240 research outputs found
Geometric Spanners of Bounded Tree-Width
No full textGiven a point set P in the Euclidean space, a geometric t-spanner G is a graph on P such that for every pair of points, the shortest path in G between those points is at most a factor t longer than the Euclidean distance between those points. The value t ≥ 1 is called the dilation of G. Commonly, the aim is to construct a t-spanner with additional desirable properties. In graph theory, a powerful tool to admit efficient algorithms is bounded tree-width. We therefore investigate the problem of computing geometric spanners with bounded tree-width and small dilation t.
Let d be a fixed integer and P ⊂ ℝ^d be a point set with n points. We give a first algorithm to compute an (n/k^{d/(d-1)})-spanner on P with tree-width at most k. The dilation obtained by the algorithm is asymptotically worst-case optimal for graphs with tree-width k: We show that there is a set of n points such that every spanner of tree-width k has dilation (n/k^{d/(d-1)}). We further prove a tight dependency between tree-width and the number of edges in sparse connected planar graphs, which admits, for point sets in ℝ², a plane spanner with tree-width at most k and small maximum vertex degree.
Finally, we show an almost tight bound on the minimum dilation of a spanning tree of n equally spaced points on a circle
Review: Doing educational research : a guide for first time researchers
No full textTitle: Doing Educational Research : a guide for first time researchers
Author/Editor: Clive Opie
Publisher: Sage Publications
Publication Date: 2004
ISBN: Paperback 0761970029
Price: £18.99
Reviewed by: Torben Steeg, Independent D&T Consultan
Visual Author-ship: Creativity and Intentionality in Media
No full textBook review of Torben Grodal (ed.): Visual Author-ship: Creativity and Intentionality in Media Northern Lights, vol. 3, 2004, Museum Tusculanum Press/University of Copenhage
Hybrid Logic Tableaux Systems
No full textTableaux systems are a tool to evaluate the satisfiability of logic formula. Hybrid logic tableaux systems have an important quality to them, namely their need for a loop check to ensure that the system is both finite and complete. This loop check ensures that the system terminates and does not enter a ”loop” of generating information that is not needed to evaluate the satisfiability of a given formula. This loop check is an important tool for other logic types, such as description logic, to investigating these systems can be valuable. Since the resulting tableaux system for a formula can often grow large, it is convenient to test such systems using a computer, where the system and its rules are implemented in a program and tested thoroughly.Therefore this project aims to implement the hybrid logic tableaux system presented in Torben Brau¨ner’s book, ”Hybrid logic and its proof theory” [3] into a Java program with the aim of testing the system itself and also evaluating the ease of implementation. If the system and its rules are implemented correctly, the program should not make a mistake or oversight while implementing the rules, it is therefore a safer way of testing and using a tableaux system.The most prominent issue with implementing the system presented in [3] was the fact that is was non-deterministic. Therefore it was necessary to carefully structure the program to ensure completeness, even when some rules had no specific time that would set them off.Ultimately the system was fully implemented in the Java program, and it passed all tests. The program is therefore considered complete. The strength of implementing a tableaux system into a computer program was displayed when the program discovered that one example from [3], example 4 page 74, did not have a complete tableaux tree. The author had accidentally neglected two rule applications from the tree, this did not result in any erroneous conclusions about the root formula as the rules were not particularly ”important”, but it did showcase the value of computer assisted tableaux
The case for a symmetric reaction function of the European Central Bank
No full textIn a macro-economic framework where the European Central Bank targets individual country data, the nature of strategic interactions between fiscal authorities in the euro-zone can be described as a stag hunt game with (at least) two equilibria that can be pareto-ranked. In fact we show that, because of the indiscriminate nature of its monetary response, an ECB strategy of monetary retaliation to any individual countrys over-expenditure affects all eleven countries to the same extent. This collective effect is similar to the teachers old favorite all children stay behind in the class if one misbehaves. This mechanism, we show, makes the game between fiscal authorities a multiple equilibria co-ordination game. We subsequently address the problem of equilibrium selection that is of particular importance to co-ordination games. Following Kandori et al. (1993), we apply Harsanyi and Seltens (1988) riskdominance criterion to single out the conditions for fiscal restraint to emerge as the equilibrium selected by interacting actors. Our main conclusions are that the ECB can ensure convergence of fiscal authorities upon the pareto-optimal equilibrium (that is, fiscal restraint) by adopting a reward-oriented, counter-cyclical strategy that compensates fiscal authorities at the output level both for giving up fiscal discretion and for incurring the risk of being hit by a monetary tightening in response to developments elsewhere in the euro-economy. This means that interest rates' movements should smoothen economic fluctuations in order to give economic actors sufficient incentives to maintain restraint. -- In einem makroökonomischen Kontext, in dem die Europäische Zentralbank die wirtschaftlichen Daten einzelner Länder anvisiert, können die strategischen Interaktionen zwischen den Finanzbehörden der Euro-Zone als ein stag hunt- Spiel mit (mindestens) zwei pareto-Equilibrien beschrieben werden. Wir zeigen daß, aufgrund der ungezielten Art der monetären Reaktion, eine EZB-Strategie der monetären Vergeltung für zu hohe Ausgaben eines einzelnen Landes alle elf Länder gleichermaßen betrifft. Dieser Kollektiveffekt erinnert an die alte Lehrermethode: Alle Kinder müssen nachsitzen, wenn eins aus der Reihe tanzt. Dieser Mechanismus macht das Spiel zwischen den Finanzbehörden zu einem Koordinationsspiel mit mehreren Equilibrien. Anschließend befassen wir uns mit dem in Koordinationsspielen besonders bedeutsamen Problem der Wahl zwischen Equilibrien. In Anlehnung an Kandori et al. (1993) wenden wir Harsanyi und Selten's (1988) Risikodominanzkriterium an, um die Bedingungen herauszufiltern, unter denen fiskale Zurückhaltung das Equilibrium bildet, das von den beteiligten Akteuren gewählt wird. Unsere wesentlichen Schlußfolgerungen sind, daß die EZB eine Konvergenz der Finanzbehörden auf das pareto-optimale Equilibrium (d.h. fiskale Zurückhaltung) sicherstellen kann, indem sie eine auf Belohnung ausgerichte, antizyklische Strategie verfolgt, bei der die Finanzbehörden auf der Output-Ebene entschädigt werden -sowohl für die Abgabe fiskaler Entscheidungsfreiheit als auch für das Risiko, einer monetären Kontraktion ausgesetzt zu werden, die auf Entwicklungen anderswo in der Euro-Wirtschaft abzielt. Das bedeutet, daß Zinsentwicklungen wirtschaftliche Fluktuationen ausgleichen sollten, um den relevanten Akteuren ausreichende Anreize für fiskale Zurückhaltung zu bieten.
New species can broaden myelin research: suitability of little skate, Leucoraja erinacea
No full text© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Moebius, W., Huemmert, S., Ruhwedel, T., Kuzirian, A., & Gould, R. New species can broaden myelin research: suitability of little skate, Leucoraja erinacea. Life, 11(2), (2021): 136, https://doi.org/10.3390/life11020136.Although myelinated nervous systems are shared among 60,000 jawed vertebrates, studies aimed at understanding myelination have focused more and more on mice and zebrafish. To obtain a broader understanding of the myelination process, we examined the little skate, Leucoraja erinacea. The reasons behind initiating studies at this time include: the desire to study a species belonging to an out group of other jawed vertebrates; using a species with embryos accessible throughout development; the availability of genome sequences; and the likelihood that mammalian antibodies recognize homologs in the chosen species. We report that the morphological features of myelination in a skate hatchling, a stage that supports complex behavioral repertoires needed for survival, are highly similar in terms of: appearances of myelinating oligodendrocytes (CNS) and Schwann cells (PNS); the way their levels of myelination conform to axon caliber; and their identity in terms of nodal and paranodal specializations. These features provide a core for further studies to determine: axon–myelinating cell communication; the structures of the proteins and lipids upon which myelinated fibers are formed; the pathways used to transport these molecules to sites of myelin assembly and maintenance; and the gene regulatory networks that control their expressions.This research received no external funding
Guidelines on how to quantify extremes in models using EVT (Milestone MS4)
No full textBlue-Action project
Milestone: MS4
Work package in charge: WP1 Improving seasonal long range forecast skill of risks for hazardous
weather and climate events
Actual achievement date of this milestone: Project‐month 18
Partner organisation in charge of the milestone and lead author:
The University of Reading (UREAD): Tamas Bodai
Other contributing authors:
Danish Meteorological Institute (DMI): Torben Schmith, Shuting Yang
Milestone Type: Report
Dissemination level: Public
Means of verification of attainment of the milestone: Analysis routines uploaded to data
Achieved: Yes
Abstract: The objective of this part of the project is to establish the statistical framework of predicting extremes
by a seasonal forecast system. This report summarises some preliminary results. Nonstationary extreme
value statistics of cold temperatures in Kiev has been evaluated, with some index of the NAO as a covariate
responsible for nonstationary conditions. We found that while mean DJF temperatures depend
more on negative values of an NAO index, some extremal features depend more on its positive values.
Furthermore, the lowest temperatures occur for intermediate values of the NAO index.The Blue-Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852 www.blue-action.e
Dan Turèll og Onkel Danny - Dan Turèll i feltet mellem populærkultur og finkultur
No full textThis project examines the way in which the Danish author and poet Dan Turèll achieves to combine high and popular culture through his literary works, as well as through his public persona. To understand the literary context in which he worked, we first establish him as being a part of the Danish postmodern movement, more concretely, the so-called formal breakthrough. The project paper contains an investigative analysis of four representations of his work as author and persona, these being: Vangede Billeder, essays from his collection of so-called mediemontager: Vaskeægte valfrändskaper og lyriske lærere, Menneske Myte Maskinen and Storebror am, two crime novels Mord i mørket and Mord på medierne and lastly his appearance in the Danish talk-show Lørdagshjørnet. The theoretical frame of this examination is built mainly on the thoughts of Pierre Bourdieu’s reflections on capitals and taste, John Storey and Stuart Hall’s on popular culture and Gérard Genette’s account of the literary interpretation context of paratexts. The theoretical and analytical insights will be connected in the course of this project, leading us to the conclusion that Turéll negotiated between cultural positions and thus influenced the way in which the public understood him as an author and persona, affecting both his career, as well as contributing in blurring the distinction between high and popular culture in the Danish culture landscape in general
The Poetic Gap : Arts-Based Learning from Secondary School Students´ Perspective
No full textTitle in English: The Poetic Gap – Arts-Based Learning from Secondary School Students´ Perspective Author: Torben FreytagLanguage: Swedish, with an English summaryKeywords: Aesthetic Learning, Drama, Film, Music, Phenomenography, Multimodality, Focus Group Interviews, Practice-Based Research This practice-based and phenomenographic study belongs to the field of aesthetic teaching and learning, covering an intersection of subjects, such as Drama, Music, Visual Arts and Swedish (mother tongue). The study focuses on how secondary school students experience teaching where different aesthetic forms of expression are included. Several research reviews use terms as transfer to describe how it affects students’ learning in school. The voices that are heard in this research field are usually from a teacher and school leader perspective. However, classroom studies where students’ voices constitute sources are rare. This study may therefore be of interest for teachers, school leaders and researchers in the field of education. Point of departure for this study is John Dewey’s theories about the importance of experience for learning and the role of arts. The theoretical framework is built on theories of multimodality and a multimodal perspective on learning. To investigate the students' learning, a four-week teaching design was planned. The following questions were posed: How do lower secondary school students experience to express themselves aesthetically? How do lower secondary school students experience teaching and learning that includes aesthetic expressions when reading fiction? To answer these questions, the following research methods were used: practice-based research, focus group interviews and art-based methods. In essence, the interviews with the students formed the basis for the analysis. The phenomenographic analysis of the material led to four descriptive categories of students´ aesthetic experience: To express freely, To interpret and figure out, To try different perspectives and To get others to understand. The students’ experiences of arts-based teaching are also described in four categories: To learn through creativity, To learn through collaboration, To learn media-specific and To not learn so much. The categories represent variations of how the students experienced their aesthetic self-expression and their views on this kind of teaching. Since the students’ responses pointed to a multimodal understanding, multimodal concepts such as cultures of recognition, transformation, transduction, simulation, signs, and representations of learning were applied. The discussion takes up how teaching through aesthetic learning can be developed and highlights how students' experiences and creativity can be seen as important ingredients in teaching and as a form of knowledge of its own.Examinator: Docent, Ketil Thorgersen</p
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