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Geopolitics - Sand as Strategic Resource
Get PDFSand is a mineral granular material and its sources, i.e., sand, gravel, and crushed rock are the second most exploited natural resource in the world after water. The use has tripled in the last two decades to an estimated 40-50 billion tons per year, but will increase further due to population growth, economic growth, and urbanization. Sand is primarily used by the construction sector, but also for land reclamation and other industrial uses such as glass and computer chips. On the other hand, sand is a critical ecological factor, e.g., for water filtration, shoreline protection, aquifers, and as habitat for many species. Most desert sand cannot be used for concrete and land reclaiming, as only sand types of a certain granularity and shape can be used for construction; even Gulf States need to import sand for construction. Given the rapidly increasing use of sand that can be used for construction and industry, there is a risk of a global shortage of technically usable sand. The United Nations Environment Programme (UNEP) argues for an appropriate regulation and monitoring of sand use, as there is a lack of coherent governance and only limited data for sand mining and trade. However, trade represents only a small part of the sand use as many countries have domestic production as well. In 2021, China produced 2.5 billion tons of cement and utilized 25 billion tons of sand for construction purposes, i.e., approximately half of the estimated annual global sand production.
Crushed rock, sand and gravels are extracted and traded illegally in some regions by criminal organizations called ‘sand mafias’. There is also a grey economy with a fragmented industry which makes tracking and documentation even more difficult. It can be concluded that it is not only necessary to have a coherent international governance, but also sufficient monitoring activities of sand mining as this is often poorly or not documented.
A geopolitical issue is the land reclamation. The city state of Singapore extended its landmass from 585 km² in 1959 to 724 km² in 2022, the sand demand led to loss of more than 20 Indonesian islands. Islands are strategic assets as they secure exclusive economic zones and sea borders. Sand can also be used to expand natural formations or to build artificial islands which are of major strategic importance for China to secure territorial claims. Sand trade is very attractive and even states that are aware of the potential damages continue to sell sand. Substitutes for sand in concrete could be waste products, crushed granite, barite powder, quarry dust or recycled construction and demolition waste. An alternative could be tall wood buildings based on mass timbers, i.e., large-format panelized wood products, such as the Ascent Tower with 19 stories of mass timber over a 6-level concrete podium. This paper analyzes sand as a new strategic resource, provides an overview on the current situation and problems and shows the need for global databases, improved monitoring, and international regulations
Polymerelektrolyte auf Basis einer Polyethylenoxidmatrix für 3D-Stromableiter in Lithium-Ionen-Batterien
Get PDFEine dreidimensionale (3D)-Elektrodenarchitektur von Lithium-Ionen-Batterien (LIBs) ermöglicht eine höhere Beladung mit Aktivmaterial pro Flächeneinheit, wodurch die gravimetrische Energiedichte gesteigert werden kann – ein wichtiges Merkmal für zukünftige Energiespeicher. Ebenso notwendig für neue Batteriegenerationen ist die Substitution von leicht entflammbaren Flüssigelektrolyten mit sicheren Polymerelektrolyten (PEs).
Im Rahmen dieser Arbeit wurde eine innovative Prototypzelle aus der Kombination einer anspruchsvollen 3D-Metallschaumkathode mit einem speziell entwickelten quasi-Polymerfestelektrolyt (QPFE) auf Basis einer Polyethylenoxid-Matrix verwirklicht. Bei einer spezifischen Fläche von 0.785 cm2 erreichte die 3D-LIB eine hohe Arbeitsspannung von 2.28 V und eine Flächenkapazität von bis zu 1.74 mAh cm 2 im ersten Ladezyklus. Die Vollzelle überstand 50 Lade-/Entladezyklen bei einer Stromdichte von 10 µA cm-2 und zeigt damit enormes Potential für den Übergang zur 3D-Architektur mit sicheren PEs. Hinsichtlich der Elektrolytanpassung an die 3D-Geometrie und die erforderlichen LIB-Anforderungen wurden die Einflüsse der Komponentenverhältnisse, des Leitsalzgehalts und des Weichmacheranteils mittels thermogravimetrischer Analyse, dynamischer Differenzkalorimetrie und diverser elektrochemischer Messmethoden, etwa der Zyklovoltammetrie oder der elektrochemischen Impedanzspektroskopie, analysiert. Komplementär dazu kamen spektroskopische Methoden zum Einsatz, die Aufschluss über morphologische und strukturelle Merkmale gaben. Als Resultat der Untersuchungen wurde ein QPFE synthetisiert, der einen neuartigen Weichmacher beinhaltet. Die positive Auswirkung auf die Dissoziation des Lithiumsalzes und den Lithiumtransport mit zunehmendem Weichmachergehalt beruhte auf der Kombination von Nitril-Endgruppen und Ethylenoxid-Ketten. Neben einer hohen ionischen Leitfähigkeit von 1.8 x 10 4 S cm-1 bei 30 °C und 1.3 x 10 3 S cm-1 bei 80 °C, einer Spannungsstabilität bis 5 V gegen Lithium, einer niedrigen Glasübergangstemperatur von -55.7 °C und einer thermischen Stabilität über 200 °C, konnte ebenfalls die Kompatibilität mit Lithiummetall nachgewiesen werden. Zudem wurde in weiterführenden Experimenten eine Methode ausgearbeitet, um ein interpenetrierdendes Netzwerk (IPN) aus den hergestellten PEs und einem elektroaktiven, heterozyklischen Polymer darzustellen. Die Integration von bis zu 30 Gew.-% überoxidiertem Polymethylpyrrol in die Matrixstruktur führte zu einer hundertfachen Steigerung der ionischen Leitfähigkeit. Die bei der Überoxidation entstehenden lithiumaffinen Gruppen senkten die Aktivierungsenergie drastisch von 34.86 kJ mol-1 auf 4.09 kJ mol-1 und erleichtern somit den Lithiumtransport innerhalb des IPN
Development and application of advanced correlative light and electron microscopy methods for biological samples
Get PDFSample preparation for electron microscopy (EM) has become extremely versatile and complex over the recent decades. Integration of light microscopy (LM) into such EM workflows, known as correlative light and electron microscopy (CLEM), has been shown to greatly enrich and facilitate ultrastructural studies. Even though CLEM represents an important milestone of microscopy, combining EM and LM further complicates sample preparation and imaging. Often, specially adapted imaging and sample preparation workflows are necessary for CLEM. Furthermore, due to the in-herently diverse nature of biological specimens, preparation methods also have to be adapted in this regard.
In this thesis, in cooperation with different working groups, a conventional in-resin CLEM workflow and two workflows integrating high-pressure freezing (HPF) and freeze substitution (FS) into sample preparation were developed or established. For this, a set of different biological model systems was employed.
For post-embedding in-resin CLEM, several fluorescent dyes and the green fluores-cent protein StayGold were identified to resist harsh EM sample preparation. Fluo-rescence retainment after EM preparation was systematically evaluated. The results led to the identification of Janelia Fluor X 554 (JFX554) and JFX549 as the most promising candidates with highest signal intensities. As ligand-conjugates of self-labeling enzyme tags these dyes were suitable to label different cellular components including mitochondria, Golgi apparatus and endoplasmic reticulum (ER) and still display fluorescence after embedding for TEM. Furthermore, in combination with JF525 or StayGold, dual-color CLEM experiments were achieved.
In a second part, the first ever CLEM workflow of Dictyostelium discoideum infected with Mycobacterium marinum including HPF and FS was developed. This protocol allowed for identification and 3D visualization of ruptured and intact membranes of Mycobacteria-containing vacuoles (MCV).
Finally, a robust and reproducible protocol for HPF and FS of Saccharomyces cere-visiae was established and tested with several mutant strains. By this, first evidence was found suggesting possible interactions of endocytic compartments and lipid droplets (LDs) via membrane contact sites (MCS)
The Safety of AI-based Research
Get PDFArtificial Intelligence (AI) is commonly understood as the ability of machines to perform tasks that normally require human intelligence. The definitions of human intelligence include the mental capacity to recognize, analyze and solve problems, and a human is then more intelligent if this can be done faster and/or for more complex problems.
Currently, the development of AI is heading towards an Artificial General Intelligence AGI reaching human level of cognition with the final goal to achieve an Artificial Super-Intelligence ASI which goes beyond human intelligence. A rapidly evolving AI application is the Generative AI where the AI can create content like new images, texts, sounds, and videos based on short instructions, the prompts. Meanwhile, OpenAI develops Q* (Q Star) as advanced AI-based research engine in the Project Strawberry and Q*/Strawberry will likely be integrated into the next release of ChatGPT5 which may be released in the coming months. The planned Q* capabilities include the ability to conduct deep research by autonomous internet retrieval, to plan and execute multi-step long-horizon tasks, to conduct logic reasoning and the ability to solve mathematic problems on an academic level. In August 2024, the Tokyo-based company Sakana released the first version of its ‘AI Scientist’, an AI agent that can conduct all parts of a research from idea generation to publication automatically. Despite this is a relatively lean tool and neither an AGI nor self-aware, it caused safety issues by autonomously creating new codes to re-launch itself, overriding time limits for experiments, saving more data resulting in a Terabyte of extra data and importing new Python code from libraries. As this AI agent utilizes LLMs like ChatGPT4o, the release of ChatGPT5 may amplify the capabilities and safety issues of the AI Scientist and other AI agents as well. Due to their design, these AI research engines should be able to grow dynamically and theoretically indefinitely. For developers, it is challenging to achieve creativity, autonomy, and safety of a research engine simultaneously. Further issues are bypassing of humans, AI deception and the use of these tools for open-source intelligence OSINT and cyber espionage operations, as well as for biological and chemical weapons. The training of AI is dependent from high-quality data created by humans, because a training with AI-generated data leads to a rapid loss of quality, the so-called model collapse. While the use of AI in science has a very large potential to generate hypotheses, design experiments, to collect and interpret large datasets with detection of unknown patterns and relations and to take over routine work, there is a creeping contamination of scientific publications by undeclared AI-generated texts. The human knowledge base is also influenced by the planned or already ongoing use of AI as gatekeeper in search engines which transforms them into Question & Answer engines. The paper briefly presents the chances and safety issues of AI-based and AI-supported research and discusses potential precautionary measures like containerization and the option for an emergency shutdown
Saliency-driven explainable deep learning in medical imaging: bridging visual explainability and statistical quantitative analysis
Get PDFDeep learning shows great promise for medical image analysis but often lacks explainability, hindering its adoption in healthcare. Attribution techniques that explain model reasoning can potentially increase trust in deep learning among clinical stakeholders. In the literature, much of the research on attribution in medical imaging focuses on visual inspection rather than statistical quantitative analysis.
In this paper, we proposed an image-based saliency framework to enhance the explainability of deep learning models in medical image analysis. We use adaptive path-based gradient integration, gradient-free techniques, and class activation mapping along with its derivatives to attribute predictions from brain tumor MRI and COVID-19 chest X-ray datasets made by recent deep convolutional neural network models.
The proposed framework integrates qualitative and statistical quantitative assessments, employing Accuracy Information Curves (AICs) and Softmax Information Curves (SICs) to measure the effectiveness of saliency methods in retaining critical image information and their correlation with model predictions. Visual inspections indicate that methods such as ScoreCAM, XRAI, GradCAM, and GradCAM++ consistently produce focused and clinically interpretable attribution maps. These methods highlighted possible biomarkers, exposed model biases, and offered insights into the links between input features and predictions, demonstrating their ability to elucidate model reasoning on these datasets. Empirical evaluations reveal that ScoreCAM and XRAI are particularly effective in retaining relevant image regions, as reflected in their higher AUC values. However, SICs highlight variability, with instances of random saliency masks outperforming established methods, emphasizing the need for combining visual and empirical metrics for a comprehensive evaluation.
The results underscore the importance of selecting appropriate saliency methods for specific medical imaging tasks and suggest that combining qualitative and quantitative approaches can enhance the transparency, trustworthiness, and clinical adoption of deep learning models in healthcare. This study advances model explainability to increase trust in deep learning among healthcare stakeholders by revealing the rationale behind predictions. Future research should refine empirical metrics for stability and reliability, include more diverse imaging modalities, and focus on improving model explainability to support clinical decision-making
Lindblad dynamics from spatio-temporal correlation functions in nonintegrable spin-1/2 chains with different boundary conditions
Get PDFWe investigate the Lindblad equation in the context of boundary-driven magnetization transport in spin-1/2 chains. Our central question is whether the nonequilibrium steady state of the open system, including its buildup in time, can be described on the basis of the dynamics in the closed system. To this end, we rely on a previous study [Heitmann et al., Phys. Rev. B 108, L201119 (2023)], in which a description in terms of spatio-temporal correlation functions was suggested in the case of weak driving and small system-bath coupling. Because this work focused on integrable systems and periodic boundary conditions, we here extend the analysis in three directions: (1) We consider nonintegrable systems, (2) we take into account open boundary conditions and other bath-coupling geometries, and (3) we provide a comparison to time-evolving block decimation. While we find that nonintegrability plays a minor role, the choice of the specific boundary conditions can be crucial due to potentially nondecaying edge modes. Our large-scale numerical simulations suggest that a description based on closed-system correlation functions is a useful alternative to already existing state-of-the-art approaches
Idiosyncratic gesture use in a mother-infant dyad in chimpanzees (Pan troglodytes schweinfurthii) in the wild
Get PDFOne promising method to tackle the question, “In which modality did language evolve?” is by studying the ontogenetic trajectory of signals in human’s closest living relatives, including chimpanzees (Pan troglodytes). Concerning gestures, current debates centre on four different hypotheses: “phylogenetic ritualization”, “social transmission through imitation”, “ontogenetic ritualization”, and “social negotiation”. These differ in their predictions regarding idiosyncratic gestures, making such occurrences a crucial area of investigation. Here, we describe a novel and potential idiosyncratic behaviour — ‘hand-on-eye’ — which was initially observed in one mother-infant dyad in a community of chimpanzees living in the wild. We systematically investigated the form, sequential organisation, intentionality, usage, function, and distribution of the behaviour over a five-year period. The results showed that ‘hand-on-eye’ was nearly exclusively deployed in a single mother-infant dyad, was accompanied by hallmarks of intentionality, and served to initiate or resume joint dorsal travel. Although the behaviour was observed once in each of three other mother-infant dyads, these lacked the same frequency and hallmarks of intentionality. ‘Hand-on-eye’ thus qualifies as an idiosyncratic gesture. The proposed developmental pathway gives support to both the “ontogenetic ritualization” and “social negotiation” hypotheses. It also stresses the crucial need for longitudinal approaches to tackle developmental processes that are triggered by unique circumstances and unfold over relatively long time windows
Darboux transformation of symmetric Jacobi matrices and Toda lattices
Get PDFLet J be a symmetric Jacobi matrix associated with some Toda lattice. We find conditions for Jacobi matrix J to admit factorization J = LU (or J = ) with L (or ) and U (or ) being lower and upper triangular two-diagonal matrices, respectively. In this case, the Darboux transformation of J is the symmetric Jacobi matrix J(p) = UL (or J(d) = ), which is associated with another Toda lattice. In addition, we found explicit transformation formulas for orthogonal polynomials, m-functions and Toda lattices associated with the Jacobi matrices and their Darboux transformations
The Geopolitics of Antarctica
No full textThe paper analyzes the geopolitics of the Antarctic (South Pole) region which is dominated by strategies for the time after the end of the Antarctic Treaty in 2041. Antarctica with 13.2 million square kilometers and a landmass under the ice shield is protected as common heritage of mankind by the Antarctic Treaty from 1959 that came into force in 1961; the treaty is the legal framework and guarantees the free access and research rights for the international community. In 2023, the treaty had 56 parties; of these, 29 of them are Antarctic Treaty Consultative Parties (ATCP) which currently maintain approximately 80 research stations in Antarctica. While the Antarctic Treaty is valid until 2041, there are also territorial claims from the days of the South Pole expeditions by Australia, New Zealand, France, Norway, Argentina, Chile, and United Kingdom. All claims are ‘frozen’ by the Antarctic Treaty until 2041, but the geopolitics is already looking forward to the time after. The Antarctic Treaty System ATS consists of the Antarctic Treaty and related agreements and conventions, the Agreed Measures for the Conservation for Flora and Fauna of 1964, the Convention for the Conservation of Antarctic Seals (CCAS) of 1972, the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) of 1980, the Convention on the Regulation of Antarctic Mineral Resource Activities (CRAMRA) of 1988, as well as of the Protocol on Environmental Protection to the Antarctic Treaty of 1991, also known as Madrid Protocol. As the end of the Antarctic Treaty in 2041 is coming closer, the actors start to bring themselves into an advantageous position on the Antarctic chessboard. The most important activity is the strategic positioning of research stations. While those countries with territorial claims focus on their territory, United States, Russia, and China place their stations across the claimed territories. Antarctic projects are typically national projects without international cooperation. The United States control the South pole with the centrally located Amundsen-Scott Station and have permanent stations in all sectors which are claimed by other states. Russia is also present with large stations that are used for space research and installations for the Navigation Satellite System GLONASS. Like for the Chinese satellite system BeiDou, the Western states are concerned about the dual use-potential of such installations. China has now five large stations and is expanding its capabilities and infrastructure also by an airstrip construction, modern icebreakers, and the systematic use of ports and gateways to Antarctica. Australia and Chile already made claims of continental shelves adjacent to Antarctica while Norway extended its territorial claims to the South Pole in 2015. The debate about exploitation of resources such as minerals, oil, gas, metals, gold etc. is still more theoretical. Environmental aspects are the climate change with the melting ice shield, threats to biodiversity by invasive alien species, the increasing microplastic pollution and the biosecurity where giant viruses and virophages (viruses that infect other viruses) are important matters. It is unrealistic that the states with territorial claims would be able to squeeze out the large powers United States, China, and Russia out of their territories. For this reason, Antarctica is at risk to dissolve into a patchwork of territories with factual control by various nations, a phenomenon that is already known from the Spratly islands in the South Chinese Sea
Cyberwar Grundlagen Methoden Beispiele
No full textDer Cyberwar (Cyberkrieg) ist die kriegerische Auseinandersetzung mit den Mitteln der Informationstechnologie. Dieses Arbeitspapier unternimmt eine aktuelle Bestandsaufnahme und geht auf die theoretischen und praktischen Probleme ein. In der Praxis ist der Cyberwar ein integraler Bestandteil militärischen Handelns, lässt sich jedoch nicht ganz von der Spionage trennen, da das Eindringen in und Aufklären von gegnerischen Systemen wesentlich für das weitere Vorgehen ist. Nach einem Überblick über Angriffsmethoden, Angreifer (Advanced Persistent Threats), Spionagetools, Cyberwaffen und der Cyberverteidigung liegt ein besonderes Augenmerk auf der Einordnung von Cyberangriffen (Attribution) und der Smart Industry (Industrie 4.0). Anschließend werden die Cyberwar-Strategien der USA, Chinas, Russlands und weiterer führender Akteure besprochen. Weitere Kapitel befassen sich der Künstlichen Intelligenz einschließlich Large Language-Modellen und der Generativen KI, der Smart Industry, smarten Systemen und biologischen Anwendungen