Computation of Implicit Representation of Volumetric Shells with Predefined Thickness

We propose and validate a method to find an implicit representation of a surface placed at a distance h from another implicit surface. With two such surfaces on either side of the original surface, a volumetric shell of predefined thickness can be obtained. The usability of the proposed method is demonstrated through providing solid models of triply periodic minimal surface (TPMS) geometries with a predefined constant and variable thickness. The method has an adjustable order of convergence. If applied to surfaces with spatially varying thickness, the convergence order is limited to second order. This accuracy is still substantially higher than the accuracy of any contemporary 3D printer that could benefit from the function as an infill volume for shells with predefined thicknesses

2-Undecanone : a new attractant for anthropophilic mosquitoes

Stechmücken der Art Stegomyia aegypti (ehemals Aedes aegypti, REINERT et al. 2004) sind die wichtigsten Überträger von Gelbfieber- und Dengueviren. Diverse Arten der Gattung Anopheles verbreiten die Erreger der Malaria. Bei Versuchen, Malaria, Gelbfieber und Dengue einzudämmen, wurden in den letzten Jahrzehnten wiederholt Kampagnen gegen Stechmücken geführt. Dabei wurden Insektizide vielfach flächendeckend ausgebracht. Dies führte kurzfristig zu geringeren Mückendichten, allerdings entwickelten sich auch vielerorts gegen diese Gifte resistente Mückenpopulationen. Anstelle des flächendeckenden Gifteinsatzes wird heute versucht, die Insektizide örtlich und zeitlich effektiv einzusetzen, um so die Gefahr weiterer Resistenzbildung zu minimieren und sowohl die Kosten als auch die Belastung für Umwelt und Bevölkerung möglichst gering zu halten. Um Insektizide zur richtigen Zeit gezielt ausbringen zu können, ist ein Monitoring der Mücken erforderlich. Mückenfallen, die durch optische Effekte und Duftstoffe gezielt anthropophile Stechmückenarten anlocken, sind für ein derartiges Bestandsmonitoring besonders geeignet. Auf der Suche nach attraktiven Duftstoffen, welche die Effektivität solcher Fallen erhöhen, wurde unter anderem auch 2-Undecanon getestet. In Verhaltensversuchen mit den anthropophilen Mückenarten Stegomyia aegypti und Anopheles stephensi konnte die Attraktivität dieser Substanz sowohl als Einzelreiz als auch in Kombination mit anderen Attraktanzien gezeigt und quantifiziert werden.The attractiveness of 2-undecanone to host-seeking female Stegomyia aegpyti (former Aedes aegypti) and female Anopheles stephensi (Diptera: Culicidae) mosquitoes was tested in a Y-tube bioassay under laboratory conditions. -Undecanone alone in a concentration of 40 ppm was significantly more attractive to S. aegypti mosquitoes than pure air. In combination with other kairomones such as caproic acid, lactic acid and ammonia doses of 2-undecanone from 4 ppm up to 130 ppm augmented significantly the attractiveness of these kairomones. The synergism of 2-undecanone with other attractants is comparable to that one described for lactic acid. The combination of 2-undecanone with lactic acid, however, was more attractive than the two compounds as single stimuli. Interestingly 2-undecanone is neither known as an human skin compound nor as a volatile in human breath. First field experiments near Regensburg in Germany with BG-Sentinel® mosquito traps could not confirm the attractive effect of 2-undecanone (ROSE et al. 2006) for Culex species. A possible explanation could be that the tested dose of 2-undecanone was not in the optimum range or that the studied species do not respond to this compound

A Parallel Coupled Lattice Boltzmann-Volume of Fluid Framework for Modeling Porous Media Evolution

In this paper, we present a framework for the modeling and simulation of a subset of physical/chemical processes occurring on different spatial and temporal scales in porous materials. In order to improve our understanding of such processes on multiple spatio-temporal scales, small-scale simulations of transport and reaction are of vital importance. Due to the geometric complexity of the pore space and the need to consider a representative elementary volume, such simulations require substantial numerical resolutions, leading to potentially huge computation times. An efficient parallelization of such numerical methods is thus vital to obtain results in acceptable wall-clock time. The goal of this paper was to improve available approaches based on lattice Boltzmann methods (LBMs) to reliably and accurately predict the combined effects of mass transport and reaction in porous media. To this end, we relied on the factorized central moment LBM as a second-order accurate approach for modeling transport. In order to include morphological changes due to the dissolution of the solid phase, the volume of fluid method with the piece-wise linear interface construction algorithm was employed. These developments are being integrated into the LBM research code VirtualFluids. After the validation of the analytic test cases, we present an application of diffusion-controlled dissolution for a pore space obtained from computer tomography (CT) scans

Medienkompetenzentwicklung in einem außerschulischen Lernvideoprojekt für Kinder: Erfahrungen aus dem Modellprojekt "Ich zeig es Dir - HOCH 2"

Ich zeig es Dir – HOCH 2 (kurz IZED2) ist ein medienpädagogisches Praxisprojekt des BIMS e.V., bei dem Lernvideos von Kindern für Kinder erstellt wurden. Zentrale Kompetenzen welche die Teilnehmer des Projekts erwerben sollten waren die technische Kompetenz (iPad, Schnitt, Apps), die didaktische Gestaltung von Lernvideos (Präsentation der Lerninhalte, Gestaltung) und rechtliche Komponenten (Relevantes zu Urheberrecht und Persönlichkeitsrecht, z.B. Darstellung von Personen im Bild). In der ersten Projektphase wurden die teilnehmenden Kinder durch ExperteInnen unterwiesen. In der zweiten Phase wurden die TeilnehmerInnen mit einem Peer–to–Peer–Ansatz zu ExpertInnen und zeigen anderen Kindern („Peers“), in unserem Fall auch Erwachsenen, wie man Lernvideos mit iPads erstellt. In der projekteigenen Begleitforschung, die mit Unterstützung der Technischen Universität Graz durchgeführt wurde, wurden dazu unterschiedliche Verfahren eingesetzt um den Fortschritt der Kompetenzentwicklung nachzuzeichnen. Neben Fragebögen, Gruppeninterviews und Beobachtung wurden auch die Lernvideos analysiert und das Projekttagebuch hinzugezogen

The BG-Sentinel, a novel mosquito trap for research and surveillance

Um Informationen zur Verbreitung und Populationsdichte von Stechmücken zu gewinnen, werden verschiedene Methoden verwendet. Neben der Suche nach Larven oder Puppen in den Brutgewässern, dem Absuchen von Ruheplätzen nach Adulten und den Fang aktiver, wirtssuchender Mückenweibchen durch freiwillige Mückenfänger werden vor allem unterschiedliche Fallentypen verwendet. Abgesehen von zwar preiswerten, aber wenig effizienten Fallen für gravide (also nicht mehr wirtsuchende) Mückenweibchen werden bisher Fallen mit unspezifische Lockreizen betrieben (Farbkontraste, Licht, Kohlendioxid). Letzteres ist in seiner Verwendung zudem aufwendig und teuer, da es aus Trockeneis, aus Gasflaschen oder der Verbrennung von Propangas freigesetzt werden muß. Wir stellen einen neuartigen Fallentypus für Stechmücken vor, den BG-Sentinel (Abb. 1). Die Falle wurde ursprünglich für die Überwachung der Gelbfiebermücke Stegomyia aegypti (ehemals Aedes aegypti, REINERT et al. 2004) entwickelt, ist aber auch für eine Reihe anderer Mücken attraktiv. Der BG-Sentinel ist die erste Falle, die neben visuellen Reizen auch, wie ein natürlicher Wirt, eine aufwärtsgerichtete Luftströmung produziert. Diese Luftströmung kann durch Zugabe geeigneter Düfte mit Lockstoffen beladen werden. Wir stellen außerdem mit der sogenannten BG-Lure einen neuen Mückenlockstoff vor, der aus Substanzen besteht, die auch auf der menschlichen Haut vorkommt. Die Konstruktion des BG-Sentinel ermöglicht es, eine Vielzahl verschiedener Reize auf ihre Attraktivität im Feld zu testen. Im Folgenden werden Feldtests des BG-Sentinel mit Stegomyia aegypti in Brasilien und Culex pipiens in Deutschland beschrieben.We introduce a novel, patent pending type of mosquito trap, the BG-Sentinel®. The trap consists of an easy to transport, collapsible white bucket with white gauze covering its opening. In the middle of the gauze cover, there is a black tube through which a down flow is created by a fan that draws approaching mosquitoes into a catch bag. The air then exits the trap through the gauze; the design therefore generates ascending currents. These are similar to convection currents produced by a human host, both in its direction, its geometrical structure, and, due to the addition of attractants, also in its chemical composition. The attractants are given off by the so-called BG-Lure®, a dispenser which releases a defined, patent pending combination of lactic acid, ammonia, and caproic acid, all substances that are found on human skin. The dispenser emits the attractants for up to 5 month. The addition of CO2 is not necessary for species such as Stegomyia aegypti (syn. Aedes aegypti) or St. albopicta (syn Ae. albopictus). In field tests in Belo Horizonte, Brazil, the BGSentinel with the BG-Lure was much more efficient in catching the yellow fever mosquito St. aegypti than a propane-powered CO2-trap and a bidirectional Fay-Prince trap. The tests also indicate that the BG-Sentinel can be a sensitive and easy-to-use alternative to human landing/biting collections in the surveillance of adult host seeking Dengue vectors. Further field tests near Regensburg in Germany showed that the BG-Sentinel with the BG-Lure is also an efficient trap for Culex pipiens. The addition of CO2 or 2-Undecanone did not further improve the attractiveness of the BG-Lure. Due to its design, the BG-Sentinel can be used with a variety of other potential mosquito attractants, making it a versatile tool for mosquito research and surveillance

Experimental and finite element analyses of multifunctional skins for morphing wing applications

As a consequence of operational efficiency because of rising energy costs, future transport systems need to be mission-adaptive. Especially in aircraft design the limits of lightweight construction, reduced aerodynamic drag and optimized propulsion are pushed further and further. The first two aspects can be addressed by using a morphing leading edge. Great economic advantages can be expected as a result of gapless surfaces which feature longer areas of laminar flow. Instead of focusing on the kinematics, which are already published in a great number of varieties, this paper emphasizes as major challenge, the qualification of a multi-material layup which meets the compromise of needed stiffness, flexibility and essential functions to match the flight worthiness requirements, such as erosion shielding, impact safety, lighting protection and de-icing. It is the aim to develop an gapless leading edge device and to prepare the path for higher technology readiness levels resulting in an airborne application. During several national and European projects the DLR developed a gapless smart droop nose concept, which functionality was successfully demonstrated using a two-dimensional 5 m in span prototype in low speed (up to 50 m/s) wind tunnel tests. The basic structure is made of commercially available and certified glass-fiber reinforced plastics (GFRP, Hexcel Hexply 913). This paper presents 4-point bending tests to characterize the composite with its integrated functions. The integrity and aging/fatigue issues of different material combinations are analyzed by experiments. It can be demonstrated that only by adding functional layers the mentioned requirements such as erosion-shielding or de-icing can be satisfied. The total thickness of the composite skin increases by more than 100 % when required functions are integrated as additional layers. This fact has a tremendous impact on the maximum strain of the outer surface if it features a complete monolithic build-up. Based on experimental results a numerical model can be set up for further structural optimizaton of the multi-functional laminate. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

On the Convergence of Experimental Methodologies for Distributed Systems: Where do we stand?

International audienceUnderstanding distributed systems is a complex task. There are many subsystems involved, such as network equipment, disk and CPU, which effect behavior. In order to analyze this kind of applications, different approaches have been proposed: simulation, emulation and experimentation. Each paradigm has evolved independently, providing their own set of tools and methodologies. This paper explores how these tools and methodologies can be combined in practice. Given a simple question on a particular system, we explore how different experimental frameworks can be combined in practice. We use a representative framework for each methodology: Simgrid for simulation, Distem for emulation and Grid'5000 for experimentation. Our experiments are formally described using the workflow logic provided by the XP Flow tool. Our long term goal is to foster a coherent methodological framework for the study of distributed systems. The contributions of this article to that end are the following: we identify a set of pitfalls in each paradigm that experimenters may encounter regarding models, platform descriptions and others. We propose a set of general guidelines to avoid these pitfalls. We show these guidelines may lead to accurate simulation results. Finally, we provide some insight to framework developers in order to improve the tools and thus facilitate this convergence

Bile acid retention and activation of endogenous hepatic farnesoid-X-receptor in the pathogenesis of fatty liver disease in ob/ob-mice

The nuclear bile acid receptor FXR (farnesoid-X-receptor) has recently been implicated in the pathophysiology of non-alcoholic fatty liver disease because selective FXR-agonists improve glucose and lipid metabolism in rodent models of obesity. However, the regulation of FXR and other relevant nuclear receptors as well as their lipogenic target genes in fatty liver is still not revealed in detail. Livers were harvested from 14-week-old male ob/ob mice and wild-type controls. Serum bile acids were quantified by radioimmunoassay. mRNA and protein expression of transporters and nuclear receptors was analyzed by reverse transcriptase-polymerase chain reaction and Western blotting, whereas DNA binding to the IR-1 element was examined by electrophoretic mobility shift assay. In this study we show: (i) bile acid retention in ob/ob mice, (ii) a resulting FXR upregulation and binding to the IR-1 element in ob/ob animals and (iii) concomitant activation of the fatty acid synthase as a potential lipogenic FXR target gene in vivo. The present study suggests a potential role of hepatic bile acid retention and FXR activation in the induction of lipogenic target genes. Differences between intestinal and hepatic FXR could explain apparent contradictory information regarding its effects on fatty liver diseas