A Library of OpenGL-Based Mathematical Image Filters

International audienceThere are a lot of transformations that can turn one raster image into a derived one in a mathematically interesting way. This article describes a collection of such filters, implemented in OpenGL in order to use the high degree of parallelism modern GPUs provide, thereby providing performance required to process e.g. live camera images in real-time. The filters contained in this library include wallpaper groups, conformal maps described by meromorphic functions, as well as hyperbolic symmetry groups. Using examples of increasing complexity, several key implementation techniques are explained, including texture wrap configurations, user-configurable control points, and custom fragment shader programs. This work might exhibit aesthetic aspects of mathematics to the masses and provide useful building blocks for scientists as well as artists

Trade-based estimation of bluefin tuna catches in the Eastern Atlantic and Mediterranean, 2005-2011

The Eastern Atlantic and Mediterranean stock of Bluefin tuna Thunnus thynnus (BFTE) has long been considered overfished and at risk of collapse. Although ICCAT quotas for this stock have decreased considerably over the past years, uncertainty exists about the degree of catch beyond this quota. The extent of such catch is an important piece of information in stock assessment models as well as being an indicator of the effectiveness of fisheries management. We present a model using Bluefin tuna trade data to infer actual catches. Basing our calculations on 25 countries involved in BFTE trade, we estimate that between 2005 and 2011, allowable quotas were exceeded by 44 percent. This gap between catch and quotas has slightly increased over past years, leading to estimated excess catches of 57 percent for the period between 2008 and 2011. To improve assessments, preparation and design of BFTE management, we suggest that the estimated total removals reported in this paper be included in stock assessment models for BFTE. An implication of our findings is that ICCAT member states should take stronger measures to monitor and enforce compliance with quotas

Discrete conformal maps and ideal hyperbolic polyhedra

We establish a connection between two previously unrelated topics: a particular discrete version of conformal geometry for triangulated surfaces, and the geometry of ideal polyhedra in hyperbolic three-space. Two triangulated surfaces are considered discretely conformally equivalent if the edge lengths are related by scale factors associated with the vertices. This simple definition leads to a surprisingly rich theory featuring M\"obius invariance, the definition of discrete conformal maps as circumcircle preserving piecewise projective maps, and two variational principles. We show how literally the same theory can be reinterpreted to addresses the problem of constructing an ideal hyperbolic polyhedron with prescribed intrinsic metric. This synthesis enables us to derive a companion theory of discrete conformal maps for hyperbolic triangulations. It also shows how the definitions of discrete conformality considered here are closely related to the established definition of discrete conformality in terms of circle packings.Comment: 62 pages, 22 figures. v2: typos corrected, references added and updated, minor changes in exposition. v3, final version: typos corrected, improved exposition, some material moved to appendice

Kulturlandschaften Landkreis Meißen: Forschungsprojekt im Auftrag des Landratsamtes Meißen, gefördert über die Richtlinie zur Förderung der Regionalentwicklung (FR-Regio) durch den Freistaat Sachsen

„...der Landkreis Meißen zählt durch seine Lage, seine natürliche und kulturelle Vielfalt sowie seine ausgewogene Sozial- und Wirtschaftsstruktur zu den attraktivsten Regionen im Freistaat Sachsen. Reizvolle Städte und Gemeinden mit historisch bedeutsame Gebäudeensembles werden dabei eingebettet in lebenswerte und vielfältige Kulturlandschaften, die unsere Region unverwechselbar machen. Die vorliegende Forschungsarbeit der Technischen Universität Dresden dokumentiert eindrucksvoll, wie unsere abwechslungsreichen Kulturlandschaften unsere Heimat prägen und so zur regionalen Identität beitragen. Es wird aufgezeigt, dass sie mit ihren typischen Eigenarten nicht nur Teil unseres kulturellen, sondern auch unseres Naturerbes sind. Ihre Verletzbarkeit mahnt uns, mit diesen Werten verantwortungsvoll umzugehen und macht deutlich, dass deren Schutz und behutsame Nutzung als Querschnittsthema zahlreiche Lebensbereiche berührt. Der Umgang mit den Herausforderungen des Klimawandels und der demographischen Entwicklung wird im zukünftigen Bild unserer Kulturlandschaften sichtbar werden. Mit unseren Entscheidungen und unserem Handeln von heute beeinflussen wir das Lebensumfeld unserer Kinder, Enkel und Urenkel von morgen. Das Kulturlandschaftsprojekt bietet dabei die fachlichen Grundlagen für das Treffen der richtigen Entscheidungen und die Umsetzung konkreter Maßnahmen u. a. zum Klimaschutz, zur nachhaltigen Nutzung unserer Ressourcen und zum Erhalt unseres Kultur- und Naturerbes in den nächsten Jahrzehnten. Allen Personen, die zum Gelingen des Kulturlandschaftsprojektes im Landkreis Meißen beigetragen haben, danke ich für ihr Engagement. Mein besonderer Dank und meine Anerkennung für das Kompendium der Kulturlandschaftsentwicklung gelten dem Team von wissenschaftlichen Mitarbeiterinnen und Mitarbeitern sowie Studentinnen und Studenten rund um Frau Prof. Dr. Catrin Schmidt und natürlich ihr selbst für ihre hochgeschätzte, fundierte Arbeit.” Ralf Hänsel Landra

Metrics and Methods for Evaluation of Over-The-Air Performance of MIMO User Equipment

Commercial User Equipment (UE) testing and certification has become more complex for state-of-the-art mobile communication standards such as 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) due to the extensive use of Multiple Input-Multiple Output (MIMO) transmission techniques. The variety of different MIMO operating modes and the almost unlimited choice of possible multipath channel conditions under which UE performance may be evaluated are not accounted for by established Single Input-Single Output (SISO) Over-The-Air (OTA) performance metrics like Total Isotropic Sensitivity (TIS) and Total Radiated Power (TRP). As pointed out in this contribution, meaningful metrics and cost-effective, low-complexity measurement methods can, nevertheless, be derived by focusing on characterization of the physical attributes of UE and by adopting statistical metrics. Starting from a brief review of the most important MIMO operating modes in the 3GPP LTE standard, the relation between UE properties and UE performance, which is observed in these operating modes, is discussed. Two complementary metrics and corresponding measurement procedures for evaluation of MIMO OTA performance are presented in order to address the diversity of possible propagation scenarios. Measurement results from preliminary implementations of the two proposed measurement procedures, including comparison between different LTE devices, are presented

Structured health care for subjects with diabetic foot ulcers results in a reduction of major amputation rates

OBJECTIVE: We tested the effects of structured health care for the diabetic foot in one region in Germany aiming to reduce the number of major amputations. RESEARCH DESIGN AND METHODS: In a prospective study we investigated patients with diabetic foot in a structured system of outpatient, in-patient and rehabilitative treatment. Subjects were recruited between January 1(st), 2000 and December 31, 2007. All participants underwent a two-year follow-up. The modified University of Texas Wound Classification System (UT) was the basis for documentation and data analysis. We evaluated numbers of major amputations, rates of ulcer healing and mortality. In order to compare the effect of the structured health care program with usual care in patients with diabetic foot we evaluated the same parameters at another regional hospital without interdisciplinary care of diabetic foot (controls). RESULTS: 684 patients with diabetic foot and 508 controls were investigated. At discharge from hospital 28.3% (structured health care program, SHC) vs. 23.0% (controls) of all ulcers had healed completely. 51.5% (SHC) vs. 49.8% (controls) were in UT grade 1. Major amputations were performed in 32 subjects of the structured health care program group (4.7%) vs. 110 (21.7%) in controls (p<0.0001). Mortality during hospitalization was 2.5% (SHC) vs. 9.4% in controls (p<0.001). CONCLUSIONS: With the structured health care program we achieved a significant reduction of major amputation rates by more than 75% as compared to standard care

Kirja fragment

Gagern, Maximilian von, 1810-1889, saksa poliiti