TY - CHAP A1 - Becker, Jörg A1 - Eggert, Mathias A1 - Heddier, Marcel A1 - Knackstedt, Ralf T1 - Merging Conceptual Modeling and Law for Legally Compliant Information Systems Design - A Framework-Based Research Agenda T2 - 45th Hawaii International Conference on System Sciences 2012 Y1 - 2012 SN - 978-0-7695-4525-7 U6 - https://doi.org/10.1109/HICSS.2012.428 SP - 5241 EP - 5248 ER - TY - CHAP A1 - Becker, Jörg A1 - Eggert, Mathias A1 - Schwittay, Sebastian ED - Mattfeld, Dirk Christian T1 - How to Evaluate the Practical Relevance of Business Process Compliance Checking Approaches? T2 - Multikonferenz Wirtschaftsinformatik 2012 - Tagungsband der MKWI 2012 Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:084-13011115376 SP - 849 EP - 862 PB - Institut für Wirtschaftsinformatik CY - Braunschweig ER - TY - CHAP A1 - Borggrafe, Andreas A1 - Ohndorf, Andreas A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang T1 - Analysis of interplanetary solar sail trajectories with attitude dynamics T2 - Dynamics and Control of Space Systems 2012 N2 - We present a new approach to the problem of optimal control of solar sails for low-thrust trajectory optimization. The objective was to find the required control torque magnitudes in order to steer a solar sail in interplanetary space. A new steering strategy, controlling the solar sail with generic torques applied about the spacecraft body axes, is integrated into the existing low-thrust trajectory optimization software InTrance. This software combines artificial neural networks and evolutionary algorithms to find steering strategies close to the global optimum without an initial guess. Furthermore, we implement a three rotational degree-of-freedom rigid-body attitude dynamics model to represent the solar sail in space. Two interplanetary transfers to Mars and Neptune are chosen to represent typical future solar sail mission scenarios. The results found with the new steering strategy are compared to the existing reference trajectories without attitude dynamics. The resulting control torques required to accomplish the missions are investigated, as they pose the primary requirements to a real on-board attitude control system. Y1 - 2012 SN - 978-0-87703-587-9 SP - 1553 EP - 1569 PB - Univelt Inc CY - San Diego ER - TY - JOUR A1 - Herzwurm, Georg A1 - Krams, Benedikt A1 - Pietsch, Wolfram A1 - Schockert, Sixten T1 - Report from the 3rd international workshop on requirements prioritization for customer oriented software development (RePriCo’12) JF - ACM SIGSOFT Software Engineering Notes N2 - Prioritization is an essential task within requirements engineering to cope with complexity and to establish focus properly. The 3rd Workshop on Requirements Prioritization for customer oriented Software Development (RePriCo’12) focused on requirements prioritization and adjacent themes in the context of customer oriented development of bespoke and standard software. Five submissions have been accepted for the proceedings and for presentation. The report summarizes and points out key findings. KW - Requirements relations KW - Discourse ethics KW - Tool support KW - Consensus KW - Requirements prioritization Y1 - 2012 U6 - https://doi.org/10.1145/2237796.2237817 SN - 0163-5948 VL - 37 IS - 4 SP - 32 EP - 34 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Lindel, Tomasz Dawid A1 - Greiser, Andreas A1 - Waxman, Patrick A1 - Dietterle, Martin A1 - Seifert, Frank A1 - Fontius, Ulrich A1 - Renz, Wolfgang A1 - Dieringer, Matthias A. A1 - Frauenrath, Tobias A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf A1 - Ittermann, Bernd T1 - Cardiac CINE MRI at 7 T using a transmit array T2 - 2012 ISMRM Annual Meeting Proceedings N2 - With its need for high SNR and short acquisition times, Cardiac MRI (CMR) is an intriguing target application for ultrahigh field MRI. Due to the sheer size of the upper torso, however, the known RF issues of 7T MRI are also most prominent in CMR. Recent years brought substantial progress but the full potential of the ultrahigh field for CMR is yet to be exploited. Parallel transmission (pTx) is a promising approach in this context and several groups have already reported B1 shimming for 7T CMR. In such a static pTx application amplitudes and phases of all Tx channels are adjusted individually but otherwise imaging techniques established in current clinical practice 1.5 T and 3 T are applied. More advanced forms of pTx as spatially selective excitation (SSE) using Transmit SENSE promise additional benefits like faster imaging with reduced fields of view or improved SAR control. SSE requires the full dynamic capabilities of pTx, however, and for the majority of today's implemented pTx hardware the internal synchronization of the Tx array does not easily permit external triggering as needed for CMR. Here we report a software solution to this problem and demonstrate the feasibility of CINE CMR at 7 T using a Tx array. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - CHAP A1 - Niendorf, Thoralf A1 - Winter, Lukas A1 - Frauenrath, Tobias ED - Millis, Richard T1 - Electrocardiogram in an MRI environment: Clinical needs, practical considerations, safety implications, technical solutions and fFuture directions T2 - Advances in Electrocardiograms - Methods and Analysis Y1 - 2012 SN - 978-953-307-923-3 (print) SN - 978-953-51-6762-4 (eBook) U6 - https://doi.org/10.5772/24340 SP - 309 EP - 324 PB - IntechOpen CY - London ER - TY - GEN A1 - Frauenrath, Tobias A1 - Pfeiffer, Harald A1 - Hezel, Fabian A1 - Dieringer, Matthias A. A1 - Winter, Lukas A1 - Gräßl, Andreas A1 - Santoro, Davide A1 - Özerdem, Celal A1 - Renz, Wolfgang A1 - Greiser, Andreas A1 - Niendorf, Thoralf T1 - Lessons learned from cardiac MRI at 7.0 T: LV function assessment at 3.0 T using local multi-channel transceiver coil arrays T2 - 2012 ISMRM Annual Meeting Proceedings N2 - Cardiac MR (CMR) is of proven clinical value but also an area of vigorous ongoing research since image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Recent developments of CMR at 7.0 T have been driven by pioneering explorations into novel multichannel transmit and receive coil array technology to tackle the challenges B1+-field inhomogeneities, to offset specific-absorption rate (SAR) constraints and to reduce banding artifacts in SSFP imaging. For this study, recognition of the benefits and performance of local surface Tx/Rx-array structures recently established at 7.0 T inspired migration to 3.0 T, where RF inhomogeneities and SAR limitations encountered in routine clinical CMR, though somewhat reduced versus the 7.0 T situation, remain significant. For all these reasons, this study was designed to build and examine the feasibility of a local four channel Tx/Rx cardiac coil array for anatomical and functional cardiac imaging at 3.0 T. For comparison, a homebuilt 4 channel Rx cardiac coil array exhibiting the same geometry as the Tx/Rx coil and a Rx surface coil array were used. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - GEN A1 - Frauenrath, Tobias A1 - Fuchs, Katharina A1 - Hezel, Fabian A1 - Dieringer, Matthias A. A1 - Rieger, Jan A1 - Niendorf, Thoralf T1 - Improved cardiac triggering by combining multiple physiological signals: a cardiac MR feasibility study at 7.0 T T2 - 2012 ISMRM Annual Meeting Proceedings N2 - In current clinical cardiovascular MR (CMR) practice cardiac motion is commonly dealt with using ECG based synchronization. However, ECG is corrupted by magneto-hydrodynamic (MHD) effects in magnetic fields. This leads to artifacts in the ECG trace and evokes severe T-wave elevations, which might be misinterpreted as R-waves resulting in erroneous triggering. At (ultra)high field strengths, the propensity of ECG recordings to MHD effects is further pronounced. Pulse oximetry (POX) being inherently sensitive to blood oxygenation provides an alternative approach for cardiac gating. However, due to the travel time of the blood the peak of maximum oxygenation and hence the trigger is delayed by approx. 300 ms with respect to the ECG's R-wave. Also the peak of maximum oxygenation shows a jitter of up to 65 ms. Alternative triggering approaches include acoustic cardiac triggering (ACT). In current clinical practice cardiac gating / triggering commonly relies on using single physiological signals only. Realizing this limitation this study proposes a combined triggering approach which exploits multiple physiological signals including ECG, POX or ACT to track cardiac activity. The feasibility of the coupled approach is examined for LV function assessment at 7.0 T. For this purpose, breath-held 2D-CINE imaging in conjunction with cardiac synchronization was performed paralleled by real time logging of physiological waveforms to track (mis)synchronization between the cardiac cycle and data acquisition. Combinations of the ECG, POX and ACT signals were evaluated and processed in real time to facilitate reliable trigger information. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - GEN A1 - Tkachenko, Valeriy A1 - von Knobelsdorff-Brenkenhoff, Florian A1 - Kleindienst, Denise A1 - Winter, Lukas A1 - Rieger, Jan A1 - Frauenrath, Tobias A1 - Dieringer, Matthias A. A1 - Santoro, Davide A1 - Niendorf, Thoralf A1 - Schulz-Menger, Jeanette T1 - Cardiovasular MR at 7Tesla: assessment of the right ventricle T2 - 2012 ISMRM Annual Meeting Proceedings N2 - The assessment of the right ventricle (RV) is a challenge in today's cardiology, but of growing clinical impact regarding patient prognosis in different cardiac diseases. The detection and differentiation of small wall motion abnormalities may help to enhance the differentiation of cardiomyopathies including Arrhythmogenic Rightventricular Cardiomyopathy. Cardiovascular magnetic resonance (CMR) at 1.5T is the accepted gold standard for RV quantification. The higher spatial resolution achievable at ultrahigh field strength (UHF) offers the potential to gain new insights into the structure and function of the RV. To approach this goal accurate RV chamber quantification at 7T has to be proven. Consequently this study examines the feasibility of assessment of RV dimensions and function at 7T using improved spatial resolution enabled by the intrinsic sensitivity gain of UHF CMR. For this purpose, a dedicated 16 channel TX/RX RF coil array is used together with 2D CINE fast gradient echo (FGRE) imaging. For comparison RV chamber quantification is conducted at 1.5T using a SSFP based state of the art clinical protocol. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - GEN A1 - Gräßl, Andreas A1 - Renz, Wolfgang A1 - Hezel, Fabian A1 - Frauenrath, Tobias A1 - Pfeiffer, Harald A1 - Hoffmann, Werner A1 - Kellmann, Peter A1 - Martin, Conrad A1 - Niendorf, Thoralf T1 - Design, evaluation and application of a modular 32 channel transmit/receive surface coil array for cardiac MRI at 7T T2 - 2012 ISMRM Annual Meeting Proceedings N2 - Cardiac MR (CMR) at ultrahigh (≥7.0 T) fields is regarded as one of the most challenging MRI applications. At 7.0 T image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Detrimental effects bear the potential to spoil the signal-to-noise (SNR) and contrast-to-noise (CNR) benefits of cardiac MR (CMR) at 7.0 T. B₁⁺-inhomogeneities and signal voids represent the main challenges. Various pioneering coil concepts have been proposed to tackle these issues, enabling cardiac MRI at 7.0 T. This includes a trend towards an ever larger number of transmit and receive channels. This approach affords multi-dimensional B₁⁺ modulations to improve B₁⁺ shimming performance and to enhance RF efficiency. Also, parallel imaging benefits from a high number of receive channels enabling two-dimensional acceleration. Realizing the limitations of existing coil designs tailored for UHF CMR and recognizing the opportunities of a many element TX/RX channel architecture this work proposes a modular, two dimensional 32-channel transmit and receive array using loop elements and examines its efficacy for enhanced B¹+ homogeneity and improved parallel imaging performance. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - JOUR A1 - Frauenrath, Tobias A1 - Fuchs, Katharina A1 - Dieringer, Matthias A. A1 - Özerdem, Celal A1 - Patel, Nishan A1 - Renz, Wolfgang A1 - Greiser, Andreas A1 - Elgeti, Thomas A1 - Niendorf, Thoralf T1 - Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study JF - Journal of Magnetic Resonance Imaging N2 - Purpose: To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle. Materials and Methods: The MHD effect was scrutinized using a pulsatile flow phantom at B0 = 7.0 T. MHD effects were examined in vivo in healthy volunteers (n = 10) for B0 ranging from 0.05–7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steady-state free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization. Results: The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B0 and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B0 = 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs. Conclusion: This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle. J. Magn. Reson. Imaging 2012;36:364–372. © 2012 Wiley Periodicals, Inc. Y1 - 2012 U6 - https://doi.org/10.1002/jmri.23634 SN - 1522-2586 VL - 36 IS - 2 SP - 364 EP - 372 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Grande, Marion A1 - Meffert, Elisabeth A1 - Schoenberger, Eva A1 - Jung, Stefanie A1 - Frauenrath, Tobias A1 - Huber, Walter A1 - Hussmann, Katja A1 - Moormann, Mareike A1 - Heim, Stefan T1 - From a concept to a word in a syntactically complete sentence: An fMRI study on spontaneous language production in an overt picture description task JF - NeuroImage N2 - Spontaneous language has rarely been subjected to neuroimaging studies. This study therefore introduces a newly developed method for the analysis of linguistic phenomena observed in continuous language production during fMRI. Most neuroimaging studies investigating language have so far focussed on single word or — to a smaller extent — sentence processing, mostly due to methodological considerations. Natural language production, however, is far more than the mere combination of words to larger units. Therefore, the present study aimed at relating brain activation to linguistic phenomena like word-finding difficulties or syntactic completeness in a continuous language fMRI paradigm. A picture description task with special constraints was used to provoke hesitation phenomena and speech errors. The transcribed speech sample was segmented into events of one second and each event was assigned to one category of a complex schema especially developed for this purpose. The main results were: conceptual planning engages bilateral activation of the precuneus. Successful lexical retrieval is accompanied – particularly in comparison to unsolved word-finding difficulties – by the left middle and superior temporal gyrus. Syntactic completeness is reflected in activation of the left inferior frontal gyrus (IFG) (area 44). In sum, the method has proven to be useful for investigating the neural correlates of lexical and syntactic phenomena in an overt picture description task. This opens up new prospects for the analysis of spontaneous language production during fMRI. Y1 - 2012 U6 - https://doi.org/10.1016/j.neuroimage.2012.03.087 SN - 1522-2586 VL - 61 IS - 3 SP - 702 EP - 714 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Tippkötter, Nils A1 - Ulber, Roland T1 - Rezension zu: Encyclopedia of Industrial Biotechnology, Vol. 1–7. By MC Flickinger. JF - Chemie Ingenieur Technik Y1 - 2012 U6 - https://doi.org/10.1002/cite.201290052 SN - 0009-286X SN - 1522-2640 (eISSN) VL - 6 IS - 84 SP - 936 PB - Wiley-VCH CY - Weinheim ER -