TY - JOUR A1 - Esfahani, Reza Dokht Dolatabadi A1 - Gholami, Ali A1 - Ohrnberger, Matthias T1 - An inexact augmented Lagrangian method for nonlinear dispersion-curve inversion using Dix-type global linear approximation JF - Geophysics : a journal of general and applied geophysics N2 - Dispersion-curve inversion of Rayleigh waves to infer subsurface shear-wave velocity is a long-standing problem in seismology. Due to nonlinearity and ill-posedness, sophisticated regularization techniques are required to solve the problem for a stable velocity model. We have formulated the problem as a minimization problem with nonlinear operator constraint and then solve it by using an inexact augmented Lagrangian method, taking advantage of the Haney-Tsai Dix-type relation (a global linear approximation of the nonlinear forward operator). This replaces the original regularized nonlinear problem with iterative minimization of a more tractable regularized linear problem followed by a nonlinear update of the phase velocity (data) in which the update can be performed accurately with any forward modeling engine, for example, the finite-element method. The algorithm allows discretizing the medium with thin layers (for the finite-element method) and thus omitting the layer thicknesses from the unknowns and also allows incorporating arbitrary regularizations to shape the desired velocity model. In this research, we use total variation regularization to retrieve the shear-wave velocity model. We use two synthetic and two real data examples to illustrate the performance of the inversion algorithm with total variation regularization. We find that the method is fast and stable, and it converges to the solution of the original nonlinear problem. KW - surface wave KW - nonlinear KW - inversion KW - modeling KW - finite element Y1 - 2020 U6 - https://doi.org/10.1190/geo2019-0717.1 SN - 0016-8033 SN - 1942-2156 VL - 85 IS - 3 SP - EN77 EP - EN85 PB - GeoScienceWorld CY - Tulsa, Okla. ER - TY - JOUR A1 - Horn, Juliane A1 - Becher, Matthias A. A1 - Johst, Karin A1 - Kennedy, Peter J. A1 - Osborne, Juliet L. A1 - Radchuk, Viktoriia A1 - Grimm, Volker T1 - Honey bee colony performance affected by crop diversity and farmland structure BT - a modeling framework JF - Ecological applications N2 - 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. KW - apis mellifera KW - BEEHAVE KW - colony viability KW - crop diversity KW - cropping system KW - decline KW - forage availability KW - forage gaps KW - honey bees KW - landscape generator KW - modeling Y1 - 2020 U6 - https://doi.org/10.1002/eap.2216 SN - 1939-5582 SN - 1051-0761 VL - 31 IS - 1 SP - 1 EP - 22 PB - Wiley Periodicals LLC CY - Washington DC ER - TY - GEN A1 - Horn, Juliane A1 - Becher, Matthias A. A1 - Johst, Karin A1 - Kennedy, Peter J. A1 - Osborne, Juliet L. A1 - Radchuk, Viktoriia A1 - Grimm, Volker T1 - Honey bee colony performance affected by crop diversity and farmland structure BT - a modeling framework T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1351 KW - apis mellifera KW - BEEHAVE KW - colony viability KW - crop diversity KW - cropping system KW - decline KW - forage availability KW - forage gaps KW - honey bees KW - landscape generator KW - modeling Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-556943 SN - 1866-8372 IS - 1 ER - TY - JOUR A1 - Abramova, Olga A1 - Batzel, Katharina A1 - Modesti, Daniela T1 - Collective response to the health crisis among German Twitter users BT - a structural topic modeling approach JF - International Journal of Information Management Data Insights N2 - 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. KW - social media KW - Twitter KW - modeling KW - regulatory focus theory KW - crisis management KW - text mining Y1 - 2022 U6 - https://doi.org/10.1016/j.jjimei.2022.100126 SN - 2667-0968 VL - 2 IS - 2 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Omarova, Zhansaya A1 - Yerezhep, Darkhan A1 - Aldiyarov, Abdurakhman A1 - Tokmoldin, Nurlan T1 - In Silico Investigation of the Impact of Hole-Transport Layers on the Performance of CH3NH3SnI3 Perovskite Photovoltaic Cells JF - Crystals N2 - 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. KW - perovskite solar cells KW - CH3NH3SnI3 KW - SCAPS-1D KW - modeling KW - HTL Y1 - 2022 U6 - https://doi.org/10.3390/cryst12050699 SN - 2073-4352 VL - 12 IS - 5 PB - MDPI CY - Basel ER - TY - THES A1 - Malem-Shinitski, Noa T1 - Bayesian inference and modeling for point processes with applications from neuronal activity to scene viewing T1 - Bayessche Inferenz und Modellierung für Punktprozesse mit Anwendungen von neuronaler Aktivität bis Szenenbetrachtung N2 - 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. N2 - Punktprozesse sind eine gängige Methode zur Modellierung von Ereignismengen. Von Erdbeben bis zu Social-Media-Posts, von den neuronalen Spikes bis zum Zeitpunkt von Verbrechen, von Aktienkursen bis zur Ausbreitung von Krankheiten - diese Phänomene lassen sich auf das Auftreten von Ereignissen reduzieren, die in Punkten konzentriert sind. Häufig treten diese Ereignisse nacheinander auf und bilden eine Zeitreihe. Modelle von Punktprozessen können verwendet werden, um unser Verständnis solcher Ereignisse für Klassifizierung und Vorhersage zu vertiefen. Solche Modelle umfassen einen zugrunde liegenden Zufallsprozess, der die Ereignisse erzeugt. In dieser Arbeit wird die Bayes'sche Methodik verwendet, um den zugrunde liegenden generativen Prozess aus den beobachteten Daten abzuleiten. Wir leisten einen doppelten Beitrag: Wir entwickeln neue Modelle und neue Inferenzmethoden für diese Prozesse. Wir schlagen ein Modell vor, das die Familie der Punktprozesse erweitert, bei denen das Auftreten eines Ereignisses von den vorherigen Ereignissen abhängt. Diese Familie ist als Hawkes-Prozesse bekannt. Während in den meisten bestehenden Modellen solcher Prozesse davon ausgegangen wird, dass vergangene Ereignisse nur eine exzitatorische Wirkung auf zukünftige Ereignisse haben, konzentrieren wir uns auf den neu entwickelten nichtlinearen Hawkes-Prozess, bei dem vergangene Ereignisse exzitatorische und hemmende Wirkungen haben können. Nach der Definition des Modells stellen wir seine Inferenzmethode vor und wenden sie auf Daten aus verschiedenen Bereichen an, unter anderem auf die neuronale Aktivität. Das zweite Modell, das in dieser Arbeit beschrieben wird, betrifft einen speziellen Fall von Punktprozessen - den Entscheidungsprozess, der der menschlichen Blicksteuerung zugrunde liegt. Dieser Prozess führt zu einer Reihe von fixierten Positionen in einem Bild. Wir haben ein neues Modell entwickelt, um diesen Prozess zu beschreiben, motiviert durch das bekannte Exploration-Exploitation-Dilemma. Neben dem Modell stellen wir einen Bayes'schen Inferenzalgorithmus vor, um die Modellparameter abzuleiten. Wir bleiben auf dem Gebiet der menschlichen Szenenbetrachtung und stellen fest, dass es in diesem Bereich keine bewährten Verfahren für die Bayes'sche Inferenz gibt. Wir geben einen Überblick über vier gängige Algorithmen und vergleichen ihre Leistungen bei der Ableitung von Parametern für zwei Scanpfadmodelle. Die in dieser Dissertation vorgestellten neuen Modelle und Inferenzalgorithmen bereichern das Verständnis von Punktprozessdaten und ermöglichen es uns, sinnvolle Erkenntnisse zu gewinnen. KW - Bayesian inference KW - point process KW - statistical machine learning KW - sampling KW - modeling KW - Bayessche Inferenz KW - Modellierung KW - Punktprozess KW - Stichprobenentnahme aus einem statistischen Modell KW - statistisches maschinelles Lernen Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-614952 ER - TY - THES A1 - Stoltnow, Malte T1 - Magmatic-hydrothermal processes along the porphyry to epithermal transition T1 - Magmatisch-hydrothermale Prozesse entlang des porphyrisch-epithermalen Übergangs N2 - 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. N2 - Magmatisch-hydrothermale Systeme bilden eine Vielzahl von Erzlagerstätten in unterschiedlicher Entfernung zu wasserhaltigen Magmakammern in der oberen Erdkruste, von der Greisenbildung in der Dachzone der Intrusion über die Porphyrmineralisierung in mittleren Tiefen bis hin zu epithermalen Ganglagerstätten nahe der Erdoberfläche. Die physikalischen Transportprozesse und chemischen Ausfällungsmechanismen variieren zwischen den verschiedenen Lagerstättentypen und werden immer noch häufig diskutiert. Die meisten magmatisch-hydrothermalen Erzlagerstätten befinden sich entlang des Pazifischen Feuerrings, dessen östlicher Teil durch die mesozoischen bis känozoischen orogenen Gürtel des westlichen Nord- und Südamerikas, zusammen die Amerikanische Kordillere, vertreten ist. Zu den wichtigsten magmatisch-hydrothermalen Erzlagerstätten entlang der Amerikanischen Kordillere gehören (i) Cu(-Mo-Au)-Porphyrlagerstätten (entlang der westlichen Kordilleren Mexikos, der westlichen USA, Kanadas, Chiles, Perus und Argentiniens); (ii) Mo-Lagerstätten vom Climax- (und Sub-)Typ (Colorado Mineral Belt und nördliches New Mexico); und (iii) porphyrische und epithermale Sn(-W-Ag)-Lagerstätten vom IS-Typ des Zentralandinen-Zinngürtels (Bolivien, Peru und Nordargentinien). Die einzelnen Studien dieser Arbeit konzentrieren sich in erster Linie auf die Bildung verschiedener Vererzungsstypen, die sich in unterschiedlicher Entfernung zur Intrusion in magmatisch-hydrothermalen Systemen entlang der amerikanischen Kordillere befinden. Dazu gehören (i) zwei geochemische Einzelstudien über die Sweet Home-Mine im Colorado Mineral Belt (potenzielles Endglied der peripheren Mineralisierung des Climax-Typs); (ii) eine numerische Modellierungsstudie in einem generischen Cu-Porphyr-Setup; und (iii) eine numerische Modellierungsstudie über die Pirquitas-Mine des Zentralandinen-Zinn-Typs in Nordwest-Argentinien. Mikrothermometrische Daten von Fluideinschlüssen, die in Greisenquarz und -fluorit aus der Sweet Home-Mine (Detroit City Portal) eingeschlossen sind, deuten darauf hin, dass die Mineralisierung im Frühstadium aus CO2-haltigen Fluiden mit niedrigem bis mittlerem Salzgehalt (1,5-11,5 Gew.-% NaCl-Äquivalent) bei Temperaturen zwischen 360 und 415 °C und in einer Tiefe von mindestens 3,5 km ausgefällt wurde. Daten zu stabilen Isotopen und Edelgasisotopen zeigen, dass die Greisenbildung und die Buntmetallvererzung in der Sweet Home-Mine mit Fluiden unterschiedlichen Ursprungs in Verbindung stehen. Frühe magmatische Fluide waren die Hauptquelle für aus dem Mantel stammende Volatile (CO2, H2S/SO2, Edelgase), die sich anschließend mit erheblichen Mengen erhitzten meteorischen Wassers vermischten. Die Vermischung von magmatischen Fluiden mit meteorischem Wasser wird durch die Zusammenhänge von δ2Hw-δ18Ow der Fluideinschlüsse belegt. Die tiefe hydrothermale Vererzung in der Sweet Home-Mine weist ähnliche Merkmale auf wie die tiefe hydrothermale Gangvererzung in Mo-Lagerstätten vom Climax-Typ oder in deren Peripherie. Dies deutet darauf hin, dass die Fluidmigration und die Ausfällung von Erz und Gangmineralen in der Sweet Home-Mine durch eine tief sitzende magmatische Intrusion angeregt wurde. Die zweite Studie über die Sweet Home Mine präsentiert ein Re-Os-Molybdänit-Alter von 65,86±0,30 Ma aus einer Mo-vererzten Abschiebung, namentlich der Contact Structure, und ein multimineralisches Rb-Sr-Isochronen-Alter von 26,26±0,38 Ma und 25,3±3,0 Ma von Gangmineralen in Greisenvergesellschaftungen. Die Altersdaten deuten darauf hin, dass die Vererzungen in der Sweet Home Mine während zweier separater Ereignisse entstand: In der späten Kreidezeit (im Zusammenhang mit der Laramidischen Orogenese) und im Oligozän (im Zusammenhang mit dem Rio Grande Rift). Das Alter der Mo-Vererzung in der Sweet Home Mine liegt demnach eindeutig vor dem der oligozänen Climax-Lagerstätten anderswo im Colorado Mineral Belt. Die Re-Os- und Rb-Sr-Alter grenzen auch das Alter der jüngsten Deformation entlang der Contact Structure, die von spätkreidezeitlichen und oligozänen Fluiden genutzt und/oder geschnitten wurde, auf 62,77±0,50 Ma und 26,26±0,38 Ma ein. Entlang der Contact Structure ist spätkreidezeitlicher Molybdänit räumlich mit Mineralen aus dem Oligozän in demselben Gangsystem vergesellschaftet, was eine Rekristallisierung oder Ausfällung von Molybdänit durch oligozäne Fluide ausschließt. Die Erzausfällung in porphyrischen Kupfersystemen ist im Allgemeinen durch eine Metallzonierung (Cu-Mo bis Zn-Pb-Ag) gekennzeichnet, die vermutlich mit der Abnahme der Löslichkeit während der Fluidabkühlung, den Wechselwirkungen zwischen Fluid und Gestein, der Partitionierung während der Phasenseparation des Fluids und der Mischung mit externen Fluiden in Zusammenhang steht. Die numerische Modellierung, die in einer generischen Porphyr-Cu-Umgebung durchgeführt wurde, stellt neue Fortschritte eines numerischen Prozessmodells dar, indem sie veröffentlichte Randbedingungen für die temperatur- und salinitätsabhängige Löslichkeit von Cu, Pb und Zn im Erzfluid berücksichtigt. Diese Studie untersucht die Rolle der Dampf-Sole-Separation, der Halitsättigung, des anfänglichen Metallgehalts, der Fluidmischung und der Remobilisierung als Einflussfaktoren erster Ordnung der physikalischen Hydrologie auf die Erzbildung. Die Ergebnisse zeigen, dass die magmatischen Dampf- und Solephasen mit unterschiedlichen Verweilzeiten, aber als mischbare Fluide aufsteigen, wobei eine Erhöhung des Salzgehalts zu einem metall-ungesättigten Gesamtfluid führt. Die Freisetzungsraten der magmatischen Fluide wirken sich auf die Lage der thermohalinen Fronten aus, was zu widersprüchlichen Mechanismen für die Erzausfällung führt: Höhere Raten führen zu einer Halitsättigung ohne signifikante Metallzonierung, niedrigere Raten erzeugen zonierte Erzschalen aufgrund der Mischung mit meteorischem Wasser. Unterschiedliche Metallgehalte können sich auf die Reihenfolge der endgültigen Metallausfällung auswirken. Die Wiederauflösung bereits ausgefällter Metalle führt zu zonierten Erzschalenmustern in periphereren Bereichen und entkoppelt auch die Halitsättigung von der Erzausfällung. Die epithermale Pirquitas Sn-Ag-Pb-Zn-Mine im Nordwesten Argentiniens befindet sich in einem Bereich metamorphisierter Sedimente ohne geologische Hinweise auf vulkanische Aktivitäten in einer Entfernung von etwa 10 km zur Lagerstätte. Jüngste geochemische Untersuchungen von Fluideinschlüssen im Erzstadium deuten jedoch auf einen bedeutenden Beitrag von magmatischen Volatilen hin. In dieser Studie wurden verschiedene Entstehungsmodelle getestet, indem ein bestehendes numerisches Prozessmodell für porphyrisch-epithermale Systeme mit einer magmatischen Intrusion angewandt wurde, die sich entweder in einer Entfernung von etwa 10 km unterhalb des nächstgelegenen aktiven Vulkans oder verborgen unterhalb der Lagerstätte befindet. Die Ergebnisse zeigen, dass die Migration der Erzflüssigkeit über eine Entfernung von 10 km zu einer Metallausfällung durch Abkühlung führt, bevor die Lagerstätte erreicht wird. Im Gegensatz dazu stimmen die Simulationen mit einer verborgenen magmatischen Intrusion unter der Pirquitas-Lagerstätte mit den Feldbeobachtungen überein, die mineralisierte hydrothermale Brekzien im Lagerstättenbereich umfassen. KW - magmatic KW - hydrothermal KW - ore KW - deposits KW - copper KW - lead KW - zinc KW - molybdenum KW - numerical KW - modeling KW - Sweet KW - Home KW - Pirquitas KW - Colorado KW - Argentina KW - Argentinien KW - Colorado KW - Home KW - Pirquitas KW - Sweet KW - Kupfer KW - Lagerstätte KW - hydrothermal KW - Blei KW - magmatisch KW - Modellierung KW - Molybdän KW - numerisch KW - Erz KW - Zink Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-611402 ER - TY - JOUR A1 - Heckenbach, Esther Lina A1 - Brune, Sascha A1 - Glerum, Anne C. A1 - Bott, Judith T1 - Is there a speed limit for the thermal steady-state assumption in continental rifts? JF - Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences N2 - 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. KW - basin analysis KW - geodynamics KW - numerical modeling KW - rifting KW - thermal KW - modeling Y1 - 2021 U6 - https://doi.org/10.1029/2020GC009577 SN - 1525-2027 VL - 22 IS - 3 PB - Wiley CY - Hoboken, NJ ER - TY - CHAP A1 - Haase, Jennifer A1 - Thim, Christof A1 - Bender, Benedict ED - Marrella, Andrea ED - Weber, Barbara T1 - Expanding modeling notations BT - requirements for creative process modeling T2 - Business process management workshops N2 - 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. KW - modeling KW - requirements KW - pockets of creativity KW - creative process Y1 - 2022 SN - 978-3-030-94342-4 SN - 978-3-030-94344-8 SN - 978-3-030-94343-1 U6 - https://doi.org/10.1007/978-3-030-94343-1_15 VL - 436 SP - 197 EP - 208 PB - Springer CY - Cham ER - TY - JOUR A1 - Natho, Stephanie A1 - Tschikof, Martin A1 - Bondar-Kunze, Elisabeth A1 - Hein, Thomas T1 - Modeling the effect of enhanced lateral connectivity on nutrient retention capacity in large river floodplains BT - how much connected floodplain do we need? JF - Frontiers in Environmental Science N2 - Floodplains have been degraded in Central Europe for centuries, resulting in less dynamic and less diverse ecosystems than in the past. They provide essential ecosystem services like nutrient retention to improve overall water quality and thus fulfill naturally what EU legislation demands, but this service is impaired by reduced connectivity patterns. Along the second-longest river in Europe, the Danube, restoration measures have been carried out and are planned for the near future in the Austrian Danube Floodplain National Park in accordance with navigation purposes. We investigated nutrient retention capacity in seven currently differently connected side arms and the effects of proposed restoration measures using two complementary modeling approaches. We modeled nutrient retention capacity in two scenarios considering different hydrological conditions, as well as the consequences of planned restoration measures for side arm connectivity. With existing monitoring data on hydrology, nitrate, and total phosphorus concentrations for three side arms, we applied a statistical model and compared these results to a semi-empirical retention model. The latter was originally developed for larger scales, based on transferable causalities of retention processes and set up for this floodplain with publicly available data. Both model outcomes are in a comparable range for NO3-N (77-198 kg ha(-1)yr(-1)) and TP (1.4-5.7 kg ha(-1)yr(-1)) retention and agree in calculating higher retention in floodplains, where reconnection allows more frequent inundation events. However, the differences in the model results are significant for specific aspects especially during high flows, where the semi-empirical model complements the statistical model. On the other hand, the statistical model complements the semi-empirical model when taking into account nutrient retention at times of no connection between the remaining water bodies left in the floodplain. Overall, both models show clearly that nutrient retention in the Danube floodplains can be enhanced by restoring lateral hydrological reconnection and, for all planned measures, a positive effect on the overall water quality of the Danube River is expected. Still, a frequently hydrologically connected stretch of national park is insufficient to improve the water quality of the whole Upper Danube, and more functional floodplains are required. KW - floodplain KW - lateral hydrological connectivity KW - Danube KW - restoration KW - reconnection KW - inundation KW - nutrient retention KW - modeling Y1 - 2020 U6 - https://doi.org/10.3389/fenvs.2020.00074 SN - 2296-665X VL - 8 PB - Frontiers Media CY - Lausanne ER -