@article{KraffBitzBreyeretal.2011, author = {Kraff, Oliver and Bitz, Andreas and Breyer, Tobias and Kruszona, Stefan and Maderwald, Stefan and Brote, Irina and Gizewski, Elke R. and Ladd, Mark E. and Quick, Harald H.}, title = {A transmit/receive radiofrequency array for imaging the carotid arteries at 7 Tesla: coil design and first in vivo results}, series = {Investigative Radiology}, volume = {46}, journal = {Investigative Radiology}, number = {4}, publisher = {Wolters Kluwer}, address = {K{\"o}ln}, issn = {1536-0210}, doi = {10.1097/RLI.0b013e318206cee4}, pages = {246 -- 254}, year = {2011}, abstract = {Objective: To develop a transmit/receive radiofrequency (RF) array for magnetic resonance imaging (MRI) of the carotid arteries at 7 T. The prototype is characterized in numerical simulations and bench measurements, and the feasibility of plaque imaging at 7 T is demonstrated in first in vivo images. Materials and Methods: The RF phased array coil consists of 8 surface loop coils. To allow imaging of both sides of the neck, the RF array is divided into 2 coil clusters, each with 4 overlapping loop elements. For safety validation, numerical computations of the RF field distribution and the corresponding specific absorption rate were performed on the basis of a heterogeneous human body model. To validate the coil model, maps of the transmit B1+ field were compared between simulation and measurement. In vivo images of a healthy volunteer and a patient (ulcerating plaque and a 50\% stenosis of the right internal carotid artery) were acquired using a 3-dimensional FLASH sequence with a high isotropic spatial resolution of 0.54 mm as well as using pulse-triggered proton density (PD)/T2-weighted turbo spin echo sequences. Results: Measurements of the S-parameters yielded a reflection and isolation of the coil elements of better than -18 and -13 dB, respectively. Measurements of the g-factor indicated good image quality for parallel imaging acceleration factors up to 2.4. A similar distribution and a very good match of the absolute values were found between the measured and simulated B1+ transmit RF field for the validation of the coil model. In vivo images revealed good signal excitation of both sides of the neck and a high vessel-to-background image contrast for the noncontrast-enhanced 3-dimensional FLASH sequence. Imaging at 7 T could depict the extent of stenosis, and revealed the disruption and ulcer of the plaque. Conclusions: This study demonstrates that 2 four-channel transmit/receive RF arrays for each side of the neck is a suitable concept for in vivo MRI of the carotid arteries at 7 Tesla. Further studies are needed to explore and exploit the full potential of 7 T high-field MRI for carotid atherosclerotic plaque imaging.}, language = {en} } @article{ElQuardiStreckertBitzetal.2011, author = {El Quardi, A. and Streckert, J. and Bitz, Andreas and M{\"u}nkner, S. and Engel, J. and Hansen, V.}, title = {New fin-line devices for radiofrequency exposure of small biological samples in vitro allowing whole-cell patch clamp recordings}, series = {Bioelectromagnetics}, volume = {32}, journal = {Bioelectromagnetics}, number = {2}, publisher = {Wiley}, address = {Weinheim}, issn = {1521-186X}, doi = {10.1002/bem.20621}, pages = {102 -- 112}, year = {2011}, abstract = {The development and analysis of three waveguides for the exposure of small biological in vitro samples to mobile communication signals at 900 MHz (GSM, Global System for Mobile Communications), 1.8 GHz (GSM), and 2 GHz (UMTS, Universal Mobile Telecommunications System) is presented. The waveguides were based on a fin-line concept and the chamber containing the samples bathed in extracellular solution was placed onto two fins with a slot in between, where the exposure field concentrates. Measures were taken to allow for patch clamp recordings during radiofrequency (RF) exposure. The necessary power for the achievement of the maximum desired specific absorption rate (SAR) of 20 W/kg (average over the mass of the solution) was approximately Pin = 50 mW, Pin = 19 mW, and Pin = 18 mW for the 900 MHz, 1800 MHz, and 2 GHz devices, respectively. At 20 W/kg, a slight RF-induced temperature elevation in the solution of no more than 0.3 °C was detected, while no thermal offsets due to the electromagnetic exposure could be detected at the lower SAR settings (2, 0.2, and 0.02 W/kg). A deviation of 10\% from the intended solution volume yielded a calculated SAR deviation of 8\% from the desired value. A maximum ±10\% variation in the local SAR could occur when the position of the patch clamp electrode was altered within the area where the cells to be investigated were located.}, language = {en} } @article{UmutluOrzadaKinneretal.2011, author = {Umutlu, Lale and Orzada, Stephan and Kinner, Sonja and Maderwald, Stefan and Bronte, Irina and Bitz, Andreas and Kraff, Oliver and Ladd, Susanne C. and Antoch, Gerald and Ladd, Mark E. and Quick, Harald H. and Lauenstein, Thomas C.}, title = {Renal imaging at 7 Tesla: preliminary results}, series = {European Radiology}, volume = {21}, journal = {European Radiology}, number = {4}, publisher = {Springer}, address = {Berlin}, issn = {1432-1084}, pages = {841 -- 849}, year = {2011}, abstract = {Objective To investigate the feasibility of 7T MR imaging of the kidneys utilising a custom-built 8-channel transmit/receive radiofrequency body coil. Methods In vivo unenhanced MR was performed in 8 healthy volunteers on a 7T whole-body MR system. After B0 shimming the following sequences were obtained: 1) 2D and 3D spoiled gradient-echo sequences (FLASH, VIBE), 2) T1-weighted 2D in and opposed phase 3) True-FISP imaging and 4) a T2-weighted turbo spin echo (TSE) sequence. Visual evaluation of the overall image quality was performed by two radiologists. Results Renal MRI at 7T was feasible in all eight subjects. Best image quality was found using T1-weighted gradient echo MRI, providing high anatomical details and excellent conspicuity of the non-enhanced vasculature. With successful shimming, B1 signal voids could be effectively reduced and/or shifted out of the region of interest in most sequence types. However, T2-weighted TSE imaging remained challenging and strongly impaired because of signal heterogeneities in three volunteers. Conclusion The results demonstrate the feasibility and diagnostic potential of dedicated 7T renal imaging. Further optimisation of imaging sequences and dedicated RF coil concepts are expected to improve the acquisition quality and ultimately provide high clinical diagnostic value.}, language = {en} } @article{BooysenRiegerFerrein2011, author = {Booysen, Tracy and Rieger, Michael and Ferrein, Alexander}, title = {Towards inexpensive robots for science \& technology teaching and education in Africa}, publisher = {IEEE}, address = {New York}, isbn = {978-1-61284-992-8}, pages = {1 -- 6}, year = {2011}, language = {en} } @article{GspandlPillReipetal.2011, author = {Gspandl, Stephan and Pill, Ingo and Reip, Michael and Steinbauer, Gerald and Ferrein, Alexander}, title = {Belief Management for High-Level Robot Programs}, series = {Proceedings of the Twenty-Second International Joint Conference on Artificial Intelligence [electronic resource] : Barcelona, Catalonia, Spain, 16 - 22 July 2011 / sponsored by International Joint Conferences on Artificial Intelligence (IJCAI) and the Association for the Advancement of Artificial Intelligence (AAAI). Ed. by Toby Walsh}, journal = {Proceedings of the Twenty-Second International Joint Conference on Artificial Intelligence [electronic resource] : Barcelona, Catalonia, Spain, 16 - 22 July 2011 / sponsored by International Joint Conferences on Artificial Intelligence (IJCAI) and the Association for the Advancement of Artificial Intelligence (AAAI). Ed. by Toby Walsh}, pages = {900 -- 905}, year = {2011}, language = {en} } @inproceedings{DammRitzStrauch2011, author = {Damm, Sebastian and Ritz, Thomas and Strauch, Jakob}, title = {Muster und Cloud Computing als Plattformstrategie f{\"u}r mobile Unternehmenssoftware}, series = {Mobile und ubiquit{\"a}re Informationssysteme : MMS 2011 ; proceedings der 6. Konferenz, 28. Februar 2011 in Kaiserslautern, Deutschland. - (GI-Edition lecture notes in informatics ; 185)}, booktitle = {Mobile und ubiquit{\"a}re Informationssysteme : MMS 2011 ; proceedings der 6. Konferenz, 28. Februar 2011 in Kaiserslautern, Deutschland. - (GI-Edition lecture notes in informatics ; 185)}, editor = {H{\"o}pfner, Hagen}, publisher = {Ges. f{\"u}r Informatik}, address = {Bonn}, isbn = {978-3-88579-279-6}, pages = {91 -- 104}, year = {2011}, language = {de} } @article{SchifferFerreinLakemeyer2011, author = {Schiffer, Stefan and Ferrein, Alexander and Lakemeyer, Gerhard}, title = {Reasoning with Qualitative Positional Information for Domestic Domains in the Situation Calculus}, series = {Journal of Intelligent \& Robotic Systems}, volume = {63}, journal = {Journal of Intelligent \& Robotic Systems}, number = {2}, publisher = {Springer}, address = {Berlin}, isbn = {0921-0296}, pages = {273 -- 300}, year = {2011}, language = {en} } @article{FuchsRitz2011, author = {Fuchs, Britta and Ritz, Thomas}, title = {Absatzkan{\"a}le kaum verkn{\"u}pft}, series = {IT-Mittelstand : IT-Business im Mittelstand}, volume = {2011}, journal = {IT-Mittelstand : IT-Business im Mittelstand}, number = {9}, publisher = {Medienhaus-Verlag}, address = {Bergisch-Gladbach}, pages = {16}, year = {2011}, language = {de} } @inproceedings{BragardRongeDeDoncker2011, author = {Bragard, Michael and Ronge, C. and De Doncker, R. W.}, title = {Sandwich design of high-power thyristor based devices with integrated MOSFET structure}, series = {Proceedings of the 2011 - 14th - European Conference on Power Electronics and Applications (EPE 2011) : Aug. 30, 2011 - Sept. 1, 2011, Birmingham, United Kingdom}, booktitle = {Proceedings of the 2011 - 14th - European Conference on Power Electronics and Applications (EPE 2011) : Aug. 30, 2011 - Sept. 1, 2011, Birmingham, United Kingdom}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-61284-167-0 (Print)}, year = {2011}, language = {en} } @inproceedings{BragardGottschlichDeDoncker2011, author = {Bragard, Michael and Gottschlich, J. and De Doncker, R. W.}, title = {Design and realization of a credit card size driver stage for high power thyristor based devices with integrated MOS structure}, series = {2011 IEEE 8th International Conference on Power Electronics and ECCE Asia (ICPE \& ECCE 2011) : Jeju, South Korea, 30 May 2011 - 3 June 2011 / [co-sponsored by the Korean Institute of Power Electronics ...]}, booktitle = {2011 IEEE 8th International Conference on Power Electronics and ECCE Asia (ICPE \& ECCE 2011) : Jeju, South Korea, 30 May 2011 - 3 June 2011 / [co-sponsored by the Korean Institute of Power Electronics ...]}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-61284-958-4 (Print)}, doi = {10.1109/ICPE.2011.5944661}, pages = {1182 -- 1189}, year = {2011}, language = {en} }