Terskey Range, following the reactivation of the bounding structure before 26 Ma, likely caused significant surface uplift across the range, which in turn lead to enhanced orographic precipitation. These wetter conditions have been inferred from stable isotope data collected in the two magnetostratigraphically-dated sections in the Issyk Kul basin. Subsequently, in the late Miocene (~12‒5 Ma), more mountain ranges and inherited structures appear to have started actively deforming. Importantly, the onset of deformation at these locations in the late Miocene coincides with an increase in exhumation of ranges that had started deforming earlier in the late Oligocene‒early Miocene. Based on this observation, I have suggested that there must have been an overall increase in the rate of horizontal crustal shortening across the Central Kyrgyz Tien Shan, which likely relates to regional tectonic changes that affected much of Central Asia. Many of the mountain ranges that started deforming in the late Miocene were associated with out-of-sequence tectonic reactivation and initiation, which lead to the partitioning of larger intermontane basins. Moreover, within most of the intermontane basins in the Central Kyrgyz Tien Shan, this inferred late Miocene increase in horizontal crustal shortening occurs roughly at the same time as an increase in sedimentation rates and a significant change sediment composition. Therefore, I have suggested that the overall magnitude of deformational processes increased in the late Miocene, promoting more flexural subsidence in the intermontane basins of the Central Kyrgyz Tien Shan.}, language = {en} } @article{NakanoIzutsu2013, author = {Nakano, Yoshiaki and Izutsu, Katsunobu}, title = {The new course of study and a prospect of information studies education in Japan}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {6}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64522}, pages = {89 -- 96}, year = {2013}, abstract = {Japan launched the new Course of Study in April 2012, which has been carried out in elementary schools and junior high schools. It will also be implemented in senior high schools from April 2013. This article presents an overview of the information studies education in the new Course of Study for K-12. Besides, the authors point out what role experts of informatics and information studies education should play in the general education centered around information studies that is meant to help people of the nation to lead an active, powerful, and flexible life until the satisfying end.}, language = {en} } @inproceedings{Putten2013, author = {Putten, Saskia van}, title = {The meaning of the avatime additive particle tsyɛ}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66081}, year = {2013}, abstract = {Avatime, a Kwa language of Ghana, has an additive particle tsyɛ that at first sight looks similar to additive particles such as too and also in English. However, on closer inspection, the Avatime particle behaves differently. Contrary to what is usually claimed about additive particles, tsyɛ does not only associate with focused elements. Moreover, unlike its English equivalents, tsyɛ does not come with a requirement of identity between the expressed proposition and an alternative. Instead, it indicates that the proposition it occurs in is similar to or compatible with a presupposed alternative proposition.}, language = {en} } @article{Su2013, author = {Su, Qin}, title = {The Growth and Challenges of Small- and Medium-Sized Banks in China}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68685}, pages = {55 -- 71}, year = {2013}, abstract = {1. Introduction 2. The growth of China's SMBs and the changes of the banking market structure - a land of small- and medium-sized companies 2.1 The characteristics of China's banking market structure 2.2 The growth of China's SMBs 2.3 The changes of China's banking market structure 3. The opportunities and challenges facing SMBs in China 3.1 Opportunities 3.2 Challenges 4. Conclusion}, language = {en} } @article{Faltermeier2013, author = {Faltermeier, Rudolf}, title = {The German Banking System}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68657}, pages = {13 -- 25}, year = {2013}, abstract = {1. The German banking system 1.1 Three pillar structure 1.2 Business aims 2. The German economy 2.1 A land of small and medium-sized companies 2.2 Banking system and economy fit together 3. Experience in the crisis 3.1 Customer behaviour 3.2 Risk situation 3.3 Profitability 4. Conclusion}, language = {en} } @misc{HelfertWarschburger2013, author = {Helfert, Susanne and Warschburger, Petra}, title = {The face of appearance-related social pressure}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401155}, pages = {11}, year = {2013}, abstract = {Background Appearance-related social pressure plays an important role in the development of a negative body image and self-esteem as well as severe mental disorders during adolescence (e.g. eating disorders, depression). Identifying who is particularly affected by social pressure can improve targeted prevention and intervention, but findings have either been lacking or controversial. Thus the aim of this study is to provide a detailed picture of gender, weight, and age-related variations in the perception of appearance-related social pressure by peers and parents. Methods 1112 German students between grades 7 and 9 (mean age: M = 13.38, SD = .81) filled in the Appearance-Related Social Pressure Questionnaire (German: FASD), which considers different sources (peers, parents) as well as various kinds of social pressure (e.g. teasing, modeling, encouragement). Results Girls were more affected by peer pressure, while gender differences in parental pressure seemed negligible. Main effects of grade-level suggested a particular increase in indirect peer pressure (e.g. appearance-related school and class norms) from early to middle adolescence. Boys and girls with higher BMI were particularly affected by peer teasing and exclusion as well as by parental encouragement to control weight and shape. Conclusion The results suggest that preventive efforts targeting body concerns and disordered eating should bring up the topic of appearance pressure in a school-based context and should strengthen those adolescents who are particularly at risk - in our study, girls and adolescents with higher weight status. Early adolescence and school transition appear to be crucial periods for these efforts. Moreover, the comprehensive assessment of appearance-related social pressure appears to be a fruitful way to further explore social risk-factors in the development of a negative body image.}, language = {en} } @article{Menichetti2013, author = {Menichetti, Marco et al.}, title = {The Exchange Rate Dimension in International Asset Allocation}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68810}, pages = {85 -- 101}, year = {2013}, abstract = {1. Motivation and introduction 2. International asset allocation 2.1 Risk and return drivers in international asset allocation 2.2 Passive and active investment approaches 2.3 Is international diversification advantageous? 3. Case 4. Interaction levels of the exchange rate dimension 4.1 Role of the reference currency 4.2 Decision on hedging exchange rate risks 4.3 Role of the investment currency 4.4 Role of the investment claim 5. Conclusion}, language = {en} } @article{Brooks2013, author = {Brooks, Clare}, title = {The EVE curriculum framework}, series = {Potsdamer geographische Praxis}, journal = {Potsdamer geographische Praxis}, number = {3}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2194-1599}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65918}, pages = {23 -- 27}, year = {2013}, abstract = {1. The new approach 2. Changes to the Curriculum Framework}, language = {en} } @article{Sommer2013, author = {Sommer, Albrecht}, title = {The European Financial Crisis, European Central Bank Policy, and the Deutsche Bundesbank}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68635}, pages = {9 -- 10}, year = {2013}, language = {en} } @inproceedings{OPUS4-6578, title = {The Euro Financial Crisis : impacts on banking, capital markets, and regulation ; report of the international workshop in Potsdam on July 20/21, 2012}, editor = {Hummel, Detlev}, isbn = {978-3-86956-252-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65228}, year = {2013}, abstract = {On July 20/21 in 2012, an international workshop was held on the subject of the global impact of the Euro-Financial-Crisis at the University of Potsdam. Prof. Dr. Detlev Hummel, faculty Finance and Banking, was the host of the event. Academic colleagues from Beijing, Moscow and Connecticut (USA) as well as domestic capital market and banking experts presented their analyses. Different aspects of national and international finance markets were examined, with a focus on the European region, China and Russia. Mistakes and failures of the banking regulations were identified as one, but note the sole cause of the economic problems. A lack of budget discipline of some politicians and the loss of business competitiveness of certain European nations were mentioned, too. Some members of the European Union did not succeed in mastering the challenges of the global economy. There have been structural issues in some states that impede their competitiveness in the global market, for example with China. The participants pointed out a number of other reasons for the crisis, like dubious distribution types as well as a lack of transparency of certain financial products. Furthermore, remuneration and incentive schemas of investment banks and especially the reckless risk management policy of large banks were identified as other factors for the crisis. The participants of the international workshop in Potsdam agree that the birth of the Euro-currency was a political event and will remain a challenge. The reform of the banking supervision and further steps towards an economic and fiscal union are new research tasks.}, language = {en} } @article{Chen2013, author = {Chen, Tao}, title = {The Effect of Chinese Monetary Policy on Banking During the Global Financial Crisis}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68663}, pages = {27 -- 41}, year = {2013}, abstract = {1. Abstract 2. Introduction to the main monetary policy tools in China 2.1 Reserve requirements 2.2 Open market operations 2.3 Interest rate policy 2.4 Credit policy and window guidance 2.5 Real estate credit control 3. Loosening monetary policy and its effect on the banking 3.1 Loosening monetary policy measures 3.2 The effect of the expansionary monetary policy on the banking 4. Sound monetary policy with tight trend and its effect on banking 4.1 Main measures of the sound monetary policy with tight trend 4.2 The effect of sound monetary policy with tight trend on banking 5. Conclusion}, language = {en} } @article{Hummel2013, author = {Hummel, Detlev}, title = {The Corporate Governance of Banks}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68779}, pages = {177 -- 191}, year = {2013}, abstract = {1. Introduction 2. The role of banks and what is different in banks? 3. Corporate Governance and risk management 4. Risk taking and executive board composition 5. Compensation structures - how to improve models for banks? 6. Banking supervision and regulation 7. Reform of European institutions for financial stability}, language = {en} } @unpublished{KiselevTarkhanov2013, author = {Kiselev, Oleg and Tarkhanov, Nikolai Nikolaevich}, title = {The capture of a particle into resonance at potential hole with dissipative perturbation}, issn = {2193-6943}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64725}, year = {2013}, abstract = {We study the capture of a particle into resonance at a potential hole with dissipative perturbation and periodic outside force. The measure of resonance solutions is evaluated. We also derive an asymptotic formula for the parameter range of those solutions which are captured into resonance.}, language = {en} } @misc{WinterThielZabeletal.2013, author = {Winter, Alette and Thiel, Kerstin and Zabel, Andr{\´e} and Klamroth, Tillmann and P{\"o}ppl, Andreas and Kelling, Alexandra and Schilde, Uwe and Taubert, Andreas and Strauch, Peter}, title = {Tetrahalidocuprates(II) - structure and EPR spectroscopy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95012}, pages = {1019 -- 1030}, year = {2013}, abstract = {We present and discuss the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of five tetrachloridocuprate(II) complexes to supply a useful tool for the structural characterisation of the [CuCl4]2- moiety in the liquid state, for example in ionic liquids, or in solution. Bis(benzyltriethylammonium)-, bis(trimethylphenylammonium)-, bis(ethyltriphenylphosphonium)-, bis(benzyltriphenylphosphonium)-, and bis(tetraphenylarsonium)tetrachloridocuprate(II) were synthesised and characterised by elemental, IR, EPR and X-ray analyses. The results of the crystallographic analyses show distorted tetrahedral coordination geometry of all [CuCl4]2- anions in the five complexes and prove that all investigated complexes are stabilised by hydrogen bonds of different intensities. Despite the use of sterically demanding ammonium, phosphonium and arsonium cations to obtain the separation of the paramagnetic Cu(II) centres for EPR spectroscopy no hyperfine structure was observed in the EPR spectra but the principal values of the electron Zeeman tensor, g∥ and g⊥, could be determined. With these EPR data and the crystallographic parameters we were able to carry out a correlation study to anticipate the structural situation of tetrachloridocuprates in different physical states. This correlation is in good agreement with DFT calculations.}, language = {en} } @phdthesis{Perscheid2013, author = {Perscheid, Michael}, title = {Test-driven fault navigation for debugging reproducible failures}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68155}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The correction of software failures tends to be very cost-intensive because their debugging is an often time-consuming development activity. During this activity, developers largely attempt to understand what causes failures: Starting with a test case that reproduces the observable failure they have to follow failure causes on the infection chain back to the root cause (defect). This idealized procedure requires deep knowledge of the system and its behavior because failures and defects can be far apart from each other. Unfortunately, common debugging tools are inadequate for systematically investigating such infection chains in detail. Thus, developers have to rely primarily on their intuition and the localization of failure causes is not time-efficient. To prevent debugging by disorganized trial and error, experienced developers apply the scientific method and its systematic hypothesis-testing. However, even when using the scientific method, the search for failure causes can still be a laborious task. First, lacking expertise about the system makes it hard to understand incorrect behavior and to create reasonable hypotheses. Second, contemporary debugging approaches provide no or only partial support for the scientific method. In this dissertation, we present test-driven fault navigation as a debugging guide for localizing reproducible failures with the scientific method. Based on the analysis of passing and failing test cases, we reveal anomalies and integrate them into a breadth-first search that leads developers to defects. This systematic search consists of four specific navigation techniques that together support the creation, evaluation, and refinement of failure cause hypotheses for the scientific method. First, structure navigation localizes suspicious system parts and restricts the initial search space. Second, team navigation recommends experienced developers for helping with failures. Third, behavior navigation allows developers to follow emphasized infection chains back to root causes. Fourth, state navigation identifies corrupted state and reveals parts of the infection chain automatically. We implement test-driven fault navigation in our Path Tools framework for the Squeak/Smalltalk development environment and limit its computation cost with the help of our incremental dynamic analysis. This lightweight dynamic analysis ensures an immediate debugging experience with our tools by splitting the run-time overhead over multiple test runs depending on developers' needs. Hence, our test-driven fault navigation in combination with our incremental dynamic analysis answers important questions in a short time: where to start debugging, who understands failure causes best, what happened before failures, and which state properties are infected.}, language = {en} } @article{Linck2013, author = {Linck, Barbara}, title = {Test items for and misconceptions of competences in the domain of logic programming}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {6}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64461}, pages = {25 -- 34}, year = {2013}, abstract = {Development of competence-oriented curricula is still an important theme in informatics education. Unfortunately informatics curricula, which include the domain of logic programming, are still input-orientated or lack detailed competence descriptions. Therefore, the development of competence model and of learning outcomes' descriptions is essential for the learning process in this domain. A prior research developed both. The next research step is to formulate test items to measure the described learning outcomes. This article describes this procedure and exemplifies test items. It also relates a test in school to the items and shows which misconceptions and typical errors are important to discuss in class. The test result can also confirm or disprove the competence model. Therefore, this school test is important for theoretical research as well as for the concrete planning of lessons. Quantitative analysis in school is important for evaluation and improvement of informatics education.}, language = {en} } @phdthesis{Raetzel2013, author = {R{\"a}tzel, Dennis}, title = {Tensorial spacetime geometries and background-independent quantum field theory}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65731}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Famously, Einstein read off the geometry of spacetime from Maxwell's equations. Today, we take this geometry that serious that our fundamental theory of matter, the standard model of particle physics, is based on it. However, it seems that there is a gap in our understanding if it comes to the physics outside of the solar system. Independent surveys show that we need concepts like dark matter and dark energy to make our models fit with the observations. But these concepts do not fit in the standard model of particle physics. To overcome this problem, at least, we have to be open to matter fields with kinematics and dynamics beyond the standard model. But these matter fields might then very well correspond to different spacetime geometries. This is the basis of this thesis: it studies the underlying spacetime geometries and ventures into the quantization of those matter fields independently of any background geometry. In the first part of this thesis, conditions are identified that a general tensorial geometry must fulfill to serve as a viable spacetime structure. Kinematics of massless and massive point particles on such geometries are introduced and the physical implications are investigated. Additionally, field equations for massive matter fields are constructed like for example a modified Dirac equation. In the second part, a background independent formulation of quantum field theory, the general boundary formulation, is reviewed. The general boundary formulation is then applied to the Unruh effect as a testing ground and first attempts are made to quantize massive matter fields on tensorial spacetimes.}, language = {en} } @unpublished{LeonardRoellyZambrini2013, author = {L{\´e}onard, Christian and Roelly, Sylvie and Zambrini, Jean-Claude}, title = {Temporal symmetry of some classes of stochastic processes}, issn = {2193-6943}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64599}, year = {2013}, abstract = {In this article we analyse the structure of Markov processes and reciprocal processes to underline their time symmetrical properties, and to compare them. Our originality consists in adopting a unifying approach of reciprocal processes, independently of special frameworks in which the theory was developped till now (diffusions, or pure jump processes). This leads to some new results, too.}, language = {en} } @misc{Frank2013, type = {Master Thesis}, author = {Frank, Mario}, title = {TEMPLAR : efficient determination of relevant axioms in big formula sets for theorem proving}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72112}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {This document presents a formula selection system for classical first order theorem proving based on the relevance of formulae for the proof of a conjecture. It is based on unifiability of predicates and is also able to use a linguistic approach for the selection. The scope of the technique is the reduction of the set of formulae and the increase of the amount of provable conjectures in a given time. Since the technique generates a subset of the formula set, it can be used as a preprocessor for automated theorem proving. The document contains the conception, implementation and evaluation of both selection concepts. While the one concept generates a search graph over the negation normal forms or Skolem normal forms of the given formulae, the linguistic concept analyses the formulae and determines frequencies of lexemes and uses a tf-idf weighting algorithm to determine the relevance of the formulae. Though the concept is built for first order logic, it is not limited to it. The concept can be used for higher order and modal logik, too, with minimal adoptions. The system was also evaluated at the world championship of automated theorem provers (CADE ATP Systems Competition, CASC-24) in combination with the leanCoP theorem prover and the evaluation of the results of the CASC and the benchmarks with the problems of the CASC of the year 2012 (CASC-J6) show that the concept of the system has positive impact to the performance of automated theorem provers. Also, the benchmarks with two different theorem provers which use different calculi have shown that the selection is independent from the calculus. Moreover, the concept of TEMPLAR has shown to be competitive to some extent with the concept of SinE and even helped one of the theorem provers to solve problems that were not (or slower) solved with SinE selection in the CASC. Finally, the evaluation implies that the combination of the unification based and linguistic selection yields more improved results though no optimisation was done for the problems.}, language = {en} } @article{KimPark2013, author = {Kim, Seungyon and Park, Seongbin}, title = {Teaching NP completeness in secondary schools}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {6}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64476}, pages = {35 -- 38}, year = {2013}, abstract = {In this paper, we show how the theory of NP completeness can be introduced to students in secondary schools. The motivation of this research is that although there are difficult issues that require technical backgrounds, students are already familiar with demanding computational problems through games such as Sudoku or Tetris. Our intention is to bring together important concepts in the theory of NP completeness in such a way that students in secondary schools can easily understand them. This is part of our ongoing research about how to teach fundamental issues in Computer Science in secondary schools. We discuss what needs to be taught in which sequence in order to introduce ideas behind NP completeness to students without technical backgrounds.}, language = {en} } @book{RokvenSiebenHalmanetal.2013, author = {Rokven, Josja and Sieben, Inge and Halman, Loek and Uhlenwinkel, Anke and Brooks, Clare and Caner, Havva Ay{\c{s}}e and Seggie, Fatma Nevra and Baars, Daniela and Dal, Adem and Şim{\c{s}}ek, Esra and G{\"u}ltekin, Emrah and Karaduman, Dursun and Weiser, Ines and Ak{\c{c}}ay, P{\i}nar and D{\"u}{\c{s}}er, Ece and Nozon, Hannes and Strehmel, Christian and Groell, Janine and Stern, Caroline and Turgut, Pelin and Demirci, Kadriye and Erdem, Didem Tuğ{\c{c}}e and Kanera, Elisa and Erbil, Fethiye and Rogge, Lisa and Şen, Nazile and Siwick, Markus and Pažick{\´y}, Michal and Chlapik, Matej and Liškov{\´a}, Lenka and van den Broek, Carola and Willemse, Marloes and Malchova, Lenka and Majer, Zdenko and Laban, Pieter and Bechtold, Sander and Hogendoorn, Thirza and Koh{\´u}tov{\´a}, Vivien and Potočanov{\´a}, Katar{\´i}na and Medved', Jakub and Matisovskŷ, Tom{\´a}ŝ and Suijkerbuijk, Maico and Povalačov{\´a}, Diana and Leffers, Marjon and Scheepens, Evelien and Kools, Hanneke and Oleksakova, Daniela and White, R{\´o}is{\´i}n}, title = {Teaching about the family values of Europeans : critical reflections from the third student exchange of the EVE-project}, editor = {Uhlenwinkel, Anke}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-234-6}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64412}, publisher = {Universit{\"a}t Potsdam}, pages = {134}, year = {2013}, abstract = {The European Values Education (EVE) project is a large-scale, cross-national, and longitudinal survey research programme on basic human values. The main topic of its second stage was family values in Europe. Student teachers of several universities in Europe worked together in multicultural exchange groups. Their results are presented in this issue.}, language = {en} } @misc{MondalBhuniaDemeshkoetal.2013, author = {Mondal, Suvendu Sekhar and Bhunia, Asamanjoy and Demeshko, Serhiy and Kelling, Alexandra and Schilde, Uwe and Janiak, Christoph and Holdt, Hans-J{\"u}rgen}, title = {Synthesis of a Co(II)-imidazolate framework from an anionic linker precursor}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-94424}, pages = {39 -- 42}, year = {2013}, abstract = {A Co(II)-imidazolate-4-amide-5-imidate based MOF, IFP-5, is synthesized by using an imidazolate anion-based novel ionic liquid as a linker precursor under solvothermal conditions. IFP-5 shows significant amounts of gas (N2, CO2, CH4 and H2) uptake capacities. IFP-5 exhibits an independent high spin Co(II) centre and antiferromagnetic coupling.}, language = {en} } @misc{Metzke2013, type = {Master Thesis}, author = {Metzke, Sarah}, title = {Synthesis and characterization of transition metal nitrides and carbides for catalysis and electrochemistry application}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69835}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {It was the goal of this work to explore two different synthesis pathways using green chemistry. The first part of this thesis is focusing on the use of the urea-glass route towards single phase manganese nitride and manganese nitride/oxide nano-composites embedded in carbon, while the second part of the thesis is focusing on the use of the "saccharide route" (namely cellulose, sucrose, glucose and lignin) towards metal (Ni0), metal alloy (Pd0.9Ni0.1, Pd0.5Ni0.5, Fe0.5Ni0.5, Cu0.5Ni0.5 and W0.15Ni0.85) and ternary carbide (Mn0.75Fe2.25C) nanoparticles embedded in carbon. In the interest of battery application, MnN0.43 nanoparticles surrounded by a graphitic shell and embedded in carbon with a high surface area (79 m^2/g) were synthesized, following a previously set route.The comparison of the material characteristics before and after the discharge showed no remarkable difference in terms of composition and just slight differences in the morphological point of view, meaning the particles are stable but agglomerate. The graphitic shell is contributing to the resistance of the material and leads to a fine cyclic stability over 140 cycles of 230 mAh/g after the first charge/discharge and coulombic efficiencies close to 100\%. Due to the low voltage towards Li/Li+ and the low polarization, it might be an attractive anode material for lithium ion batteries. However, the capacity is still noticeably lower than the theoretical value for MnN0.43. A mixture of MnN0.43 and MnO nanoparticles embedded in carbon (surface area 93 m^2/g) was able to improve the cyclic stability to over 160 cycles giving a capacity of 811 mAh/g, which is considerably higher than the capacity of the conventional material graphite (372 mAh/g). This nano-composite seems to agglomerate less during the process of discharge. Interestingly, although the capacity is much higher than of the single phase manganese nitride, the nano-composite seems to only contain MnN0.43 nanoparticles after the process of discharge with no oxide phase to be found. Concerning catalysis application, different metal, metal alloy, and metal carbide nanoparticles were synthesized using the saccharide route. At first, systems that were already investigated before, being Pd0.9Ni0.1, Pd0.5Ni0.5, Fe0.5Ni0.5 and Mn0.75Fe2.25C using cellulose as the carbon source were prepared and tested in an alkylation reaction of toluene with benzylchloride. Unexpectedly, the metal alloys did not show any catalytic activity, but the ternary carbide Mn0.75Fe2.25C showed fine catalytic activity of 98\% conversion after 9 hour reaction time (110 °C). In a second step, the saccharide route was modified towards other carbon sources and carbon to metal ratios in order to improve the homogeneity of the samples and accessibility of the particle surfaces. The used carbon sources sucrose and glucose are similar in their basic structure of carbohydrates, but reducing the (polymeric) chain length. Indeed, the cellulose could be successfully replaced by sucrose and glucose. A lower carbon to metal ratio was found to influence the size, homogeneity and accessibility (as evidenced by TEM) of the samples. Since sucrose is an aliment, glucose is the better choice as a carbon source. Using glucose, the synthesis of Cu0.5Ni0.5 and W0.15Ni0.85 nano-composites was also possible, although the later was never obtained as pure phase. These alloy nano-composites were tested, along with nickel0 nanoparticles also prepared with glucose and on their catalytic activity towards the reduction of phenylacetylene. The results obtained let believe that any (poly) saccharide, including lignin, could be used as carbon source. The nickel0 nano-composites prepared with lignin as a carbon source were tested along with those prepared with cellulose and sucrose for their catalytic activity in the transfer hydrogenation of nitrobenzene (results compared with exposed nickel nanoparticles and nickel supported on carbon) leading to very promising results. Based on the urea-glass route and the saccharide route, simple equipment and transition metals, it was possible to have a one-pot synthesize with scale-up possibilities towards new material that can be applied in catalysis and battery systems.}, language = {en} } @phdthesis{Santan2013, author = {Santan, Harshal Diliprao}, title = {Synthesis and characterization of thermosensitive hydrogels derived from polysaccharides}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69793}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In this work, thermosensitive hydrogels having tunable thermo-mechanical properties were synthesized. Generally the thermal transition of thermosensitive hydrogels is based on either a lower critical solution temperature (LCST) or critical micelle concentration/ temperature (CMC/ CMT). The temperature dependent transition from sol to gel with large volume change may be seen in the former type of thermosensitive hydrogels and is negligible in CMC/ CMT dependent systems. The change in volume leads to exclusion of water molecules, resulting in shrinking and stiffening of system above the transition temperature. The volume change can be undesired when cells are to be incorporated in the system. The gelation in the latter case is mainly driven by micelle formation above the transition temperature and further colloidal packing of micelles around the gelation temperature. As the gelation mainly depends on concentration of polymer, such a system could undergo fast dissolution upon addition of solvent. Here, it was envisioned to realize a thermosensitive gel based on two components, one responsible for a change in mechanical properties by formation of reversible netpoints upon heating without volume change, and second component conferring degradability on demand. As first component, an ABA triblockcopolymer (here: Poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) (PEPE) with thermosensitive properties, whose sol-gel transition on the molecular level is based on micellization and colloidal jamming of the formed micelles was chosen, while for the additional macromolecular component crosslinking the formed micelles biopolymers were employed. The synthesis of the hydrogels was performed in two ways, either by physical mixing of compounds showing electrostatic interactions, or by covalent coupling of the components. Biopolymers (here: the polysaccharides hyaluronic acid, chondroitin sulphate, or pectin, as well as the protein gelatin) were employed as additional macromolecular crosslinker to simultaneously incorporate an enzyme responsiveness into the systems. In order to have strong ionic/electrostatic interactions between PEPE and polysaccharides, PEPE was aminated to yield predominantly mono- or di-substituted PEPEs. The systems based on aminated PEPE physically mixed with HA showed an enhancement in the mechanical properties such as, elastic modulus (G′) and viscous modulus (G′′) and a decrease of the gelation temperature (Tgel) compared to the PEPE at same concentration. Furthermore, by varying the amount of aminated PEPE in the composition, the Tgel of the system could be tailored to 27-36 °C. The physical mixtures of HA with di-amino PEPE (HA·di-PEPE) showed higher elastic moduli G′ and stability towards dissolution compared to the physical mixtures of HA with mono-amino PEPE (HA·mono-PEPE). This indicates a strong influence of electrostatic interaction between -COOH groups of HA and -NH2 groups of PEPE. The physical properties of HA with di-amino PEPE (HA·di-PEPE) compare beneficially with the physical properties of the human vitreous body, the systems are highly transparent, and have a comparable refractive index and viscosity. Therefore,this material was tested for a potential biological application and was shown to be non-cytotoxic in eluate and direct contact tests. The materials will in the future be investigated in further studies as vitreous body substitutes. In addition, enzymatic degradation of these hydrogels was performed using hyaluronidase to specifically degrade the HA. During the degradation of these hydrogels, increase in the Tgel was observed along with decrease in the mechanical properties. The aminated PEPE were further utilised in the covalent coupling to Pectin and chondroitin sulphate by using EDC as a coupling agent. Here, it was possible to adjust the Tgel (28-33 °C) by varying the grafting density of PEPE to the biopolymer. The grafting of PEPE to Pectin enhanced the thermal stability of the hydrogel. The Pec-g-PEPE hydrogels were degradable by enzymes with slight increase in Tgel and decrease in G′ during the degradation time. The covalent coupling of aminated PEPE to HA was performed by DMTMM as a coupling agent. This method of coupling was observed to be more efficient compared to EDC mediated coupling. Moreover, the purification of the final product was performed by ultrafiltration technique, which efficiently removed the unreacted PEPE from the final product, which was not sufficiently achieved by dialysis. Interestingly, the final products of these reaction were in a gel state and showed enhancement in the mechanical properties at very low concentrations (2.5 wt\%) near body temperature. In these hydrogels the resulting increase in mechanical properties was due to the combined effect of micelle packing (physical interactions) by PEPE and covalent netpoints between PEPE and HA. PEPE alone or the physical mixtures of the same components were not able to show thermosensitive behavior at concentrations below 16 wt\%. These thermosensitive hydrogels also showed on demand solubilisation by enzymatic degradation. The concept of thermosensitivity was introduced to 3D architectured porous hydrogels, by covalently grafting the PEPE to gelatin and crosslinking with LDI as a crosslinker. Here, the grafted PEPE resulted in a decrease in the helix formation in gelatin chains and after fixing the gelatin chains by crosslinking, the system showed an enhancement in the mechanical properties upon heating (34-42 °C) which was reversible upon cooling. A possible explanation of the reversible changes in mechanical properties is the strong physical interactions between micelles formed by PEPE being covalently linked to gelatin. Above the transition temperature, the local properties were evaluated by AFM indentation of pore walls in which an increase in elastic modulus (E) at higher temperature (37 °C) was observed. The water uptake of these thermosensitive architectured porous hydrogels was also influenced by PEPE and temperature (25 °C and 37 °C), showing lower water up take at higher temperature and vice versa. In addition, due to the lower water uptake at high temperature, the rate of hydrolytic degradation of these systems was found to be decreased when compared to pure gelatin architectured porous hydrogels. Such temperature sensitive architectured porous hydrogels could be important for e.g. stem cell culturing, cell differentiation and guided cell migration, etc. Altogether, it was possible to demonstrate that the crosslinking of micelles by a macromolecular crosslinker increased the shear moduli, viscosity, and stability towards dissolution of CMC-based gels. This effect could be likewise be realized by covalent or non-covalent mechanisms such as, micelle interactions, physical interactions of gelatin chains and physical interactions between gelatin chains and micelles. Moreover, the covalent grafting of PEPE will create additional net-points which also influence the mechanical properties of thermosensitive architectured porous hydrogels. Overall, the physical and chemical interactions and reversible physical interactions in such thermosensitive architectured porous hydrogels gave a control over the mechanical properties of such complex system. The hydrogels showing change of mechanical properties without a sol-gel transition or volume change are especially interesting for further study with cell proliferation and differentiation.}, language = {en} } @misc{MondalDeyBaburinetal.2013, author = {Mondal, Suvendu Sekhar and Dey, Subarna and Baburin, Igor A. and Kelling, Alexandra and Schilde, Uwe and Seifert, Gotthard and Janiak, Christoph and Holdt, Hans-J{\"u}rgen}, title = {Syntheses of two imidazolate-4-amide-5-imidate linker-based hexagonal metal-organic frameworks with flexible ethoxy substituent}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-94360}, pages = {9394 -- 9399}, year = {2013}, abstract = {A rare example of in situ linker generation with the formation of soft porous Zn- and Co-MOFs (IFP-9 and -10, respectively) is reported. The flexible ethoxy groups of IFP-9 and -10 protrude into the 1D hexagonal channels. The gas-sorption behavior of both materials for H2, CO2 and CH4 showed wide hysteretic isotherms, typical for MOFs having a flexible substituent which can give rise to a gate effect.}, language = {en} } @phdthesis{Schuetz2013, author = {Sch{\"u}tz, Felina}, title = {Surface heat flow and lithospheric thermal structure of the northwestern Arabian Plate}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69622}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The surface heat flow (qs) is paramount for modeling the thermal structure of the lithosphere. Changes in the qs over a distinct lithospheric unit are normally directly reflecting changes in the crustal composition and therewith the radiogenic heat budget (e.g., Rudnick et al., 1998; F{\"o}rster and F{\"o}rster, 2000; Mareschal and Jaupart, 2004; Perry et al., 2006; Hasterok and Chapman, 2011, and references therein) or, less usual, changes in the mantle heat flow (e.g., Pollack and Chapman, 1977). Knowledge of this physical property is therefore of great interest for both academic research and the energy industry. The present study focuses on the qs of central and southern Israel as part of the Sinai Microplate (SM). Having formed during Oligocene to Miocene rifting and break-up of the African and Arabian plates, the SM is characterized by a young and complex tectonic history. Resulting from the time thermal diffusion needs to pass through the lithosphere, on the order of several tens-of-millions of years (e.g., Fowler, 1990); qs-values of the area reflect conditions of pre-Oligocene times. The thermal structure of the lithosphere beneath the SM in general, and south-central Israel in particular, has remained poorly understood. To address this problem, the two parameters needed for the qs determination were investigated. Temperature measurements were made at ten pre-existing oil and water exploration wells, and the thermal conductivity of 240 drill core and outcrop samples was measured in the lab. The thermal conductivity is the sensitive parameter in this determination. Lab measurements were performed on both, dry and water-saturated samples, which is labor- and time-consuming. Another possibility is the measurement of thermal conductivity in dry state and the conversion to a saturated value by using mean model approaches. The availability of a voluminous and diverse dataset of thermal conductivity values in this study allowed (1) in connection with the temperature gradient to calculate new reliable qs values and to use them to model the thermal pattern of the crust in south-central Israel, prior to young tectonic events, and (2) in connection with comparable datasets, controlling the quality of different mean model approaches for indirect determination of bulk thermal conductivity (BTC) of rocks. The reliability of numerically derived BTC values appears to vary between different mean models, and is also strongly dependent upon sample lithology. Yet, correction algorithms may significantly reduce the mismatch between measured and calculated conductivity values based on the different mean models. Furthermore, the dataset allowed the derivation of lithotype-specific conversion equations to calculate the water-saturated BTC directly from data of dry-measured BTC and porosity (e.g., well log derived porosity) with no use of any mean model and thus provide a suitable tool for fast analysis of large datasets. The results of the study indicate that the qs in the study area is significantly higher than previously assumed. The new presented qs values range between 50 and 62 mW m⁻². A weak trend of decreasing heat flow can be identified from the east to the west (55-50 mW m⁻²), and an increase from the Dead Sea Basin to the south (55-62 mW m⁻²). The observed range can be explained by variation in the composition (heat production) of the upper crust, accompanied by more systematic spatial changes in its thickness. The new qs data then can be used, in conjunction with petrophysical data and information on the structure and composition of the lithosphere, to adjust a model of the pre-Oligocene thermal state of the crust in south-central Israel. The 2-D steady-state temperature model was calculated along an E-W traverse based on the DESIRE seismic profile (Mechie et al., 2009). The model comprises the entire lithosphere down to the lithosphere-asthenosphere boundary (LAB) involving the most recent knowledge of the lithosphere in pre-Oligocene time, i.e., prior to the onset of rifting and plume-related lithospheric thermal perturbations. The adjustment of modeled and measured qs allows conclusions about the pre-Oligocene LAB-depth. After the best fitting the most likely depth is 150 km which is consistent with estimations made in comparable regions of the Arabian Shield. It therefore comprises the first ever modelled pre-Oligocene LAB depth, and provides important clues on the thermal state of lithosphere before rifting. This, in turn, is vital for a better understanding of the (thermo)-dynamic processes associated with lithosphere extension and continental break-up.}, language = {en} } @misc{WolffBrand2013, author = {Wolff, Wanja and Brand, Ralf}, title = {Subjective stressors in school and their relation to neuroenhancement}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401131}, pages = {6}, year = {2013}, abstract = {Background: The use of psychoactive substances to neuroenhance cognitive performance is prevalent. Neuroenhancement (NE) in everyday life and doping in sport might rest on similar attitudinal representations, and both behaviors can be theoretically modeled by comparable means-to-end relations (substance-performance). A behavioral (not substance-based) definition of NE is proposed, with assumed functionality as its core component. It is empirically tested whether different NE variants (lifestyle drug, prescription drug, and illicit substance) can be regressed to school stressors. Findings: Participants were 519 students (25.8 +/- 8.4 years old, 73.1\% female). Logistic regressions indicate that a modified doping attitude scale can predict all three NE variants. Multiple NE substance abuse was frequent. Overwhelming demands in school were associated with lifestyle and prescription drug NE. Conclusions: Researchers should be sensitive for probable structural similarities between enhancement in everyday life and sport and systematically explore where findings from one domain can be adapted for the other. Policy makers should be aware that students might misperceive NE as an acceptable means of coping with stress in school, and help to form societal sensitivity for the topic of NE among our younger ones in general.}, language = {en} } @unpublished{ShlapunovTarkhanov2013, author = {Shlapunov, Alexander and Tarkhanov, Nikolai Nikolaevich}, title = {Sturm-Liouville problems in domains with non-smooth edges}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67336}, year = {2013}, abstract = {We consider a (generally, non-coercive) mixed boundary value problem in a bounded domain for a second order elliptic differential operator A. The differential operator is assumed to be of divergent form and the boundary operator B is of Robin type. The boundary is assumed to be a Lipschitz surface. Besides, we distinguish a closed subset of the boundary and control the growth of solutions near this set. We prove that the pair (A,B) induces a Fredholm operator L in suitable weighted spaces of Sobolev type, the weight function being a power of the distance to the singular set. Moreover, we prove the completeness of root functions related to L.}, language = {en} } @misc{InalKoelschChiappisietal.2013, author = {Inal, Sahika and K{\"o}lsch, Jonas D. and Chiappisi, Leonardo and Janietz, Dietmar and Gradzielski, Michael and Laschewsky, Andr{\´e} and Neher, Dieter}, title = {Structure-related differences in the temperature-regulated fluorescence response of LCST type polymers}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95379}, pages = {6603 -- 6612}, year = {2013}, abstract = {We demonstrate new fluorophore-labelled materials based on acrylamide and on oligo(ethylene glycol) (OEG) bearing thermoresponsive polymers for sensing purposes and investigate their thermally induced solubility transitions. It is found that the emission properties of the polarity-sensitive (solvatochromic) naphthalimide derivative attached to three different thermoresponsive polymers are highly specific to the exact chemical structure of the macromolecule. While the dye emits very weakly below the LCST when incorporated into poly(N-isopropylacrylamide) (pNIPAm) or into a polyacrylate backbone bearing only short OEG side chains, it is strongly emissive in polymethacrylates with longer OEG side chains. Heating of the aqueous solutions above their cloud point provokes an abrupt increase of the fluorescence intensity of the labelled pNIPAm, whereas the emission properties of the dye are rather unaffected as OEG-based polyacrylates and methacrylates undergo phase transition. Correlated with laser light scattering studies, these findings are ascribed to the different degrees of pre-aggregation of the chains at low temperatures and to the extent of dehydration that the phase transition evokes. It is concluded that although the temperature-triggered changes in the macroscopic absorption characteristics, related to large-scale alterations of the polymer chain conformation and aggregation, are well detectable and similar for these LCST-type polymers, the micro-environment provided to the dye within each polymer network differs substantially. Considering sensing applications, this finding is of great importance since the temperature-regulated fluorescence response of the polymer depends more on the macromolecular architecture than the type of reporter fluorophore.}, language = {en} } @phdthesis{Kyprianidis2013, author = {Kyprianidis, Jan Eric}, title = {Structure adaptive stylization of images and video}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64104}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In the early days of computer graphics, research was mainly driven by the goal to create realistic synthetic imagery. By contrast, non-photorealistic computer graphics, established as its own branch of computer graphics in the early 1990s, is mainly motivated by concepts and principles found in traditional art forms, such as painting, illustration, and graphic design, and it investigates concepts and techniques that abstract from reality using expressive, stylized, or illustrative rendering techniques. This thesis focuses on the artistic stylization of two-dimensional content and presents several novel automatic techniques for the creation of simplified stylistic illustrations from color images, video, and 3D renderings. Primary innovation of these novel techniques is that they utilize the smooth structure tensor as a simple and efficient way to obtain information about the local structure of an image. More specifically, this thesis contributes to knowledge in this field in the following ways. First, a comprehensive review of the structure tensor is provided. In particular, different methods for integrating the minor eigenvector field of the smoothed structure tensor are developed, and the superiority of the smoothed structure tensor over the popular edge tangent flow is demonstrated. Second, separable implementations of the popular bilateral and difference of Gaussians filters that adapt to the local structure are presented. These filters avoid artifacts while being computationally highly efficient. Taken together, both provide an effective way to create a cartoon-style effect. Third, a generalization of the Kuwahara filter is presented that avoids artifacts by adapting the shape, scale, and orientation of the filter to the local structure. This causes directional image features to be better preserved and emphasized, resulting in overall sharper edges and a more feature-abiding painterly effect. In addition to the single-scale variant, a multi-scale variant is presented, which is capable of performing a highly aggressive abstraction. Fourth, a technique that builds upon the idea of combining flow-guided smoothing with shock filtering is presented, allowing for an aggressive exaggeration and an emphasis of directional image features. All presented techniques are suitable for temporally coherent per-frame filtering of video or dynamic 3D renderings, without requiring expensive extra processing, such as optical flow. Moreover, they can be efficiently implemented to process content in real-time on a GPU.}, language = {en} } @phdthesis{Kroencke2013, author = {Kr{\"o}ncke, Klaus}, title = {Stability of Einstein Manifolds}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69639}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {This thesis deals with Einstein metrics and the Ricci flow on compact mani- folds. We study the second variation of the Einstein-Hilbert functional on Ein- stein metrics. In the first part of the work, we find curvature conditions which ensure the stability of Einstein manifolds with respect to the Einstein-Hilbert functional, i.e. that the second variation of the Einstein-Hilbert functional at the metric is nonpositive in the direction of transverse-traceless tensors. The second part of the work is devoted to the study of the Ricci flow and how its behaviour close to Einstein metrics is influenced by the variational be- haviour of the Einstein-Hilbert functional. We find conditions which imply that Einstein metrics are dynamically stable or unstable with respect to the Ricci flow and we express these conditions in terms of stability properties of the metric with respect to the Einstein-Hilbert functional and properties of the Laplacian spectrum.}, language = {en} } @phdthesis{May2013, author = {May, Felix}, title = {Spatial models of plant diversity and plant functional traits : towards a better understanding of plant community dynamics in fragmented landscapes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68444}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The fragmentation of natural habitat caused by anthropogenic land use changes is one of the main drivers of the current rapid loss of biodiversity. In face of this threat, ecological research needs to provide predictions of communities' responses to fragmentation as a prerequisite for the effective mitigation of further biodiversity loss. However, predictions of communities' responses to fragmentation require a thorough understanding of ecological processes, such as species dispersal and persistence. Therefore, this thesis seeks an improved understanding of community dynamics in fragmented landscapes. In order to approach this overall aim, I identified key questions on the response of plant diversity and plant functional traits to variations in species' dispersal capability, habitat fragmentation and local environmental conditions. All questions were addressed using spatially explicit simulations or statistical models. In chapter 2, I addressed scale-dependent relationships between dispersal capability and species diversity using a grid-based neutral model. I found that the ratio of survey area to landscape size is an important determinant of scale-dependent dispersal-diversity relationships. With small ratios, the model predicted increasing dispersal-diversity relationships, while decreasing dispersal-diversity relationships emerged, when the ratio approached one, i.e. when the survey area approached the landscape size. For intermediate ratios, I found a U-shaped pattern that has not been reported before. With this study, I unified and extended previous work on dispersal-diversity relationships. In chapter 3, I assessed the type of regional plant community dynamics for the study area in the Southern Judean Lowlands (SJL). For this purpose, I parameterised a multi-species incidence-function model (IFM) with vegetation data using approximate Bayesian computation (ABC). I found that the type of regional plant community dynamics in the SJL is best characterized as a set of isolated "island communities" with very low connectivity between local communities. Model predictions indicated a significant extinction debt with 33\% - 60\% of all species going extinct within 1000 years. In general, this study introduces a novel approach for combining a spatially explicit simulation model with field data from species-rich communities. In chapter 4, I first analysed, if plant functional traits in the SJL indicate trait convergence by habitat filtering and trait divergence by interspecific competition, as predicted by community assembly theory. Second, I assessed the interactive effects of fragmentation and the south-north precipitation gradient in the SJL on community-mean plant traits. I found clear evidence for trait convergence, but the evidence for trait divergence fundamentally depended on the chosen null-model. All community-mean traits were significantly associated with the precipitation gradient in the SJL. The trait associations with fragmentation indices (patch size and connectivity) were generally weaker, but statistically significant for all traits. Specific leaf area (SLA) and plant height were consistently associated with fragmentation indices along the precipitation gradient. In contrast, seed mass and seed number were interactively influenced by fragmentation and precipitation. In general, this study provides the first analysis of the interactive effects of climate and fragmentation on plant functional traits. Overall, I conclude that the spatially explicit perspective adopted in this thesis is crucial for a thorough understanding of plant community dynamics in fragmented landscapes. The finding of contrasting responses of local diversity to variations in dispersal capability stresses the importance of considering the diversity and composition of the metacommunity, prior to implementing conservation measures that aim at increased habitat connectivity. The model predictions derived with the IFM highlight the importance of additional natural habitat for the mitigation of future species extinctions. In general, the approach of combining a spatially explicit IFM with extensive species occupancy data provides a novel and promising tool to assess the consequences of different management scenarios. The analysis of plant functional traits in the SJL points to important knowledge gaps in community assembly theory with respect to the simultaneous consequences of habitat filtering and competition. In particular, it demonstrates the importance of investigating the synergistic consequences of fragmentation, climate change and land use change on plant communities. I suggest that the integration of plant functional traits and of species interactions into spatially explicit, dynamic simulation models offers a promising approach, which will further improve our understanding of plant communities and our ability to predict their dynamics in fragmented and changing landscapes.}, language = {en} } @misc{KarpuzCevikKoppitzetal.2013, author = {Karpuz, Eylem Guzel and {\c{C}}evik, Ahmet Sinan and Koppitz, J{\"o}rg and Cangul, Ismail Naci}, title = {Some fixed-point results on (generalized) Bruck-Reilly ∗-extensions of monoids}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {942}, issn = {1866-8372}, doi = {10.25932/publishup-43270}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432701}, pages = {11}, year = {2013}, abstract = {In this paper, we determine necessary and sufficient conditions for Bruck-Reilly and generalized Bruck-Reilly ∗-extensions of arbitrary monoids to be regular, coregular and strongly π-inverse. These semigroup classes have applications in various field of mathematics, such as matrix theory, discrete mathematics and p-adic analysis (especially in operator theory). In addition, while regularity and coregularity have so many applications in the meaning of boundaries (again in operator theory), inverse monoids and Bruck-Reilly extensions contain a mixture fixed-point results of algebra, topology and geometry within the purposes of this journal.}, language = {en} } @misc{GrubmuellerGoetschKrieger2013, author = {Grubm{\"u}ller, Verena and G{\"o}tsch, Katharina and Krieger, Bernhard}, title = {Social media analytics for future oriented policy making}, series = {Postprints der Universit{\"a}t Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe}, number = {121}, issn = {1867-5808}, doi = {10.25932/publishup-43200}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432007}, pages = {11}, year = {2013}, abstract = {Research indicates that evidence-based policy making is most successful when public administrators refer to diversified information portfolios. With the rising prominence of social media in the last decade, this paper argues that governments can benefit from integrating this publically available, user-generated data through the technique of social media analytics (SMA). There are already several initiatives set up to predict future policy issues, e.g. for the policy fields of crisis mitigation or migrant integration insights. The authors analyse these endeavours and their potential for providing more efficient and effective public policies. Furthermore, they scrutinise the challenges to governmental SMA usage in particular with regards to legal and ethical aspects. Reflecting the latter, this paper provides forward-looking recommendations on how these technologies can best be used for future policy making in a legally and ethically sound manner.}, language = {en} } @phdthesis{Ohl2013, author = {Ohl, Sven}, title = {Small eye movements during fixation : the case of postsaccadic fixation and preparatory influences}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69862}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Describing human eye movement behavior as an alternating sequence of saccades and fixations turns out to be an oversimplification because the eyes continue to move during fixation. Small-amplitude saccades (e.g., microsaccades) are typically observed 1-2 times per second during fixation. Research on microsaccades came in two waves. Early studies on microsaccades were dominated by the question whether microsaccades affect visual perception, and by studies on the role of microsaccades in the process of fixation control. The lack of evidence for a unique role of microsaccades led to a very critical view on the importance of microsaccades. Over the last years, microsaccades moved into focus again, revealing many interactions with perception, oculomotor control and cognition, as well as intriguing new insights into the neurophysiological implementation of microsaccades. In contrast to early studies on microsaccades, recent findings on microsaccades were accompanied by the development of models of microsaccade generation. While the exact generating mechanisms vary between the models, they still share the assumption that microsaccades are generated in a topographically organized saccade motor map that includes a representation for small-amplitude saccades in the center of the map (with its neurophysiological implementation in the rostral pole of the superior colliculus). In the present thesis I criticize that models of microsaccade generation are exclusively based on results obtained during prolonged presaccadic fixation. I argue that microsaccades should also be studied in a more natural situation, namely the fixation following large saccadic eye movements. Studying postsaccadic fixation offers a new window to falsify models that aim to account for the generation of small eye movements. I demonstrate that error signals (visual and extra-retinal), as well as non-error signals like target eccentricity influence the characteristics of small-amplitude eye movements. These findings require a modification of a model introduced by Rolfs, Kliegl and Engbert (2008) in order to account for the generation of small-amplitude saccades during postsaccadic fixation. Moreover, I present a promising type of survival analysis that allowed me to examine time-dependent influences on postsaccadic eye movements. In addition, I examined the interplay of postsaccadic eye movements and postsaccadic location judgments, highlighting the need to include postsaccadic eye movements as covariate in the analyses of location judgments in the presented paradigm. In a second goal, I tested model predictions concerning preparatory influences on microsaccade generation during presaccadic fixation. The observation, that the preparatory set significantly influenced microsaccade rate, supports the critical model assumption that increased fixation-related activity results in a larger number of microsaccades. In the present thesis I present important influences on the generation of small-amplitude saccades during fixation. These eye movements constitute a rich oculomotor behavior which still poses many research questions. Certainly, small-amplitude saccades represent an interesting source of information and will continue to influence future studies on perception and cognition.}, language = {en} } @phdthesis{D'Abreu2013, author = {D'Abreu, Lylla Cysne Frota}, title = {Sexual aggression and victimization among college students in Brazil : prevalence and vulnerability factors}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69238}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Despite the increased attention devoted to sexual aggression among young people in the international scientific literature, Brazil has little research on the subject exclusively among this group. There is evidence that sexual aggression and victimization may start early. Identifying the magnitude and factors that increase the chance for the onset and persistence of sexual victimization are the first steps for prevention efforts among this group. Using both cross-sectional and prospective analyses, this study examined the prevalence of, and vulnerability factors for sexual aggression and victimization in female and male college students (N = 742; M = 20.1 years) in Brazil, of whom a subgroup (n = 354) took part in two measurements six months apart. At Time 1, a Portuguese version of the Short Form of the Sexual Experiences Survey (Koss et al., 2007) was administered to collect information from men and women as both victims and perpetrators of sexual aggression since the age of 14. The students were also asked to provide information on their cognitive representations (sexual scripts) of a consensual sexual encounter, their actual sexual behavior, use of pornography, and experiences of child abuse. At Time 2, the same items from the SES were presented again to assess the incidence of sexual aggression in the 6-month period since T1. The overall prevalence rate of victimization was 27\% among men and 29\% among women. In contrast, perpetration rates were significantly higher among men (33.7\%) than among women (3\%). Confirming the hypotheses, cognitive (i.e., risky sexual scripts, normative beliefs), behavioral (i.e., pornography use, sexual behavior patterns) and biographical (i.e., childhood abuse) risk factors were linked to male sexual aggression and to male and female victimization both cross-sectionally and longitudinally with the path models analyses demonstrating good fit with the data. The results supported: a) the role of the sexual script for a first consensual sexual encounter as an underlying factor of real sexual behavior and sexual victimization or perpetration; b) the role of pornography as "inputs" for sexual scripts, increasing indirectly the risk for victimization, and directly and indirectly the risk for perpetration; c) the direct and indirect link between childhood experiences of (sexual) abuse and male sexual aggression and victimization mediated by sexual behavior; and d) the direct link between child sexual abuse and sexual victimization among women. Few gender differences were found in the victimization model. The findings challenge societal beliefs that sexual aggression is restricted to groups with low socio-economic status and that men are unlikely to be sexually coerced. The disparity between male victimization and female perpetration rates is discussed based on traditional gender roles in Brazil. This study is also the first prospective investigation of risk factors for sexual aggression and victimization in Brazil, demonstrating the role of behavioral, cognitive and biographical factors that increase the vulnerability among college students.}, language = {en} } @misc{EccardHerde2013, author = {Eccard, Jana and Herde, Antje}, title = {Seasonal variation in the behaviour of a short-lived rodent}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401370}, pages = {9}, year = {2013}, abstract = {Background: Short lived, iteroparous animals in seasonal environments experience variable social and environmental conditions over their lifetime. Animals can be divided into those with a "young-of-the-year" life history (YY, reproducing and dying in the summer of birth) and an "overwinter" life history (OW, overwintering in a subadult state before reproducing next spring). We investigated how behavioural patterns across the population were affected by season and sex, and whether variation in behaviour reflects the variation in life history patterns of each season. Applications of pace-of-life (POL) theory would suggest that long-lived OW animals are shyer in order to increase survival, and YY are bolder in order to increase reproduction. Therefore, we expected that in winter and spring samples, when only OW can be sampled, the animals should be shyer than in summer and autumn, when both OW and YY animals can be sampled. We studied common vole (Microtus arvalis) populations, which express typical, intra-annual density fluctuation. We captured a total of 492 voles at different months over 3 years and examined boldness and activity level with two standardised behavioural experiments. Results: Behavioural variables of the two tests were correlated with each other. Boldness, measured as short latencies in both tests, was extremely high in spring compared to other seasons. Activity level was highest in spring and summer, and higher in males than in females. Conclusion: Being bold in laboratory tests may translate into higher risk-taking in nature by being more mobile while seeking out partners or valuable territories. Possible explanations include asset-protection, with OW animals being rather old with low residual reproductive value in spring. Therefore, OW may take higher risks during this season. Offspring born in spring encounter a lower population density and may have higher reproductive value than offspring of later cohorts. A constant connection between life history and animal personality, as suggested by the POL theory, however, was not found. Nevertheless, correlations of traits suggest the existence of animal personalities. In conclusion, complex patterns of population dynamics, seasonal variation in life histories, and variability of behaviour due to asset-protection may cause complex seasonal behavioural dynamics in a population.}, language = {en} } @phdthesis{Kunze2013, author = {Kunze, Matthias}, title = {Searching business process models by example}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68844}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Business processes are fundamental to the operations of a company. Each product manufactured and every service provided is the result of a series of actions that constitute a business process. Business process management is an organizational principle that makes the processes of a company explicit and offers capabilities to implement procedures, control their execution, analyze their performance, and improve them. Therefore, business processes are documented as process models that capture these actions and their execution ordering, and make them accessible to stakeholders. As these models are an essential knowledge asset, they need to be managed effectively. In particular, the discovery and reuse of existing knowledge becomes challenging in the light of companies maintaining hundreds and thousands of process models. In practice, searching process models has been solved only superficially by means of free-text search of process names and their descriptions. Scientific contributions are limited in their scope, as they either present measures for process similarity or elaborate on query languages to search for particular aspects. However, they fall short in addressing efficient search, the presentation of search results, and the support to reuse discovered models. This thesis presents a novel search method, where a query is expressed by an exemplary business process model that describes the behavior of a possible answer. This method builds upon a formal framework that captures and compares the behavior of process models by the execution ordering of actions. The framework contributes a conceptual notion of behavioral distance that quantifies commonalities and differences of a pair of process models, and enables process model search. Based on behavioral distances, a set of measures is proposed that evaluate the quality of a particular search result to guide the user in assessing the returned matches. A projection of behavioral aspects to a process model enables highlighting relevant fragments that led to a match and facilitates its reuse. The thesis further elaborates on two search techniques that provide concrete behavioral distance functions as an instantiation of the formal framework. Querying enables search with a notion of behavioral inclusion with regard to the query. In contrast, similarity search obtains process models that are similar to a query, even if the query is not precisely matched. For both techniques, indexes are presented that enable efficient search. Methods to evaluate the quality and performance of process model search are introduced and applied to the techniques of this thesis. They show good results with regard to human assessment and scalability in a practical setting.}, language = {en} } @inproceedings{Titov2013, author = {Titov, Elena}, title = {Scrambling and interfaces}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66073}, year = {2013}, abstract = {This paper proposes a novel analysis of the Russian OVS construction and argues that the parametric variation in the availability of OVS cross-linguistically depends on the type of relative interpretative argument prominence that a language encodes via syntactic structure. When thematic and information-structural prominence relations do not coincide, only one of them can be structurally/linearly represented. The relation that is not structurally/linearly encoded must be made visible at the PF interface either via prosody or morphology.}, language = {en} } @misc{SchmidtElizarovBergeretal.2013, author = {Schmidt, Bernd and Elizarov, Nelli and Berger, Ren{\´e} and H{\"o}lter, Frank}, title = {Scope and limitations of the Heck-Matsuda-coupling of phenol diazonium salts and styrenes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95070}, pages = {3674 -- 3691}, year = {2013}, abstract = {4-Phenol diazonium salts undergo Pd-catalyzed Heck reactions with various styrenes to 4'-hydroxy stilbenes. In almost all cases higher yields and fewer side products were observed, compared to the analogous 4-methoxy benzene diazonium salts. In contrast, the reaction fails completely with 2- and 3-phenol diazonium salts. For these substitution patterns the methoxy-substituted derivatives are superior.}, language = {en} } @phdthesis{Dawoud2013, author = {Dawoud, Wesam}, title = {Scalability and performance management of internet applications in the cloud}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68187}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Cloud computing is a model for enabling on-demand access to a shared pool of computing resources. With virtually limitless on-demand resources, a cloud environment enables the hosted Internet application to quickly cope when there is an increase in the workload. However, the overhead of provisioning resources exposes the Internet application to periods of under-provisioning and performance degradation. Moreover, the performance interference, due to the consolidation in the cloud environment, complicates the performance management of the Internet applications. In this dissertation, we propose two approaches to mitigate the impact of the resources provisioning overhead. The first approach employs control theory to scale resources vertically and cope fast with workload. This approach assumes that the provider has knowledge and control over the platform running in the virtual machines (VMs), which limits it to Platform as a Service (PaaS) and Software as a Service (SaaS) providers. The second approach is a customer-side one that deals with the horizontal scalability in an Infrastructure as a Service (IaaS) model. It addresses the trade-off problem between cost and performance with a multi-goal optimization solution. This approach finds the scale thresholds that achieve the highest performance with the lowest increase in the cost. Moreover, the second approach employs a proposed time series forecasting algorithm to scale the application proactively and avoid under-utilization periods. Furthermore, to mitigate the interference impact on the Internet application performance, we developed a system which finds and eliminates the VMs suffering from performance interference. The developed system is a light-weight solution which does not imply provider involvement. To evaluate our approaches and the designed algorithms at large-scale level, we developed a simulator called (ScaleSim). In the simulator, we implemented scalability components acting as the scalability components of Amazon EC2. The current scalability implementation in Amazon EC2 is used as a reference point for evaluating the improvement in the scalable application performance. ScaleSim is fed with realistic models of the RUBiS benchmark extracted from the real environment. The workload is generated from the access logs of the 1998 world cup website. The results show that optimizing the scalability thresholds and adopting proactive scalability can mitigate 88\% of the resources provisioning overhead impact with only a 9\% increase in the cost.}, language = {en} } @phdthesis{Hassler2013, author = {Haßler, Sibylle Kathrin}, title = {Saturated hydraulic conductivity in the humid tropics : sources of variability, implications for monitoring and effects on near-surface hydrological flow paths}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66864}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Large areas in the humid tropics are currently undergoing land-use change. The decrease of tropical rainforest, which is felled for land clearing and timber production, is countered by increasing areas of tree plantations and secondary forests. These changes are known to affect the regional water cycle as a result of plant-specific water demand and by influencing key soil properties which determine hydrological flow paths. One of these key properties sensitive to land-use change is the saturated hydraulic conductivity (Ks) as it governs vertical percolation of water within the soil profile. Low values of Ks in a certain soil depth can form an impeding layer and lead to perched water tables and the development of predominantly lateral flow paths such as overland flow. These processes can induce nutrient redistribution, erosion and soil degradation and thus affect ecosystem services and human livelihoods. Due to its sensitivity to land-use change, Ks is commonly used to assess the associated changes in hydrological flow paths. The objective of this dissertation was to assess the effect of land-use change on hydrological flow paths by analysing Ks as indicator variable. Sources of Ks variability, their implications for Ks monitoring and the relationship between Ks and near-surface hydrological flow paths in the context of land-use change were studied. The research area was located in central Panama, a country widely experiencing the abovementioned changes in land use. Ks is dependent on both static, soil-inherent properties such as particle size and clay mineralogy and dynamic, land use-dependent properties such as organic carbon content. By conducting a pair of studies with one of these influences held constant in each, the importance of static and dynamic properties for Ks was assessed. Applying a space-for-time approach to sample Ks under secondary forests of different age classes on comparable soils, a recovery of Ks from the former pasture use was shown to require more than eight years. The process was limited to the 0-6 cm sampling depth and showed large variability among replicates. A wavelet analysis of a Ks transect crossing different soil map units under comparable land cover, old-growth tropical rainforest, showed large small-scale variability, which was attributed to biotic influences, as well as a possible but non-conclusive influence of soil types. The two results highlight the importance of dynamic, land use-dependent influences on Ks. Monitoring studies can help to quantify land use-induced change of Ks, but there is a variety of sampling designs which differ in efficiency of estimating mean Ks. A comparative study of four designs and their suitability for Ks monitoring is used to give recommendations about designing a Ks monitoring scheme. Quantifying changes in spatial means of Ks for small catchments with a rotational stratified sampling design did not prove to be more efficient than Simple Random Sampling. The lack of large-scale spatial structure prevented benefits of stratification, and large small-scale variability resulting from local biotic processes and artificial effects of destructive sampling caused a lack of temporal consistency in the re-sampling of locations, which is part of the rotational design. The relationship between Ks and near-surface hydrological flow paths is of critical importance when assessing the consequences of land-use change in the humid tropics. The last part of this dissertation aimed at disclosing spatial relationships between Ks and overland flow as influenced by different land cover types. The effects of Ks on overland-flow generation were spatially variable, different between planar plots and incised flowlines and strongly influenced by land-cover characteristics. A simple comparison of Ks values and rainfall intensities was insufficient to describe the observed pattern of overland flow. Likewise, event flow in the stream was apparently not directly related to overland flow response patterns within the catchments. The study emphasises the importance of combining pedological, hydrological, meteorological and botanical measurements to comprehensively understand the land use-driven change in hydrological flow paths. In summary, Ks proved to be a suitable parameter for assessing the influence of land-use change on soils and hydrological processes. The results illustrated the importance of land cover and spatial variability of Ks for decisions on sampling designs and for interpreting overland-flow generation. As relationships between Ks and overland flow were shown to be complex and dependent on land cover, an interdisciplinary approach is required to comprehensively understand the effects of land-use change on soils and near-surface hydrological flow paths in the humid tropics.}, language = {en} } @misc{GoychukKharchenko2013, author = {Goychuk, Igor and Kharchenko, Vasyl O.}, title = {Rocking subdiffusive ratchets}, series = {Mathematical Modelling of Natural Phenomena}, journal = {Mathematical Modelling of Natural Phenomena}, number = {622}, issn = {1866-8372}, doi = {10.1051/mmnp/20138210}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-416138}, pages = {15}, year = {2013}, abstract = {We study origin, parameter optimization, and thermodynamic efficiency of isothermal rocking ratchets based on fractional subdiffusion within a generalized non-Markovian Langevin equation approach. A corresponding multi-dimensional Markovian embedding dynamics is realized using a set of auxiliary Brownian particles elastically coupled to the central Brownian particle (see video on the journal web site). We show that anomalous subdiffusive transport emerges due to an interplay of nonlinear response and viscoelastic effects for fractional Brownian motion in periodic potentials with broken space-inversion symmetry and driven by a time-periodic field. The anomalous transport becomes optimal for a subthreshold driving when the driving period matches a characteristic time scale of interwell transitions. It can also be optimized by varying temperature, amplitude of periodic potential and driving strength. The useful work done against a load shows a parabolic dependence on the load strength. It grows sublinearly with time and the corresponding thermodynamic efficiency decays algebraically in time because the energy supplied by the driving field scales with time linearly. However, it compares well with the efficiency of normal diffusion rocking ratchets on an appreciably long time scale.}, language = {en} } @phdthesis{Inal2013, author = {Inal, Sahika}, title = {Responsive polymers for optical sensing applications}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70806}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {LCST-type synthetic thermoresponsive polymers can reversibly respond to certain stimuli in aqueous media with a massive change of their physical state. When fluorophores, that are sensitive to such changes, are incorporated into the polymeric structure, the response can be translated into a fluorescence signal. Based on this idea, this thesis presents sensing schemes which transduce the stimuli-induced variations in the solubility of polymer chains with covalently-bound fluorophores into a well-detectable fluorescence output. Benefiting from the principles of different photophysical phenomena, i.e. of fluorescence resonance energy transfer and solvatochromism, such fluorescent copolymers enabled monitoring of stimuli such as the solution temperature and ionic strength, but also of association/disassociation mechanisms with other macromolecules or of biochemical binding events through remarkable changes in their fluorescence properties. For instance, an aqueous ratiometric dual sensor for temperature and salts was developed, relying on the delicate supramolecular assembly of a thermoresponsive copolymer with a thiophene-based conjugated polyelectrolyte. Alternatively, by taking advantage of the sensitivity of solvatochromic fluorophores, an increase in solution temperature or the presence of analytes was signaled as an enhancement of the fluorescence intensity. A simultaneous use of the sensitivity of chains towards the temperature and a specific antibody allowed monitoring of more complex phenomena such as competitive binding of analytes. The use of different thermoresponsive polymers, namely poly(N-isopropylacrylamide) and poly(meth)acrylates bearing oligo(ethylene glycol) side chains, revealed that the responsive polymers differed widely in their ability to perform a particular sensing function. In order to address questions regarding the impact of the chemical structure of the host polymer on the sensing performance, the macromolecular assembly behavior below and above the phase transition temperature was evaluated by a combination of fluorescence and light scattering methods. It was found that although the temperature-triggered changes in the macroscopic absorption characteristics were similar for these polymers, properties such as the degree of hydration or the extent of interchain aggregations differed substantially. Therefore, in addition to the demonstration of strategies for fluorescence-based sensing with thermoresponsive polymers, this work highlights the role of the chemical structure of the two popular thermoresponsive polymers on the fluorescence response. The results are fundamentally important for the rational choice of polymeric materials for a specific sensing strategy.}, language = {en} } @phdthesis{Rothe2013, author = {Rothe, Monique}, title = {Response of intestinal Escherichia coli to dietary factors in the mouse intestine}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66387}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Diet is a major force influencing the intestinal microbiota. This is obvious from drastic changes in microbiota composition after a dietary alteration. Due to the complexity of the commensal microbiota and the high inter-individual variability, little is known about the bacterial response at the cellular level. The objective of this work was to identify mechanisms that enable gut bacteria to adapt to dietary factors. For this purpose, germ-free mice monoassociated with the commensal Escherichia coli K-12 strain MG1655 were fed three different diets over three weeks: a diet rich in starch, a diet rich in non-digestible lactose and a diet rich in casein. Two dimensional gel electrophoresis and electrospray tandem mass spectrometry were applied to identify differentially expressed proteins of E. coli recovered from small intestine and caecum of mice fed the lactose or casein diets in comparison with those of mice fed the starch diet. Selected differentially expressed bacterial proteins were characterised in vitro for their possible roles in bacterial adaptation to the various diets. Proteins belonging to the oxidative stress regulon oxyR such as alkyl hydroperoxide reductase subunit F (AhpF), DNA protection during starvation protein (Dps) and ferric uptake regulatory protein (Fur), which are required for E. coli's oxidative stress response, were upregulated in E. coli of mice fed the lactose-rich diet. Reporter gene analysis revealed that not only oxidative stress but also carbohydrate-induced osmotic stress led to the OxyR-dependent expression of ahpCF and dps. Moreover, the growth of E. coli mutants lacking the ahpCF or oxyR genes was impaired in the presence of non-digestible sucrose. This indicates that some OxyR-dependent proteins are crucial for the adaptation of E. coli to osmotic stress conditions. In addition, the function of two so far poorly characterised E. coli proteins was analysed: 2 deoxy-D gluconate 3 dehydrogenase (KduD) was upregulated in intestinal E. coli of mice fed the lactose-rich diet and this enzyme and 5 keto 4 deoxyuronate isomerase (KduI) were downregulated on the casein-rich diet. Reporter gene analysis identified galacturonate and glucuronate as inducers of the kduD and kduI gene expression. Moreover, KduI was shown to facilitate the breakdown of these hexuronates, which are normally degraded by uronate isomerase (UxaC), altronate oxidoreductase (UxaB), altronate dehydratase (UxaA), mannonate oxidoreductase (UxuB) and mannonate dehydratase (UxuA), whose expression was repressed by osmotic stress. The growth of kduID-deficient E. coli on galacturonate or glucuronate was impaired in the presence of osmotic stress, suggesting KduI and KduD to compensate for the function of the regular hexuronate degrading enzymes under such conditions. This indicates a novel function of KduI and KduD in E. coli's hexuronate metabolism. Promotion of the intracellular formation of hexuronates by lactose connects these in vitro observations with the induction of KduD on the lactose-rich diet. Taken together, this study demonstrates the crucial influence of osmotic stress on the gene expression of E. coli enzymes involved in stress response and metabolic processes. Therefore, the adaptation to diet-induced osmotic stress is a possible key factor for bacterial colonisation of the intestinal environment.}, language = {en} } @phdthesis{Boedecker2013, author = {Boedecker, Geesche}, title = {Resonance Fluorescence in a Photonic Crystal}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69591}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The problem under consideration in the thesis is a two level atom in a photonic crystal and a pumping laser. The photonic crystal provides an environment for the atom, that modifies the decay of the exited state, especially if the atom frequency is close to the band gap. The population inversion is investigated als well as the emission spectrum. The dynamics is analysed in the context of open quantum systems. Due to the multiple reflections in the photonic crystal, the system has a finite memory that inhibits the Markovian approximation. In the Heisenberg picture the equations of motion for the system variables form a infinite hierarchy of integro-differential equations. To get a closed system, approximations like a weak coupling approximation are needed. The thesis starts with a simple photonic crystal that is amenable to analytic calculations: a one-dimensional photonic crystal, that consists of alternating layers. The Bloch modes inside and the vacuum modes outside a finite crystal are linked with a transformation matrix that is interpreted as a transfer matrix. Formulas for the band structure, the reflection from a semi-infinite crystal, and the local density of states in absorbing crystals are found; defect modes and negative refraction are discussed. The quantum optics section of the work starts with the discussion of three problems, that are related to the full resonance fluorescence problem: a pure dephasing model, the driven atom and resonance fluorescence in free space. In the lowest order of the system-environment coupling, the one-time expectation values for the full problem are calculated analytically and the stationary states are discussed for certain cases. For the calculation of the two time correlation functions and spectra, the additional problem of correlations between the two times appears. In the Markovian case, the quantum regression theorem is valid. In the general case, the fluctuation dissipation theorem can be used instead. The two-time correlation functions are calculated by the two different methods. Within the chosen approximations, both methods deliver the same result. Several plots show the dependence of the spectrum on the parameters. Some examples for squeezing spectra are shown with different approximations. A projection operator method is used to establish two kinds of Markovian expansion with and without time convolution. The lowest order is identical with the lowest order of system environment coupling, but higher orders give different results.}, language = {en} } @book{RoggeSoltiMansvanderAalstetal.2013, author = {Rogge-Solti, Andreas and Mans, Ronny S. and van der Aalst, Wil M. P. and Weske, Mathias}, title = {Repairing event logs using stochastic process models}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-258-2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66797}, publisher = {Universit{\"a}t Potsdam}, pages = {19}, year = {2013}, abstract = {Companies strive to improve their business processes in order to remain competitive. Process mining aims to infer meaningful insights from process-related data and attracted the attention of practitioners, tool-vendors, and researchers in recent years. Traditionally, event logs are assumed to describe the as-is situation. But this is not necessarily the case in environments where logging may be compromised due to manual logging. For example, hospital staff may need to manually enter information regarding the patient's treatment. As a result, events or timestamps may be missing or incorrect. In this paper, we make use of process knowledge captured in process models, and provide a method to repair missing events in the logs. This way, we facilitate analysis of incomplete logs. We realize the repair by combining stochastic Petri nets, alignments, and Bayesian networks. We evaluate the results using both synthetic data and real event data from a Dutch hospital.}, language = {en} } @article{Kroeger2013, author = {Kr{\"o}ger, Bj{\"o}rn}, title = {Remarks on a scene, depicting the primeval world}, series = {HIN : Alexander von Humboldt im Netz ; international review for Humboldtian studies}, volume = {XIV}, journal = {HIN : Alexander von Humboldt im Netz ; international review for Humboldtian studies}, number = {27}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1617-5239}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69848}, pages = {7 -- 35}, year = {2013}, abstract = {The Prussian geologist Leopold von Buch was a lifelong friend of Alexander von Humboldt and had a significant influence on Humboldt's geological ideas. In a talk, held in Berlin in 1831, which is published here for the first time, von Buch presented the Duria Antiquior of 1830 by the English geologist Henry De La Beche. The Duria Antiquior is widely regarded as the earliest depiction of a scene of prehistoric life from deep time. The print raised new questions about the processes of geohistorical change. The talk reveals that Leopold von Buch was a true scientist of the Romantic Age. His descriptions of geohistorical organismic transformations are taken from pictorial examples of organismic transformation from the classical literature. The talk also illustrates how influential English geologists were for geo-historical reconstructions in Germany.}, language = {en} } @article{ChlapikLiškovaBroeketal.2013, author = {Chlapik, Matej and Liškov{\´a}, Lenka and Broek, Carola van den and Willemse, Marloes}, title = {Relating to the students}, series = {Potsdamer geographische Praxis}, journal = {Potsdamer geographische Praxis}, number = {3}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2194-1599}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65994}, pages = {89 -- 95}, year = {2013}, abstract = {1. Strategies 2. Feedback from pupils and student teachers 3. Conclusion}, language = {en} } @article{BaarsDalŞimşek2013, author = {Baars, Daniela and Dal, Adem and Şim{\c{s}}ek, Esra}, title = {Relating to students}, series = {Potsdamer geographische Praxis}, journal = {Potsdamer geographische Praxis}, number = {3}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2194-1599}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65935}, pages = {37 -- 43}, year = {2013}, abstract = {1. What does relating to students mean? 2. Student teachers' perceptions of relating the topic to the pupils 3. Conceptions of the pupils 4. Pupils' perspective 5. Expectations of the pupils 6. Pupils' evaluation of the strategies 7. Problems and suggestions 8. Conclusion / Summary}, language = {en} } @misc{WolffBaumgartenBrand2013, author = {Wolff, Wanja and Baumgarten, Franz and Brand, Ralf}, title = {Reduced self-control leads to disregard of an unfamiliar behavioral option}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401386}, pages = {6}, year = {2013}, abstract = {Background: Neuroenhancement (NE), the use of psychoactive substances in order to enhance a healthy individual's cognitive functioning from a proficient to an even higher level, is prevalent in student populations. According to the strength model of self-control, people fail to self-regulate and fall back on their dominant behavioral response when finite self-control resources are depleted. An experiment was conducted to test the hypothesis that ego-depletion will prevent students who are unfamiliar with NE from trying it. Findings: 130 undergraduates, who denied having tried NE before (43\% female, mean age = 22.76 +/- 4.15 years old), were randomly assigned to either an ego-depletion or a control condition. The dependent variable was taking an "energy-stick" (a legal nutritional supplement, containing low doses of caffeine, taurine and vitamin B), offered as a potential means of enhancing performance on the bogus concentration task that followed. Logistic regression analysis showed that ego-depleted participants were three times less likely to take the substance, OR = 0.37, p = .01. Conclusion: This experiment found that trying NE for the first time was more likely if an individual's cognitive capacities were not depleted. This means that mental exhaustion is not predictive for NE in students for whom NE is not the dominant response. Trying NE for the first time is therefore more likely to occur as a thoughtful attempt at self-regulation than as an automatic behavioral response in stressful situations. We therefore recommend targeting interventions at this inter-individual difference. Students without previous reinforcing NE experience should be provided with information about the possible negative health outcomes of NE. Reconfiguring structural aspects in the academic environment (e.g. lessening workloads) might help to deter current users.}, language = {en} } @unpublished{Roelly2013, author = {Roelly, Sylvie}, title = {Reciprocal processes : a stochastic analysis approach}, issn = {2193-6943}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64588}, year = {2013}, abstract = {Reciprocal processes, whose concept can be traced back to E. Schr{\"o}dinger, form a class of stochastic processes constructed as mixture of bridges, that satisfy a time Markov field property. We discuss here a new unifying approach to characterize several types of reciprocal processes via duality formulae on path spaces: The case of reciprocal processes with continuous paths associated to Brownian diffusions and the case of pure jump reciprocal processes associated to counting processes are treated. This presentation is based on joint works with M. Thieullen, R. Murr and C. L{\´e}onard.}, language = {en} } @article{Brodehser2013, author = {Brodehser, Peter}, title = {Quo Vadis Infrastructure Financing?}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68738}, pages = {119 -- 132}, year = {2013}, abstract = {1. Introduction 2. The project finance market in 2006/2007 3. Areas affected by the global financial crisis 4. Areas affected by the euro financial crisis 5. Basel III and the consequences for infrastructure financing 6. Outlook - Where do we go from here?}, language = {en} } @phdthesis{Adhikari2013, author = {Adhikari, Rishi Ram}, title = {Quantification of total microbial biomass and metabolic activity in subsurface sediments}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67773}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Metabolically active microbial communities are present in a wide range of subsurface environments. Techniques like enumeration of microbial cells, activity measurements with radiotracer assays and the analysis of porewater constituents are currently being used to explore the subsurface biosphere, alongside with molecular biological analyses. However, many of these techniques reach their detection limits due to low microbial activity and abundance. Direct measurements of microbial turnover not just face issues of insufficient sensitivity, they only provide information about a single specific process but in sediments many different process can occur simultaneously. Therefore, the development of a new technique to measure total microbial activity would be a major improvement. A new tritium-based hydrogenase-enzyme assay appeared to be a promising tool to quantify total living biomass, even in low activity subsurface environments. In this PhD project total microbial biomass and microbial activity was quantified in different subsurface sediments using established techniques (cell enumeration and pore water geochemistry) as well as a new tritium-based hydrogenase enzyme assay. By using a large database of our own cell enumeration data from equatorial Pacific and north Pacific sediments and published data it was shown that the global geographic distribution of subseafloor sedimentary microbes varies between sites by 5 to 6 orders of magnitude and correlates with the sedimentation rate and distance from land. Based on these correlations, global subseafloor biomass was estimated to be 4.1 petagram-C and ~0.6 \% of Earth's total living biomass, which is significantly lower than previous estimates. Despite the massive reduction in biomass the subseafloor biosphere is still an important player in global biogeochemical cycles. To understand the relationship between microbial activity, abundance and organic matter flux into the sediment an expedition to the equatorial Pacific upwelling area and the north Pacific Gyre was carried out. Oxygen respiration rates in subseafloor sediments from the north Pacific Gyre, which are deposited at sedimentation rates of 1 mm per 1000 years, showed that microbial communities could survive for millions of years without fresh supply of organic carbon. Contrary to the north Pacific Gyre oxygen was completely depleted within the upper few millimeters to centimeters in sediments of the equatorial upwelling region due to a higher supply of organic matter and higher metabolic activity. So occurrence and variability of electron acceptors over depth and sites make the subsurface a complex environment for the quantification of total microbial activity. Recent studies showed that electron acceptor processes, which were previously thought to thermodynamically exclude each other can occur simultaneously. So in many cases a simple measure of the total microbial activity would be a better and more robust solution than assays for several specific processes, for example sulfate reduction rates or methanogenesis. Enzyme or molecular assays provide a more general approach as they target key metabolic compounds. Since hydrogenase enzymes are ubiquitous in microbes, the recently developed tritium-based hydrogenase radiotracer assay is applied to quantify hydrogenase enzyme activity as a parameter of total living cell activity. Hydrogenase enzyme activity was measured in sediments from different locations (Lake Van, Barents Sea, Equatorial Pacific and Gulf of Mexico). In sediment samples that contained nitrate, we found the lowest cell specific enzyme activity around 10^(-5) nmol H_(2) cell^(-1) d^(-1). With decreasing energy yield of the electron acceptor used, cell-specific hydrogenase activity increased and maximum values of up to 1 nmol H_(2) cell^(-1) d^(-1) were found in samples with methane concentrations of >10 ppm. Although hydrogenase activity cannot be converted directly into a turnover rate of a specific process, cell-specific activity factors can be used to identify specific metabolism and to quantify the metabolically active microbial population. In another study on sediments from the Nankai Trough microbial abundance and hydrogenase activity data show that both the habitat and the activity of subseafloor sedimentary microbial communities have been impacted by seismic activities. An increase in hydrogenase activity near the fault zone revealed that the microbial community was supplied with hydrogen as an energy source and that the microbes were specialized to hydrogen metabolism.}, language = {en} } @phdthesis{Mabrok2013, author = {Mabrok, Hoda Hussein Bakr}, title = {Protective role of lignan-converting bacteria on chemically-induced breast cancer in gnotobiotic rats}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64933}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Enterolignans (enterodiol and enterolactone) exhibit structural similarity to estradiol and have therefore been hypothesized to modulate hormone related cancers such as breast cancer. The bioactivation of the plant lignan secoisolariciresinol diglucoside (SDG) requires the transformation by intestinal bacteria including the deglycosylation of SDG to secoisolariciresinol (SECO) followed by demethylation and dehydroxylation of SECO to enterodiol (ED). Finally, ED is dehydrogenated to enterolactone (EL). It is unclear whether the bacterial activation of SDG to ED and EL is crucial for the cancer preventing effects of dietary lignans. The possible protective effect of bacterial lignan transformation on a 7,12 dimethylbenz(a)anthracene (DMBA)-induced breast cancer in gnotobiotic rats was investigated. Germ-free rats were associated with a defined lignan-converting consortium (Clostridium saccharogumia, Blautia producta, Eggerthella lenta, and Lactonifactor longoviformis). The rats colonized with lignan-converting bacteria consortium (LCC) were fed a lignan-rich flaxseed diet and breast cancer was chemical induced. Identically treated germ-free rats served as control. All bacteria of the consortium successfully colonized the intestine of the LCC rats. The plant lignan SDG was converted into the enterolignans ED and EL in the LCC rats but not in the germ-free rats. This transformation did not influence cancer incidence but significantly decreased tumor numbers per tumor-bearing rat, and tumor size. Cell proliferation was significantly inhibited and apoptosis was significantly induced in LCC rats. No differences between LCC and control rats were observed in the expression of the genes encoding the estrogen receptors (ERα and ERβ) and G-coupled protein receptor 30 (GPR30). Similar findings were observed for both insulin-like growth factor 1 (IGF-1) and epidermal growth factor receptor (EGFR) genes involved in tumor growth. Proteome analysis revealed that 24 proteins were differentially expressed in tumor tissue from LCC and germ-free. RanBP-type and C3HC4-type zinc finger-containing protein 1 (RBCK1) and poly(rC)-binding protein 1 (PBCP1) were down-regulated by 3.2- and 2.0-fold, respectively. These proteins are associated with cell proliferation. The activity of selected enzymes involved in the degradation of oxidants in plasma and liver was significantly increased in the LCC rats. However, plasma and liver concentrations of reduced glutathione (non-enzymatic antioxidant) and malondialdehyde (oxidative stress marker) did not differ between the groups. In conclusion, the bacterial conversion of plant lignan to enterolignans beneficially influences their anti-cancer effect. However, the mechanisms involved in these effects remain elusive.}, language = {en} } @phdthesis{Gollrad2013, author = {Gollrad, Anja}, title = {Prosodic cue weighting in sentence comprehension}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-81954}, school = {Universit{\"a}t Potsdam}, pages = {148}, year = {2013}, abstract = {Gegenstand der Dissertation ist die Untersuchung der Gewichtung prosodischer Korrelate der Phrasierung im Deutschen, insbesondere der Dauer- und Grundfrequenzeigenschaften auf der Ebene der phonologischen Phrase (φ) und der Intonationsphrase (ι). F{\"u}r die prosodische Dom{\"a}ne der phonologischen Phrase und der Intonationsphrase gilt als belegt, dass sie h{\"a}upts{\"a}chlich durch phonetische Parameter der pr{\"a}finalen Dehnung (Lehiste, 1973; Klatt, 1976; Price et al., 1991; Turk \& White, 1999), der Pausendauer (Fant \& Kruckenberg, 1996) und der Ver{\"a}nderung der Grundfrequenz (Pierrehumbert, 1980) ausgedr{\"u}ckt werden, wobei die phonetischen grenzmarkierenden Eigenschaften eher quantitativer als qualitativer Natur sind. Ebenfalls ist bekannt, dass auf der anderen Seite H{\"o}rer diese phonetischen Eigenschaften der Sprecher nutzen, um die prosodische Struktur einer {\"A}ußerung zu ermitteln (Snedeker \& Trueswell, 2003; Kraljic \& Brennan, 2005). Perzeptuelle Evidenz aus dem Englischen und Niederl{\"a}ndischen deuten allerdings darauf hin, dass sich Sprachen hinsichtlich der entscheidenden Korrelate, die f{\"u}r die Perzeption der Dom{\"a}nen konsultiert werden, unterscheiden (Aasland \& Baum, 2003; Sanderman \& Collier, 1997; Scott, 1982; Streeter, 1978). Die grenzmarkierenden phonetischen Korrelate der Dom{\"a}nen werden in der Perzeption unterschiedlich stark gewichtet, was sich im Konzept eines sprachspezifischen prosodischen cue weightings ausdr{\"u}ckt. F{\"u}r das Deutsche ist allerdings nicht hinreichend bekannt, welche dieser drei phonetischen Parameter die wichtigste Rolle f{\"u}r die Perzeption der phonologischen Phrasengrenze und der Intonationsphrasengrenze spielt. Ziel der Dissertation war es, diejenigen phonetischen Merkmale zu identifizieren, die f{\"u}r die Perzeption der phonologischen Phrasengrenze und der Intonationsphrasengrenze entscheidend sind und sich somit f{\"u}r die Bildung der jeweiligen prosodischen Phrasengrenze als notwendig herausstellen. Die Identifikation und Gewichtung eines phonetischen Merkmals erfolgte in der vorliegenden Arbeit durch die Effekte prosodischer Manipulation der phonetischen Korrelate an phonologischen Phrasengrenzen und Intonationsphrasengrenzen auf die Disambiguierung lokaler syntaktischer Ambiguit{\"a}ten in der Perzeption. Der Einfluss einzelner phonetischer Merkmale wurde in einem forced-choice Experiment evaluiert, bei dem H{\"o}rern syntaktisch ambige Satzfragmente auditiv pr{\"a}sentiert wurden und ihnen anschließend die Aufgabe zukam, aus einer Auswahl an disambiguierenden Satzvervollst{\"a}ndigung zu w{\"a}hlen. Die Anzahl der ausgew{\"a}hlten Satzvervollst{\"a}ndigungen pro Satzbedingung {\"a}nderte sich in Abh{\"a}ngigkeit der prosodischen Manipulation der pr{\"a}finalen Dehnung, der Pausendauer und der Grundfrequenz, wodurch der Einfluss eines einzelnen phonetischen Merkmals auf den Disambiguierungsprozess sichtbar wurde. Ein phonetischer Parameter wurde genau dann als notwendig klassifiziert, wenn sich durch seine Manipulation die F{\"a}higkeit zur Disambiguierung der syntaktischen Strukturen signifikant reduzierte, oder g{\"a}nzlich scheiterte, und somit die Wahrnehmung prosodischer Kategorien beinflusst wurde (Heldner, 2001). Hat sich in der Perzeption ein phonetisches Merkmal als notwendig herausgestellt, wurde nachfolgend eine optimalit{\"a}tstheoretische Modellierung vorgeschlagen, die die phonetischen Eigenschaften auf eine (abstrakte) phonologische Strukturerstellung beschreibt. Dieser Verarbeitungsschritt entspricht dem Teilbereich des Perzeptionsprozesses, der in Boersma \& Hamann (2009), Escudero (2009) und F{\´e}ry et al. (2009) unter anderen als Phonetik-Phonologie-Mapping beschrieben wird. Die Dissertation hat folgende Hauptergebnisse hervorgebracht: (1) F{\"u}r die Perzeption phonologischer Phrasengrenzen und Intonationsphrasengrenzen werden nicht alle messbaren phonetischen Grenzmarkierungen gleichermaßen stark genutzt. Das phonetische Merkmal der pr{\"a}finalen Dehnung ist auf der Ebene der kleineren prosodischen Dom{\"a}ne, der phonologischen Phrase, notwendig. Die Information der Grundfrequenz in der Form von Grenzt{\"o}nen ist in der gr{\"o}ßeren Dom{\"a}ne der Intonationsphrase notwendig und damit ausschlaggebend f{\"u}r die Perzeption der prosodischen Phrasengrenze. (2) Auf der Ebene der φ-Phrase werden phonetische Eigenschaften der segmentalen Dauer in Form pr{\"a}finalen Dehnung zur Bildung abstrakter phonologischer Repr{\"a}sentationen herangezogen werden. L{\"a}ngenconstraints schreiben syntaktische Konstituenten aufgrund ihrer Inputdauern einer prosodischen Kategorie zu. Inputdauern der ersten Nominalphrase von 500ms und mehr signalisieren Finalit{\"a}t und sind durch eine φ- Grenze am rechten Rand markiert. Inputdauern von 400ms und weniger signalisieren Kontinuit{\"a}t und werden durch das Ausbleiben einer φ-Grenze am rechten Rand der ersten Nominalphrase markiert. Inputdauern, die zwischen den kritischen L{\"a}ngen von 400ms und 500ms variieren sind bez{\"u}glich der Bildung von φ- Grenzen ambig und k{\"o}nnen in der Perzeption nicht eindeutig disambiguiert werden. (3) Auf der Ebene der ι-Phrase wird die Bildung einer prosodischen Struktur durch die reine tonale Kontur (steigend oder fallend) an der ersten Nominalphrase gelenkt. Eine fallende Grundfrequenzkontur an der ersten Nominalphrase signalisiert Finalit{\"a}t und wird durch eine ι-Grenze am rechten Rand markiert. Eine steigende Kontur an der ersten Nominalphrase signalisiert phrasale Kontinuit{\"a}t und ist bei den vorliegenden S{\"a}tzen der Genitivbedingung gerade durch das Ausbleiben einer ι-Grenze auf der phonologischen Repr{\"a}sentationseben gekennzeichnet.}, language = {en} } @unpublished{RoellyRuszel2013, author = {Roelly, Sylvie and Ruszel, Wioletta M.}, title = {Propagation of Gibbsianness for infinite-dimensional diffusions with space-time interaction}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69014}, year = {2013}, abstract = {We consider infinite-dimensional diffusions where the interaction between the coordinates has a finite extent both in space and time. In particular, it is not supposed to be smooth or Markov. The initial state of the system is Gibbs, given by a strong summable interaction. If the strongness of this initial interaction is lower than a suitable level, and if the dynamical interaction is bounded from above in a right way, we prove that the law of the diffusion at any time t is a Gibbs measure with absolutely summable interaction. The main tool is a cluster expansion in space uniformly in time of the Girsanov factor coming from the dynamics and exponential ergodicity of the free dynamics to an equilibrium product measure.}, language = {en} } @article{Ragonis2013, author = {Ragonis, Noa}, title = {Problem-solving strategies must be taught implicitly}, series = {Commentarii informaticae didacticae : (CID)}, journal = {Commentarii informaticae didacticae : (CID)}, number = {6}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1868-0844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64645}, pages = {155 -- 157}, year = {2013}, abstract = {Problem solving is one of the central activities performed by computer scientists as well as by computer science learners. Whereas the teaching of algorithms and programming languages is usually well structured within a curriculum, the development of learners' problem-solving skills is largely implicit and less structured. Students at all levels often face difficulties in problem analysis and solution construction. The basic assumption of the workshop is that without some formal instruction on effective strategies, even the most inventive learner may resort to unproductive trial-and-error problemsolving processes. Hence, it is important to teach problem-solving strategies and to guide teachers on how to teach their pupils this cognitive tool. Computer science educators should be aware of the difficulties and acquire appropriate pedagogical tools to help their learners gain and experience problem-solving skills.}, language = {en} } @phdthesis{Scheffler2013, author = {Scheffler, Thomas}, title = {Privacy enforcement with data owner-defined policies}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67939}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {This thesis proposes a privacy protection framework for the controlled distribution and use of personal private data. The framework is based on the idea that privacy policies can be set directly by the data owner and can be automatically enforced against the data user. Data privacy continues to be a very important topic, as our dependency on electronic communication maintains its current growth, and private data is shared between multiple devices, users and locations. The growing amount and the ubiquitous availability of personal private data increases the likelihood of data misuse. Early privacy protection techniques, such as anonymous email and payment systems have focused on data avoidance and anonymous use of services. They did not take into account that data sharing cannot be avoided when people participate in electronic communication scenarios that involve social interactions. This leads to a situation where data is shared widely and uncontrollably and in most cases the data owner has no control over further distribution and use of personal private data. Previous efforts to integrate privacy awareness into data processing workflows have focused on the extension of existing access control frameworks with privacy aware functions or have analysed specific individual problems such as the expressiveness of policy languages. So far, very few implementations of integrated privacy protection mechanisms exist and can be studied to prove their effectiveness for privacy protection. Second level issues that stem from practical application of the implemented mechanisms, such as usability, life-time data management and changes in trustworthiness have received very little attention so far, mainly because they require actual implementations to be studied. Most existing privacy protection schemes silently assume that it is the privilege of the data user to define the contract under which personal private data is released. Such an approach simplifies policy management and policy enforcement for the data user, but leaves the data owner with a binary decision to submit or withhold his or her personal data based on the provided policy. We wanted to empower the data owner to express his or her privacy preferences through privacy policies that follow the so-called Owner-Retained Access Control (ORAC) model. ORAC has been proposed by McCollum, et al. as an alternate access control mechanism that leaves the authority over access decisions by the originator of the data. The data owner is given control over the release policy for his or her personal data, and he or she can set permissions or restrictions according to individually perceived trust values. Such a policy needs to be expressed in a coherent way and must allow the deterministic policy evaluation by different entities. The privacy policy also needs to be communicated from the data owner to the data user, so that it can be enforced. Data and policy are stored together as a Protected Data Object that follows the Sticky Policy paradigm as defined by Mont, et al. and others. We developed a unique policy combination approach that takes usability aspects for the creation and maintenance of policies into consideration. Our privacy policy consists of three parts: A Default Policy provides basic privacy protection if no specific rules have been entered by the data owner. An Owner Policy part allows the customisation of the default policy by the data owner. And a so-called Safety Policy guarantees that the data owner cannot specify disadvantageous policies, which, for example, exclude him or her from further access to the private data. The combined evaluation of these three policy-parts yields the necessary access decision. The automatic enforcement of privacy policies in our protection framework is supported by a reference monitor implementation. We started our work with the development of a client-side protection mechanism that allows the enforcement of data-use restrictions after private data has been released to the data user. The client-side enforcement component for data-use policies is based on a modified Java Security Framework. Privacy policies are translated into corresponding Java permissions that can be automatically enforced by the Java Security Manager. When we later extended our work to implement server-side protection mechanisms, we found several drawbacks for the privacy enforcement through the Java Security Framework. We solved this problem by extending our reference monitor design to use Aspect-Oriented Programming (AOP) and the Java Reflection API to intercept data accesses in existing applications and provide a way to enforce data owner-defined privacy policies for business applications.}, language = {en} } @phdthesis{Haider2013, author = {Haider, Peter}, title = {Prediction with Mixture Models}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69617}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Learning a model for the relationship between the attributes and the annotated labels of data examples serves two purposes. Firstly, it enables the prediction of the label for examples without annotation. Secondly, the parameters of the model can provide useful insights into the structure of the data. If the data has an inherent partitioned structure, it is natural to mirror this structure in the model. Such mixture models predict by combining the individual predictions generated by the mixture components which correspond to the partitions in the data. Often the partitioned structure is latent, and has to be inferred when learning the mixture model. Directly evaluating the accuracy of the inferred partition structure is, in many cases, impossible because the ground truth cannot be obtained for comparison. However it can be assessed indirectly by measuring the prediction accuracy of the mixture model that arises from it. This thesis addresses the interplay between the improvement of predictive accuracy by uncovering latent cluster structure in data, and further addresses the validation of the estimated structure by measuring the accuracy of the resulting predictive model. In the application of filtering unsolicited emails, the emails in the training set are latently clustered into advertisement campaigns. Uncovering this latent structure allows filtering of future emails with very low false positive rates. In order to model the cluster structure, a Bayesian clustering model for dependent binary features is developed in this thesis. Knowing the clustering of emails into campaigns can also aid in uncovering which emails have been sent on behalf of the same network of captured hosts, so-called botnets. This association of emails to networks is another layer of latent clustering. Uncovering this latent structure allows service providers to further increase the accuracy of email filtering and to effectively defend against distributed denial-of-service attacks. To this end, a discriminative clustering model is derived in this thesis that is based on the graph of observed emails. The partitionings inferred using this model are evaluated through their capacity to predict the campaigns of new emails. Furthermore, when classifying the content of emails, statistical information about the sending server can be valuable. Learning a model that is able to make use of it requires training data that includes server statistics. In order to also use training data where the server statistics are missing, a model that is a mixture over potentially all substitutions thereof is developed. Another application is to predict the navigation behavior of the users of a website. Here, there is no a priori partitioning of the users into clusters, but to understand different usage scenarios and design different layouts for them, imposing a partitioning is necessary. The presented approach simultaneously optimizes the discriminative as well as the predictive power of the clusters. Each model is evaluated on real-world data and compared to baseline methods. The results show that explicitly modeling the assumptions about the latent cluster structure leads to improved predictions compared to the baselines. It is beneficial to incorporate a small number of hyperparameters that can be tuned to yield the best predictions in cases where the prediction accuracy can not be optimized directly.}, language = {en} } @misc{StreckerKampeSuetterlinetal.2013, author = {Strecker, Manfred and Kampe, Heike and S{\"u}tterlin, Sabine and Horn-Conrad, Antje and Zimmermann, Matthias and Eckardt, Barbara and G{\"o}rlich, Petra}, title = {Portal Wissen = Layers}, number = {01/2013}, organization = {University of Potsdam, Press and Public Relations Department}, issn = {2198-9974}, doi = {10.25932/publishup-44140}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441404}, pages = {53}, year = {2013}, abstract = {The latest edition of our Potsdam Research Magazine "Portal Wissen" addresses the topic "Layers" in many different ways. Geoscientists often deal with layers: layers of soil, sediment, or rock are the evidence of repeated and long-lasting processes of erosion and sedimentation that took place in the early history of the earth. For instance, mountains are eroded by water, ice and wind. The sand that results from that erosion might eventually form a new layer on the ocean floor known as a sediment horizon. After tens of millions of years, tectonic plate movements can deform the ocean floor, pushing it upwards as mountains are created, bringing the layers of sand from former mountain chains together with fossilized sea dwellers into the realm of climbers and mountaineers - a fundamental cycle within the Earth system that was succinctly described by Ibn Sina nearly 1000 years ago, and later by Charles Darwin when he was crossing the Andes. The landscape around us overlays the products of recent processes with those from the past. Slow processes or extreme events that happen very rarely - like floods, earthquakes or rockslides - wipe out certain characteristics, while others remain on the surface. In this sense, the landscape is like a palimpsest - a piece of parchment that monks in the Middle Ages scraped clean again and again to write something new. Analysing rock layers and soil is similar to the work of a detective. Geophysical deep sounding with sound and radar waves, precise measurements of motions related to earthquakes, and deep boreholes each provide a glimpse of the characteristics of what lies beneath us, giving us a better understanding of spatial distribution of the various layers. Fossils can tell us the age of a layer of sediment, while radiometric isotopes in minerals reveal how quickly a rock moved from deep within the Earth up to the surface, perhaps during the process of mountain building. Thin layers of ash tell us when there was a devastating volcanic eruption that influenced environmental conditions. The shape, gradation, and surface conditions of sand grains reflect whether wind or water was responsible for their transport. We know, for instance, that northern Germany was a desert landscape more than 260 million years ago. At that time, the wind made huge dunes migrate across the region. Over time, climate and vegetation slowly alter the physical and chemical characteristics of sand and rock at the surface, turning them into soil, the epidermis of our planet. Mineralogical analyses of layers of the soil layer tell us whether the climate was dry or wet. These kinds of observations allow us to reconstruct links between our climate system and processes that have taken place on the Earth's surface, as well as those processes that originate at much deeper levels. The clues we use might be hidden under the surface of the earth or clearly visible on the surface, like in the mountains, or even in freshly cut rock alongside roads. On the following pages, we invite you to accompany scientists from Potsdam into their world of research. They track hidden traces of longgone earthquakes in the Tien Shan Mountains; they discover ancient forms of life in deep-sea sediments. They even examine layers in outer space that can tell us something about the formation of planets. "Portal Wissen" not only presents scientists of the University of Potsdam who deal with the sequence of layers formed by solid rock, but also those scientists who deal with levels of education or social strata. Research scientists explain how to implement the social mission of inclusion in teaching, and how pupils from the Berlin district Kreuzberg examine language in urban neighbourhoods together with students from the University of Potsdam. Although these types of "layers" are very different, they all have something in common. Their structure and profile are evidence of continuously changing conditions. The present will leave traces and layers that future geoscientists will measure and examine. We already speak of the Anthropocene, a geological era dominated by humans, which is characterized by far-reaching changes in erosion and sedimentation rates, and the displacement of natural habitats. I hope that you will discover exciting and inspiring stories in this edition. And remember - it is always worth having a look beneath the surface. Prof. Manfred Strecker, PHD Professor of Geology}, language = {en} } @misc{DemskeSuetterlinRostetal.2013, author = {Demske, Ulrike and S{\"u}tterlin, Sabine and Rost, Sophia and Zimmermann, Matthias and Kampe, Heike and Eckardt, Barbara and Horn-Conrad, Antje}, title = {Portal Wissen = Borders}, number = {02/2013}, organization = {University of Potsdam, Press and Public Relations Department}, issn = {2198-9974}, doi = {10.25932/publishup-44143}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441430}, pages = {55}, year = {2013}, abstract = {The new edition of the Potsdam Research Magazine "Portal Wissen" approaches the subject "Borders" from different perspectives. As a linguist, this headline makes me think of linguistic borders and the effects that might result from the contact of two languages at a particular border. There is, for instance, ample evidence of code-switching, i.e. the use of material from at least two languages in a single utterance. The reasons for code-switching can be manifold. On the one hand, code-switching may result from a limited language competence, for example if a speaker lacks a particular word in a nonnative language. On the other hand, code-switching may be a matter of prestige if the speaker wants to demonstrate his or her affiliation to a certain social group by switching languages. If code-switching does not only occur sporadically but involves whole language communities over a longer period of time, it can result in significant changes of the involved languages. Which language "gives" and which one "takes" is determined by sociolinguistic factors. It is, hence, quite easy to predict that German varieties spoken in language islands in South and Eastern Europe as well as in North and Latin America will absorb more and more language material from their neighbouring languages until they disappear unless political will strives to preserve these language varieties. Increasing mobility of modern societies has multiplied the extent and the intensity of language contact and certainly comprises a large number of different contact situations besides the one most commonly known, i.e. the contact between German and English. From a historic point of view, German witnesses a strong influence of various Romance languages such as Latin, French and Italian. In Potsdam, one cannot help being reminded of the French influence during the 18th century. Overcoming language borders becomes also apparent in the everyday life of an international research university. In March this year, the Annual Conference of the German Linguistic Society took place in Potsdam, with more than 500 participants. Lingua franca of this conference was English. Compared to previous conferences, this further increased the number of international participants. The articles in this edition illustrate various approaches to the topic "Borders": On the trail of "Boundary Surveys", we follow the Australian explorer Ludwig Leichhardt. "Travellers Across Borders" is focussed on articles dealing with the literature of the colonial Caribbean or with the work of an Italian geologist deep beneath the earth's surface, for example. Looking for the "Boundless", our authors follow scientists who discuss questions like "Why love hurts?". The present issue of "Portal Wissen" also takes into account "Drawing Up Borders" in an article that is concerned with the limits of workrelated stress. Instances of successful "Border Crossing" are provided by the "Handkerchief Lab" as well as by new biotechnological applications. I would like to wish you inspiring border experiences, hoping that you will get many impulses for crossing professional borders in your field of expertise. Prof. Ulrike Demske Professor of the History and the Varieties of the German Language Vice President International Affairs, Alumni and Fundraising}, language = {en} } @misc{CherstvyMetzler2013, author = {Cherstvy, Andrey G. and Metzler, Ralf}, title = {Population splitting, trapping, and non-ergodicity in heterogeneous diffusion processes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-94468}, pages = {20220 -- 20235}, year = {2013}, abstract = {We consider diffusion processes with a spatially varying diffusivity giving rise to anomalous diffusion. Such heterogeneous diffusion processes are analysed for the cases of exponential, power-law, and logarithmic dependencies of the diffusion coefficient on the particle position. Combining analytical approaches with stochastic simulations, we show that the functional form of the space-dependent diffusion coefficient and the initial conditions of the diffusing particles are vital for their statistical and ergodic properties. In all three cases a weak ergodicity breaking between the time and ensemble averaged mean squared displacements is observed. We also demonstrate a population splitting of the time averaged traces into fast and slow diffusers for the case of exponential variation of the diffusivity as well as a particle trapping in the case of the logarithmic diffusivity. Our analysis is complemented by the quantitative study of the space coverage, the diffusive spreading of the probability density, as well as the survival probability.}, language = {en} } @phdthesis{Patra2013, author = {Patra, Pintu}, title = {Population dynamics of bacterial persistence}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69253}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The life of microorganisms is characterized by two main tasks, rapid growth under conditions permitting growth and survival under stressful conditions. The environments, in which microorganisms dwell, vary in space and time. The microorganisms innovate diverse strategies to readily adapt to the regularly fluctuating environments. Phenotypic heterogeneity is one such strategy, where an isogenic population splits into subpopulations that respond differently under identical environments. Bacterial persistence is a prime example of such phenotypic heterogeneity, whereby a population survives under an antibiotic attack, by keeping a fraction of population in a drug tolerant state, the persister state. Specifically, persister cells grow more slowly than normal cells under growth conditions, but survive longer under stress conditions such as the antibiotic administrations. Bacterial persistence is identified experimentally by examining the population survival upon an antibiotic treatment and the population resuscitation in a growth medium. The underlying population dynamics is explained with a two state model for reversible phenotype switching in a cell within the population. We study this existing model with a new theoretical approach and present analytical expressions for the time scale observed in population growth and resuscitation, that can be easily used to extract underlying model parameters of bacterial persistence. In addition, we recapitulate previously known results on the evolution of such structured population under periodically fluctuating environment using our simple approximation method. Using our analysis, we determine model parameters for Staphylococcus aureus population under several antibiotics and interpret the outcome of cross-drug treatment. Next, we consider the expansion of a population exhibiting phenotype switching in a spatially structured environment consisting of two growth permitting patches separated by an antibiotic patch. The dynamic interplay of growth, death and migration of cells in different patches leads to distinct regimes in population propagation speed as a function of migration rate. We map out the region in parameter space of phenotype switching and migration rate to observe the condition under which persistence is beneficial. Furthermore, we present an extended model that allows mutation from the two phenotypic states to a resistant state. We find that the presence of persister cells may enhance the probability of resistant mutation in a population. Using this model, we explain the experimental results showing the emergence of antibiotic resistance in a Staphylococcus aureus population upon tobramycin treatment. In summary, we identify several roles of bacterial persistence, such as help in spatial expansion, development of multidrug tolerance and emergence of antibiotic resistance. Our study provides a theoretical perspective on the dynamics of bacterial persistence in different environmental conditions. These results can be utilized to design further experiments, and to develop novel strategies to eradicate persistent infections.}, language = {en} } @unpublished{Eckstein2013, author = {Eckstein, Lars}, title = {Politics of passion and the production of human illegality}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-85512}, pages = {20}, year = {2013}, language = {en} } @misc{DiFlorioBruendermannYadavallietal.2013, author = {Di Florio, Giuseppe and Br{\"u}ndermann, Erik and Yadavalli, Nataraja Sekhar and Santer, Svetlana and Havenith, Martina}, title = {Polarized 3D Raman and nanoscale near-field optical microscopy of optically inscribed surface relief gratings}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95233}, pages = {1544 -- 1554}, year = {2013}, abstract = {We have used polarized confocal Raman microspectroscopy and scanning near-field optical microscopy with a resolution of 60 nm to characterize photoinscribed grating structures of azobenzene doped polymer films on a glass support. Polarized Raman microscopy allowed determining the reorientation of the chromophores as a function of the grating phase and penetration depth of the inscribing laser in three dimensions. We found periodic patterns, which are not restricted to the surface alone, but appear also well below the surface in the bulk of the material. Near-field optical microscopy with nanoscale resolution revealed lateral two-dimensional optical contrast, which is not observable by atomic force and Raman microscopy.}, language = {en} } @misc{WessigMatthes2013, author = {Wessig, Pablo and Matthes, Annika}, title = {Photochemical synthesis and properties of 1,6- and 1,8-Naphthalenophanes}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1042}, issn = {1866-8372}, doi = {10.25932/publishup-47667}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-476675}, pages = {13}, year = {2013}, abstract = {Various 1,6- and 1,8-naphthalenophanes were synthesized by using the Photo-Dehydro-Diels-Alder (PDDA) reaction of bis-ynones. These compounds are easily accessible from omega-(3-iodophenyl)carboxylic acids in three steps. The obtained naphthalenophanes are axially chiral and the activation barrier for the atropisomerization could be determined in some cases by means of dynamic NMR (DNMR) and/or dynamic HPLC (DHPLC) experiments.}, language = {en} } @misc{SchoenbornHartke2013, author = {Sch{\"o}nborn, Jan Boyke and Hartke, Bernd}, title = {Photochemical dynamics of E-methylfurylfulgide}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-94516}, pages = {2483 -- 2490}, year = {2013}, abstract = {With the present theoretical study of the photochemical switching of E-methylfurylfulgide we contribute an important step towards the understanding of the photochemical processes in furylfulgide-related molecules. We have carried out large-scale, full-dimensional direct semiempirical configuration-interaction surface-hopping dynamics of the photoinduced ring-closure reaction. Simulated static and dynamical UV/Vis-spectra show good agreement with experimental data of the same molecule. By a careful investigation of our dynamical data, we were able to identify marked differences to the dynamics of the previously studied E-isopropylfurylfulgide. With our simulations we can not only reproduce the experimentally observed quantum yield differences qualitatively but we can also pinpoint two reasons for them: kinematics and pre-orientation. With our analysis, we thus offer straightforward molecular explanations for the high sensitivity of the photodynamics towards seemingly minor changes in molecular constitution. Beyond the realm of furylfulgides, these insights provide additional guidance to the rational design of photochemically switchable molecules.}, language = {en} } @phdthesis{Nitschke2013, author = {Nitschke, Felix}, title = {Phosphorylation of polyglycans, especially glycogen and starch}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67396}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Functional metabolism of storage carbohydrates is vital to plants and animals. The water-soluble glycogen in animal cells and the amylopectin which is the major component of water-insoluble starch granules residing in plant plastids are chemically similar as they consist of α-1,6 branched α-1,4 glucan chains. Synthesis and degradation of transitory starch and of glycogen are accomplished by a set of enzymatic activities that to some extend are also similar in plants and animals. Chain elongation, branching, and debranching are achieved by synthases, branching enzymes, and debranching enzymes, respectively. Similarly, both types of polyglucans contain low amounts of phosphate esters whose abundance varies depending on species and organs. Starch is selectively phosphorylated by at least two dikinases (GWD and PWD) at the glucosyl carbons C6 and C3 and dephosphorylated by the phosphatase SEX4 and SEX4-like enzymes. In Arabidopsis insufficiency in starch phosphorylation or dephosphorylation results in largely impaired starch turnover, starch accumulation, and often in retardation of growth. In humans the progressive neurodegenerative epilepsy, Lafora disease, is the result of a defective enzyme (laforin) that is functional equivalent to the starch phosphatase SEX4 and capable of glycogen dephosphorylation. Patients lacking laforin progressively accumulate unphysiologically structured insoluble glycogen-derived particles (Lafora bodies) in many tissues including brain. Previous results concerning the carbon position of glycogen phosphate are contradictory. Currently it is believed that glycogen is esterified exclusively at the carbon positions C2 and C3 and that the monophosphate esters, being incorporated via a side reaction of glycogen synthase (GS), lack any specific function but are rather an enzymatic error that needs to be corrected. In this study a versatile and highly sensitive enzymatic cycling assay was established that enables quantification of very small G6P amounts in the presence of high concentrations of non-target compounds as present in hydrolysates of polysaccharides, such as starch, glycogen, or cytosolic heteroglycans in plants. Following validation of the G6P determination by analyzing previously characterized starches G6P was quantified in hydrolysates of various glycogen samples and in plant heteroglycans. Interestingly, glucosyl C6 phosphate is present in all glycogen preparations examined, the abundance varying between glycogens of different sources. Additionally, it was shown that carbon C6 is severely hyperphosphorylated in glycogen of Lafora disease mouse model and that laforin is capable of removing C6 phosphate from glycogen. After enrichment of phosphoglucans from amylolytically degraded glycogen, several techniques of two-dimensional NMR were applied that independently proved the existence of 6-phosphoglucosyl residues in glycogen and confirmed the recently described phosphorylation sites C2 and C3. C6 phosphate is neither Lafora disease- nor species-, or organ-specific as it was demonstrated in liver glycogen from laforin-deficient mice and in that of wild type rabbit skeletal muscle. The distribution of 6-phosphoglucosyl residues was analyzed in glycogen molecules and has been found to be uneven. Gradual degradation experiments revealed that C6 phosphate is more abundant in central parts of the glycogen molecules and in molecules possessing longer glucan chains. Glycogen of Lafora disease mice consistently contains a higher proportion of longer chains while most short chains were reduced as compared to wild type. Together with results recently published (Nitschke et al., 2013) the findings of this work completely unhinge the hypothesis of GS-mediated phosphate incorporation as the respective reaction mechanism excludes phosphorylation of this glucosyl carbon, and as it is difficult to explain an uneven distribution of C6 phosphate by a stochastic event. Indeed the results rather point to a specific function of 6-phosphoglucosyl residues in the metabolism of polysaccharides as they are present in starch, glycogen, and, as described in this study, in heteroglycans of Arabidopsis. In the latter the function of phosphate remains unclear but this study provides evidence that in starch and glycogen it is related to branching. Moreover a role of C6 phosphate in the early stages of glycogen synthesis is suggested. By rejecting the current view on glycogen phosphate to be a stochastic biochemical error the results permit a wider view on putative roles of glycogen phosphate and on alternative biochemical ways of glycogen phosphorylation which for many reasons are likely to be mediated by distinct phosphorylating enzymes as it is realized in starch metabolism of plants. Better understanding of the enzymology underlying glycogen phosphorylation implies new possibilities of Lafora disease treatment.}, language = {en} } @article{Noack2013, author = {Noack, Harald}, title = {Perspectives of European Banking Regulations}, series = {Protokollband 2013}, journal = {Protokollband 2013}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68760}, pages = {167 -- 175}, year = {2013}, abstract = {1. Introduction 2. The architecture of the financial market regulation in Europe prior to the crisis 3. The new architecture of the financial market regulation in Europe 4. Actual issues of the political discussion on further needs to adapt the regulation and the structure of the financial markets in Europe 5. A brief summary}, language = {en} }