@inproceedings{SuryoputriGhaderiLinderetal.2017, author = {Suryoputri, Nathania and Ghaderi, Aydin and Linder, Peter and Kotliar, Konstantin and G{\"o}ttler, Jens and Sorg, Christian and Grimmer, Timo}, title = {Does hemodynamic response function change in Alzheimer disease?}, series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, editor = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus}, publisher = {Universit{\"a}t Duisburg-Essen}, address = {Duisburg}, organization = {MedTech Symposium}, isbn = {978-3-9814801-9-1}, doi = {10.17185/duepublico/43984}, pages = {92}, year = {2017}, language = {en} } @inproceedings{JabbariBhattaraiAndingetal.2017, author = {Jabbari, Medisa and Bhattarai, Aroj and Anding, Ralf and Staat, Manfred}, title = {Biomechanical simulation of different prosthetic meshes for repairing uterine/vaginal vault prolapse}, series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, editor = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus}, publisher = {Universit{\"a}t Duisburg-Essen}, address = {Duisburg}, organization = {MedTech Symposium}, isbn = {978-3-9814801-9-1}, doi = {10.17185/duepublico/43984}, pages = {118 -- 119}, year = {2017}, language = {en} } @inproceedings{BirgelLeschingerWegmannetal.2017, author = {Birgel, Stefan and Leschinger, Tim and Wegmann, Kilian and Staat, Manfred}, title = {Calculation of muscle forces and joint reaction loads in shoulder area via an OpenSim based computer calculation}, series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, editor = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus}, publisher = {Universit{\"a}t Duisburg-Essen}, address = {Duisburg}, organization = {MedTech Symposium}, isbn = {978-3-9814801-9-1}, doi = {10.17185/duepublico/43984}, pages = {116 -- 117}, year = {2017}, language = {en} } @inproceedings{AbelPerezVianaCiritsisetal.2017, author = {Abel, Alexander and P{\´e}rez-Viana, Daniel and Ciritsis, Bernard and Staat, Manfred}, title = {Prevention of femur neck fractures through femoroplasty}, series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West}, editor = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus}, publisher = {Universit{\"a}t Duisburg-Essen}, address = {Duisburg}, organization = {MedTech Symposium}, isbn = {978-3-9814801-9-1}, doi = {10.17185/duepublico/43984}, pages = {114 -- 115}, year = {2017}, language = {en} } @article{MichaelMayerWeberetal.2017, author = {Michael, Hackl and Mayer, Katharina and Weber, Mareike and Staat, Manfred and van Riet, Roger and Burkhart, Klau Josef and M{\"u}ller, Lars Peter and Wegmann, Kilian}, title = {Plate osteosynthesis of proximal ulna fractures : a biomechanical micromotion analysis}, series = {The journal of hand surgery}, volume = {42}, journal = {The journal of hand surgery}, number = {10}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0363-5023}, doi = {10.1016/j.jhsa.2017.05.014}, pages = {834.e1 -- 834.e7}, year = {2017}, language = {en} } @article{YoshinobuMiyamotoWerneretal.2017, author = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Werner, Frederik and Poghossian, Arshak and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species}, series = {Annual Review of Analytical Chemistry}, volume = {10}, journal = {Annual Review of Analytical Chemistry}, publisher = {Annual Reviews}, address = {Palo Alto, Calif.}, issn = {1936-1327}, doi = {10.1146/annurev-anchem-061516-045158}, pages = {225 -- 246}, year = {2017}, abstract = {A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed.}, language = {en} } @article{SousaSiqueiraVerciketal.2017, author = {Sousa, Marcos A. M. and Siqueira, Jose R. Jr. and Vercik, Andres and Sch{\"o}ning, Michael Josef and Oliveira, Osvaldo N. Jr.}, title = {Determining the optimized layer-by-layer film architecture with dendrimer/carbon nanotubes for field-effect sensors}, series = {IEEE Sensors Journal}, volume = {17}, journal = {IEEE Sensors Journal}, number = {6}, publisher = {IEEE}, address = {New York}, issn = {1558-1748}, doi = {10.1109/JSEN.2017.2653238}, pages = {1735 -- 1740}, year = {2017}, abstract = {The capacitive electrolyte-insulator-semiconductor (EIS) structure is a typical device based on a field-effect sensor platform. With a simple silicon-based structure, EIS have been useful for several sensing applications, especially with incorporation of nanostructured films to modulate the ionic transport and the flat-band potential. In this paper, we report on ion transport and changes in flat-band potential in EIS sensors made with layer-by-layer films containing poly(amidoamine) (PAMAM) dendrimer and single-walled carbon nanotubes (SWNTs) adsorbed on p-Si/SiO 2 /Ta 2 O 5 chips with an Al ohmic contact. The impedance spectra were fitted using an equivalent circuit model, from which we could determine parameters such as the double-layer capacitance. This capacitance decreased with the number of bilayers owing to space charge accumulated at the electrolyte-insulator interface, up to three PAMAM/SWNTs bilayers, after which it stabilized. The charge-transfer resistance was also minimum for three bilayers, thus indicating that this is the ideal architecture for an optimized EIS performance. The understanding of the influence of nanostructures and the fine control of operation parameters pave the way for optimizing the design and performance of new EIS sensors.}, language = {en} } @article{GamellaZakharchenkoGuzetal.2017, author = {Gamella, Maria and Zakharchenko, Andrey and Guz, Nataliia and Masi, Madeline and Minko, Sergiy and Kolpashchikov, Dmitry M. and Iken, Heiko and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Katz, Evgeny}, title = {DNA computing system activated by electrochemically triggered DNA realease from a polymer-brush-modified electrode array}, series = {Electroanalysis}, volume = {29}, journal = {Electroanalysis}, number = {2}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-4109}, doi = {10.1002/elan.201600389}, pages = {398 -- 408}, year = {2017}, abstract = {An array of four independently wired indium tin oxide (ITO) electrodes was used for electrochemically stimulated DNA release and activation of DNA-based Identity, AND and XOR logic gates. Single-stranded DNA molecules were loaded on the mixed poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA)/poly(methacrylic acid) (PMAA) brush covalently attached to the ITO electrodes. The DNA deposition was performed at pH 5.0 when the polymer brush is positively charged due to protonation of tertiary amino groups in PDMAEMA, thus resulting in electrostatic attraction of the negatively charged DNA. By applying electrolysis at -1.0 V(vs. Ag/AgCl reference) electrochemical oxygen reduction resulted in the consumption of hydrogen ions and local pH increase near the electrode surface. The process resulted in recharging the polymer brush to the negative state due to dissociation of carboxylic groups of PMAA, thus repulsing the negatively charged DNA and releasing it from the electrode surface. The DNA release was performed in various combinations from different electrodes in the array assembly. The released DNA operated as input signals for activation of the Boolean logic gates. The developed system represents a step forward in DNA computing, combining for the first time DNA chemical processes with electronic input signals.}, language = {en} } @inproceedings{SchreiberKraftZuendorf2017, author = {Schreiber, Marc and Kraft, Bodo and Z{\"u}ndorf, Albert}, title = {Metrics Driven Research Collaboration: Focusing on Common Project Goals Continuously}, series = {39th International Conference on Software Engineering, May 20-28, 2017 - Buenos Aires, Argentina}, booktitle = {39th International Conference on Software Engineering, May 20-28, 2017 - Buenos Aires, Argentina}, pages = {8 Seiten}, year = {2017}, abstract = {Research collaborations provide opportunities for both practitioners and researchers: practitioners need solutions for difficult business challenges and researchers are looking for hard problems to solve and publish. Nevertheless, research collaborations carry the risk that practitioners focus on quick solutions too much and that researchers tackle theoretical problems, resulting in products which do not fulfill the project requirements. In this paper we introduce an approach extending the ideas of agile and lean software development. It helps practitioners and researchers keep track of their common research collaboration goal: a scientifically enriched software product which fulfills the needs of the practitioner's business model. This approach gives first-class status to application-oriented metrics that measure progress and success of a research collaboration continuously. Those metrics are derived from the collaboration requirements and help to focus on a commonly defined goal. An appropriate tool set evaluates and visualizes those metrics with minimal effort, and all participants will be pushed to focus on their tasks with appropriate effort. Thus project status, challenges and progress are transparent to all research collaboration members at any time.}, language = {en} } @inproceedings{BitzStreckertHansenetal.2000, author = {Bitz, Andreas and Streckert, J. and Hansen, V.W. and Buschmann, J.}, title = {RF exposure of non restrained animals in an overmoded radial waveguide}, series = {22nd BEMS Annual Meeting, Munich, Germany, 2000}, booktitle = {22nd BEMS Annual Meeting, Munich, Germany, 2000}, publisher = {Bioelectromagnetics Society}, address = {Frederick, MD}, pages = {63}, year = {2000}, language = {en} } @inproceedings{BitzStreckertHansenetal.2000, author = {Bitz, Andreas and Streckert, J.R. and Hansen, V.W. and Lerchl, A.}, title = {Freely moving or restrained animals in bioelec-tromagnetic experiments - pros and cons}, series = {AP 2000 : Millennium Conference on Antennas \& Propagation, Davos, Switzerland, 9 - 14 April 2000}, booktitle = {AP 2000 : Millennium Conference on Antennas \& Propagation, Davos, Switzerland, 9 - 14 April 2000}, number = {Band 1}, editor = {Danesy, Dorothea}, publisher = {ESA Publications Division, ESTEC}, address = {Noordwijk}, pages = {489}, year = {2000}, language = {en} } @inproceedings{BitzStreckertHansenetal.2001, author = {Bitz, Andreas and Streckert, J. and Hansen, V.W. and Stogbauer, F.}, title = {Shielded RF-exposure system with an integrated LF-measuring system for in vitro experiments with cell-layers}, series = {Proceedings of the Ebea 2001 : 5th International Congress of the European Bioelectromagnetics Association (Ebea) ; 6-8 September 2001, Marina Congress Center, Helsinki, Finland}, booktitle = {Proceedings of the Ebea 2001 : 5th International Congress of the European Bioelectromagnetics Association (Ebea) ; 6-8 September 2001, Marina Congress Center, Helsinki, Finland}, editor = {Hietanen, Maila and Jokela, Kari and Juutilainen, Jukka and Työterveyslaitos,}, publisher = {Finnish Institute of Occupational Health}, address = {Helsinki}, isbn = {9789518024401}, pages = {67 -- 68}, year = {2001}, language = {en} } @inproceedings{BitzAlaydrusStreckertetal.2001, author = {Bitz, Andreas and Alaydrus, M. and Streckert, J. and Hansen, V.W.}, title = {Base station antennas embedded in complex environments: rf exposure in controlled areas}, series = {23rd BEMS Annual Meeting, St. Paul, Minnesota, USA, 49-50, June 2001}, booktitle = {23rd BEMS Annual Meeting, St. Paul, Minnesota, USA, 49-50, June 2001}, publisher = {Bioelectromagnetics Society}, address = {Frederick, MD}, pages = {49 -- 50}, year = {2001}, language = {en} } @inproceedings{BitzAlaydrusStreckertetal.2002, author = {Bitz, Andreas and Alaydrus, M. and Streckert, J. and Hansen, V.W.}, title = {Absorption rates inside human body due to radiated electro-magnetic fields of multi-band base station antennas. Boundary value problems with electrically large and high-resolution bodies}, series = {24th BEMS Annual Meeting, Quebec City, Quebec, Canada, 23 - 27 June 2002}, booktitle = {24th BEMS Annual Meeting, Quebec City, Quebec, Canada, 23 - 27 June 2002}, publisher = {Bioelectromagnetics Society}, address = {Frederick, MD}, pages = {40 -- 41}, year = {2002}, language = {en} } @inproceedings{BitzAlaydrusStreckertetal.2002, author = {Bitz, Andreas and Alaydrus, M. and Streckert, J. and Hansen, V.}, title = {Combination of the hybrid/sup [2]/-method and the FDTD-method for solution of boundary value problems with electrically large and high-resolution bodies}, series = {IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313) 2002 : San Antonio, TX, USA, 16-21 June}, booktitle = {IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313) 2002 : San Antonio, TX, USA, 16-21 June}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {0-7803-7330-8}, doi = {10.1109/APS.2002.1018209}, pages = {278 -- 281}, year = {2002}, language = {en} } @inproceedings{BitzElOuardiStreckertetal.2005, author = {Bitz, Andreas and El Ouardi, A. and Streckert, J. and Hansen, V.}, title = {Efficient calculation of human exposure in front of base station antennas by a combination of the FDTD and Hybrid(2)-method}, series = {Proceedings of the 16th International Zurich Symposium on Electromagnetic Compatibility, Topical Meeting on Biomedical EMC, Zurich, Switzerland, February 2005}, booktitle = {Proceedings of the 16th International Zurich Symposium on Electromagnetic Compatibility, Topical Meeting on Biomedical EMC, Zurich, Switzerland, February 2005}, publisher = {ETH Zentrum}, address = {Z{\"u}rich}, isbn = {3-9521199-9-7}, pages = {115 -- 118}, year = {2005}, language = {en} } @inproceedings{BitzKlompLadd2009, author = {Bitz, Andreas and Klomp, D.W. and Ladd, M.E.}, title = {Experimental and numerical determination of SAR and temperature distribution of a human endorectal coil for MR imaging of the prostate at 7T (903.)}, series = {16th annual ISMRM scientific meeting and exhibition 2008 : Toronto, Ontario, Canada, 3 - 9 May 2008}, booktitle = {16th annual ISMRM scientific meeting and exhibition 2008 : Toronto, Ontario, Canada, 3 - 9 May 2008}, publisher = {Curran}, address = {Red Hook, NY}, isbn = {978-1-61567-196-0}, year = {2009}, language = {en} } @inproceedings{GranatHoefkenSchuba2017, author = {Granat, Andreas and H{\"o}fken, Hans-Wilhelm and Schuba, Marko}, title = {Intrusion Detection of the ICS Protocol EtherCAT}, pages = {1 -- 5}, year = {2017}, abstract = {Control mechanisms like Industrial Controls Systems (ICS) and its subgroup SCADA (Supervisory Control and Data Acquisition) are a prerequisite to automate industrial processes. While protection of ICS on process management level is relatively straightforward - well known office IT security mechanisms can be used - protection on field bus level is harder to achieve as there are real-time and production requirements like 24x7 to consider. One option to improve security on field bus level is to introduce controls that help to detect and to react on attacks. This paper introduces an initial set of intrusion detection mechanisms for the field bus protocol EtherCAT. To this end existing Ethernet attack vectors including packet injection and man-in-the-middle attacks are tested in an EtherCAT environment, where they could interrupt the EtherCAT network and may even cause physical damage. Based on the signatures of such attacks, a preprocessor and new rule options are defined for the open source intrusion detection system Snort demonstrating the general feasibility of intrusion detection on field bus level.}, language = {en} } @inproceedings{SchwankeHoefkenSchuba2017, author = {Schwanke, Peter and H{\"o}fken, Hans-Wilhelm and Schuba, Marko}, title = {Security Analysis of the ADS Protocol of a Beckhoff CX2020 PLC}, pages = {1 -- 5}, year = {2017}, abstract = {ICSs (Industrial Control Systems) and its subset SCADA systems (Supervisory Control and Data Acquisition) are getting exposed to a constant stream of new threats. The increasing importance of IT security in ICS requires viable methods to assess the security of ICS, its individual components, and its protocols. This paper presents a security analysis with focus on the communication protocols of a single PLC (Programmable Logic Controller). The PLC, a Beckhoff CX2020, is examined and new vulnerabilities of the system are revealed. Based on these findings recommendations are made to improve security of the Beckhoff system and its protocols.}, language = {en} } @article{BronderPoghossianKeusgenetal.2017, author = {Bronder, Thomas and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Label-free detection of double-stranded DNA molecules with polyelectrolyte-modified capacitive field-effect sensors}, series = {tm - Technisches Messen}, volume = {84}, journal = {tm - Technisches Messen}, number = {10}, publisher = {De Gruyter}, address = {Oldenbourg}, doi = {10.1515/teme-2017-0015}, pages = {628 -- 634}, year = {2017}, abstract = {In this study, polyelectrolyte-modified field-effect-based electrolyte-insulator-semiconductor (EIS) devices have been used for the label-free electrical detection of double-stranded deoxyribonucleic acid (dsDNA)molecules. The sensor-chip functionalization with a positively charged polyelectrolyte layer provides the possibility of direct adsorptive binding of negatively charged target DNA oligonucleotides onto theSiO2-chip surface.EIS sensors can be utilized as a tool to detect surface-charge changes; the electrostatic adsorption of oligonucleotides onto the polyelectrolyte layer leads to a measureable surface-potential change. Signals of 39mV have been recorded after the incubation with the oligonucleotide solution. Besides the electrochemical experiments, the successful adsorption of dsDNA onto the polyelectrolyte layer has been verified via fluorescence microscopy. The presented results demonstrate that the signal recording of EISchips, which are modified with a polyelectrolyte layer, canbe used as a favorable approach for a fast, cheap and simple detection method for dsDNA.}, language = {en} } @article{ArreolaOberlaenderMaetzkowetal.2017, author = {Arreola, Julio and Oberl{\"a}nder, Jan and M{\"a}tzkow, M. and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Surface functionalization for spore-based biosensors with organosilanes}, series = {Electrochimica Acta}, volume = {241}, journal = {Electrochimica Acta}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2017.04.157}, pages = {237 -- 243}, year = {2017}, abstract = {In the present work, surface functionalization of different sensor materials was studied. Organosilanes are well known to serve as coupling agent for biomolecules or cells on inorganic materials. 3-aminopropyltriethoxysilane (APTES) was used to attach microbiological spores time to an interdigitated sensor surface. The functionality and physical properties of APTES were studied on isolated sensor materials, namely silicon dioxide (SiO2) and platinum (Pt) as well as the combined material on sensor level. A predominant immobilization of spores could be demonstrated on SiO2 surfaces. Additionally, the impedance signal of APTES-functionalized biosensor chips has been investigated.}, language = {en} } @inproceedings{BitzKraffOrzadaetal.2010, author = {Bitz, Andreas and Kraff, O. and Orzada, S. and Maderwald, S. and Brote, I. and Ladd, M.}, title = {Experimental and Numerical Assessment of RF Safety of Transmit Coils at 7 Tesla}, series = {ISMRM workshop on MR safety 2010 : RF heating of the human in MRI : workshop series. The Washington County Historic Courthouse, Stillwater, Minnesota, USA, 15 - 17 October 2010}, booktitle = {ISMRM workshop on MR safety 2010 : RF heating of the human in MRI : workshop series. The Washington County Historic Courthouse, Stillwater, Minnesota, USA, 15 - 17 October 2010}, isbn = {978-1-62276-088-6}, pages = {195}, year = {2010}, language = {en} } @inproceedings{BitzKraffOrzadaetal.2012, author = {Bitz, Andreas and Kraff, O. and Orzada, S. and Maderwald, S. and Brote, I. and Johst, S. and Ladd, E.}, title = {Assessment of RF Safety of Transmit Coils at 7 Tesla by Experimental and Numerical Procedures (490.)}, series = {19th annual ISMRM scientific meeting and exhibition 2011 : Montreal, Quebec, Canada, 7 - 13 May 2011}, booktitle = {19th annual ISMRM scientific meeting and exhibition 2011 : Montreal, Quebec, Canada, 7 - 13 May 2011}, number = {Volume 1}, publisher = {Curran}, address = {Red Hook, NY}, isbn = {978-1-61839-284-8}, pages = {475}, year = {2012}, language = {en} } @inproceedings{BitzKobusScheenenetal.2013, author = {Bitz, Andreas and Kobus, Thiele and Scheenen, Tom W. J. and Ladd, Mark E.}, title = {RF Safety of the Combination of a 31P Tx/Rx Endorectal Coil \& a 1H Tx/Rx Body Array for 31P MRSI of the Prostate at 7T (311.)}, series = {20th Annual ISMRM scientific meeting and exhibition 2012 : Melbourne, Australia, 5 - 11 May 2012}, booktitle = {20th Annual ISMRM scientific meeting and exhibition 2012 : Melbourne, Australia, 5 - 11 May 2012}, number = {Volume 1}, publisher = {Curran}, address = {Red Hook, NY}, isbn = {978-1-62276-943-8}, issn = {1545-4428}, pages = {311}, year = {2013}, language = {en} } @article{HansenBitzStreckert1999, author = {Hansen, Volkert W. and Bitz, Andreas and Streckert, Joachim R.}, title = {RF Exposure of Biological Systems in Radial Waveguides}, series = {IEEE Transactions on Electromagnetic Compatibility}, volume = {41}, journal = {IEEE Transactions on Electromagnetic Compatibility}, number = {4}, issn = {1558-187X}, doi = {10.1109/15.809852}, pages = {487 -- 493}, year = {1999}, language = {en} } @article{SommerStreckertBitzetal.2004, author = {Sommer, Angela M. and Streckert, Joachim and Bitz, Andreas and Hansen, Volkert W. and Lerchl, Alexander}, title = {No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice}, series = {BMC Cancer}, volume = {77}, journal = {BMC Cancer}, number = {4}, doi = {10.1186/1471-2407-4-77}, year = {2004}, language = {en} } @article{NdoumbeMbonjoMbonjoStreckertBitzetal.2004, author = {Ndoumb{\`e} Mbonjo Mbonjo, H. and Streckert, J. and Bitz, Andreas and Hansen, V. and Glasmachers, A. and Gencol, S. and Rozic, D.}, title = {Generic UMTS test signal for RF bioelectromagnetic studies}, series = {Bioelectromagnetics}, volume = {25}, journal = {Bioelectromagnetics}, number = {6}, issn = {1521-186X}, doi = {10.1002/bem.20007}, pages = {415 -- 425}, year = {2004}, language = {en} } @inproceedings{ThurnGebhardt2017, author = {Thurn, Laura and Gebhardt, Andreas}, title = {Arousing Enthusiasm for STEM: Teaching 3D Printing Technology}, series = {Conference Proceedings: New Perspectives in Science Education}, booktitle = {Conference Proceedings: New Perspectives in Science Education}, publisher = {liberiauniversitaria.it}, address = {Padua}, isbn = {978-88-6292-847-2}, pages = {87 -- 92}, year = {2017}, language = {en} } @inproceedings{NeuJanserKhatibietal.2016, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Orifici, Adrian C.}, title = {In-flight vibration-based structural health monitoring of aircraft wings}, series = {30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea}, booktitle = {30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea}, pages = {10 Seiten}, year = {2016}, abstract = {This work presents a methodology for automated damage-sensitive feature extraction and anomaly detection under multivariate operational variability for in-flight assessment of wings. The method uses a passive excitation approach, i. e. without the need for artificial actuation. The modal system properties (natural frequencies and damping ratios) are used as damage-sensitive features. Special emphasis is placed on the use of Fiber Bragg Grating (FBG) sensing technology and the consideration of Operational and Environmental Variability (OEV). Measurements from a wind tunnel investigation with a composite cantilever equipped with FBG and piezoelectric sensors are used to successfully detect an impact damage. In addition, the feasibility of damage localisation and severity estimation is evaluated based on the coupling found between damageand OEV-induced feature changes.}, language = {en} } @inproceedings{SchirraBauschatWatmuff2014, author = {Schirra, Julian and Bauschat, J.-Michael and Watmuff, J.H.}, title = {Accurate induced drag prediction for highly non-planar lifting systems}, series = {19th Australasian Fluid Mechanics Conference : 8.-11. Dezember 2014, Melbourne, Australia}, booktitle = {19th Australasian Fluid Mechanics Conference : 8.-11. Dezember 2014, Melbourne, Australia}, pages = {4 Seiten}, year = {2014}, abstract = {The impact of wake model effects is investigated for two highly non-planar lifting systems. Dependent on the geometrical arrangement of the configuration, the wake model shape is found to considerably affect the estimation. Particularly at higher angles of attack, an accurate estimation based on the common linear wake model approaches is involved.}, language = {en} } @inproceedings{WuKemper2016, author = {Wu, Ziyi and Kemper, Hans}, title = {The optimal 48 V - battery pack for a specific load profile of a heavy duty vehicle}, series = {8. Internationale Fachtagung Kraftwerk Batterie : 26. - 27. April 2016, M{\"u}nster, Deutschland}, booktitle = {8. Internationale Fachtagung Kraftwerk Batterie : 26. - 27. April 2016, M{\"u}nster, Deutschland}, year = {2016}, language = {en} } @article{WissenBogdanskiScheeretal.2005, author = {Wissen, M. and Bogdanski, N. and Scheer, H.-C. and Bitz, Andreas and Ahrens, G. and Gruetzner, G.}, title = {Implication of the light polarisation for UV curing of pre-patterned resists}, series = {Microelectronic Engineering}, volume = {78-79}, journal = {Microelectronic Engineering}, issn = {0167-9317}, doi = {10.1016/j.mee.2004.12.099}, pages = {659 -- 664}, year = {2005}, language = {en} } @article{FrankeStreckertBitzetal.2005, author = {Franke, Helmut and Streckert, Joachim and Bitz, Andreas and Goeke, Johannes and Hansen, Volkert and Ringelstein, E. Bernd and Nattk{\"a}mper, Heiner and Galle, Hans-Joachim and St{\"o}gbauer, Florian}, title = {Effects of Universal Mobile Telecommunications System (UMTS) electromagnetic fields on the blood-brain barrier in vitro}, series = {Radiation Research}, volume = {164}, journal = {Radiation Research}, number = {3}, issn = {1938-5404}, doi = {10.1667/RR3424.1}, pages = {258 -- 269}, year = {2005}, language = {en} } @article{SukhotinaStreckertBitzetal.2006, author = {Sukhotina, Irina and Streckert, Joachim R. and Bitz, Andreas and Hansen, Volkert W. and Lerchl, Alexander}, title = {1800 MHz electromagnetic field effects on melatonin release from isolated pineal glands}, series = {Journal of Pineal Research}, volume = {40}, journal = {Journal of Pineal Research}, number = {1}, issn = {1600-079X}, doi = {10.1111/j.1600-079X.2005.00284.x}, pages = {86 -- 91}, year = {2006}, language = {en} } @article{SommerBitzStreckertetal.2007, author = {Sommer, Angela M. and Bitz, Andreas and Streckert, Joachim and Hansen, Volkert W. and Lerchl, Alexander}, title = {Lymphoma development in mice chronically exposed to UMTS-modulated radiofrequency electromagnetic fields}, series = {Radiation Research}, volume = {168}, journal = {Radiation Research}, number = {1}, issn = {1938-5404}, doi = {10.1667/RR0857.1}, pages = {72 -- 80}, year = {2007}, language = {en} } @article{ReinhardtBitzElOuardietal.2007, author = {Reinhardt, T. and Bitz, Andreas and El Ouardi, A. and Streckert, J. and Sommer, A. and Lerchl, A. and Hansen, V.}, title = {Exposure set-ups for in vivo experiments using radial waveguides}, series = {Radiation Protection Dosimetry}, volume = {124}, journal = {Radiation Protection Dosimetry}, number = {1}, issn = {1742-3406}, doi = {10.1093/rpd/ncm370}, pages = {21 -- 26}, year = {2007}, language = {en} } @article{LerchlKruegerNiehausetal.2008, author = {Lerchl, Alexander and Kr{\"u}ger, Heike and Niehaus, Michael and Streckert, Joachim R. and Bitz, Andreas and Hansen, Volkert}, title = {Effects of mobile phone electromagnetic fields at nonthermal SAR values on melatonin and body weight of Djungarian hamsters (Phodopus sungorus)}, series = {Journal of Pineal Research}, volume = {44}, journal = {Journal of Pineal Research}, number = {3}, issn = {1600-079X}, doi = {10.1111/j.1600-079X.2007.00522.x}, pages = {267 -- 272}, year = {2008}, language = {en} } @article{KlompBitzHeerschapetal.2009, author = {Klomp, D. W. J. and Bitz, Andreas and Heerschap, A. and Scheenen, T. W. J.}, title = {Proton spectroscopic imaging of the human prostate at 7 T}, series = {NMR in Biomedicine}, volume = {22}, journal = {NMR in Biomedicine}, number = {5}, issn = {1099-1492}, doi = {10.1002/nbm.1360}, pages = {495 -- 501}, year = {2009}, language = {en} } @article{KraffBitzKruszonaetal.2009, author = {Kraff, Oliver and Bitz, Andreas and Kruszona, Stefan and Orzada, Stephan and Schaefer, Lena C. and Theysohn, Jens M. and Maderwald, Stefan and Ladd, Mark E. and Quick, Harald H.}, title = {An eight-channel phased array RF coil for spine MR imaging at 7 T}, series = {Investigative Radiology}, volume = {44}, journal = {Investigative Radiology}, number = {11}, publisher = {Lippincott Williams \& Wilkins}, issn = {1536-0210}, doi = {10.1097/RLI.0b013e3181b24ab7}, pages = {734 -- 740}, year = {2009}, language = {en} } @article{SchlamannYoonMaderwaldetal.2010, author = {Schlamann, Marc and Yoon, Min-Suk and Maderwald, Stefan and Pietrzyk, Thomas and Bitz, Andreas and Gerwig, Marcus and Forsting, Michael and Ladd, Susanne C. and Ladd, Mark E. and Kastrup, Oliver}, title = {Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T}, series = {Academic Radiology}, volume = {17}, journal = {Academic Radiology}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1076-6332}, doi = {10.1016/j.acra.2009.10.004}, pages = {277 -- 281}, year = {2010}, abstract = {Rationale and Objectives The increasing spread of high-field and ultra-high-field magnetic resonance imaging (MRI) scanners has encouraged new discussion of the safety aspects of MRI. Few studies have been published on possible cognitive effects of MRI examinations. The aim of this study was to examine whether changes are measurable after MRI examinations at 1.5 and 7 T by means of transcranial magnetic stimulation (TMS). Materials and Methods TMS was performed in 12 healthy, right-handed male volunteers. First the individual motor threshold was specified, and then the cortical silent period (SP) was measured. Subsequently, the volunteers were exposed to the 1.5-T MRI scanner for 63 minutes using standard sequences. The MRI examination was immediately followed by another TMS session. Fifteen minutes later, TMS was repeated. Four weeks later, the complete setting was repeated using a 7-T scanner. Control conditions included lying in the 1.5-T scanner for 63 minutes without scanning and lying in a separate room for 63 minutes. TMS was performed in the same way in each case. For statistical analysis, Wilcoxon's rank test was performed. Results Immediately after MRI exposure, the SP was highly significantly prolonged in all 12 subjects at 1.5 and 7 T. The motor threshold was significantly increased. Fifteen minutes after the examination, the measured value tended toward normal again. Control conditions revealed no significant differences. Conclusion MRI examinations lead to a transient and highly significant alteration in cortical excitability. This effect does not seem to depend on the strength of the static magnetic field.}, language = {en} } @article{BitzZhouElQuardietal.2009, author = {Bitz, Andreas and Zhou, Yi and El Quardi, Abdessamad and Streckert, Joachim}, title = {Occupational Exposure at Mobile Communication Base Station Antenna Sites}, series = {Frequenz}, volume = {63}, journal = {Frequenz}, number = {7-8}, issn = {2191-6349}, doi = {10.1515/FREQ.2009.63.7-8.123}, pages = {123 -- 128}, year = {2009}, language = {en} } @article{SchlamannVoigtMaderwaldetal.2010, author = {Schlamann, Marc and Voigt, Melanie A. and Maderwald, Stefan and Bitz, Andreas and Kraff, Oliver and Ladd, Susanne C. and Ladd, Mark E. and Forsting, Michael and Wilhelm, Hans}, title = {Exposure to high-field MRI does not affect cognitive function}, series = {Journal of Magnetic Resonance Imaging}, volume = {31}, journal = {Journal of Magnetic Resonance Imaging}, number = {5}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2586}, doi = {10.1002/jmri.22065}, pages = {1061 -- 1066}, year = {2010}, abstract = {Purpose To assess potential cognitive deficits under the influence of static magnetic fields at various field strengths some studies already exist. These studies were not focused on attention as the most vulnerable cognitive function. Additionally, mostly no magnetic resonance imaging (MRI) sequences were performed. Materials and Methods In all, 25 right-handed men were enrolled in this study. All subjects underwent one MRI examination of 63 minutes at 1.5 T and one at 7 T within an interval of 10 to 30 days. The order of the examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Differences in neuropsychological variables between the timepoints before and after each MRI examination were assessed and P-values were calculated Results Only six subtests revealed significant differences between pre- and post-MRI. In these tests the subjects achieved better results in post-MRI testing than in pre-MRI testing (P = 0.013-0.032). The other tests revealed no significant results. Conclusion The improvement in post-MRI testing is only explicable as a result of learning effects. MRI examinations, even in ultrahigh-field scanners, do not seem to have any persisting influence on the attention networks of human cognition immediately after exposure.}, 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{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{CiritsisHorbachStaatetal.2018, author = {Ciritsis, Alexander and Horbach, Andreas and Staat, Manfred and Kuhl, Christiane K. and Kraemer, Nils Andreas}, title = {Porosity and tissue integration of elastic mesh implants evaluated in vitro and in vivo}, series = {Journal of Biomedical Materials Research: Part B: Applied Biomaterials}, volume = {106}, journal = {Journal of Biomedical Materials Research: Part B: Applied Biomaterials}, number = {2}, publisher = {Wiley}, address = {New York, NY}, issn = {1552-4981}, doi = {10.1002/jbm.b.33877}, pages = {827 -- 833}, year = {2018}, abstract = {Purpose In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model. Material and Methods Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio). Results In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm2 (± 5.7 cm2) at 0 mmHg pneumoperitoneum and 274.6 cm2 (± 5.2 cm2) at 15 mmHg; for PVDF the mean areas were 205.5 cm2 (± 8.8 cm2) and 221.5 cm2 (± 11.8 cm2), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4\% for TPU and of 1.2\% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF. Conclusion The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 827-833, 2018.}, language = {en} } @article{KraffBitzDammannetal.2010, author = {Kraff, Oliver and Bitz, Andreas and Dammann, Philipp and Ladd, Susanne C. and Ladd, Mark E. and Quick, Harald H.}, title = {An eight-channel transmit/receive multipurpose coil for musculoskeletal MR imaging at 7 T}, series = {Medical Physics}, volume = {37}, journal = {Medical Physics}, number = {12}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {2473-4209}, doi = {10.1118/1.3517176}, pages = {6368 -- 6376}, year = {2010}, abstract = {Purpose: MRI plays a leading diagnostic role in assessing the musculoskeletal (MSK) system and is well established for most questions at clinically used field strengths (up to 3 T). However, there are still limitations in imaging early stages of cartilage degeneration, very fine tendons and ligaments, or in locating nerve lesions, for example. 7 T MRI of the knee has already received increasing attention in the current published literature, but there is a strong need to develop new radiofrequency (RF) coils to assess more regions of the MSK system. In this work, an eight-channel transmit/receive RF array was built as a multipurpose coil for imaging some of the thus far neglected regions. An extensive coil characterization protocol and first in vivo results of the human wrist, shoulder, elbow, knee, and ankle imaged at 7 T will be presented. Methods: Eight surface loop coils with a dimension ofurn:x-wiley:00942405:media:mp7176:mp7176-math-0001 were machined from FR4 circuit board material. To facilitate easy positioning, two coil clusters, each with four loop elements, were combined to one RF transmit/receive array. An overlapped and shifted arrangement of the coil elements was chosen to reduce the mutual inductance between neighboring coils. A phantom made of body-simulating liquid was used for tuning and matching on the bench. Afterward, the S-parameters were verified on a human wrist, elbow, and shoulder. For safety validation, a detailed compliance test was performed including full wave simulations of the RF field distribution and the corresponding specific absorption rate (SAR) for all joints. In vivo images of four volunteers were assessed with gradient echo and spin echo sequences modified to obtain optimal image contrast, full anatomic coverage, and the highest spatial resolution within a reasonable acquisition time. The performance of the RF coil was additionally evaluated by in vivo B1 mapping. Results: A comparison of B1 per unit power, flip angle distribution, and anatomic images showed a fairly homogeneous excitation for the smaller joints (elbow, wrist, and ankle), while for the larger joints, the shoulder and especially the knee, B1 inhomogeneities and limited penetration depth were more pronounced. However, the greater part of the shoulder joint could be imaged.In vivo images rendered very fine anatomic details such as fascicles of the median nerve and the branching of the nerve bundles. High-resolution images of cartilage, labrum, and tendons could be acquired. Additionally, turbo spin echo (TSE) and inversion recovery sequences performed very well. Conclusions: This study demonstrates that the concept of two four-channel transmit/receive RF arrays can be used as a multipurpose coil for high-resolutionin vivo MR imaging of the musculoskeletal system at 7 T. Not only gradient echo but also typical clinical and SAR-intensive sequences such as STIR and TSE performed well. Imaging of small structures and peripheral nerves could in particular benefit from this technique.}, language = {en} } @article{OrzadaBitzSchaeferetal.2011, author = {Orzada, Stephan and Bitz, Andreas and Sch{\"a}fer, Lena C. and Ladd, Susanne C. and Ladd, Mark E. and Maderwald, Stefan}, title = {Open design eight-channel transmit/receive coil for high-resolution and real-time ankle imaging at 7 T}, series = {Medical Physics}, volume = {38}, journal = {Medical Physics}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {2473-4209}, doi = {10.1118/1.3553399}, pages = {1162 -- 1167}, year = {2011}, abstract = {Purpose: At 1.5 T, real-time MRI of joint movement has been shown to be feasible. However, 7 T, provides higher SNR and thus an improved potential for parallel imaging acceleration. The purpose of this work was to build an open, U-shaped eight-channel transmit/receive microstrip coil for 7 T MRI to enable high-resolution and real-time imaging of the moving ankle joint. Methods: A U-shaped eight-channel transmit/receive array for the human ankle was built.urn:x-wiley:00942405:mp3399:equation:mp3399-math-0001-parameters and urn:x-wiley:00942405:mp3399:equation:mp3399-math-0002-factor were measured. SAR calculations of different ankle postures were performed to ensure patient safety. Inhomogeneities in the transmit field consequent to the open design were compensated for by the use of static RF shimming. High-resolution and real-time imaging was performed in human volunteers. Results: The presented array showed good performance with regard to patient comfort and image quality. High acceleration factors of up to 4 are feasible without visible acceleration artifacts. Reasonable image homogeneity was achieved with RF shimming. Conclusions: Open, noncylindrical designs for transmit/receive coils are practical at 7 T and real-time imaging of the moving joint is feasible with the presented coil design.}, language = {en} } @article{ProchnowGebingLadageetal.2011, author = {Prochnow, Nora and Gebing, Tina and Ladage, Kerstin and Krause-Finkeldey, Dorothee and Ourdi, Abessamad El and Bitz, Andreas and Streckert, Joachim and Hansen, Volkert and Dermietzel, Rolf}, title = {Electromagnetic field effect or simply stress? Effects of UMTS exposure on hippocampal longterm plasticity in the context of procedure related hormone release}, series = {PLoS one}, volume = {6}, journal = {PLoS one}, number = {5}, publisher = {PLOS}, address = {San Francisco}, doi = {10.1371/journal.pone.0019437}, pages = {e19437}, year = {2011}, abstract = {Harmful effects of electromagnetic fields (EMF) on cognitive and behavioural features of humans and rodents have been controversially discussed and raised persistent concern about adverse effects of EMF on general brain functions. In the present study we applied radio-frequency (RF) signals of the Universal Mobile Telecommunications System (UMTS) to full brain exposed male Wistar rats in order to elaborate putative influences on stress hormone release (corticosteron; CORT and adrenocorticotropic hormone; ACTH) and on hippocampal derived synaptic long-term plasticity (LTP) and depression (LTD) as electrophysiological hallmarks for memory storage and memory consolidation. Exposure was computer controlled providing blind conditions. Nominal brain-averaged specific absorption rates (SAR) as a measure of applied mass-related dissipated RF power were 0, 2, and 10 W/kg over a period of 120 min. Comparison of cage exposed animals revealed, regardless of EMF exposure, significantly increased CORT and ACTH levels which corresponded with generally decreased field potential slopes and amplitudes in hippocampal LTP and LTD. Animals following SAR exposure of 2 W/kg (averaged over the whole brain of 2.3 g tissue mass) did not differ from the sham-exposed group in LTP and LTD experiments. In contrast, a significant reduction in LTP and LTD was observed at the high power rate of SAR (10 W/kg). The results demonstrate that a rate of 2 W/kg displays no adverse impact on LTP and LTD, while 10 W/kg leads to significant effects on the electrophysiological parameters, which can be clearly distinguished from the stress derived background. Our findings suggest that UMTS exposure with SAR in the range of 2 W/kg is not harmful to critical markers for memory storage and memory consolidation, however, an influence of UMTS at high energy absorption rates (10 W/kg) cannot be excluded.}, language = {en} } @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{UmutluBitzMaderwaldetal.2013, author = {Umutlu, Lale and Bitz, Andreas and Maderwald, Stefan and Orzada, Stephan and Kinner, Sonja and Kraff, Oliver and Brote, Irina and Ladd, Susanne C. and Schroeder, Tobias and Forsting, Michael}, title = {Contrast-enhanced ultra-high-field liver MRI: a feasibility trial}, series = {European Journal of Radiology}, volume = {82}, journal = {European Journal of Radiology}, number = {5}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0720-048X}, doi = {10.1016/j.ejrad.2011.07.004}, pages = {760 -- 767}, year = {2013}, language = {en} }