@article{ArvidssonPerezRodriguezMuellerRoeber2011, author = {Arvidsson, Samuel Janne and Perez-Rodriguez, Paulino and M{\"u}ller-R{\"o}ber, Bernd}, title = {A growth phenotyping pipeline for Arabidopsis thaliana integrating image analysis and rosette area modeling for robust quantification of genotype effects}, series = {New phytologist : international journal of plant science}, volume = {191}, journal = {New phytologist : international journal of plant science}, number = {3}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0028-646X}, doi = {10.1111/j.1469-8137.2011.03756.x}, pages = {895 -- 907}, year = {2011}, abstract = {To gain a deeper understanding of the mechanisms behind biomass accumulation, it is important to study plant growth behavior. Manually phenotyping large sets of plants requires important human resources and expertise and is typically not feasible for detection of weak growth phenotypes. Here, we established an automated growth phenotyping pipeline for Arabidopsis thaliana to aid researchers in comparing growth behaviors of different genotypes. The analysis pipeline includes automated image analysis of two-dimensional digital plant images and evaluation of manually annotated information of growth stages. It employs linear mixed-effects models to quantify genotype effects on total rosette area and relative leaf growth rate (RLGR) and ANOVAs to quantify effects on developmental times. Using the system, a single researcher can phenotype up to 7000 plants d(-1). Technical variance is very low (typically < 2\%). We show quantitative results for the growth-impaired starch-excessmutant sex4-3 and the growth-enhancedmutant grf9. We show that recordings of environmental and developmental variables reduce noise levels in the phenotyping datasets significantly and that careful examination of predictor variables (such as d after sowing or germination) is crucial to avoid exaggerations of recorded phenotypes and thus biased conclusions.}, language = {en} } @phdthesis{Kneis2007, author = {Kneis, David}, title = {A water quality model for shallow river-lake systems and its application in river basin management}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14647}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {This work documents the development and application of a new model for simulating mass transport and turnover in rivers and shallow lakes. The simulation tool called 'TRAM' is intended to complement mesoscale eco-hydrological catchment models in studies on river basin management. TRAM aims at describing the water quality of individual water bodies, using problem- and scale-adequate approaches for representing their hydrological and ecological characteristics. The need for such flexible water quality analysis and prediction tools is expected to further increase during the implementation of the European Water Framework Directive (WFD) as well as in the context of climate change research. The developed simulation tool consists of a transport and a reaction module with the latter being highly flexible with respect to the description of turnover processes in the aquatic environment. Therefore, simulation approaches of different complexity can easily be tested and model formulations can be chosen in consideration of the problem at hand, knowledge of process functioning, and data availability. Consequently, TRAM is suitable for both heavily simplified engineering applications as well as scientific ecosystem studies involving a large number of state variables, interactions, and boundary conditions. TRAM can easily be linked to catchment models off-line and it requires the use of external hydrodynamic simulation software. Parametrization of the model and visualization of simulation results are facilitated by the use of geographical information systems as well as specific pre- and post-processors. TRAM has been developed within the research project 'Management Options for the Havel River Basin' funded by the German Ministry of Education and Research. The project focused on the analysis of different options for reducing the nutrient load of surface waters. It was intended to support the implementation of the WFD in the lowland catchment of the Havel River located in North-East Germany. Within the above-mentioned study TRAM was applied with two goals in mind. In a first step, the model was used for identifying the magnitude as well as spatial and temporal patterns of nitrogen retention and sediment phosphorus release in a 100~km stretch of the highly eutrophic Lower Havel River. From the system analysis, strongly simplified conceptual approaches for modeling N-retention and P-remobilization in the studied river-lake system were obtained. In a second step, the impact of reduced external nutrient loading on the nitrogen and phosphorus concentrations of the Havel River was simulated (scenario analysis) taking into account internal retention/release. The boundary conditions for the scenario analysis such as runoff and nutrient emissions from river basins were computed by project partners using the catchment models SWIM and ArcEGMO-Urban. Based on the output of TRAM, the considered options of emission control could finally be evaluated using a site-specific assessment scale which is compatible with the requirements of the WFD. Uncertainties in the model predictions were also examined. According to simulation results, the target of the WFD -- with respect to total phosphorus concentrations in the Lower Havel River -- could be achieved in the medium-term, if the full potential for reducing point and non-point emissions was tapped. Furthermore, model results suggest that internal phosphorus loading will ease off noticeably until 2015 due to a declining pool of sedimentary mobile phosphate. Mass balance calculations revealed that the lakes of the Lower Havel River are an important nitrogen sink. This natural retention effect contributes significantly to the efforts aimed at reducing the river's nitrogen load. If a sustainable improvement of the river system's water quality is to be achieved, enhanced measures to further reduce the immissions of both phosphorus and nitrogen are required.}, language = {en} } @phdthesis{MalemShinitski2023, author = {Malem-Shinitski, Noa}, title = {Bayesian inference and modeling for point processes with applications from neuronal activity to scene viewing}, doi = {10.25932/publishup-61495}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-614952}, school = {Universit{\"a}t Potsdam}, pages = {vii, 129}, year = {2023}, abstract = {Point processes are a common methodology to model sets of events. From earthquakes to social media posts, from the arrival times of neuronal spikes to the timing of crimes, from stock prices to disease spreading -- these phenomena can be reduced to the occurrences of events concentrated in points. Often, these events happen one after the other defining a time--series. Models of point processes can be used to deepen our understanding of such events and for classification and prediction. Such models include an underlying random process that generates the events. This work uses Bayesian methodology to infer the underlying generative process from observed data. Our contribution is twofold -- we develop new models and new inference methods for these processes. We propose a model that extends the family of point processes where the occurrence of an event depends on the previous events. This family is known as Hawkes processes. Whereas in most existing models of such processes, past events are assumed to have only an excitatory effect on future events, we focus on the newly developed nonlinear Hawkes process, where past events could have excitatory and inhibitory effects. After defining the model, we present its inference method and apply it to data from different fields, among others, to neuronal activity. The second model described in the thesis concerns a specific instance of point processes --- the decision process underlying human gaze control. This process results in a series of fixated locations in an image. We developed a new model to describe this process, motivated by the known Exploration--Exploitation dilemma. Alongside the model, we present a Bayesian inference algorithm to infer the model parameters. Remaining in the realm of human scene viewing, we identify the lack of best practices for Bayesian inference in this field. We survey four popular algorithms and compare their performances for parameter inference in two scan path models. The novel models and inference algorithms presented in this dissertation enrich the understanding of point process data and allow us to uncover meaningful insights.}, language = {en} } @article{AliHomannKreiseletal.2012, author = {Ali, Mostafa and Homann, Thomas and Kreisel, Janka and Khalil, Mahmoud and Puhlmann, Ralf and Kruse, Hans-Peter and Rawel, Harshadrai Manilal}, title = {Characterization and modeling of the interactions between coffee storage proteins and phenolic compounds}, series = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, volume = {60}, journal = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, number = {46}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-8561}, doi = {10.1021/jf303372a}, pages = {11601 -- 11608}, year = {2012}, abstract = {This study addresses the interactions of coffee storage proteins with coffee-specific phenolic compounds. Protein profiles, of Coffea arabica and Coffea canephora (var robusta) were compared. Major Phenolic compounds were extracted and analyzed with appropriate methods. The polyphenol-protein interactions during protein extraction have been addressed by different analytical setups [reversed-phase high-performance liquid chromatography (RP-HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS), and Trolox equivalent antioxidant capacity (TEAC) assays], with focus directed toward identification of covalent adduct formation. The results indicate that C. arabica proteins are more susceptible to these interactions and the polyphenol oxidase activity seems to be a crucial factor for the formation of these addition products. A tentative allocation of the modification type and site in the protein has been attempted. Thus, the first available in silico modeling of modified coffee proteins is reported. The extent of these modifications may contribute to the structure and function of "coffee melanoidins" and are discussed in the context of coffee flavor formation.}, language = {en} } @misc{AyzelIzhitskiy2019, author = {Ayzel, Georgy and Izhitskiy, Alexander}, title = {Climate change impact assessment on freshwater inflow into the Small Aral Sea}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1071}, issn = {1866-8372}, doi = {10.25932/publishup-47279}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472794}, pages = {21}, year = {2019}, abstract = {During the last few decades, the rapid separation of the Small Aral Sea from the isolated basin has changed its hydrological and ecological conditions tremendously. In the present study, we developed and validated the hybrid model for the Syr Darya River basin based on a combination of state-of-the-art hydrological and machine learning models. Climate change impact on freshwater inflow into the Small Aral Sea for the projection period 2007-2099 has been quantified based on the developed hybrid model and bias corrected and downscaled meteorological projections simulated by four General Circulation Models (GCM) for each of three Representative Concentration Pathway scenarios (RCP). The developed hybrid model reliably simulates freshwater inflow for the historical period with a Nash-Sutcliffe efficiency of 0.72 and a Kling-Gupta efficiency of 0.77. Results of the climate change impact assessment showed that the freshwater inflow projections produced by different GCMs are misleading by providing contradictory results for the projection period. However, we identified that the relative runoff changes are expected to be more pronounced in the case of more aggressive RCP scenarios. The simulated projections of freshwater inflow provide a basis for further assessment of climate change impacts on hydrological and ecological conditions of the Small Aral Sea in the 21st Century.}, language = {en} } @article{AyzelIzhitskiy2019, author = {Ayzel, Georgy and Izhitskiy, Alexander}, title = {Climate Change Impact Assessment on Freshwater Inflow into the Small Aral Sea}, series = {Water}, volume = {11}, journal = {Water}, number = {11}, publisher = {MDPI}, address = {Basel}, issn = {2073-4441}, doi = {10.3390/w11112377}, pages = {19}, year = {2019}, abstract = {During the last few decades, the rapid separation of the Small Aral Sea from the isolated basin has changed its hydrological and ecological conditions tremendously. In the present study, we developed and validated the hybrid model for the Syr Darya River basin based on a combination of state-of-the-art hydrological and machine learning models. Climate change impact on freshwater inflow into the Small Aral Sea for the projection period 2007-2099 has been quantified based on the developed hybrid model and bias corrected and downscaled meteorological projections simulated by four General Circulation Models (GCM) for each of three Representative Concentration Pathway scenarios (RCP). The developed hybrid model reliably simulates freshwater inflow for the historical period with a Nash-Sutcliffe efficiency of 0.72 and a Kling-Gupta efficiency of 0.77. Results of the climate change impact assessment showed that the freshwater inflow projections produced by different GCMs are misleading by providing contradictory results for the projection period. However, we identified that the relative runoff changes are expected to be more pronounced in the case of more aggressive RCP scenarios. The simulated projections of freshwater inflow provide a basis for further assessment of climate change impacts on hydrological and ecological conditions of the Small Aral Sea in the 21st Century.}, language = {en} } @article{AbramovaBatzelModesti2022, author = {Abramova, Olga and Batzel, Katharina and Modesti, Daniela}, title = {Collective response to the health crisis among German Twitter users}, series = {International Journal of Information Management Data Insights}, volume = {2}, journal = {International Journal of Information Management Data Insights}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2667-0968}, doi = {10.1016/j.jjimei.2022.100126}, pages = {13}, year = {2022}, abstract = {We used structural topic modeling to analyze over 800,000 German tweets about COVID-19 to answer the questions: What patterns emerge in tweets as a response to a health crisis? And how do topics discussed change over time? The study leans on the goals associated with the health information seeking (GAINS) model, discerning whether a post aims at tackling and eliminating the problem (i.e., problem-focused) or managing the emotions (i.e., emotion-focused); whether it strives to maximize positive outcomes (promotion focus) or to minimize negative outcomes (prevention focus). The findings indicate four clusters salient in public reactions: 1) "Understanding" (problem-promotion); 2) "Action planning" (problem-prevention); 3) "Hope" (emotion-promotion) and 4) "Reassurance" (emotion-prevention). Public communication is volatile over time, and a shift is evidenced from self-centered to community-centered topics within 4.5 weeks. Our study illustrates social media text mining's potential to quickly and efficiently extract public opinions and reactions. Monitoring fears and trending topics enable policymakers to rapidly respond to deviant behavior, like resistive attitudes toward containment measures or deteriorating physical health. Healthcare workers can use the insights to provide mental health services for battling anxiety or extensive loneliness from staying home.}, language = {en} } @book{BeckerGiese2012, author = {Becker, Basil and Giese, Holger}, title = {Cyber-physical systems with dynamic structure : towards modeling and verification of inductive invariants}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-217-9}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-62437}, publisher = {Universit{\"a}t Potsdam}, pages = {iv, 27}, year = {2012}, abstract = {Cyber-physical systems achieve sophisticated system behavior exploring the tight interconnection of physical coupling present in classical engineering systems and information technology based coupling. A particular challenging case are systems where these cyber-physical systems are formed ad hoc according to the specific local topology, the available networking capabilities, and the goals and constraints of the subsystems captured by the information processing part. In this paper we present a formalism that permits to model the sketched class of cyber-physical systems. The ad hoc formation of tightly coupled subsystems of arbitrary size are specified using a UML-based graph transformation system approach. Differential equations are employed to define the resulting tightly coupled behavior. Together, both form hybrid graph transformation systems where the graph transformation rules define the discrete steps where the topology or modes may change, while the differential equations capture the continuous behavior in between such discrete changes. In addition, we demonstrate that automated analysis techniques known for timed graph transformation systems for inductive invariants can be extended to also cover the hybrid case for an expressive case of hybrid models where the formed tightly coupled subsystems are restricted to smaller local networks.}, language = {en} } @article{Ayzel2021, author = {Ayzel, Georgy}, title = {Deep neural networks in hydrology}, series = {Vestnik of Saint Petersburg University. Earth Sciences}, volume = {66}, journal = {Vestnik of Saint Petersburg University. Earth Sciences}, number = {1}, publisher = {Univ. Press}, address = {St. Petersburg}, issn = {2541-9668}, doi = {10.21638/spbu07.2021.101}, pages = {5 -- 18}, year = {2021}, abstract = {For around a decade, deep learning - the sub-field of machine learning that refers to artificial neural networks comprised of many computational layers - modifies the landscape of statistical model development in many research areas, such as image classification, machine translation, and speech recognition. Geoscientific disciplines in general and the field of hydrology in particular, also do not stand aside from this movement. Recently, the proliferation of modern deep learning-based techniques and methods has been actively gaining popularity for solving a wide range of hydrological problems: modeling and forecasting of river runoff, hydrological model parameters regionalization, assessment of available water resources. identification of the main drivers of the recent change in water balance components. This growing popularity of deep neural networks is primarily due to their high universality and efficiency. The presented qualities, together with the rapidly growing amount of accumulated environmental information, as well as increasing availability of computing facilities and resources, allow us to speak about deep neural networks as a new generation of mathematical models designed to, if not to replace existing solutions, but significantly enrich the field of geophysical processes modeling. This paper provides a brief overview of the current state of the field of development and application of deep neural networks in hydrology. Also in the following study, the qualitative long-term forecast regarding the development of deep learning technology for managing the corresponding hydrological modeling challenges is provided based on the use of "Gartner Hype Curve", which in the general details describes a life cycle of modern technologies.}, language = {en} } @misc{Huebner2021, type = {Master Thesis}, author = {H{\"u}bner, Andrea}, title = {Ein multityper Verzweigungsprozess als Modell zur Untersuchung der Ausbreitung von Covid-19}, doi = {10.25932/publishup-50922}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-509225}, school = {Universit{\"a}t Potsdam}, year = {2021}, abstract = {Im Zuge der Covid-19 Pandemie werden zwei Werte t{\"a}glich diskutiert: Die zuletzt gemeldete Zahl der neu Infizierten und die sogenannte Reproduktionsrate. Sie gibt wieder, wie viele weitere Menschen ein an Corona erkranktes Individuum im Durchschnitt ansteckt. F{\"u}r die Sch{\"a}tzung dieses Wertes gibt es viele M{\"o}glichkeiten - auch das Robert Koch-Institut gibt in seinem t{\"a}glichen Situationsbericht stets zwei R-Werte an: Einen 4-Tage-R-Wert und einen weniger schwankenden 7-Tage-R-Wert. Diese Arbeit soll eine weitere M{\"o}glichkeit vorstellen, einige Aspekte der Pandemie zu modellieren und die Reproduktionsrate zu sch{\"a}tzen. In der ersten H{\"a}lfte der Arbeit werden die mathematischen Grundlagen vorgestellt, die man f{\"u}r die Modellierung ben{\"o}tigt. Hierbei wird davon ausgegangen, dass der Leser bereits ein Basisverst{\"a}ndnis von stochastischen Prozessen hat. Im Abschnitt Grundlagen werden Verzweigungsprozesse mit einigen Beispielen eingef{\"u}hrt und die Ergebnisse aus diesem Themengebiet, die f{\"u}r diese Arbeit wichtig sind, pr{\"a}sentiert. Dabei gehen wir zuerst auf einfache Verzweigungsprozesse ein und erweitern diese dann auf Verzweigungsprozesse mit mehreren Typen. Um die Notation zu erleichtern, beschr{\"a}nken wir uns auf zwei Typen. Das Prinzip l{\"a}sst sich aber auf eine beliebige Anzahl von Typen erweitern. Vor allem soll die Wichtigkeit des Parameters λ herausgestellt werden. Dieser Wert kann als durchschnittliche Zahl von Nachfahren eines Individuums interpretiert werden und bestimmt die Dynamik des Prozesses {\"u}ber einen l{\"a}ngeren Zeitraum. In der Anwendung auf die Pandemie hat der Parameter λ die gleiche Rolle wie die Reproduktionsrate R. In der zweiten H{\"a}lfte dieser Arbeit stellen wir eine Anwendung der Theorie {\"u}ber Multitype Verzweigungsprozesse vor. Professor Yanev und seine Mitarbeiter modellieren in ihrer Ver{\"o}ffentlichung Branching stochastic processes as models of Covid-19 epidemic development die Ausbreitung des Corona Virus' {\"u}ber einen Verzweigungsprozess mit zwei Typen. Wir werden dieses Modell diskutieren und Sch{\"a}tzer daraus ableiten: Ziel ist es, die Reproduktionsrate zu ermitteln. Außerdem analysieren wir die M{\"o}glichkeiten, die Dunkelziffer (die Zahl nicht gemeldeter Krankheitsf{\"a}lle) zu sch{\"a}tzen. Wir wenden die Sch{\"a}tzer auf die Zahlen von Deutschland an und werten diese schließlich aus.}, language = {de} } @incollection{HaaseThimBender2022, author = {Haase, Jennifer and Thim, Christof and Bender, Benedict}, title = {Expanding modeling notations}, series = {Business process management workshops}, volume = {436}, booktitle = {Business process management workshops}, editor = {Marrella, Andrea and Weber, Barbara}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-94342-4}, doi = {10.1007/978-3-030-94343-1_15}, pages = {197 -- 208}, year = {2022}, abstract = {Creativity is a common aspect of business processes and thus needs a proper representation through process modeling notations. However, creative processes constitute highly flexible process elements, as new and unforeseeable outcome is developed. This presents a challenge for modeling languages. Current methods representing creative-intensive work are rather less able to capture creative specifics which are relevant to successfully run and manage these processes. We outline the concept of creative-intensive processes and present an example from a game design process in order to derive critical process aspects relevant for its modeling. Six aspects are detected, with first and foremost: process flexibility, as well as temporal uncertainty, experience, types of creative problems, phases of the creative process and individual criteria. By first analyzing what aspects of creative work modeling notations already cover, we further discuss which modeling extensions need to be developed to better represent creativity within business processes. We argue that a proper representation of creative work would not just improve the management of those processes, but can further enable process actors to more efficiently run these creative processes and adjust them to better fit to the creative needs.}, language = {en} } @article{SimikWierzba2017, author = {Simik, Radek and Wierzba, Marta}, title = {EXPRESSION OF INFORMATION STRUCTURE IN WEST SLAVIC: MODELING THE IMPACT OF PROSODIC AND WORD-ORDER FACTORS}, series = {Language : journal of the Linguistic Society of America}, volume = {93}, journal = {Language : journal of the Linguistic Society of America}, publisher = {Linguistic Society of America}, address = {Washington}, issn = {0097-8507}, doi = {10.1353/lan.2017.0040}, pages = {671 -- 709}, year = {2017}, abstract = {The received wisdom is that word-order alternations in Slavic languages arise as a direct consequence of word-order-related information-structure constraints such as 'Place given expressions before new ones'. In this article, we compare the word-order hypothesis with a competing one, according to which word-order alternations arise as a consequence of a prosodic constraint: 'Avoid stress on given expressions'. Based on novel experimental and modeling data, we conclude that the prosodic hypothesis is more adequate than the word-order hypothesis. Yet we also show that combining the strengths of both hypotheses provides the best fit for the data. Methodologically, our article is based on gradient acceptability judgments and multiple regression, which allows us to evaluate whether violations of generalizations like 'Given precedes new' or 'Given lacks stress' lead to a consistent decrease in acceptability and to quantify the size of their respective effects. Focusing on the empirical adequacy of such generalizations rather than on specific theoretical implementations also makes it possible to bridge the gap between different linguistic traditions and to directly compare predictions emerging from formal and functional approaches.}, language = {en} } @misc{HornBecherJohstetal.2020, author = {Horn, Juliane and Becher, Matthias A. and Johst, Karin and Kennedy, Peter J. and Osborne, Juliet L. and Radchuk, Viktoriia and Grimm, Volker}, title = {Honey bee colony performance affected by crop diversity and farmland structure}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1}, issn = {1866-8372}, doi = {10.25932/publishup-55694}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-556943}, pages = {24}, year = {2020}, abstract = {Forage availability has been suggested as one driver of the observed decline in honey bees. However, little is known about the effects of its spatiotemporal variation on colony success. We present a modeling framework for assessing honey bee colony viability in cropping systems. Based on two real farmland structures, we developed a landscape generator to design cropping systems varying in crop species identity, diversity, and relative abundance. The landscape scenarios generated were evaluated using the existing honey bee colony model BEEHAVE, which links foraging to in-hive dynamics. We thereby explored how different cropping systems determine spatiotemporal forage availability and, in turn, honey bee colony viability (e.g., time to extinction, TTE) and resilience (indicated by, e.g., brood mortality). To assess overall colony viability, we developed metrics,P(H)andP(P,)which quantified how much nectar and pollen provided by a cropping system per year was converted into a colony's adult worker population. Both crop species identity and diversity determined the temporal continuity in nectar and pollen supply and thus colony viability. Overall farmland structure and relative crop abundance were less important, but details mattered. For monocultures and for four-crop species systems composed of cereals, oilseed rape, maize, and sunflower,P(H)andP(P)were below the viability threshold. Such cropping systems showed frequent, badly timed, and prolonged forage gaps leading to detrimental cascading effects on life stages and in-hive work force, which critically reduced colony resilience. Four-crop systems composed of rye-grass-dandelion pasture, trefoil-grass pasture, sunflower, and phacelia ensured continuous nectar and pollen supply resulting in TTE > 5 yr, andP(H)(269.5 kg) andP(P)(108 kg) being above viability thresholds for 5 yr. Overall, trefoil-grass pasture, oilseed rape, buckwheat, and phacelia improved the temporal continuity in forage supply and colony's viability. Our results are hypothetical as they are obtained from simplified landscape settings, but they nevertheless match empirical observations, in particular the viability threshold. Our framework can be used to assess the effects of cropping systems on honey bee viability and to develop land-use strategies that help maintain pollination services by avoiding prolonged and badly timed forage gaps.}, language = {en} } @article{HornBecherJohstetal.2020, author = {Horn, Juliane and Becher, Matthias A. and Johst, Karin and Kennedy, Peter J. and Osborne, Juliet L. and Radchuk, Viktoriia and Grimm, Volker}, title = {Honey bee colony performance affected by crop diversity and farmland structure}, series = {Ecological applications}, volume = {31}, journal = {Ecological applications}, number = {1}, publisher = {Wiley Periodicals LLC}, address = {Washington DC}, issn = {1939-5582}, doi = {10.1002/eap.2216}, pages = {1 -- 22}, year = {2020}, abstract = {Forage availability has been suggested as one driver of the observed decline in honey bees. However, little is known about the effects of its spatiotemporal variation on colony success. We present a modeling framework for assessing honey bee colony viability in cropping systems. Based on two real farmland structures, we developed a landscape generator to design cropping systems varying in crop species identity, diversity, and relative abundance. The landscape scenarios generated were evaluated using the existing honey bee colony model BEEHAVE, which links foraging to in-hive dynamics. We thereby explored how different cropping systems determine spatiotemporal forage availability and, in turn, honey bee colony viability (e.g., time to extinction, TTE) and resilience (indicated by, e.g., brood mortality). To assess overall colony viability, we developed metrics,P(H)andP(P,)which quantified how much nectar and pollen provided by a cropping system per year was converted into a colony's adult worker population. Both crop species identity and diversity determined the temporal continuity in nectar and pollen supply and thus colony viability. Overall farmland structure and relative crop abundance were less important, but details mattered. For monocultures and for four-crop species systems composed of cereals, oilseed rape, maize, and sunflower,P(H)andP(P)were below the viability threshold. Such cropping systems showed frequent, badly timed, and prolonged forage gaps leading to detrimental cascading effects on life stages and in-hive work force, which critically reduced colony resilience. Four-crop systems composed of rye-grass-dandelion pasture, trefoil-grass pasture, sunflower, and phacelia ensured continuous nectar and pollen supply resulting in TTE > 5 yr, andP(H)(269.5 kg) andP(P)(108 kg) being above viability thresholds for 5 yr. Overall, trefoil-grass pasture, oilseed rape, buckwheat, and phacelia improved the temporal continuity in forage supply and colony's viability. Our results are hypothetical as they are obtained from simplified landscape settings, but they nevertheless match empirical observations, in particular the viability threshold. Our framework can be used to assess the effects of cropping systems on honey bee viability and to develop land-use strategies that help maintain pollination services by avoiding prolonged and badly timed forage gaps.}, language = {en} } @article{OmarovaYerezhepAldiyarovetal.2022, author = {Omarova, Zhansaya and Yerezhep, Darkhan and Aldiyarov, Abdurakhman and Tokmoldin, Nurlan}, title = {In Silico Investigation of the Impact of Hole-Transport Layers on the Performance of CH3NH3SnI3 Perovskite Photovoltaic Cells}, series = {Crystals}, volume = {12}, journal = {Crystals}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2073-4352}, doi = {10.3390/cryst12050699}, pages = {17}, year = {2022}, abstract = {Perovskite solar cells represent one of the recent success stories in photovoltaics. The device efficiency has been steadily increasing over the past years, but further work is needed to enhance the performance, for example, through the reduction of defects to prevent carrier recombination. SCAPS-1D simulations were performed to assess efficiency limits and identify approaches to decrease the impact of defects, through the selection of an optimal hole-transport material and a hole-collecting electrode. Particular attention was given to evaluation of the influence of bulk defects within light-absorbing CH3NH3SnI3 layers. In addition, the study demonstrates the influence of interface defects at the TiO2/CH3NH3SnI3 (IL1) and CH3NH3SnI3/HTL (IL2) interfaces across the similar range of defect densities. Finally, the optimal device architecture TiO2/CH3NH3SnI3/Cu2O is proposed for the given absorber layer using the readily available Cu2O hole-transporting material with PCE = 27.95\%, FF = 84.05\%, V-OC = 1.02 V and J(SC) = 32.60 mA/cm(2), providing optimal performance and enhanced resistance to defects.}, language = {en} } @article{HeckenbachBruneGlerumetal.2021, author = {Heckenbach, Esther Lina and Brune, Sascha and Glerum, Anne C. and Bott, Judith}, title = {Is there a speed limit for the thermal steady-state assumption in continental rifts?}, series = {Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences}, volume = {22}, journal = {Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences}, number = {3}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {1525-2027}, doi = {10.1029/2020GC009577}, pages = {18}, year = {2021}, abstract = {The lithosphere is often assumed to reside in a thermal steady-state when quantitatively describing the temperature distribution in continental interiors and sedimentary basins, but also at active plate boundaries. Here, we investigate the applicability limit of this assumption at slowly deforming continental rifts. To this aim, we assess the tectonic thermal imprint in numerical experiments that cover a range of realistic rift configurations. For each model scenario, the deviation from thermal equilibrium is evaluated. This is done by comparing the transient temperature field of every model to a corresponding steady-state model with an identical structural configuration. We find that the validity of the thermal steady-state assumption strongly depends on rift type, divergence velocity, sampling location, and depth within the rift. Maximum differences between transient and steady-state models occur in narrow rifts, at the rift sides, and if the extension rate exceeds 0.5-2 mm/a. Wide rifts, however, reside close to thermal steady-state even for high extension velocities. The transient imprint of rifting appears to be overall negligible for shallow isotherms with a temperature less than 100 degrees C. Contrarily, a steady-state treatment of deep crustal isotherms leads to an underestimation of crustal temperatures, especially for narrow rift settings. Thus, not only relatively fast rifts like the Gulf of Corinth, Red Sea, and Main Ethiopian Rift, but even slow rifts like the Kenya Rift, Rhine Graben, and Rio Grande Rift must be expected to feature a pronounced transient component in the temperature field and to therefore violate the thermal steady-state assumption for deeper crustal isotherms.}, language = {en} } @phdthesis{Bergner2003, author = {Bergner, Andreas G. N.}, title = {Lake-level fluctuations and Late Quaternary climate change in the Central Kenya Rift}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0001428}, school = {Universit{\"a}t Potsdam}, year = {2003}, abstract = {Diese Arbeit besch{\"a}ftigt sich mit der Rekonstruktion von Klima in historischen Zeiten im tropischen Ostafrika. Nach einer {\"U}bersicht {\"u}ber die heutigen klimatischen Bedingungen der Tropen und den Besonderheiten des ostafrikanischen Klimas, werden die M{\"o}glichkeiten der Klimarekonstruktion anhand von Seesedimenten diskutiert. Es zeigt sich, dass die hoch gelegenen Seen des Zentralen Keniarifts, als Teil des Ostafrikanischen Grabensystems, besonders geeignete Klimaarchive darstellen, da sie sensibel auf klimatische Ver{\"a}nderungen reagieren. Ver{\"a}nderungen der Seechemie, wie sie in den Sedimenten aufgezeichnet werden, eignen sich um die nat{\"u}rlichen Schwankungen in der Quart{\"a}ren Klimageschichte Ostafrikas nachzuzeichnen. Basierend auf der guten 40Ar/39Ar- und 14C-Datierbarkeit der Seesedimente wird eine Chronologie der pal{\"a}o{\"o}kologischen Bedingungen anhand von Diatomeenvergesellschaftungen restauriert. Dabei zeigen sich f{\"u}r die Seen Nakuru, Elmenteita und Naivasha kurzfristige Transgression/ Regressions-Zyklen im Intervall von ca. 11.000 Jahren w{\"a}hrend des letzten (ca. 12.000 bis 6.000 J.v.H.) und vorletzten Interglazials (ca. 140.000 bis 60.000 J.v.H.). Zus{\"a}tzlich kann ein allgemeiner, langfristiger Trend der Seeentwicklung von großen Frischwasserseen hin zu st{\"a}rker salinen Gew{\"a}ssern innerhalb der letzen 1 Mio. Jahre festgestellt werden. Mittels Transferfunktionen und einem hydro-klimatischen Modellansatz k{\"o}nnen die restaurierten limnologischen Bedingungen als klimatische Schwankungen des Einzugsgebietes interpretiert werden. Wenngleich auch der zus{\"a}tzliche Einfluss von tektonischen Ver{\"a}nderungen auf das Seeeinzugsgebiet und das Gewicht ver{\"a}nderter Grundwasserstr{\"o}me abgewogen werden, zeigt sich, dass allein geringf{\"u}gig erh{\"o}hte Niederschlagswerte von ca. 30±10 \% zu dramatischen Seespiegelanstiegen im Zentralen Keniarift f{\"u}hren. Aufgrund der etablierten hydrrologisch-klimatischen Wechselwirkungen werden R{\"u}ckschl{\"u}sse auf die nat{\"u}rliche Variabilit{\"a}t des ostafrikanischen Klimas gezogen. Zudem wird die Sensitivit{\"a}t der Keniarift-Seen in Bezug auf die St{\"a}rke der {\"a}quatorialen Insolation und hinsichtilch variabler Oberfl{\"a}chenwassertemperaturen des Indischen Ozeans bewertet.}, language = {en} } @phdthesis{Stoltnow2023, author = {Stoltnow, Malte}, title = {Magmatic-hydrothermal processes along the porphyry to epithermal transition}, doi = {10.25932/publishup-61140}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-611402}, school = {Universit{\"a}t Potsdam}, pages = {xxviii, 132}, year = {2023}, abstract = {Magmatic-hydrothermal systems form a variety of ore deposits at different proximities to upper-crustal hydrous magma chambers, ranging from greisenization in the roof zone of the intrusion, porphyry mineralization at intermediate depths to epithermal vein deposits near the surface. The physical transport processes and chemical precipitation mechanisms vary between deposit types and are often still debated. The majority of magmatic-hydrothermal ore deposits are located along the Pacific Ring of Fire, whose eastern part is characterized by the Mesozoic to Cenozoic orogenic belts of the western North and South Americas, namely the American Cordillera. Major magmatic-hydrothermal ore deposits along the American Cordillera include (i) porphyry Cu(-Mo-Au) deposits (along the western cordilleras of Mexico, the western U.S., Canada, Chile, Peru, and Argentina); (ii) Climax- (and sub-) type Mo deposits (Colorado Mineral Belt and northern New Mexico); and (iii) porphyry and IS-type epithermal Sn(-W-Ag) deposits of the Central Andean Tin Belt (Bolivia, Peru and northern Argentina). The individual studies presented in this thesis primarily focus on the formation of different styles of mineralization located at different proximities to the intrusion in magmatic-hydrothermal systems along the American Cordillera. This includes (i) two individual geochemical studies on the Sweet Home Mine in the Colorado Mineral Belt (potential endmember of peripheral Climax-type mineralization); (ii) one numerical modeling study setup in a generic porphyry Cu-environment; and (iii) a numerical modeling study on the Central Andean Tin Belt-type Pirquitas Mine in NW Argentina. Microthermometric data of fluid inclusions trapped in greisen quartz and fluorite from the Sweet Home Mine (Detroit City Portal) suggest that the early-stage mineralization precipitated from low- to medium-salinity (1.5-11.5 wt.\% equiv. NaCl), CO2-bearing fluids at temperatures between 360 and 415°C and at depths of at least 3.5 km. Stable isotope and noble gas isotope data indicate that greisen formation and base metal mineralization at the Sweet Home Mine was related to fluids of different origins. Early magmatic fluids were the principal source for mantle-derived volatiles (CO2, H2S/SO2, noble gases), which subsequently mixed with significant amounts of heated meteoric water. Mixing of magmatic fluids with meteoric water is constrained by δ2Hw-δ18Ow relationships of fluid inclusions. The deep hydrothermal mineralization at the Sweet Home Mine shows features similar to deep hydrothermal vein mineralization at Climax-type Mo deposits or on their periphery. This suggests that fluid migration and the deposition of ore and gangue minerals in the Sweet Home Mine was triggered by a deep-seated magmatic intrusion. The second study on the Sweet Home Mine presents Re-Os molybdenite ages of 65.86±0.30 Ma from a Mo-mineralized major normal fault, namely the Contact Structure, and multimineral Rb-Sr isochron ages of 26.26±0.38 Ma and 25.3±3.0 Ma from gangue minerals in greisen assemblages. The age data imply that mineralization at the Sweet Home Mine formed in two separate events: Late Cretaceous (Laramide-related) and Oligocene (Rio Grande Rift-related). Thus, the age of Mo mineralization at the Sweet Home Mine clearly predates that of the Oligocene Climax-type deposits elsewhere in the Colorado Mineral Belt. The Re-Os and Rb-Sr ages also constrain the age of the latest deformation along the Contact Structure to between 62.77±0.50 Ma and 26.26±0.38 Ma, which was employed and/or crosscut by Late Cretaceous and Oligocene fluids. Along the Contact Structure Late Cretaceous molybdenite is spatially associated with Oligocene minerals in the same vein system, a feature that precludes molybdenite recrystallization or reprecipitation by Oligocene ore fluids. Ore precipitation in porphyry copper systems is generally characterized by metal zoning (Cu-Mo to Zn-Pb-Ag), which is suggested to be variably related to solubility decreases during fluid cooling, fluid-rock interactions, partitioning during fluid phase separation and mixing with external fluids. The numerical modeling study setup in a generic porphyry Cu-environment presents new advances of a numerical process model by considering published constraints on the temperature- and salinity-dependent solubility of Cu, Pb and Zn in the ore fluid. This study investigates the roles of vapor-brine separation, halite saturation, initial metal contents, fluid mixing, and remobilization as first-order controls of the physical hydrology on ore formation. The results show that the magmatic vapor and brine phases ascend with different residence times but as miscible fluid mixtures, with salinity increases generating metal-undersaturated bulk fluids. The release rates of magmatic fluids affect the location of the thermohaline fronts, leading to contrasting mechanisms for ore precipitation: higher rates result in halite saturation without significant metal zoning, lower rates produce zoned ore shells due to mixing with meteoric water. Varying metal contents can affect the order of the final metal precipitation sequence. Redissolution of precipitated metals results in zoned ore shell patterns in more peripheral locations and also decouples halite saturation from ore precipitation. The epithermal Pirquitas Sn-Ag-Pb-Zn mine in NW Argentina is hosted in a domain of metamorphosed sediments without geological evidence for volcanic activity within a distance of about 10 km from the deposit. However, recent geochemical studies of ore-stage fluid inclusions indicate a significant contribution of magmatic volatiles. This study tested different formation models by applying an existing numerical process model for porphyry-epithermal systems with a magmatic intrusion located either at a distance of about 10 km underneath the nearest active volcano or hidden underneath the deposit. The results show that the migration of the ore fluid over a 10-km distance results in metal precipitation by cooling before the deposit site is reached. In contrast, simulations with a hidden magmatic intrusion beneath the Pirquitas deposit are in line with field observations, which include mineralized hydrothermal breccias in the deposit area.}, language = {en} } @article{StillmanRailsbackGiskeetal.2015, author = {Stillman, Richard A. and Railsback, Steven Floyd and Giske, Jarl and Berger, Uta and Grimm, Volker}, title = {Making Predictions in a Changing World: The Benefits of Individual-Based Ecology}, series = {Bioscience}, volume = {65}, journal = {Bioscience}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0006-3568}, doi = {10.1093/biosci/biu192}, pages = {140 -- 150}, year = {2015}, abstract = {Ecologists urgently need a better ability to predict how environmental change affects biodiversity. We examine individual-based ecology (IBE), a research paradigm that promises better a predictive ability by using individual-based models (IBMs) to represent ecological dynamics as arising from how individuals interact with their environment and with each other. A key advantage of IBMs is that the basis for predictions-fitness maximization by individual organisms-is more general and reliable than the empirical relationships that other models depend on. Case studies illustrate the usefulness and predictive success of long-term IBE programs. The pioneering programs had three phases: conceptualization, implementation, and diversification. Continued validation of models runs throughout these phases. The breakthroughs that make IBE more productive include standards for describing and validating IBMs, improved and standardized theory for individual traits and behavior, software tools, and generalized instead of system-specific IBMs. We provide guidelines for pursuing IBE and a vision for future IBE research.}, language = {en} } @article{AliHomannKhaliletal.2013, author = {Ali, Mostafa and Homann, Thomas and Khalil, Mahmoud and Kruse, Hans-Peter and Rawel, Harshadrai Manilal}, title = {Milk whey protein modification by coffee-specific phenolics effect on structural and functional properties}, series = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, volume = {61}, journal = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, number = {28}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-8561}, doi = {10.1021/jf402221m}, pages = {6911 -- 6920}, year = {2013}, abstract = {A suitable vehicle for integration of bioactive plant constituents is proposed. It involves modification of proteins using phenolics and applying these for protection of labile constituents. It dissects the noncovalent and covalent interactions of beta-lactoglobulin with coffee-specific phenolics. Alkaline and polyphenol oxidase modulated covalent reactions were compared. Tryptic digestion combined with MALDI-TOF-MS provided tentative allocation of the modification type and site in the protein, and an in silico modeling of modified beta-lactoglobulin is proposed. The modification delivers proteins with enhanced antioxidative properties. Changed structural properties and differences in solubility, surface hydrophobicity, and emulsification were observed. The polyphenol oxidase modulated reaction provides a modified beta-lactoglobulin with a high antioxidative power, is thermally more stable, requires less energy to unfold, and, when emulsified with lutein esters, exhibits their higher stability against UV light. Thus, adaptation of this modification provides an innovative approach for functionalizing proteins and their uses in the food industry.}, language = {en} }