6 research outputs found

    Discovering causal relations and equations from data

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    Physics is a field of science that has traditionally used the scientific method to answer questions about why natural phenomena occur and to make testable models that explain the phenomena. Discovering equations, laws, and principles that are invariant, robust, and causal has been fundamental in physical sciences throughout the centuries. Discoveries emerge from observing the world and, when possible, performing interventions on the system under study. With the advent of big data and data-driven methods, the fields of causal and equation discovery have developed and accelerated progress in computer science, physics, statistics, philosophy, and many applied fields. This paper reviews the concepts, methods, and relevant works on causal and equation discovery in the broad field of physics and outlines the most important challenges and promising future lines of research. We also provide a taxonomy for data-driven causal and equation discovery, point out connections, and showcase comprehensive case studies in Earth and climate sciences, fluid dynamics and mechanics, and the neurosciences. This review demonstrates that discovering fundamental laws and causal relations by observing natural phenomena is revolutionised with the efficient exploitation of observational data and simulations, modern machine learning algorithms and the combination with domain knowledge. Exciting times are ahead with many challenges and opportunities to improve our understanding of complex systems

    der Johann Wolfgang Goethe-Universität in Frankfurt am Main von

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    Gegenstand der vorliegenden Arbeit war die Untersuchung des Transports intensiver Ionenstrahlen in toroidalen Magnetfeldern und die Injektion von geladenen Teilchenstrahlen in stelleratorähnliche Ringe. Ein Speicherring mit einem toroidalen Magnetfeld wurde für die Akkumulation von intensiven Ionenstrahlen vorgeschlagen. Die Konfiguration ist ähnlich, wie bei den klassischen Stellaratoren, bei denen Toroidsegmente zu einem Torus angeordnet werden, um geladene Teilchen einzuschließen. Die sich daraus ergebenden longitudinalen Magnetfelder ermöglichen aber auch die Fokussierung eines in solch einer Apparatur eingeschlossenen Ionenstrahls. Die magnetischen Feldlinien in diesem System sind nicht einfach geschlossen, sondern bilden magnetische Flächen. Der Transport von Ionenstrahlen ist stark durch die transversalen Driften aufgrund der gebogenen Feldlinien beeinflusst, den diese führen zu einer Änderung der Strahlablage und können zu Verlusten an der Wand der Vakuumkammer führen. Die Ursache für die genannte Drift ist die Zentrifugalkraft, das bedeutet, dass die Drift in Abhängigkeit vom Kreuzprodukt R × B von der Richtung des magnetische

    Curbing the major and growing threats from invasive alien species is urgent and achievable.

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    Although invasive alien species have long been recognized as a major threat to nature and people, until now there has been no comprehensive global review of the status, trends, drivers, impacts, management and governance challenges of biological invasions. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Thematic Assessment Report on Invasive Alien Species and Their Control (hereafter 'IPBES invasive alien species assessment') drew on more than 13,000 scientific publications and reports in 15 languages as well as Indigenous and local knowledge on all taxa, ecosystems and regions across the globe. Therefore, it provides unequivocal evidence of the major and growing threat of invasive alien species alongside ambitious but realistic approaches to manage biological invasions. The extent of the threat and impacts has been recognized by the 143 member states of IPBES who approved the summary for policymakers of this assessment. Here, the authors of the IPBES assessment outline the main findings of the IPBES invasive alien species assessment and highlight the urgency to act now
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