Angewandte Programmierübung Teil III - Ferret

Version 1.0.2 (2016

Airborne Platforms Help Answer Questions in Polar Geosciences

The polar regions, with their continental ice sheets and partly ice covered oceans, play a crucial role in the Earth system. They are critical to understanding and predicting climate evolution and global sea level change. Airborne platforms offer the most amenable and powerful means of surveying these regions

Nonlinear optics of graphene in a strong magnetic field

Graphene placed in a magnetic field possesses an extremely high mid/far-infrared optical nonlinearity originating from its unusual band structure and selection rules for the optical transitions near the Dirac point. Here we study the linear and nonlinear optical response of graphene in strong magnetic and optical fields using quantum- mechanical density-matrix formalism. We calculate the power of coherent terahertz radiation generated as a result of four-wave mixing in graphene. We show that even one monolayer of graphene gives rise to appreciable nonlinear frequency conversion efficiency and Raman gain for modest intensities of incident infrared radiation.Comment: 16 pages, 6 figure

Kapitalkostenermittlung auf der Basis des Capital Asset Pricing Model

In der renditeorientierten Betrachtungsweise ist ein Investitionsprojekt lohnend, wenn dessen erwartete Verzinsung eine bestimmte Mindesthöhe überschreitet. Kapitalgeber werden nämlich nur dann die zur Durchführung einer Investition notwendigen Mittel bereitstellen, wenn das Projekt eine Rendite erwarten läßt, die über der einer Kapitalmarktanlage mit vergleichbarem Risiko liegt. Diese von den Kapitalgebern geforderte Mindestverzinsung bezeichnet man als Kapitalkosten. Sofern am Kapitalmarkt nicht bereits ein Finanzierungstitel mit vergleichbarem Risiko gehandelt wird, muß man die von den Kapitalgebern geforderte Mindestverzinsung aus kapitalmarkttheoretischen Überlegungen ableiten. Dabei kann man beispielsweise auf das Capital Asset Pricing Model (CAPM) zurückgreifen. Wie dabei vorzugehen ist, wird im folgenden genauer betrachtet. Als Ausgangsbasis für eine sinnvolle und unmittelbar nachzuvollziehende Beurteilung von Investitionsprojekten wird zunächst das Marktwertkriterium formuliert. Daraus läßt sich als ebenfalls geeignetes Vorteilhaftigkeitskriterium der Vergleich von Projektrendite und Kapitalkosten ableiten. Die Kapitalkosten selbst könnten aus der Renditegleichung des CAPM abgeleitet werden. Dies scheitert jedoch daran, daß zuvor der Marktwert der Zahlungen aus dem Projekt bekannt sein müßte. Umgehen läßt sich das Problem, indem man die Kapitalkosten lediglich näherungsweise ermittelt. Es kann gezeigt werden, daß die Verwendung des nur näherungsweise berechneten Kapitalkostensatzes stets zum richtigen Ergebnis führt. Anschließend wird demonstriert, wie sich dieses Resultat ökonomisch begründen läßt

Semiconductor-enriched single wall carbon nanotube networks applied to field effect transistors

Substantial progress on field effect transistors "FETs" consisting of semiconducting single wall carbon nanotubes "s-SWNTs" without detectable traces of metallic nanotubes and impurities is reported. Nearly perfect removal of metallic nanotubes is confirmed by optical absorption, Raman measurements, and electrical measurements. This outstanding result was made possible in particular by ultracentrifugation (150 000 g) of solutions prepared from SWNT powders using polyfluorene as an extracting agent in toluene. Such s-SWNTs processable solutions were applied to realize FET, embodying randomly or preferentially oriented nanotube networks prepared by spin coating or dielectrophoresis. Devices exhibit stable p-type semiconductor behavior in air with very promising characteristics. The on-off current ratio is 10^5, the on-current level is around 10 $\mu$A, and the estimated hole mobility is larger than 2 cm2 / V s

Pharmacokinetic analysis after implantation of everolimus-eluting self-expanding stents in the peripheral vasculature

Background: A novel self-expanding drug-eluting stent was designed to release everolimus 225 mu g/cm(2) to prevent restenosis following peripheral arterial intervention. The purpose of this study was to measure the pharmacokinetic profile of everolimus following stent implantation. Methods: One hundred four patients with symptomatic peripheral arterial disease underwent implantation of everolimus-eluting stents in the femoropopliteal arteries. In a prespecified subset of 26 patients, blood samples for assay of everolimus content were collected prior to stent implantation, at 1, 4, and 8 hours postprocedure, prior to discharge, and at 1 month postproccdure. Results: A total of 39 stents, ranging from 28 mm to 100 mm in length, were implanted in 26 patients, resulting in a total delivered everolimus dose range of 3.0 to 7.6 mg. Following the procedure, the maximum observed everolimus blood concentrations (C-max) varied from 1.83 +/- 0.05 ng/mL after implantation of a single 80-mm stent to 4.66 +/- 1.78 ng/mL after implantation of two 100-mm stents. The mean time to peak concentration (T-max) varied from 6.8 hours to 35 hours. The pharmacokinetics of everolimus were dose-proportional in that dose-normalized C-max and area under the curve values were constant over the studied dose range. Conclusions: After implantation of everolimus-eluting self-expanding stents in the femoropopliteal arteries, systemic blood concentrations of everolimus are predictable and considerably lower than blood concentrations observed following safe oral administration of everolimus

Assimilation of dynamic topography in a global model

Absolute dynamic topography, i.e. the difference between time dependent multi-mission altimetric sea surface height and one of the most recent GOCE and GRACE based geoids, is assimilated in a global ocean general circulation model. To this end we apply an ensemble based Kalman technique, the "Error Subspace Transform Kalman Filter" (ESTKF). Here we present an update of our work. First of all the geoid is improved over previous versions. The ocean model now includes better dynamics and full sea-ice ocean interactions and more realistic surface forcing. Finally the assimilation method is augmented by a fixed lag smoother technique. This smoother allows to significantly improve the model performance, most strikingly in the first adjustment phase