2972 research outputs found
Sort by
Die Geopolitik von Spitzbergen
Full text linkDer Beitrag analysiert die Geopolitik Spitzbergens, einer Inselgruppe mit 400 Inseln und Schären mit 61.022 km² Fläche und 2993 Einwohnern im Polarkreis, die von militärischen und sicherheitspolitischen Aspekten und dem besonderen Status des Gebietes durch den Spitzbergen-Vertrag dominiert wird. Der offizielle Name des Gebietes ist Svalbard (kühle Küste), in der Praxis ist aber auch der Name der Hauptinsel Spitzbergen gebräuchlich.
Insgesamt hat sich der Spitzbergen-Vertrag bewährt und das friedliche Zusammenleben der Bewohner geregelt. Durch die Weiterentwicklung des internationalen Rechts in den vergangenen 100 Jahren, insbesondere durch das Seerechtsübereinkommen der Vereinten Nationen (UNCLOS III) mit der Errichtung von 200-Meilen-Zonen als Ausschließliche Wirtschaftszonen und Ansprüchen auf Festlandssockel haben sich unterschiedliche Auslegungen des Spitzbergen-Vertrages ergeben.
Aber auch der Vertrag selbst ist eine Quelle von Diskussionen, insbesondere wenn es um Fischerei und die militärische Nutzung geht.
Für Norwegen und die NATO stellt die Präsenz der Russen und der Chinesen eine besondere Situation dar, während für die Russen Spitzbergen direkt in der Passage der Nordmeerflotte in den Atlantik liegt. Russland hat die Bestimmungen des Spitzbergen-Vertrages als erstes Land zur Errichtung der bis heute bestehenden Präsenz genutzt.
China ist seit 2004 mit der Yellow-River-Forschungsstation in Ny-Ålesund präsent und baut seine arktischen Aktivitäten weiter aus. Sicherheitspolitisch sind die SvalSat-Bodenstation für Satelliten und die Unteressekabel bedeutsam. Durch die zunehmend angespannte internationale Lage ist die Stabilität der Region jetzt Gegenstand des geopolitischen Diskurses
Transforming the energy system in multi-functional landscapes: Potential of a landscape-based modelling approach
Full text linkOne of the most important challenges of our time is the transformation towards a sustainable future. This encompasses the transition the energy system to renewable energy sources. A large part of this involves the reorganisation of the infrastructure system, in which conventional power plants such as coal and nuclear power plants must be replaced by wind power plants and photovoltaic systems. However, the transformation of the energy system is associated with major economic, ecological and social challenges. These include ensuring stable security of supply and enabling a cost-efficient transition. At the same time it is necessary to avoid undesirable side effects for the environment, economy and society. The transformation process has a large spatial component and is accompanied by structural changes to the multi-functional landscapes in which it takes place. Therefore, it is necessary to explicitly consider the complex interactions of the newly emerging energy infrastructure system with the natural and social environment. Due to the long-term nature of energy infrastructures, a proactive, integrated assessment of the possible development paths of the changing system is necessary. Modelling can provide new insights into the transformation process of the energy system and the development of intervention options that have not yet been fully understood in their consequences. This thesis aims to gain a better understanding of the transformation process of power supply infrastructures in multi-functional landscapes using the example of the energy transition in the electricity sector. An emphasis was put on demonstrating the potential of examining energy system transformations from a holistic environmental energy systems perspective. This was achieved through a dynamic landscape-based approach. In addition, the transformation of the energy system was conceptualised as a spatio-temporal process and considered as the result of allocation decisions regarding the placement of wind and solar power plants in the landscape. The first objective of this thesis was to better understand the process of transforming the energy system, and the identification of factors relevant to the security of supply. This included a systematic analysis of the interplay and relative importance of technological, economic, social and political factors that impose spatial or temporal constraints on the transformation process in terms of ensuring security of supply. Of particular interest was whether power demand can be reliably met at all times and whether interventions in the system can counteract the constraints imposed by other factors. The second objective of this thesis was to conduct a systematic analysis of the trade-offs that occur between security of supply and side effects on the social and natural environment. In addition, limiting factors for energy security were assessed, with a particular focus on the availability of land for the construction of wind power plants. This thesis also pursues a methodological objective: the development of a model to simulate the transformation from conventional to renewable power plants in multi-functional energy landscapes to assess its impact on security of supply and side effects and for a dynamic, landscape-based, proactive and integrated assessment of the transformation of the energy infrastructure system. For this purpose, the stylised and landscape-based model ELAN was developed. It simulates a transformation process from conventional to renewable power supply infrastructure elements on a model landscape. The replacement of conventional power plants by wind and solar power plants is considered as a dynamic process resulting from individual allocation decisions on where to build a power plant. It also includes an agent-based decision component in which model regions can make autonomous decisions to influence the allocation process to counteract spatial externalities. ELAN was applied to different landscape scenarios to analyse spatial and temporal dynamics of the transformation process. The findings of this thesis contribute to a better understanding of security of supply and limiting factors for the transformation process. The results show that maintaining security of supply during the transformation process does not depend on a single factor, but on a complex interplay of natural, technological and socio-economic factors, as well as the landscape-structure. The power demand was identified as a main driver of the transformation process. Furthermore, the results revealed that the landscape structure as well as an interplay of spatial and temporal factors can have a strong influence on the availability of land and on security of supply. It was shown that there are three other limiting factors: affordability, accessibility and the velocity of wind power expansion. Using ELAN, it was possible to gain a mechanistic and causal understanding of the investigated transformation processes. A major advantage of the stylised modelling approach was to break down the high system complexity of a real energy transition to simple contexts. The landscape-based approach made it possible to analyse the impacts with regard to the multi-functionality of landscapes. The dynamic approach of simulating the transformation process resulting from the allocation decisions of wind and solar power plants has revealed insights into the transformation of energy systems. Furthermore, it has facilitated the analysis of transient dynamics and the interplay between the energy system and the landscape. The facilitation of strategic infrastructure planning and proactive integrated assessment was realised in this work by applying ELAN to different scenarios. The model was able to describe plausible futures of transforming energy landscapes. These included for example the future distribution of power plants in the model landscape, the potential land consumption, the assessment of the reliability of supply security and the impact on costs, regional welfare and fairness. Using ELAN, a comprehensive understanding of temporal and spatial dynamics of the underlying system was gained. Potential negative economic, social and environmental impacts were also identified
Territory densities of heathland breeding birds are enhanced by fire on military training areas
No full textHeathland ecosystems have experienced severe declines. Today, the remaining heathlands suffer from succession and airborne nitrogen deposition. To counteract the negative effects of both, various management measures such as choppering, grazing, mowing or sod-cutting have been implemented. However, thus far, these measures only partially halted the loss of biodiversity. We compared environmental conditions and territory densities of characteristic heathland breeding bird species on 91 randomly selected plots in two large heathlands that vary in their long-term land use history: a military training area shaped by fire and a nature reserve where grazing dominates. Our study revealed strong differences in environmental conditions and territory densities. In the military training area, very open habitats accounted for more than two thirds per plot. By contrast, in the nature reserve, semi-open habitats had a share of more than one half per plot. Mean territory densities of open heathland species were 1.6 times higher in the training area compared to the nature reserve. By contrast, territory densities of semi-open heathland species did not differ. Overall, fire was assumed as the key driver of territory densities in characteristic heathland breeding birds. In comparison to traditionally managed heathlands, fire management of heathlands favoured breeding birds in two ways: First, through preserving the nutrient balance, which very likely had positive effects on insect food supply and may also on the formation of eggshells. Second, by creating early successional stages rich in bare ground that allow an easy access to invertebrate food resources. Based on our study, heathland management should aim at rejuvenating heathlands and creating early successional stages regularly without causing nutrient imbalances in the long run. Consequently, we recommend an extension of the area and frequency of prescribed burning in a mosaic-like manner in heathlands, especially outside military training areas
Hexokinase-I directly binds to a charged membrane-buried glutamate of mitochondrial VDAC1 and VDAC2
No full textBinding of hexokinase HKI to mitochondrial voltage-dependent anion channels (VDACs) has far-reaching physiological implications. However, the structural basis of this interaction is unclear. Combining computer simulations with experiments in cells, we here show that complex assembly relies on intimate contacts between the N-terminal α-helix of HKI and a charged membrane-buried glutamate on the outer wall of VDAC1 and VDAC2. Protonation of this residue blocks complex formation in silico while acidification of the cytosol causes a reversable release of HKI from mitochondria. Membrane insertion of HKI occurs adjacent to the bilayer-facing glutamate where a pair of polar channel residues mediates a marked thinning of the cytosolic leaflet. Disrupting the membrane thinning capacity of VDAC1 dramatically impairs its ability to bind HKI in silico and in cells. Our data reveal key topological and mechanistic insights into HKI-VDAC complex assembly that may benefit the development of therapeutics to counter pathogenic imbalances in this process
Landnutzungswandel an der Schnittstelle zwischen Schule und Gesellschaft - Komplexe Zusammenhänge nachhaltiger Flächennutzung adressatengerecht kommunizieren
No full textDer fortschreitende Landnutzungswandel zählt zu den zentralen Herausforderungen unserer Zeit. Das stetige Wachstum der Bevölkerung, wirtschaftliche Expansion sowie die Veränderung des globalen Klimas erfordern ein grundlegendes Umdenken in Bezug auf den Umgang mit natürlichen Ressourcen. Auch die global verfügbare Fläche rückt damit zunehmend als begrenzte und umkämpfte Ressource in den Fokus. Veränderungen der Art oder Intensität der Flächennutzung gehen häufig mit tiefgreifenden ökologischen Folgen einher. Ein nachhaltiger Umgang mit Boden- und Nutzflächen muss daher als gesamtgesellschaftliche Aufgabe mit wachsender Bedeutung verstanden werden. Trotz seiner hohen Relevanz findet das Thema Landnutzungswandel bislang nur wenig Beachtung in öffentlichen Diskursen und Bildungsprozessen. An dieser Stelle setzt die vorliegende Arbeit an. In dieser Dissertation werden interaktive Bildungsformate zur nachhaltigen Flächennutzung für verschiedene Zielgruppen entwickelt und evaluiert. Das übergeordnete Ziel dieser Arbeit ist dabei neben der Konzeption fachlich fundierter, didaktisch sinnvoll gestalteter Formate auch die empirische Überprüfung ihrer Wirksamkeit.
Die Arbeit fokussiert sich insbesondere auf zwei Formate, ein Schülerlabor für Schulklassen ab Jahrgang 9 sowie eine interaktive Ausstellung für Erwachsene aller Altersklassen. Beide Formate greifen zentrale Aspekte des Landnutzungswandels auf und weisen dabei diverse Bezüge zu einer ausgewählten Modellregion auf, anhand derer die Inhalte experimentell und kontextbezogen vermittelt werden.
Die Wirksamkeit beider Formate wurde im Rahmen einer empirischen Begleitstudie evaluiert. Im Schülerlabor erfolgte die Befragung im Prä-Post-Follow-Up-Design, in der interaktiven Ausstellung in einer Prä-Post-Erhebung. In beiden Angeboten wurde die Wirksamkeit auf das Umweltbewusstsein, das Interesse sowie das Relevanzempfinden untersucht. Darüber hinaus wurde im Schülerlabor die mittelfristige Stabilität des Fachwissens überprüft. Die Ergebnisse weisen unter anderem auf positive Effekte in Bezug auf das Umweltbewusstsein sowie das Relevanzempfinden der Teilnehmenden hin. Zudem bestätigen sie die Verständlichkeit der vermittelten Inhalte sowie das Potenzial interaktiver Formate zur Förderung nachhaltigkeitsbezogener Kompetenzen im Sinne der Scientific Literacy. Insgesamt trägt die Arbeit zur Entwicklung und Etablierung zielgruppenspezifischer Bildungsangebote
zum Thema Landnutzungswandel bei und zeigt exemplarisch, wie komplexe Umweltprobleme verständlich und wirksam vermittelt werden können
Außerschulische Nachhaltigkeitsbildung während und nach der Pandemie - Resilienz, Teilhabe und öffentlicher Diskurs zwischen KlimaLab_OS und Make@thons
No full textMit Ausbreitung der COVID-19-Pandemie über die frühen 2020er Jahre und damit einhergehenden politischen Konsequenzen wie Kontaktbeschränkungen und Schulschließungen bedurfte es in Deutschland und darüber hinaus neuer Möglichkeiten des (nicht nur schulischen) Lernens. Neben den pandemiebedingten Einschränkungen der vergangenen Jahre sieht sich die Weltbevölkerung jedoch auch weiteren, insbesondere geopolitisch-ökologischen Herausforderungen konfrontiert. Politische und wirtschaftliche Krisen, Energie- sowie Klimakrise erfordern langfristig Resilienz, Persistenz und zukunftsorientierte Bildung für alle. Außerschulisches Lernen und Nachhaltigkeitsbildung stellen auch aufgrund ihrer Position in der Bildungslandschaft zentrale Säulen einer post-pandemischen Bildung für nachhaltige Entwicklung dar. Losgelöst vom schulischen Rahmen können sie Meinungsbildung, Werte und Kompetenzen fördern sowie Relevanz und Motivation schaffen, sodass sich Schüler*innen (aber auch allgemein Bürger*innen) handlungsorientiert für eine ganzheitlich-nachhaltige Zukunft engagieren. Mit den Make@thons wurden seit Einsetzen der Pandemie kreativitätsfordernde Projektzeiträume etabliert, in denen sich vor allem Schüler*innen aktuellen sowie zukunftsrelevanten Fragen widmen und Lösungsansätze für regionale und globale Herausforderungen entwickeln. Die im
Rahmen dieser Arbeit konzipierten und durchgeführten Make@thons zu Themen der Nachhaltigkeit wurden hinsichtlich der Rahmung als (außer-)schulisches Format evaluiert und zeigten kurzfristig positive Effekte auf durch die Teilnehmenden selbsteingeschätzte Kreativität und Problemlösekompetenz. Als begleitendes Laborsetting, in dem Teilnehmende anhand vier Sphären naturwissenschaftlich-interdisziplinär die Klimakrise adressieren und autonom forschen konnten, fand das KlimaLab_OS Einbettung in die Make@thons, nachdem es zuvor im Rahmen des außerschulischen Aktionsprogramms „Aufholen nach Corona für Kinder und Jugendliche“ konzipiert wurde. Als eigenständiges, eintägiges Schüler*innenlabor-Setting für Schüler*innen ab der achten Jahrgangsstufe wurde es hinsichtlich der Förderung affektiver Konstrukte wie Fach- und Sachinteresse am Schulfach Chemie sowie Fähigkeitsselbstkonzept untersucht. Auch hier können, insbesondere im Vergleich der Schulformen, kurzfristige, positive Effekte auf unter anderem Langeweile, Interessiertheit und Sachinteresse angenommen werden, womit das Laborsetting die Ergebnisse früherer Studien unterstreicht. Neuartige Konzepte, die Nachhaltigkeitsbildung mit (außer-)schulischem Lernen verknüpfen, wie hier die Make@thons und das KlimaLab_OS, zeigen geeignete Wege auf, wie Bildung für nachhaltige Entwicklung langfristig in die Bildungslandschaft eingebunden werden kann, um so die
globalen Herausforderungen der kommenden Jahr(zehnt)e bewältigen zu können
Applications of Drone-Based Laser Scanning in Conflict Landscape Research
No full textIn order to understand, critically reflect and learn from historical events, it is essential to document traces of past cultures, historical events or conflicts before they are lost or irretrievably transformed. Airborne laser scanning has become a central component of investigating historical landscapes. Drone-based laser scanning (UAV-LiDAR) is a relatively new technology in this context. It offers higher spatial resolution and flexibility, but also introduces challenges in flight planning, ground filtering, automated terrain anomaly detection with limited training data, and high system cost. This thesis addresses these challenges with a focus on detecting terrain anomalies in historical conflict landscapes. UAV-LiDAR data were acquired using a RIEGL miniVUX-1UAV. Vegetation, among other influencing factors, emerged as a crucial element affecting both data acquisition and ground point filtering. Leaf-off conditions were essential in deciduous forests, and in the absence of low vegetation, filter choice was less relevant (less than 6% variation). However, in areas with dense understorey, the morphological ground filter performed best. A spline-based refinement step further improved filtering, especially in dense low vegetation. Automated terrain anomaly detection was implemented using a multi-scale decomposition and a one-class SVM, applied in an unsupervised manner. The splines improved F1-scores by up to 42 percentage points (dense vegetation) and 14 points (sparse vegetation). Completeness reached values of 0.8 and 1.0 respectively. This indicates high potential for fieldwork support, as reflected by the fact that the achieved completeness consistently exceeded correctness. It tended to identify most relevant features and can therefore be suitable as a tool to assist in the planning of field prospection. To test broader applicability, two low-cost systems were additionally employed and compared: DJI Zenmuse L1 and RGB-based Structure-from-Motion (SfM). In leaf-off conditions without near-ground vegetation, both low-cost methods captured sufficient ground data and achieved completeness comparable to the high-end RIEGL miniVUX-1UAV system. In an area with dense understorey, however, only the high-end system reliably detected anomalies, SfM performed poorly. In addition to testing newly emerging low-cost UAV-LiDAR systems for applicability, future research should explore deep learning for anomaly detection under limited training data, and consider integrating LiDAR intensity or multispectral data, as these may serve as indirect indicators of subsurface features not discernible in terrain models alone
Neuartige Methoden für effiziente Inaktivierung von pathogenen Bakterien auf Lebensmitteln
No full textInfections by pathogenic bacteria from food are an ongoing problem in human nutrition. Many established decontamination measures do not fulfill consumer demands for minimally processed and residual-free foods. Novel decontamination measures that partially have not been implemented in food processing, like different kinds of irradiation or bacteriophages, could be gentle to the product but need further research on bacterial inactivation efficiency. Irradiation like electron beam or ultraviolet light harbor the limitation of penetration depth into the food product and shading. Bacteriophages on the other hand need optimal conditions to infect and inactivate their bacterial host. The aim of this study was to investigate whether and how the limitations of irradiation in processing foods can be overcome by adapting parameters like intensity, duration, acceleration energy or wavelength and if irradiation can be complemented by additional application of bacteriophages. While the physical treatment of irradiation delivered several log CFU inactivation on dried seeds (Salmonella, E. coli, E. faecium) and chicken breast (Campylobacter jejuni), the rather limited inactivation observed for Campylobacter phages (< 1 log) sparked the further question if and how phage application can be optimized for food treatment. The combination of irradiation (UV) and bacteriophages was found to have an additive effect in reducing cell counts on food, while the conditions prevailing on chicken breast seem to be unfavorable for Campylobacter phages in general and hard to be improved even under lab conditions. The data presented here can contribute to the understanding and the development of non-thermal, gentle decontamination measures and optimal design of combined hurdle technologies
Rate-Adaptive LiDAR Point Cloud Streaming Over LEO Satellite Networks
No full textEmerging Low Earth Orbit (LEO) satellite networks provide reliable connectivity in rural areas, enabling an autonomous agriculture comprising fleets of fully connected robots. Many agricultural robots are equipped with Light Detection and Ranging (LiDAR) sensors, which generate large, three-dimensional point clouds that are often offloaded to dedicated cloud-based computing centers for complex processing tasks. However, the produced data rates can reach hundreds of Mbit/s, overwhelming the uplink of current LEO satellite networks of approximately 20Mbit/s, making a real-time transmission challenging. In this paper, we propose a novel solution that enables the real-time and rate-adaptive streaming of point clouds over bandwidth-restricted LEO satellite networks by introducing the concept of mini point clouds: a large point cloud is divided into smaller subsets that are individually compressed and transmitted. We develop a novel, real-time capable rate-adaptation algorithm leveraging Google Draco. It predicts optimal encoding parameters for each mini point cloud to maximize the point cloud quality under varying network conditions. It is configurable to prioritize computational speed or adaptation accuracy, and prevents congestion-induced packet loss by slightly under-utilizing the link. We extensively evaluate our algorithm on network traces from recent real-world Starlink measurements. It achieves real-time performance and near-optimal adaptation accuracy. Our solution is independent of the specific application and underlying network technology, making it broadly applicable to domains other than agriculture
Minors of algebraic matrices and sparse graph signals
No full textThis dissertation studies how combinatorial properties of graphs and simplicial complexes are reflected in the spectral and algebraic structure of their associated matrices. A central theme is the behavior of eigenvectors and the minors of eigenvector matrices, leading to general criteria for when such minors are nonzero. These results connect to uncertainty principles and also structural features of graphs.
The spectral insights developed here enable new sampling and recovery guarantees for compressed sensing on graphs and simplicial complexes, showing that sparsity in the spectral domain can be exploited through highly localized measurements. Finally, classical results from spectral graph theory are extended to higher dimensional settings