@article{YazdanbakhshSolbachBitz2012,
  author    = {Yazdanbakhsh, Pedram and Solbach, Klaus and Bitz, Andreas},
  title     = {Variable power combiner for RF mode shimming in 7-T MR imaging},
  series = {IEEE Transaction on Biomedical Engineering},
  volume    = {59},
  journal   = {IEEE Transaction on Biomedical Engineering},
  number    = {9},
  publisher = {IEEE},
  address   = {New York},
  issn      = {1558-2531},
  doi       = {10.1109/TBME.2012.2205926},
  pages     = {2549 -- 2557},
  year      = {2012},
  abstract  = {This contribution discusses the utilization of RF power in an MRI system with RF mode shimming which enables the superposition of circularly polarized modes of a transmit RF coil array driven by a Butler matrix. Since the required power for the individual modes can vary widely, mode-shimming can result in a significant underutilization of the total available RF power. A variable power combiner (VPC) is proposed to improve the power utilization: it can be realized as a reconfiguration of the MRI transmit system by the inclusion of one additional matrix network which receives the power from all transmit amplifiers at its input ports and provides any desired (combined) power distribution at its output ports by controlling the phase and amplitude of the amplifiers' input signals. The power distribution at the output ports of the VPC is then fed into the "mode" ports of the coil array Butler matrix in order to superimpose the spatial modes at the highest achievable power utilization. The VPC configuration is compared to the standard configuration of the transmit chain of our MRI system with 8 transmit channels and 16 coils. In realistic scenarios, improved power utilization was achieved from 17\% to 60\% and from 14\% to 55\% for an elliptical phantom and a region of interest in the abdomen, respectively, and an increase of the power utilization of 1 dB for a region of interest in the upper leg. In general, it is found that the VPC allows significant improvement in power utilization when the shimming solution demands only a few modes to be energized, while the technique can yield loss in power utilization in cases with many modes required at high power level.},
  language  = {en}
}
@article{HeuermannIbrahimHillebrand2007,
  author    = {Heuermann, Holger and Ibrahim, Irfan and Hillebrand, J.},
  title     = {Vector-Signal-Generator with Two ?'?'-PLL's / Ibrahim, I. ; Hillebrand, J. ; Heuermann, H.},
  series = {European Conference on Wireless Technologies, 2007. ECWT 2007 ; 8 - 10 October 2007 Munich, Germany},
  journal   = {European Conference on Wireless Technologies, 2007. ECWT 2007 ; 8 - 10 October 2007 Munich, Germany},
  isbn      = {978-2-87487-003-3},
  pages     = {1 -- 4},
  year      = {2007},
  language  = {en}
}
@article{SchollSovakarNeuschaeferRubeetal.1996,
  author    = {Scholl, Ingrid and Sovakar, Abhijit and Neuschaefer-Rube, C. and Lehmann, Thomas Martin},
  title     = {Verfolgung und Analyse von Stimmlippenkonturen in stroboskopischen Videosequenzen. Sovakar, Abhijit; Scholl, Ingrid; Neuschaefer-Rube, C.; Lehmann, Thomas Martin; Spitzer, Klaus},
  series = {Bildverarbeitung f{\"u}r die Medizin},
  journal   = {Bildverarbeitung f{\"u}r die Medizin},
  publisher = {Verlag der Augustinus-Buchhandlung},
  address   = {Aachen},
  isbn      = {3-86073-519-5},
  pages     = {235 -- 240},
  year      = {1996},
  language  = {de}
}
@article{HeuermannGraf1996,
  author    = {Heuermann, Holger and Graf, W.},
  title     = {Vergleich mehrerer Naeherungsverfahren zur Berechnung des Wellenwiderstandes von Mikrostreifenleitungen mit experimentellen Ergebnissen},
  series = {Kleinheubacher Berichte : Vortr{\"a}ge und Berichte der gemeinsamen Tagung des U.R.S.I.-Landesausschusses in der Bundesrepublik Deutschland / Hrsg.: Deutsche Telekom AG. 39. 1996 (1996)},
  journal   = {Kleinheubacher Berichte : Vortr{\"a}ge und Berichte der gemeinsamen Tagung des U.R.S.I.-Landesausschusses in der Bundesrepublik Deutschland / Hrsg.: Deutsche Telekom AG. 39. 1996 (1996)},
  year      = {1996},
  language  = {de}
}
@article{Krause2001,
  author    = {Krause, Gregor},
  title     = {Verhandeln statt Energiesparen? {\"U}ber den Umgang mit Preisnachl{\"a}ssen im Energiebereich},
  series = {extrACT: Das Magazin der Fachhochschule Aachen (2001)},
  journal   = {extrACT: Das Magazin der Fachhochschule Aachen (2001)},
  pages     = {22 -- 23},
  year      = {2001},
  language  = {de}
}
@article{Heuermann2006,
  author    = {Heuermann, Holger},
  title     = {Verringerung des Phasenrauschens von Oszillatoren durch Dual-Mode-Resonatoren},
  series = {HF-Report. 20 (2006), H. 5-6},
  journal   = {HF-Report. 20 (2006), H. 5-6},
  isbn      = {1431-827X},
  pages     = {43 -- 48},
  year      = {2006},
  language  = {en}
}
@article{Alt2005,
  author    = {Alt, Helmut},
  title     = {Versorgungssicherheit und Windenergie : Tatsachen und Fakten statt Mythen und Mysterien},
  series = {EW : das Magazin f{\"u}r die Energie-Wirtschaft},
  volume    = {Bd. 104},
  journal   = {EW : das Magazin f{\"u}r die Energie-Wirtschaft},
  number    = {H. 25},
  issn      = {0013-5496},
  pages     = {42 -- 45},
  year      = {2005},
  language  = {de}
}
@article{Mayer1996,
  author    = {Mayer, Claudia},
  title     = {Versuche einer Rebellion. Zur Anpassung des K{\"o}rpers an den Geist},
  series = {Verleiblichungen : literatur- und kulturgeschichtliche Studien {\"u}ber Strategien, Formen und Funktionen der Verleiblichung in Texten von der Fr{\"u}hzeit bis zum Cyberspace / Burkhardt Krause ... (Hrsg.)},
  journal   = {Verleiblichungen : literatur- und kulturgeschichtliche Studien {\"u}ber Strategien, Formen und Funktionen der Verleiblichung in Texten von der Fr{\"u}hzeit bis zum Cyberspace / Burkhardt Krause ... (Hrsg.)},
  publisher = {R{\"o}hrig-Univ.-Verl.},
  address   = {St. Ingbert},
  isbn      = {3-86110-089-4},
  pages     = {219 -- 246},
  year      = {1996},
  language  = {de}
}
@article{TheysohnKraffEilersetal.2014,
  author    = {Theysohn, Jens M. and Kraff, Oliver and Eilers, Kristina and Andrade, Dorian and Gerwig, Marcus and Timmann, Dagmar and Schmitt, Franz and Ladd, Mark E. and Ladd, Susanne C. and Bitz, Andreas},
  title     = {Vestibular effects of a 7 Tesla MRI examination compared to 1.5 T and 0 T in healthy volunteers},
  series = {PLoS one},
  volume    = {9},
  journal   = {PLoS one},
  number    = {3},
  publisher = {PLOS},
  address   = {San Francisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0092104},
  pages     = {e92104},
  year      = {2014},
  abstract  = {Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or "postural instability" even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B₀ (n = 20), 7 T in \& out B₀ (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in \& out B₀. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B₀) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B₀ or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in \& out B₀ exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or "over-compensation" of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role.},
  language  = {en}
}
@article{ElsenKraissKrumbiegeletal.1999,
  author    = {Elsen, Ingo and Kraiss, Karl-Friedrich and Krumbiegel, Dirk and Walter, Peter and Wickel, Jochen},
  title     = {Visual information retrieval for 3D product identification: a midterm report},
  series = {KI - K{\"u}nstliche Intelligenz},
  volume    = {13},
  journal   = {KI - K{\"u}nstliche Intelligenz},
  number    = {1},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1610-1987},
  pages     = {64 -- 67},
  year      = {1999},
  language  = {en}
}