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The existence of the common ash (Fraxinus excelsior L.) is acutely threatened by ash dieback, caused by the fungus Hymenoscyphus fraxineus. The disease may lead to reduced pollen flow due to crown damage and tree mortality, which affects the reproductive ecology of Fraxinus excelsior L. However, sexual reproduction in forest trees plays an essential role not only in species conservation and adaptive potential, but also in natural selection and the promotion of genetic diversity. The impending risk of reduced gene flow is therefore of serious concern and threatens the conservation of this valuable tree species. Therefore, it is critical to advance research on the effects of ash dieback on (effective) pollen transport and reproductive ecology of Fraxinus excelsior L. These results can be used to support forest management, such as maintaining ash genetic diversity and promoting the development of natural resistance. Therefore, this study will conduct extensive research in two seed orchards and one floodplain forest in Southern Germany from 2018 to 2021. The main objective of this dissertation was to improve our understanding of gene flow patterns by investigating (effective) pollen dispersal, pollen production and pollen and seed quality of ash trees in relation to their health status.
The main research questions were:
(1) How does ash (effective) pollen transport vary with stand density, ash abundance and meteorology?
(2) Is there a link between mating success and damage to the paternal tree?
(3) Does the health of the ash trees affect pollen and seed quality, as well as pollen quantity?
To answer these questions, different methods were used in the study areas, which differed in topography and degree of stocking. Therefore, not all parameters were examined at every site and in every year, depending on the issue concerned. The health status of the ash trees was assessed every year in July using a six-level vitality score. In addition, phenological observations were made annually in spring according to the BBCH code to determine different phenological stages such as beginning of flowering, full flowering, flower wilting and end of flowering.
Aerobiological pollen measurements were carried out in the two orchards in 2019 and 2020 using self-constructed gravimetric pollen traps of the Durham type. One of the traps was placed in the center of each orchard and up to five additional traps were placed at a maximum distance of 500 m from the orchard. Five vaseline-coated slides were attached to each trap (one in each cardinal di-rection and one horizontally) to measure pollen transport (N=4) and weekly cumulative pollen position (N=1). To study the influence of meteorological parameters, a climate station was placed in each orchard. In addition, other anemometers or data loggers for air temperature and relative humidity were installed.
For paternity analyses, cambium samples were collected for genotyping from branches and stumps of 251 ash trees in a seed orchard and floodplain forest. In addition, seeds were collected from 12 parent trees per site with different health status. Genetic analyses were performed to determine paternal trees using nuclear microsatellites. Paternities were assigned using the likelihood model implemented in Cervus 3.0.7 software.
Pollen viability of ash trees with different health status were studied at all three sites. Pollen production in the two seed orchards and seed quality in one orchard and the floodplain forest. For this purpose, inflorescences of 105 ash trees (pollen production), pollen of 125 ash trees (pollen viability) and seeds of 53 ash trees (seed quality) were collected. Pollen production was estimated from flower to tree level and pollen viability was determined using the TTC (2,3,5-triphenyltetrazolium chloride) test. In addition, pollen storage experiments were carried out to investigate the influence of meteorological factors on pollen viability. Pollen were stored for various periods at different temperatures and humidity conditions and their viability was determined. Seeds were analyzed for quantity and quality (solid, hollow grains, insect damage and germination) and seed quality was determined by both stratification and the TTC test.
The results on aerobiological pollen transport showed that pollen transport is related to meteorology, phenological development and the topography of the study site. The Schorndorf orchard, located on a slope, showed higher pollen levels at the downslope traps, likely due to the transport of pollen by cold air flow. The prevailing wind direction often corresponded with the compass direction in which the highest pollen deposition was measured. When analyzing the pollen data for individual traps, the highest pollen levels were measured outside the orchards in 2019, a year with low flower development. In contrast, most pollen were collected inside the orchard in the pollen-rich year 2020. This suggests that trees outside the orchard can potentially contribute more to pollination in a poor pollen year. In Emmendingen, minor difference in pollen quantity was found between traps at 1.5 m and 5 m height, but there were temporal differences indicating vertical variation in pollen availability. Ash pollen were found to be transported over a distance of more than 400 m, with the amount of pollen decreasing with increasing distance. About 50 % less pollen were measured at a distance of 200 m, but even at a distance of 500 m more than 10 % pollen were still detected.
The studies on effective pollen transport showed similar results: the average distance between father and mother tree was 76 m in the orchard and 166 m in the floodplain forest, with pollination success decreasing considerably with increasing distance. Despite the dense tree cover, the longest distances (> 550 m) were recorded in the floodplain forest. Based on this and the fact that 66.5 % cross-pollen input was recorded in the seed orchard, it can be assumed that pollination does not only involve local sources. However, self-pollination generally did not have a substantial effect on ash reproduction. In terms of health status, both healthy and slightly damaged parent trees showed similar mating success. However, in severely damaged trees almost no flowering could be documented. In general, it was demonstrated that both healthy and slightly diseased fathers sired more offspring than severely diseased ash trees.
The effect of ash dieback on pollen production showed no significant difference between healthy and diseased ash trees, although 53 % of severely diseased male ash trees did not produce flowers. In terms of pollen viability, there was a tendency for diseased ash trees to have less viable pollen than healthy ash trees. In addition, the viability experiments revealed a strong influence of prevailing temperatures on pollen viability, which decreased more rapidly under warmer conditions. There was also no statistical difference in seed quality between ash trees of different health status. However, non-viable seeds were often heavily infested with insects.
In summary, the studies show that a variety of factors influence the reproductive ecology and (effective) pollen transport of ash trees. However, the fact that severely affected ash trees are linked to a reduced flower production and lower pollen quality suggests that as health deteriorates, reproductive capacity also declines. It is therefore likely that severely diseased ash trees have a limited ability to pass on their genes to the next generation. Paternity analyses also suggest that high vigor has a positive effect on reproductive success and that pollen transport can occur over long distances. As susceptibility to ash dieback can be passed on from parents to offspring, these reactions to ash dieback may make ash populations less susceptible in the future.
La presente tesis doctoral analiza el discurso de una selección de letras procedentes de álbumes de pop-rock en español editados entre 1968 y 2015. Partiendo de una concepción amplia de pop-rock como práctica social comunicativa, este trabajo de investigación aborda la construcción lingüística de las letras en cuanto textos escritos para ser cantados y escuchados, así como la elección de recursos léxico-gramaticales fruto de conjugar el discurso del pop-rock anglosajón con elementos autóctonos para sugerir autenticidad local. A lo largo del estudio se evidencia el papel determinante del campo de producción cultural (local, semiglobal) y de variables sociológicas como el género de los/las intérpretes y la escena musical, características que impactan de manera directa en las opciones lingüísticas que se realizan en las letras y, por ende, en la construcción discursiva del «yo» y del «tú» desde la música popular española de los años 70 del siglo pasado hasta el denominado pop-rock latino del siglo XXI. Con el objetivo de iluminar y evaluar dichas opciones lingüísticas se lleva a cabo un análisis contrastivo de corpus y sistémico-funcional de 1.000 letras y 85 álbumes de pop-rock en español.
Finance without foundations
(2022)
This thesis examines the role of financial inclusion by way of access to formal financial services such as savings, credit, transfers and payments, in supporting the lives of refugees in protracted displacement in Jordan. It asks if such access enables smoother financial and livelihood transitions as refugees arrive and integrate into their new environments in host countries. It critically evaluates the narrative presented by humanitarian actors supporting financial inclusion as a marketled intervention to support refugee self-reliance. It argues that the limited provision of financial services through mobile wallets and micro-credit is not sufficient to financially integrate refugees. Above all, it demonstrates through the in-depth qualitative research in Jordan that in a context where refugees’ livelihoods are constrained due to a lack of foundational economic rights, financial services can only marginally improve their lives by making it more convenient to receive remittances and humanitarian transfers.
The research is embedded in a larger project called “Finance in Displacement: Exploring and strengthening financial lives of forcibly displaced persons” (FIND), which was initiated in 2019 as a collaboration between the Katholische Universität Eichstätt-Ingolstadt, the Tufts University, and the International Rescue Committee. The project was supported by the German Federal Ministry for Economic Cooperation and Development (BMZ).
Organizational Citizenship Behavior (OCB) als freiwilliges Arbeitsengagement und freiwilliges Engagement in Non-Profit-Organisationen (NPOs) im Privatleben haben positive Auswirkungen auf gesellschaftlicher, finanzieller, organisationaler sowie individueller Ebene und sind unverzichtbar. Basierend auf Freiwilligkeit und organisationaler Eingebundenheit existieren Parallelen zwischen OCB und freiwilligem Engagement in NPOs. Theoretische und empirische Aspekte sprechen für die Existenz von positiven Spillover-Effekten zwischen OCB und freiwilligem Engagement in der Freizeit. Zum einen hängen Erwerbsarbeit und Privatleben über Work-Home-Spillover miteinander zusammen. Zum anderen wirkt sich Erwerbsarbeit auf freiwilliges Engagement im Privatleben aus und vice versa. Für die wissenschaftliche Untersuchung behavioraler Spillover-Effekte fordern Studien eine Spezifikation des betrachteten Verhaltens. Angelehnt an OCB werden deshalb Hilfsbereitschaft (Hilfe gegenüber anderen Organisationsmitgliedern), Unkompliziertheit (Ertragen vorübergehender Unannehmlichkeiten) und Eigeninitiative (Auseinandersetzung mit und Teilhabe an organisationalen Themen) als konkrete Engagementdimensionen untersucht. Persönlichkeitseigenschaften, individuelle Ressourcen und Wertekongruenz stellen mögliche Erklärungsansätze für die vermuteten Spillover-Effekte dar. Der Nachweis positiver Spillover-Effekte zwischen OCB und freiwilligem Engagement in NPOs sowie deren Erklärung stehen im Zentrum der vorliegenden Studienreihe.
Das multimethodale Forschungsdesign umfasst drei quantitative und eine qualitative Studie. Die Prästudie zu freiwilligem Engagement in Sportvereinen (N = 432) fokussiert die Existenz der Spillover-Effekte. Deren zeitliche Stabilität überprüft die Längsstudie (N = 107). In der Generalisierungsstudie (N = 434) werden die Befunde auf freiwilliges Engagement unabhängig vom Engagementbereich übertragen und erklärt. Interviews mit Führungskräften (N = 27) belegen die Spillover-Effekte aus einer Fremdperspektive.
Verschiedene statistische Methoden, wie Regressionsanalysen und Mittelwertvergleiche, bestätigen die Existenz von Spillover-Effekten zwischen OCB und freiwilligem Engagement in NPOs. Diese zeigen sich für die jeweils äquivalente Engagementdimension im anderen Kontext, sodass sich beispielsweise Hilfsbereitschaft in Erwerbsarbeit und NPO gegenseitig beeinflusst. Die Studienreihe belegt größtenteils die zeitliche Stabilität, Generalisierbarkeit und Validität der untersuchten Spillover-Effekte. Eine Erklärung ergibt sich durch Differenzierung der Teilnahme an gesellschaftlichen Aktivitäten in NPOs und der Übernahme eines freiwilligen Engagements in NPOs. Soziale Verantwortung als Persönlichkeitseigenschaft und das Kompetenzerleben vermitteln den Zusammenhang zwischen OCB und freiwilligem Engagement im Privatleben zwar nicht, klären jedoch einen hohen Varianzanteil beider Formen unabhängig voneinander auf. Andere individuelle Ressourcen und Wertekongruenz spielen für freiwilliges Engagement im beruflichen und privaten Kontext dagegen eine untergeordnete Rolle.
Die Integration und Diskussion der Befunde belegen die Bedeutsamkeit von Konsistenzbestreben im Sinne der Selbstwahrnehmung für Spillover-Effekte der Hilfsbereitschaft und Unkompliziertheit. Demgegenüber sind Spillover-Effekte der Eigeninitiative auf Selbstwirksamkeit zurückzuführen. Die Ergebnisse schaffen Ansatzpunkte zur Wertschätzung und Förderung von freiwilligem Engagement durch Arbeitgebende. Darüber hinaus lassen sich Implikationen für die Personalauswahl in der Erwerbsarbeit sowie die Rekrutierung und Bindung freiwillig engagierter Personen in NPOs ableiten.
In children exposed to any traumatic experience, a conditional prevalence rate of 15.9% was estimated for posttraumatic stress disorder (PTSD; Alisic et al., 2014). In order to achieve best treatment outcomes, selecting evidence-based treatments is necessary (Durlak & DuPre, 2008). For pediatric PTSD, international guidelines recommend the use of manualized trauma-focused cognitive behavioral therapy (TF-CBT; Forbes, Bisson, Monson, & Berliner, 2020; National Institute for Health and Care Excellence, 2018; Phoenix Australia Centre for Posttraumatic Mental Health, 2013) and many effectiveness studies and initiatives (e.g. Goldbeck, Muche, Sachser, Tutus, & Rosner, 2016; Jensen et al., 2014; National Child Traumatic Stress Network, 2012) disseminated the TF-CBT manual of Cohen, Mannarino and Deblinger (2006, 2017; specific TF-CBT). However, the uptake of evidence-based treatments such as specific TF-CBT into practice is strongly affected by service providers’ attitudes toward evidence-based practice (EBP; Aarons, 2004; Aarons, Cafri, Lugo, & Sawitzky, 2012; Aarons, Sommerfeld, & Walrath-Greene, 2009; Moullin, Dickson, Stadnick, Rabin, & Aarons, 2019). These attitudes can be measured with the Evidence-Based Practice Attitudes Scale-36 (EBPAS-36; Rye, Torres, Friborg, Skre, & Aarons, 2017). In Germany, several effectiveness trials are underway further disseminating specific TF-CBT (Rosner, Barke, et al., 2020; Rosner, Sachser, et al., 2020) but a reliable and validated German version of the EBPAS-36 is missing. In addition, in terms of pooled effect sizes (ES), only one review evaluated specific TF-CBT 10 years ago (Cary & McMillen, 2012). Furthermore, little is known about the stability of its treatment effects, the concordance between children and adolescents’ and their caregivers’ ratings regarding the youths’ symptoms in this context as well as the influence of the heterogeneity of instruments used by individual studies.
Therefore, the aims of this dissertation were fourfold: Publication 1 pooled ES for specific TF-CBT regarding posttraumatic stress symptoms (PTSS) and secondary outcomes to provide an update of the literature. Large improvements were found across all outcomes and results were favorable for specific TF-CBT compared to all control conditions at post-treatment. Publication 2 pooled ES for specific TF-CBT at 12-month follow-up for the same outcomes to evaluate the stability of treatment effects and investigated concordance between participants and caregiver ratings. Again, large improvements were evident across all outcomes and TF-CBT was superior to active treatments and treatment as usual at 12-month follow-up. No significant differences were detected between participant and caregiver ratings with high reliability across almost all outcomes and assessment points. Publication 3 produced a validated German translation of the EBPAS-36 (EBPAS-36D) to facilitate EBP implementation research in Germany. Good psychometric properties and validity of the EBPAS-36D were confirmed. As additional content, this dissertation provides an unpublished report on the pooled ES of publication 1 differentiated by instruments used to assess the outcomes. ES did not differ by the instrument used to assess the respective outcome.
The conclusions that can be drawn from the studies as well as their limitations are discussed in the final section. While the EBPAS-36D was successfully validated and specific TF-CBT was strongly supported, several issues were identified that need further research attention.
Background:
Pollen allergies are widespread around the world, making the study of pollen levels in and around cities a task of high importance. This is also related to the fact that an increasing number of people is living in cities and urban areas are expanding. In addition, environmental changes in the context of climate change are expected to alter plant characteristics that affect the amount of pollen in the air. In order to assess the allergy risk, information on pollen that people are exposed to is needed. Monitoring of aeroallergens in cities is often conducted using a single trap. This trap can provide information on background pollen concentration, however, it does not reflect temporal and spatial variations of pollen at street level of the heterogeneous urban environment. The amount of pollen in the air is the result of a number of processes, one of which is pollen production. Pollen production is expected to be altered by climate change and is influenced by environmental factors such as temperature or air pollutants. To further investigate variations of allergenic pollen in cities, this thesis focuses on these central research questions:
- Are there differences in the amount of airborne pollen between urban and rural locations and do pollen loads vary at different spatial and temporal scales?
- What is the influence of land use and management on pollen loads?
- Is there a difference in pollen production of allergenic species between urban and rural locations and can the influence of environmental factors be detected?
Data and Methods:
Data on airborne pollen were gathered in two study areas with various pollen traps. In Ingolstadt, Germany, background pollen concentrations of Poaceae were measured in 2019 and 2020. Additionally, a network consisting of twelve gravimetric pollen traps was set up during the grass pollen seasons of those years. For an additional sampling campaign, portable volumetric traps were used to measure pollen concentration at street level. Investigations were also conducted in Sydney, Australia, where concentrations of Poaceae, Myrtaceae and Cupressaceae pollen and Alternaria spores were measured during three pollen seasons from 2017 to 2020. In the summer of 2019/2020, additional ten gravimetric traps were set up. For both study areas, pollen season characteristics and temporal and spatial variations of pollen concentrations and pollen deposition were analysed in context with land use, land management and meteorological parameters.
Furthermore, pollen production of the allergenic species Betula pendula, Plantago lanceolata and Dactylis glomerata was investigated in the Ingolstadt study area along an urbanisation gradient, which covered different types of land use. In total, 24 individuals of B. pendula, 82 individuals of P. lanceolata and 54 individuals of D. glomerata were analysed. Pollen production was compared between urban and rural locations and the influence of air temperature and the air pollutants nitrogen dioxide (NO2) and ozone (O3) was assessed. Air temperature was measured in the field and pollutant concentrations were computed using a land use regression model.
Results and Discussion:
In Ingolstadt, grass pollen concentrations and deposition were generally higher at rural than at urban locations as documented in peak values and seasonal totals. Diurnal variations however, did not vary between urban and rural locations. Grass pollen levels were linked to local vegetation and land use but also land management, as grass cutting was reducing pollen levels in the surroundings.
In Sydney, pollen season characteristics varied between the seasons and we found significant correlations between daily pollen and spore concentrations and meteorological parameters. There were significant positive correlations with air temperature for all analysed pollen and spore types. Correlations with humidity (Myrtaceae, Cupressaceae, Alternaria) and precipitation (Myrtaceae, Cupressaceae) were negative. Spatial variations of pollen deposition were observed, but there were no correlations with land use. This could be attributable to the drought before and during this sampling campaign as well as the temporal setting of the sampling campaign.
The results from both study areas suggest that local vegetation is the main influence on the pollen amount at street level. However, when the season’s intensity decreased, other influences such as resuspension or pollen transport become more important. Analyses of pollen production revealed statistically significant differences between urban and rural locations for B. pendula and P. lanceolata. Pollen production decreased with temperature and urbanisation for all species, however, pollen production varied at small spatial distances within species. For increasing air pollutant levels, decreases were observed for B. pendula and P. lanceolata, but increases for D. glomerata. These results suggest that environmental influences seem to be species-specific.
The results from the studies contribute to the knowledge on temporal and spatial variations of airborne pollen in cities, as well as on pollen production of allergenic species. They highlight the importance of pollen monitoring at street level and at different locations in cities to assess the amount of pollen that people are exposed to. Further research in this area should investigate the influence of land management, which was identified to influence the amount of pollen in the air, and which could be a mitigation strategy for allergy-affected people. In addition, pollen production should be further examined with different kinds of experiments, as it is the major influence of ambient pollen concentration in the air.
Vor dem Hintergrund gesellschaftlicher Veränderungen und Herausforderungen gewinnt die Kooperation zwischen Wissenschaft, Politik, Wirtschaft und Bevölkerung zunehmend an Bedeutung. An Hochschulen führt dies dazu, dass diese sich im Sinne von Third Mission stärker hin zu ihrem nichtakademischen Umfeld öffnen. Diese Entwicklung im Aufgabenbereich der Hochschulen bringt strukturelle Änderungen mit sich und erfordert eine Organisationsentwicklung für die einzelnen Hochschulen. Dieser organisationale Veränderungsprozess wird im Zuge der Dissertation exemplarisch im Kontext eines großen Veränderungsprojekts untersucht, das die Third Mission stärken soll und an zwei Hochschulen angesiedelt ist.
Die Dissertation umfasst drei Publikationen mit folgenden Forschungsschwerpunkten und Ergebnissen: In der ersten Publikation zeigen sich Zusammenhänge zwischen der Wahrnehmung des Managements sowie bestimmten Ausprägungen der Organisationskultur und den kognitiven und affektiven veränderungsbezogenen Einstellungen der Wissenschaftler*innen. Darüber hinaus legen qualitative Ergebnisse dar, welche Erwartungen die Wissenschaftler*innen an das Veränderungsmanagement im Zuge organisationaler Veränderungen an Hochschulen haben.
Im Rahmen der zweiten Publikation werden die Einstellungen der Hochschulangehörigen gegenüber der Veränderung im Längsschnitt untersucht. Die kognitiven, affektiven und intentionalen Einstellungen sind sowohl zu Beginn des Prozesses als auch nach einem Jahr positiv ausgeprägt. Vor allem bei den Wissenschaftler*innen und wissenschaftsunterstützenden Mitarbeitenden zeigt sich jedoch ein Rückgang der positiven Einstellungen im Verlauf des Prozesses.
Mit der dritten Publikation wird die Rolle der organisationalen Gerechtigkeit bei Veränderungsprozessen an Hochschulen untersucht. Für die Bereitschaft der Mitarbeitenden, die Veränderung zu unterstützen, ist die prozedurale Gerechtigkeit relevant. Im Längsschnitt erklärt das Erleben dieser die Bereitschaft der Mitarbeitenden, die Veränderung ein Jahr später zu unterstützen. Dieser Zusammenhang wird durch die erlebten positiven Affekte mediiert.
Die Studienreihe vertieft im Gesamtbild das bisher existierende Verständnis der Einstellungen von Hochschulangehörigen im Rahmen organisationaler Veränderungsprozesse an Hochschulen. Zudem können aus den Befunden praktische Implikationen für die Umsetzung von Organisationsentwicklungen an Hochschulen sowie für die Stärkung der Third Mission und des Transfers an Hochschulen abgeleitet werden.
Diese kumulative Dissertation befasst sich mit den Auswirkungen des Klimawandels auf Hochgebirgslandschaften, insbesondere mit der Morphodynamik und der langfristigen Entwicklung aktiver Blockgletscher im Kaunertal in den Ötztaler Alpen, Österreich. Darüber hinaus liefert die Arbeit am Beispiel des Zwieselbachferners in den Stubaier Alpen, Österreich, neue Erkenntnisse über die Entstehung von blockgletscherähnlichen periglazialen Landformen. Diese können durch das Zusammenwirken von Felsstürzen und dem fortschreitenden Abschmelzen von Gletschern unterhalb der Gleichgewichtslinie entstehen.
In dieser Arbeit werden sowohl moderne Fernerkundungstechnologien, wie luftgestütztes LiDAR und digitale Luftbilder, als auch historische Datenquellen, wie analoge Luftbilder, historische Karten und Messdaten, verwendet. Durch diese Kombination können Fließgeschwindigkeiten und Höhenänderungen dieser Landschaftselemente über mehrere Jahrzehnte dokumentiert werden. Darüber hinaus ermöglicht dies eine detaillierte Untersuchung der Kinematik von Blockgletschern. Dabei reichen die Analysen auf Einzugsgebietsebene bis ins Jahr 1953 zurück. Für das Fallbeispiel des Inneren Ölgruben Blockgletschers reichen die Untersuchungen sogar bis ins Jahr 1922 zurück.
Es wurde ein allgemeiner Trend in der Blockgletscherkinematik festgestellt, der mit der alpenweiten Beschleunigung seit den 1990er Jahren übereinstimmt. Die Analyse deutet darauf hin, dass dieser Trend hauptsächlich auf den Anstieg der Frühlings- und Sommertemperaturen und das frühere Eintreten des Endes der Schneebedeckung zurückzuführen ist. Dies unterstreicht die Relevanz des gegenwärtigen Klimawandels und seiner Auswirkungen auf die Blockgletscherbewegungen. Die Erkenntnisse, die durch die Erweiterung des Untersuchungszeitraums bis 1922 gewonnen werden konnten, bestätigen diese Annahmen und unterstreichen die Bedeutung kürzerer Warmphasen und der Gletscherüberprägung zum Ende der LIA auf die Kinematik. Unsere Ergebnisse deuten darauf hin, dass die Entlastung durch Gletscherschmelze und das Abschmelzen von Toteis zu einer erhöhten Wasserverfügbarkeit und zu Veränderungen des Spannungs- und Fließfeldes führen und somit erhöhte Fließbewegungen begünstigen. Die Untersuchung der multidekadischen Blockgletscherkinematik zeigte eine deutliche Variabilität in der Reaktion einzelner Blockgletscher und Blockgletscherloben. Trotz der generellen Beschleunigungstrends seit den 1990er Jahren offenbaren der Zeitpunkt, das Ausmaß und die zeitlichen Maxima der kinematischen Veränderungen eine differenzierte Sensitivität oder Reaktionsdynamik der einzelnen Blockgletscher und Blockgletscherloben gegenüber Schwankungen und Änderungen der externen Einflussfaktoren. Dies weist auf die Bedeutung interner Faktoren für die Kinematik hin und unterstreicht die Komplexität dieser Geosysteme.
Ein weiterer Schwerpunkt dieser Arbeit ist die Untersuchung der Entstehung und Entwicklung einer blockgletscherähnlichen Landschaftsform, die durch einen Felssturz auf den Zwieselbachferner verursacht wurde. Unsere Ergebnisse deuten darauf hin, dass der Klimawandel eine entscheidende Rolle bei der Entstehung und Entwicklung solcher Landschaftsformen spielt. Seine Auswirkungen sind insbesondere im Hinblick auf die Gletscherdynamik, den Schutteintrag und die thermische Isolation des darunter liegenden Eises von großer Bedeutung. In unserem Fallbeispiel führt ein Felssturz zur Bildung einer schuttbedeckten Landform mit einem Eiskern, die aufgrund der unterschiedlichen Abschmelzraten des schuttbedeckten Teils und des umgebenden Gletschers steile Fronten und Flanken aufweist. Die Extrapolation der Eisdickenentwicklung lässt vermuten, dass dieser Teil des Gletschers nach dem vollständigen Abschmelzen des umgebenden Gletschers als periglaziale blockgletscherähnliche Landform erhalten bleibt.
This cumulative dissertation investigates the newly emerged phenomenon of customer success management (CSM). CSM has received a significant amount of attention from academics and practitioners alike. However, the body of academic literature is still in its infancy, especially when comparing CSM’s relevance to the field of relationship marketing.
Manuscript 1: Zakrzewski, K., Krause, V., Pfaff, C. & Seidenstricker, S. (2023). Is customer success management a new relationship marketing practice? A review, definition, and future research agenda based on practice theory.
Manuscript 2: Zakrzewski, K., Krause, V., Eberl, D. & Rangarajan, D. (2023). Dynamic & proactive segmentation of post-sale customer relationships in B2B subscription settings: The customer health score.
Manuscript 3: Zakrzewski, K. (2023). Customer success management - closing a capability gap in the customer-focused structure toward customer centricity in B2B service contexts.
The first manuscript adopts a new approach to the investigation of CSM, providing a practice-based definition that distinguishes CSM from other relationship marketing constructs. By utilizing the 3 Ps framework of practice theory (praxis, practices, and practitioners), the definition of CSM as a strategic function was refined. In addition, the second manuscript utilized praxis to develop the customer health score, which can be used as an indicator for the dynamic and proactive segmentation of customers. The third manuscript builds on this functional definition to show how CSM’s organizational embeddedness can help overcome barriers to customer centricity by enabling adaptive organizational capability.
In forecast combination, multiple predictions are linearly combined through the assignment of weights to individual forecast models or forecasters. Various approaches exist for defining the weights, which typically involve determining the number of models to be used for combination (selection), choosing an appropriate weighting function for the forecast scenario (weighting), and using regularization techniques to adjust the calculated weights (shrinkage). The papers listed address the integration of the three approaches into holistic data analytical models.
The first paper develops a two-stage model in which weights are first calculated based on the in-sample error covariances to minimize the error on the available data by combining the individual models. Based on the selection status of a model, the weight of an individual model is then linearly shrunk either toward the mean or toward zero. The selection status is thereby derived apriori from information criteria, where Contribution 1 introduces the selection based on the model’s in-sample accuracy and performance robustness under uncertainty.
Contribution 2 modifies the two-stage model to shrink the forecasters’ weights non-proportionally to the mean or zero. Further, a new information criterion based on forward feature selection is proposed that iteratively selects the forecaster that is expected to achieve the largest increase in accuracy when combined.
Contribution 3 extends the iteration-based information criterion presented in the second contribution to consider diversity gains in addition to accuracy gains when selecting and combining forecasters.
A one-stage model for simultaneous weighting, shrinking, and selection is finally built and evaluated on simulated data in Contribution 4. Instead of requiring a prior selection criterion, the model itself learns which forecasters to shrink to the mean or to zero, while relying on a new sampling procedure to tune the model.