Characterization of harmonic modes and parasitic resonances in multi-mode superconducting coplanar resonators

Planar superconducting microwave transmission line resonators can be operated at multiple harmonic resonance frequencies. This allows covering wide spectral regimes with high sensitivity, as it is desired e.g. for cryogenic microwave spectroscopy. A common complication of such experiments is the presence of undesired 'spurious' additional resonances, which are due to standing waves within the resonator substrate or housing box. Identifying the nature of individual resonances ('designed' vs. 'spurious') can become challenging for higher frequencies or if elements with unknown material properties are included, as is common for microwave spectroscopy. Here we discuss various experimental strategies to distinguish designed and spurious modes in coplanar superconducting resonators that are operated in a broad frequency range up to 20 GHz. These strategies include tracking resonance evolution as a function of temperature, magnetic field, and microwave power. We also demonstrate that local modification of the resonator, by applying minute amounts of dielectric or ESR-active materials, lead to characteristic signatures in the various resonance modes, depending on the local strength of the electric or magnetic microwave fields

Historische Grundwissenschaften und die digitale Herausforderung

Unter Federführung von Eva Schlotheuber (Heinrich-Heine-Universität Düsseldorf / VHD-Unterausschuss "Geschichte in der digitalen Welt") und Frank Bösch (Zentrum für die Zeithistorische Forschungen Potsdam / VHD-Unterausschuss "Audiovisuelle Quellen") verabschiedete der VHD ein Grundsatzpapier zum Status der Historischen Grundwissenschaften mit dem Titel "Quellenkritik im digitalen Zeitalter: Die Historischen Grundwissenschaften als zentrale Kompetenz der Geschichtswissenschaft und benachbarter Fächer". Das Grundsatzpapier, in dem auch ein forschungsstrategisches Interesse an den Grundwissenschaften in der digitalen Transformation zum Ausdruck kommt, wurde auf H-Soz-Kult veröffentlicht und mit einem Diskussionsforum begleitet. Dazu wurde aus dem breiten Spektrum der Historischen Kulturwissenschaften eine Reihe in- und ausländischer Kolleginnen und Kollegen zur Kommentierung und Diskussion eingeladen, um die Debatte zu stimulieren

European Journal of Nuclear Medicine and Molecular Imaging / The value of [11C]-acetate PET and [18F]-FDG PET in hepatocellular carcinoma before and after treatment with transarterial chemoembolization and bevacizumab

Purpose This prospective study was to investigate the value of [11C]-acetate PET and [18F]-FDG PET in the evaluation of hepatocellular carcinoma (HCC) before and after treatment with transarterial chemoembolization (TACE) and vascular endothelial growth factor (VEGF) antibody (bevacizumab). Methods Twenty-two patients (three women, 19 men; 62 8 years) with HCC verified by histopathology were treated with TACE and bevacizumab (n = 11) or placebo (n = 11). [11C]-acetate PET and [18F]-FDG PET were performed before and after TACE with bevacizumab or placebo. Comparisons between groups were performed with t-tests and Chi-squared tests, where appropriate. Overall survival (OS) was defined as the time from start of bevacizumab or placebo until the date of death/last follow-up, respectively. Results The patient-related sensitivity of [11C]-acetate PET, [18F]-FDG PET, and combined [11C]-acetate and [18F]-FDG PET was 68%, 45%, and 73%, respectively. There was a significantly higher rate of conversion from [11C]-acetate positive lesions to negative lesions in patients treated with TACE and bevacizumab as compared with that in patients with TACE and placebo (p < 0.05). In patients with negative acetate PET, the mean OS in patients treated with TACE and bevacizumab was 259 118 days and was markedly shorter as compared with that (668 217 days) in patients treated with TACE and placebo (p < 0.05). In patients treated with TACE and placebo, there was significant difference in mean OS in patients with positive FDG PET as compared with that in patients with negative FDG PET (p < 0.05). The HCC lesions had different tracer avidities showing the heterogeneity of HCC. Conclusions Our study suggests that combining [18F]-FDG with [11C]-acetate PET could be useful for the management of HCC patients and might also provide relevant prognostic and molecular heterogeneity information.(VLID)355053