Extrusion of Aluminum Tubes with Axially Graded Wall Thickness and Mechanical Characterization

In this study the indirect extrusion of seamless aluminum tubes with variable wall thickness was investigated. Therefore, an axially moveable stepped mandrel was applied. Investigations revealed that wall thickness transitions can either be graded over the tube length or very sharp. The microstructures in thin-walled and thick-walled tube sections were investigated. The local variation of the extrusion ratio and with that the tube wall thickness, product velocity and product temperature during the process lead to significantly different local microstructures at TB=400 °C. At TB=500 °C the microstructure was homogeneously recrystallized with similar grain size in all different tube sections. Furthermore, the mechanical tube properties were characterized by three point bending tests

Does trade integration alter monetary policy transmission?

This paper explores the role of trade integration—or openness—for monetary policy transmission in a medium-scale New Keynesian model. Allowing for strategic complementarities in price-setting, we highlight a new dimension of the exchange rate channel by which monetary policy directly impacts domestic inflation. Although the strength of this effect increases with economic openness, it also requires that import prices respond to exchange rate changes. In this case domestic producers find it optimal to adjust their prices to exchange rate changes which alter the domestic currency price of their foreign competitors. We pin down key parameters of the model by matching impulse responses obtained from a vector autoregression on U.S. time series relative to an aggregate of industrialized countries. While we find evidence for strong complementarities, exchange rate pass-through is limited. Openness has therefore little bearing on monetary transmission in the estimated model

A new comparative approach to macroeconomic modeling and policy analysis

In the aftermath of the global financial crisis, the state of macroeconomic modeling and the use of macroeconomic models in policy analysis has come under heavy criticism. Macroeconomists in academia and policy institutions have been blamed for relying too much on a particular class of macroeconomic models. This paper proposes a comparative approach to macroeconomic policy analysis that is open to competing modeling paradigms. Macroeconomic model comparison projects have helped produce some very influential insights such as the Taylor rule. However, they have been infrequent and costly, because they require the input of many teams of researchers and multiple meetings to obtain a limited set of comparative findings. This paper provides a new approach that enables individual researchers to conduct model comparisons easily, frequently, at low cost and on a large scale. Using this approach a model archive is built that includes many well-known empirically estimated models that may be used for quantitative analysis of monetary and fiscal stabilization policies. A computational platform is created that allows straightforward comparisons of models’ implications. Its application is illustrated by comparing different monetary and fiscal policies across selected models. Researchers can easily include new models in the data base and compare the effects of novel extensions to established benchmarks thereby fostering a comparative instead of insular approach to model development

Defining the core proteome of the chloroplast envelope membranes

High-throughput protein localization studies require multiple strategies. Mass spectrometric analysis of defined cellular fractions is one of the complementary approaches to a diverse array of cell biological methods. In recent years, the protein content of different cellular (sub-)compartments was approached. Despite of all the efforts made, the analysis of membrane fractions remains difficult, in that the dissection of the proteomes of the envelope membranes of chloroplasts or mitochondria is often not reliable because sample purity is not always warranted. Moreover, proteomic studies are often restricted to single (model) species, and therefore limited in respect to differential individual evolution. In this study we analyzed the chloroplast envelope proteomes of different plant species, namely, the individual proteomes of inner and outer envelope (OE) membrane of Pisum sativum and the mixed envelope proteomes of Arabidopsis thaliana and Medicago sativa. The analysis of all three species yielded 341 identified proteins in total, 247 of them being unique. 39 proteins were genuine envelope proteins found in at least two species. Based on this and previous envelope studies we defined the core envelope proteome of chloroplasts. Comparing the general overlap of the available six independent studies (including ours) revealed only a number of 27 envelope proteins. Depending on the stringency of applied selection criteria we found 231 envelope proteins, while less stringent criteria increases this number to 649 putative envelope proteins. Based on the latter we provide a map of the outer and inner envelope core proteome, which includes many yet uncharacterized proteins predicted to be involved in transport, signaling, and response. Furthermore, a foundation for the functional characterization of yet unidentified functions of the inner and OE for further analyses is provided

Detektion und Klassifikation von Krafteinwirkungen auf die Fahrzeugaußenhaut auf Grundlage piezoelektrischer Signale

Die Vision dieses Forschungsprojektes ist die Überwachung der Außenhaut eines abgestellten Fahrzeuges. Das Ziel besteht in einer automatischen Detektion und Klassifikation von Krafteinwirkungen, um dem Fahrzeughalter ein Gefühl von Sicherheit zu vermitteln, wenn er nicht in direkter Umgebung seines Fahrzeuges ist. Die Schwerpunkte dieser Dissertation umfassen die Konzept- und Algorithmenerstellung eines automatisierten Überwachungssystems der Fahrzeugaußenhaut

Nutzung von Mantelwellensperren für die MR-geführte Mikrowellenablation

Bildgeführte, minimalinvasive Verfahren werden zur Biopsie suspekten Gewebes und dessen Behandlung eingesetzt. Eine weit verbreitete Methode für Letzteres sind thermoablative Verfahren wie beispielsweise die Mikrowellenablation (MWA). Mittels Bildgebung kann eine korrekte Platzierung einer für die MWA genutzten Elektrode überwacht werden. Die applizierten elektromagnetischen Felder führen aufgrund des Leistungsumsatzes im Gewebe zu einer starken Temperaturerhöhung. Studien haben gezeigt, dass unter Einhaltung eines Sicherheitssaumes von >5mm um den Tumor die Rezidivrate erheblich gesenkt werden kann [1]. Die Nutzung des MRTs bietet dazu die Möglichkeit Temperaturkarten zu erstellen, um einen geforderten Sicherheitsraum nachweisen zu können. Die MR-Bildgebung hat jedoch den Nachteil, äußerst anfällig gegenüber Interferenzen externer Geräte zu sein [2]. Eine mögliche Störquelle stellen hierbei Gleichtaktströme dar, welche sich auf den langen Zuleitungen zwischen MWA-Generator und Ablationselektrode bilden können. Um diese Gleichtaktströme zu dämpfen, gibt es in der MR-Bildgebung den Ansatz, nichtmagnetische Mantelwellensperren (MWS) zu verwenden [3]. Typischerweise wird hierfür ein geschirmter Leiter aufgewickelt und die resultierende Induktivität bildet mit einer an der Schirmung angebrachten Kapazität einen Schwingkreis, welche im Resonanzfall eine hohe Impedanz für den Gleichtaktstrom aufweist [4]. Die Effektivität der MWS hängt von deren Platzierung auf dem Kabel ab. Eine Neuplatzierung der MWS nach dem Anlöten am Kabelschirm ist mit einem erheblichen Aufwand in der MR-Umgebung verbunden [3]. Auch sollte beachtet werden, dass die Nutzung von Kabelzuleitungen für therapeutische Anwendungen den thermischen und chemischen Anforderungen einer klinischen Sterilisation genügen müssen. Durch das Anlöten der Kondensatoren der solenoiden MWS am Kabelschirm wird dieser Prozess erschwert. Alternative MWS sind zum Beispiel die Floating Cable Traps (FCTs). Bei diesen wird auf dem geschirmten Kabel ein koaxiales Leitersegment angebracht, dessen Innen- und Außenleiter an den Enden mit Kondensatoren abgeschlossen wird. Im Resonanzfall weist das koaxiale Leitersegment eine hohe Impedanz auf, welches zu einer Dämpfung des vom Schirm des Kabels in das koaxiale Leitersegment eingekoppelten Gleichtaktsignals führt. Die FCT bietet hierbei den Vorteil, dass diese Art der MWS nicht auf den Außenleiter eines Koaxialkabels angelötet werden muss. In diesem Paper soll ein Konzept vorgestellt werden, bei dem FCTs für den klinischen Einsatz einer Mikrowellenablation genutzt werden. Die Wirksamkeit wird mittels MR-Bildgebung überprüft

Manufacturing of embedded multimode waveguides by reactive lamination of cyclic olefin polymer and polymethylmethacrylate

We demonstrate the manufacturing of embedded multimode optical waveguides through linking of polymethylmethacrylate (PMMA) foils and cyclic olefin polymer (COP) filaments based on a lamination process. Since the two polymeric materials cannot be fused together through interdiffusion of polymer chains, we utilize a reactive lamination agent based on PMMA copolymers containing photoreactive 2-acryloyloxyanthraquinone units, which allows the creation of monolithic PMMA-COP substrates through C-H insertion reactions across the interface between the two materials. We elucidate the lamination process and evaluate the chemical link between filament and foils by carrying out extraction tests with a custom-built tensile testing machine. We also show attenuation measurements of the manufactured waveguides for different manufacturing parameters. The lamination process is in particular suited for large-scale and low-cost fabrication of board-level devices with optical waveguides or other micro-optical structures, e.g., optofluidic devices. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).DFG/SFB/TRR 12

Prüfung des Frost-Tausalz-Widerstandes von Beton für die Expositionsklasse XF2

In cold and moderate climates concrete can be subjected to a combined salt frost attack, which can cause scaling damage. Consequently, numerous test procedures were developed to determine the resistance of concrete compositions against this kind of attack. These tests typically mimic a severe attack with high levels of saturation, e.g. as for concrete pavements. Very few approaches exist for testing the salt frost scaling resistance of concretes, which are subjected only to medium levels of saturation, as such concrete elements typically don’t show notable scaling damage. However, the increasing use of low carbon cements with high clinker substitution rates might affect the salt frost scaling resistance of such concrete elements to some extent. To ensure adequate durability of such concretes it is thus desirable to determine their performance in an actual test procedure instead of relying on past experience. Thus, less severe test methods was developed, which are based on the Slab test and the CDF test, repectively.In kalten und gemäßigten Klimazonen kann Beton einem kombinierten Frost-Tausalz-Angriff ausgesetzt sein, der zu Schäden in Form von Abwitterungen führen kann. Daher wurden zahlreiche Prüfverfahren entwickelt, um die Widerstandsfähigkeit von Betonzusammensetzungen gegen diese Art des Angriffs zu bestimmen. Diese Tests simulieren in der Regel einen starken Angriff mit hohen Sättigungsgraden, wie z. B. bei Betonfahrbahnen. Es gibt nur sehr wenige Ansätze für die Prüfung des Widerstands von Betonen, die nur einem mittleren Sättigungsgrad ausgesetzt sind, da solche Betonelemente in der Regel keine nennenswerten Abwitterungen aufweisen. Die zunehmende Verwendung von klinkereffizienten Zementen könnte sich jedoch in gewissem Maße auf den Frost-Tausalz-Widerstand solcher Betonelemente auswirken. Um eine angemessene Dauerhaftigkeit zu gewährleisten ist es daher wünschenswert, ihre Leistungsfähigkeit in einem tatsächlichen Prüfverfahren zu ermitteln, anstatt sich auf Erfahrungswerte zu verlassen. Daher wurden Ansätze für abgeschwächte Prüfverfahren entwickelt, die auf dem Slab-Test bzw. dem CDF-Test beruhen

Cruise Report ALKOR 438 [AL438] - Foraminiferal biomonitoring in the North Sea, May 29 - May 31, 2014, Kiel (Germany) - Kiel (Germany)

The aim of R/V Alkor cruise AL438 was to investigate the assemblage composition, population density and distribution of Recent benthic foraminifera in the Elbe estuary and southern North Sea. We focused on an assessment of the present state of the ecosystems and a comparison with data from former decades. Our work resumed investigations of the Geologisch-Paläontologisches Institut of Kiel University and the Federal Hydrographic Office from 1960s till the 1980s, as well as topical studies to the west of Helgoland. We revisited the same stations and took sediment samples with historical and modern grab samplers, box corer, Minicorer and a gravity corer. These samples were accomplished with samples from new stations in order to describe the relationships of foraminiferal faunas living in the Helgoland mud area with those inhabiting the surrounding sands. The sampling was accompanied with hydrographical measurements and water sampling to document relevant environmental parameters. The foraminiferal sampling was carried out for the first time following of the FOraminiferal BIoMOnitoring group (FOBIMO) recommendations as much as possible, in order to test the practicability of the guidelines. In total, 109 deployments at 37 stations were successfully accomplished

Coagulation abnormalities in patients with COVID‐19 on venovenous ECLS increased risk for technical complications and support times but had no impact on survival

Background Patients with severe coronavirus disease-19 (COVID-19)-associated acute respiratory distress on venovenous extracorporeal lung support (V-V ECLS) showed a high incidence of vascular as well as ECLS-related thrombotic complications. The latter may influence the outcome of the patients. Methods This is a retrospective monocentric study on prospectively collected data of technical complications including 69 adult COVID-19 patients on V-V ECLS (ECLS Registry, March 2020 until April 2021) without and with system exchanges. Alterations in ECLS-specific data, hemolysis, coagulation, and hemostasis parameters were analyzed. Results Every second COVID-19 patient on V-V ECLS developed technical complications. Optimized ECLS management at our ECLS center reduced cases of acute clot formation (pump head thrombosis, acute oxygenator thrombosis) (17%), and allowed early identification of progressive clotting processes (worsened gas transfer, coagulation disorder) (14%, 54%) with a significant overhang of hyperfibrinolysis (37%). Although COVID-19 disease and technical complications caused the prolonged length of stay at the intensive care unit and ECLS support times, the proportion of successful weaning and survival rates were comparable with patients without system exchange. Conclusion The survival of ECLS patients with COVID-19 was independent of the requirement for system exchange due to technical-induced coagulation disorders. Close monitoring for circuit clotting is mandatory in COVID-19 patients and is one prerequisite for successful organ support in these difficult patients