1,960 research outputs found
Revealing Physical and Ecological Dynamics at an Ice Edge – a Robotic Approach
No full textRevealing Physical and Ecological Dynamics at an Ice Edge – a Robotic Approach
Wulff, T. (1) ; Lehmenhecker, S. (1) ; Hagemann, J. (1) ; Busack, M. (1) ; Tippenhauer, S. (1) ; Strohmeier, M. (2) ; Rothe, J. (2)
1: Alfred Wegener Institute, Bremerhaven, Germany
2: University of Wuerzburg, Wuerzburg, Germany
Marginal ice zones (MIZs) are characterized by the complex and dynamic interaction between the atmosphere, the ice, and the ocean. This high dynamics put MIZs among the – biologically – most productive regions of our planet and make them an ideal place to investigate the coupling between physics and ecology. Fostered by the last decades´ technological progress in robotics and sensor technology, marine sciences are increasingly able to monitor and understand these processes, which occur on very small scales – both temporal and spatial.
The German Alfred Wegener Institute (AWI) has regularly operated an Autonomous Underwater Vehicle (AUV) in the Arctic and especially in the MIZ of the Fram Strait since 2009. Starting in 2011 / 2012 AWI has also used Unmanned Aerial Vehicles (UAVs) to support AUV operations and gather a holistic picture of the investigated area. In our talk we will give an overview on the equipment and infrastructure used to support our AUV dives including an UAV for operations at high latitudes. We will present technical details of our vehicle´s scientific payload which is specifically designed to investigate the physical dynamics of the marginal ice zone and its ecological response
El uso del software HistCite para identificar artículos significativos en búsquedas por materias en la Web of Science
No full textHistCiteTM is a large-scale computer tool for mapping science. Its power of visualization combines
the production of historiographs on the basis of the analysis of co-citations of documents, with the
use of bibliometrics specific indicators. The objective of this article is, to present the advantages of
the new bibliometrics configuration of HistCiteTM (2004) when identifying articles to analyze the
histograms that produces HistCiteTM, in terms of cumulative advantage and aging of the citations
to do a comparative study of the results of HistCiteTM, in its indicators of amplitude and recognition.
Also is examined its treatment of the sampling problems, by formalizing the question of
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Ingrid Bohn: Kleine Geschichte Stockholms. ; Jörg-Peter Findeisen und Poul Husum: Kleine Geschichte Kopenhagens.
No full textCarl-Axel Gemzell: "Vänskap och politik. Aspekter på de engelsk-svenska relationerna under det andra världskriget"
No full textDieter Diestelmann: Kleine Braunschweiger Stadtgeschichte. ; Konrad Dittrich: Kleine Lübecker Stadtgeschichte. ; Matthias Gretzschel: Kleine Hamburger Stadtgeschichte.
No full textConstructing Light Spanners Deterministically in Near-Linear Time
No full textGraph spanners are well-studied and widely used both in theory and practice. In a recent breakthrough, Chechik and Wulff-Nilsen [Shiri Chechik and Christian Wulff-Nilsen, 2018] improved the state-of-the-art for light spanners by constructing a (2k-1)(1+epsilon)-spanner with O(n^(1+1/k)) edges and O_epsilon(n^(1/k)) lightness. Soon after, Filtser and Solomon [Arnold Filtser and Shay Solomon, 2016] showed that the classic greedy spanner construction achieves the same bounds. The major drawback of the greedy spanner is its running time of O(mn^(1+1/k)) (which is faster than [Shiri Chechik and Christian Wulff-Nilsen, 2018]). This makes the construction impractical even for graphs of moderate size. Much faster spanner constructions do exist but they only achieve lightness Omega_epsilon(kn^(1/k)), even when randomization is used.
The contribution of this paper is deterministic spanner constructions that are fast, and achieve similar bounds as the state-of-the-art slower constructions. Our first result is an O_epsilon(n^(2+1/k+epsilon')) time spanner construction which achieves the state-of-the-art bounds. Our second result is an O_epsilon(m + n log n) time construction of a spanner with (2k-1)(1+epsilon) stretch, O(log k * n^(1+1/k) edges and O_epsilon(log k * n^(1/k)) lightness. This is an exponential improvement in the dependence on k compared to the previous result with such running time. Finally, for the important special case where k=log n, for every constant epsilon>0, we provide an O(m+n^(1+epsilon)) time construction that produces an O(log n)-spanner with O(n) edges and O(1) lightness which is asymptotically optimal. This is the first known sub-quadratic construction of such a spanner for any k = omega(1).
To achieve our constructions, we show a novel deterministic incremental approximate distance oracle. Our new oracle is crucial in our construction, as known randomized dynamic oracles require the assumption of a non-adaptive adversary. This is a strong assumption, which has seen recent attention in prolific venues. Our new oracle allows the order of the edge insertions to not be fixed in advance, which is critical as our spanner algorithm chooses which edges to insert based on the answers to distance queries. We believe our new oracle is of independent interest
Karen Klitgaard Povlsen (Hg.): "Northbound. Travels, Encounters and Constructions 1700–1830"
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Peter C. Kjærgaard, Helge Kragh, Henry Nielsen, Kristian Hvidtfeldt Nielsen (eds.): Science in Denmark. A Thousand-Year History.
No full text„Ob man an die kleinen Kinder gedacht hat ...?“ Die Verhandlungen über medizinische Hilfe für deutsche Flüchtlinge in Dänemark am Ende des Zweiten Weltkriegs.
No full textAt the beginning of May 1945 almost 250.000 refugees from the eastern parts of Germany were in Denmark, having been evacuated into the occupied kingdom. From the arrival of the first refugee in February until the German capitulation in Denmark on May 5, 1945, 6.580 refugees lost their lives. Among them were more than 4.000 children who mostly died of malnutrition and pneumonia.This article examines the reasons behind this death toll and sheds light on the negotiations pertaining to medical help for the refugees between the Danish administration and the German authorities. However, due to egoistical and political considerations both on the German and Danish sides, an agreement was never settled upon
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