TY  - JOUR
A1  - Hamm, Laurits
A1  - Hartung, Frank
T1  - High Quality Visual Communication based on IMS
JF  - Mobilkommunikation : Technologien und Anwendungen ; Vorträge der 16. ITG-Fachtagung vom 18. bis 19. Mai 2011 in Osnabrück / Veranst.: Informationstechnische Gesellschaft im VDE (ITG) ... Tagungsleitung: Ralf Tönjes. Programmkomitee/Hrsg.: Peter Roer
Y1  - 2011
SN  - 978-3-8007-3352-1
N1  - ITG-Fachbericht ; 230 ; Fachtagung Mobilkommunikation <16, 2011, Osnabrück>
SP  - 80
EP  - 85
PB  - VDE-Verl.
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Hartung, Frank
A1  - Kesici, Sinan
A1  - Catrein, Daniel
T1  - DRM protected Dynamic Adaptive HTTP Streaming
JF  - Proceedings of the 2011 ACM Multimedia Systems Conference [Elektronische Ressource] : February 23 - 25, 2011, San Jose, CA, USA / sponsored by: ACM SIGMM
Y1  - 2011
SN  - 9781450305181
N1  - ACM Multimedia Systems Conference ; (2 : ; 2011.02.23-25 : ; San Jose, Calif.)
SP  - 277
EP  - 282
PB  - ACM
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Koshitz, I. N.
A1  - Svetlowa, O. V.
A1  - Zaseeva, M. V.
T1  - Physiological principles of hypotensive therapy of open-angle glaucoma during presbyopic period. Part II Promising algorithms of practical sparing applications / Koshitz, I. N. ; Svetlova, O. V. ; Zaseeva, M. V. ; Shuhaev, S. V. ; Makarov, F. N. ; Kotliar
JF  - Glaukoma (2006)
Y1  - 2006
N1  - Original in Russisch
SP  - 51
EP  - 70
PB  - -
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Koshitz, I. N.
A1  - Svetlowa, O. V.
A1  - Makarov, F. N.
T1  - Biomechanical analysis of traditional and contemporary conceptions on pathogenesis of the primary open angle glaucoma / Koshitz, I. N. ; Svetlova, O. V. ; Kotliar, K. E. ; Makarov, F. N. ;  Smolnikov, B. A.
JF  - Glaukoma (2005)
Y1  - 2005
N1  - Original in Russisch
SP  - 41
EP  - 63
PB  - -
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Svetlova, O. V.
A1  - Stegaev, V. A.
A1  - Parkhomov, S. D.
T1  - Biomechanical substantiation of relatively low efficiency of recurrent laser trabeculoplasty / Svetlova, O. V. ; Stagaev, V. A. ; Parkhomov, S. D. ; Kotliar, K. E. ; Makarov, F. N. ;  Smolnikov, B. A. ; Koshitz, I. N.
JF  - Glaukoma (2004)
Y1  - 2004
N1  - Original in Russisch
SP  - 29
EP  - 39
PB  - -
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Svetlova, O. V.
A1  - Sourjikov, A. V.
A1  - Zaseeva, M. V.
T1  - Biomechanical peculiarities of aqueous humor production system and outflow regulation system / Svetlova, O. V. ; Sourjikov, A. V. ; Kotliar, K. E. ; Zaseeva, M. V. ; Shukhaev, S. V. ; Koshitz, I. N.
JF  - Glaukoma (2004)
Y1  - 2004
N1  - Original in Russisch
SP  - 66
EP  - 76
PB  - -
ER  - 
TY  - JOUR
A1  - Miyamoto, Ko-ichiro
A1  - Kaneko, Kazumi
A1  - Matsuo, Akira
A1  - Wagner, Torsten
A1  - Kanoh, Shiníchiro
A1  - Schöning, Michael Josef
A1  - Yoshinobu, Tatsuo
T1  - Miniaturized chemical imaging sensor system using an OLED display panel
JF  - Sensors and Actuators B: Chemical
N2  - The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the two-dimensional distribution of specific ions or molecules in the solution. In this study, we developed a miniaturized chemical imaging sensor system with an OLED display panel as a light source that scans the sensor plate. In the proposed configuration, the display panel is placed directly below the sensor plate and illuminates the back surface. The measured area defined by illumination can be arbitrarily customized to fit the size and the shape of the sample to be measured. The waveform of the generated photocurrent, the current–voltage characteristics and the pH sensitivity were investigated and pH imaging with this miniaturized system was demonstrated.
KW  - LAPS
KW  - Light-addressable potentiometric sensor
KW  - Chemical imaging sensor
KW  - Organic light-emitting diode display
Y1  - 2012
U6  - https://doi.org/10.1016/j.snb.2011.02.029
SN  - 0925-4005
N1  - Part of special issue "Eurosensors XXIV, 2010"
VL  - 170
SP  - 82
EP  - 87
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kirchner, Patrick
A1  - Oberländer, Jan
A1  - Friedrich, Peter
A1  - Berger, Jörg
A1  - Rysstad, Gunnar
A1  - Schöning, Michael Josef
A1  - Keusgen, Michael
T1  - Realisation of a calorimetric gas sensor on polyimide foil for applications in aseptic food industry
JF  - Sensors and Actuators B: Chemical
N2  - A calorimetric gas sensor is presented for the monitoring of vapour-phase H2O2 at elevated temperature during sterilisation processes in aseptic food industry. The sensor was built up on a flexible polyimide foil (thickness: 25 μm) that has been chosen due to its thermal stability and low thermal conductivity. The sensor set-up consists of two temperature-sensitive platinum thin-film resistances passivated by a layer of SU-8 photo resist and catalytically activated by manganese(IV) oxide. Instead of an active heating structure, the calorimetric sensor utilises the elevated temperature of the evaporated H2O2 aerosol. In an experimental test rig, the sensor has shown a sensitivity of 4.78 °C/(%, v/v) in a H2O2 concentration range of 0%, v/v to 8%, v/v. Furthermore, the sensor possesses the same, unchanged sensor signal even at varied medium temperatures between 210 °C and 270 °C of the gas stream. At flow rates of the gas stream from 8 m3/h to 12 m3/h, the sensor has shown only a slightly reduced sensitivity at a low flow rate of 8 m3/h. The sensor characterisation demonstrates the suitability of the calorimetric gas sensor for monitoring the efficiency of industrial sterilisation processes.
KW  - Sterilisation process
KW  - Hydrogen peroxide
KW  - Polyimide
KW  - Calorimetric gas sensor
Y1  - 2012
U6  - https://doi.org/10.1016/j.snb.2011.01.032
SN  - 0925-4005
N1  - Part of special issue "Eurosensors XXIV, 2010"
VL  - 170
SP  - 60
EP  - 66
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Atlas, Glen
A1  - Brealey, David
A1  - Dhar, Sunil
A1  - Dikta, Gerhard
A1  - Singer, Meryvn
T1  - Additional hemodynamic measurements with an esophageal Doppler monitor: a preliminary report of compliance, force, kinetic energy, and afterload in the clinical setting
JF  - Journal of clinical monitoring and computing
N2  - The esophageal Doppler monitor (EDM) is a minimally-invasive hemodynamic device which evaluates both cardiac output (CO), and fluid status, by estimating stroke volume (SV) and calculating heart rate (HR). The measurement of these parameters is based upon a continuous and accurate approximation of distal thoracic aortic blood flow. Furthermore, the peak velocity (PV) and mean acceleration (MA), of aortic blood flow at this anatomic location, are also determined by the EDM. The purpose of this preliminary report is to examine additional clinical hemodynamic calculations of: compliance (C), kinetic energy (KE), force (F), and afterload (TSVRi). These data were derived using both velocity-based measurements, provided by the EDM, as well as other contemporaneous physiologic parameters. Data were obtained from anesthetized patients undergoing surgery or who were in a critical care unit. A graphical inspection of these measurements is presented and discussed with respect to each patient’s clinical situation. When normalized to each of their initial values, F and KE both consistently demonstrated more discriminative power than either PV or MA. The EDM offers additional applications for hemodynamic monitoring. Further research regarding the accuracy, utility, and limitations of these parameters is therefore indicated.
KW  - Acceleration
KW  - Velocity
KW  - Kinetic energy
KW  - Force
KW  - Compliance
KW  - Afterload
KW  - Contractility
KW  - Volume status
KW  - Esophageal Doppler monitor
Y1  - 2012
SN  - 1573-2614
U6  - https://doi.org/10.1007/s10877-012-9386-5
IS  - 26
SP  - 473
EP  - 482
PB  - Springer Nature
CY  - London
ER  - 
TY  - BOOK
A1  - Artmann, Gerhard
T1  - Stem cell engineering : principles and applications / Gerhard M. Artmann ... eds.
Y1  - 2011
SN  - 978-3-642-11864-7
PB  - Springer
CY  - Berlin [u.a.]
ER  - 
TY  - JOUR
A1  - Iken, Heiko
A1  - Kirsanov, D.
A1  - Legin, A.
A1  - Schöning, Michael Josef
T1  - Novel Thin-Film Polymeric Materials for the Detection of Heavy Metals
JF  - Procedia Engineering
N2  - A variety of transition metals, e.g., copper, zinc, cadmium, lead, etc. are widely used in industry as components for wires, coatings, alloys, batteries, paints and so on. The inevitable presence of transition metals in industrial processes implies the ambition of developing a proper analytical technique for their adequate monitoring. Most of these elements, especially lead and cadmium, are acutely toxic for biological organisms. Quantitative determination of these metals at low activity levels in different environmental and industrial samples is therefore a vital task. A promising approach to achieve an at-side or on-line monitoring on a miniaturized and cost efficient way is the combination of a common potentiometric sensor array with heavy metal-sensitive thin-film materials, like chalcogenide glasses and polymeric materials, respectively.
Y1  - 2012
U6  - https://doi.org/10.1016/j.proeng.2012.09.148
SN  - 1877-7058
N1  - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012"
IS  - 47
SP  - 322
EP  - 325
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Miyamoto, K.
A1  - Ichimura, H.
A1  - Wagner, Torsten
A1  - Yoshinobu, T.
A1  - Schöning, Michael Josef
T1  - Chemical Imaging of ion Diffusion in a Microfluidic Channel
JF  - Procedia Engineering
N2  - The chemical imaging sensor is a chemical sensor which is capable of visualizing the spatial distribution of chemical species in sample solution. In this study, a novel measurement system based on the chemical imaging sensor was developed to observe the inside of a Y-shaped microfluidic channel while injecting two sample solutions from two branches. From the collected chemical images, it was clearly observed that the injected solutions formed laminar flows in the microfluidic channel. In addition, ion diffusion across the laminar flows was observed. This label-free method can acquire quantitative data of ion distribution and diffusion in microfluidic devices, which can be used to determine the diffusion coefficients, and therefore, the molecular weights of chemical species in the sample solution.
Y1  - 2012
U6  - https://doi.org/10.1016/j.proeng.2012.09.289
SN  - 1877-7058
N1  - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012"
IS  - 47
SP  - 886
EP  - 889
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Wagner, Torsten
A1  - Shigiahara, N.
A1  - Miyamoto, K.
A1  - Suzurikawa, J.
A1  - Finger, F.
A1  - Schöning, Michael Josef
A1  - Yoshinobu, T.
T1  - Light-addressable Potentiometric Sensors and Light–addressable Electrodes as a Combined Sensor-and-manipulator Microsystem with High Flexibility
JF  - Procedia Engineering
N2  - This work describes the novel combination of the light-addressable electrode (LAE) and the light-addressable potentiometric sensor (LAPS) into a microsystem set-up. Both the LAE as well as the LAPS shares the principle of addressing the active spot by means of a light beam. This enables both systems to manipulate resp. to detect an analyte with a high spatial resolution. Hence, combining both principles into a single set-up enables the active stimulation e.g., by means of electrolysis and a simultaneous observation e.g., the response of an entrapped biological cell by detection of extracellular pH changes. The work will describe the principles of both technologies and the necessary steps to integrate them into a single set-up. Furthermore, examples of application and operation of such systems will be presented.
Y1  - 2012
U6  - https://doi.org/10.1016/j.proeng.2012.09.290
SN  - 1877-7058
N1  - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012"
IS  - 47
SP  - 890
EP  - 893
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pieper, Martin
T1  - Vector hyperinterpolation on the sphere
JF  - Journal of approximation theory. 156 (2009), H. 2
Y1  - 2009
SN  - 0021-9045
SP  - 173
EP  - 186
ER  - 
TY  - JOUR
A1  - Murib, Mohammed S.
A1  - Tran, Anh Quang
A1  - Ceuninck, Ward de
A1  - Schöning, Michael Josef
A1  - Nesladek, Milos
A1  - Serpengüzel, Ali
A1  - Wagner, Patrick
T1  - Analysis of an optical biosensor based on elastic light scattering from diamond-, glass-, and sapphire microspheres
JF  - Physica Status Solidi A
N2  - Deoxyribonucleic acid (DNA) and protein recognition are now standard tools in biology. In addition, the special optical properties of microsphere resonators expressed by the high quality factor (Q-factor) of whispering gallery modes (WGMs) or morphology dependent resonances (MDRs) have attracted the attention of the biophotonic community. Microsphere-based biosensors are considered as powerful candidates to achieve label-free recognition of single molecules due to the high sensitivity of their WGMs. When the microsphere surface is modified with biomolecules, the effective refractive index and the effective size of the microsphere change resulting in a resonant wavelength shift. The transverse electric (TE) and the transverse magnetic (TM) elastic light scattering intensity of electromagnetic waves at 600 and 1400 nm are numerically calculated for DNA and unspecific binding of proteins to the microsphere surface. The effect of changing the optical properties was studied for diamond (refractive index 2.34), glass (refractive index 1.50), and sapphire (refractive index 1.75) microspheres with a 50 µm radius. The mode spacing, the linewidth of WGMs, and the shift of resonant wavelength due to the change in radius and refractive index, were analyzed by numerical simulations. Preliminary results of unspecific binding of biomolecules are presented. The calculated shift in WGMs can be used for biomolecules detection.
Y1  - 2012
U6  - https://doi.org/10.1002/pssa.201100795
SN  - 1862-6319
N1  - Special Issue: "Fundamentals and Applications of Diamond"
VL  - 209
IS  - 9
SP  - 1804
EP  - 1810
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - CHAP
A1  - Logen, Steffen
A1  - Höfken, Hans
A1  - Schuba, Marko
T1  - Simplifying RAM Forensics : A GUI and Extensions for the Volatility Framework
T2  - 2012 Seventh International Conference on Availability, Reliability and Security (ARES), 20-24 August 2012, Prague, Czech Republic
N2  - The Volatility Framework is a collection of tools for the analysis of computer RAM. The framework offers a multitude of analysis options and is used by many investigators worldwide. Volatility currently comes with a command line interface only, which might be a hinderer for some investigators to use the tool. In this paper we present a GUI and extensions for the Volatility Framework, which on the one hand simplify the usage of the tool and on the other hand offer additional functionality like storage of results in a database, shortcuts for long Volatility Framework command sequences, and entirely new commands based on correlation of data stored in the database.
Y1  - 2012
SN  - 978-1-4673-2244-7
U6  - https://doi.org/10.1109/ARES.2012.12
SP  - 620
EP  - 624
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Bohrn, Ulrich
A1  - Stütz, Evamaria
A1  - Fleischer, Maximilian
A1  - Schöning, Michael Josef
A1  - Wagner, Patrick
T1  - Using a cell-based gas biosensor for investigation of adverse effects of acetone vapors in vitro
JF  - Biosensors and Bioelectronics. 40 (2013), H. 1
Y1  - 2013
SN  - 0956-5663
SP  - 393
EP  - 400
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - THES
A1  - Kotliar, Konstantin
T1  - Functional in-vivo assessment and biofluidmechanical analysis of age-related and pathological microstructural changes in retinal vessels [Elektronische Ressource]
Y1  - 2008
N1  - München, Techn. Univ., Diss., 2008
PB  - -
ER  - 
TY  - BOOK
A1  - Grotendorst, Johannes
T1  - Hierarchical methods for dynamics in complex molecular systems : IAS Winter School, 5 - 9 March 2012, Forschungszentrum Jülich GmbH ; lecture notes / ed. by Johannes Grotendorst, Godehard Sutmann, Gerhard Gompper, Dominik Marx
Y1  - 2012
SN  - 978-3-89336-768-9
N1  - (Schriften des Forschungszentrums Jülich IAS Series 10)
PB  - Forschungszentrum Jülich
CY  - Jülich
ER  - 
TY  - JOUR
A1  - Gutheil, Inge
A1  - Berg, Tommy
A1  - Grotendorst, Johannes
T1  - Performance Analysis of Parallel Eigensolvers of two Libraries on BlueGene/P
JF  - Journal of Mathematics and Systems Science
N2  - Many applications in computational science and engineering require the computation of eigenvalues and vectors of dense symmetric or Hermitian matrices. For example, in DFT (density functional theory) calculations on modern supercomputers 10% to 30% of the eigenvalues and eigenvectors of huge dense matrices have to be calculated. Therefore, performance and parallel scaling of the used eigensolvers is of upmost interest. In this article different routines of the linear algebra packages ScaLAPACK and Elemental for parallel solution of the symmetric eigenvalue problem are compared concerning their performance on the BlueGene/P supercomputer. Parameters for performance optimization are adjusted for the different data distribution methods used in the two libraries. It is found that for all test cases the new library Elemental which uses a two-dimensional element by element distribution of the matrices to the processors shows better performance than the old ScaLAPACK library which uses a block-cyclic distribution.
KW  - performance analysis
KW  - Elemental
KW  - ScaLAPACK
KW  - eigensolvers
KW  - Numerical linear algebra
Y1  - 2012
U6  - https://doi.org/10.17265/2159-5291/2012.04.003
SN  - 2159-5291
VL  - 2
IS  - 4
SP  - 231
EP  - 236
PB  - David Publishing
CY  - Libertyville
ER  - 
TY  - JOUR
A1  - Grotendorst, Johannes
T1  - IAS Winter School: Hierarchical Methods for Dynamics in Complex Molecular Systems
JF  - Innovatives Supercomputing in Deutschland : inSiDE. 10 (2012), H. 1
Y1  - 2012
SP  - 104
PB  - -
ER  - 
TY  - CHAP
A1  - Uibel, Thomas
A1  - Blaß, Hans Joachim
T1  - Edge Joints with Dowel Type Fasteners in Cross Laminated Timber
T2  - Proceedings. CIB-W18 Meeting 2007, Bled, Slovenia 2007
Y1  - 2007
SN  - 0945-6996
N1  - Paper 40-7-2
SP  - 1
EP  - 11
ER  - 
TY  - CHAP
A1  - Uibel, Thomas
A1  - Blaß, Hans Joachim
ED  - Cecotti, A.
T1  - Determining Suitable Spacings and Distances for Self-tapping Screws by Experimental and Numerical Studies
T2  - Proceedings of the 11th World Conference on Timber Engineering, WCTE 2010 : World Conference on Timber Engineering; [June 20 - 24, 2010, Riva del Garda, Trento, Italy] . Vol. III, Riva del Garda, Italy 2010
Y1  - 2010
N1  - Extended abstract. Full paper: DVD, Session 55, ID 108, 9 Seiten
SP  - 669
EP  - 670
ER  - 
TY  - JOUR
A1  - Hennemann, Jörg
A1  - Kohl, Claus-Dieter
A1  - Reisert, Steffen
A1  - Kirchner, Patrick
A1  - Schöning, Michael Josef
T1  - Copper oxide nanofibres for detection of hydrogen peroxide vapour at high concentrations
JF  - physica status solidi (a)
N2  - We present a sensor concept based on copper(II)oxide (CuO) nanofibres for the detection of hydrogen peroxide (H2O2) vapour in the percent per volume (% v/v) range. The fibres were produced by using the electrospinning technique. To avoid water condensation in the pores, the fibres were initially modified by an exposure to H2S to get an enclosed surface. By a thermal treatment at 350 °C the fibres were oxidised back to CuO. Thereby, the visible pores disappear which was verified by SEM analysis. The fibres show a decrease of resistance with increasing H2O2  concentration which is due to the fact that hydrogen peroxide is an oxidising gas and CuO a p-type semiconductor. The sensor shows a change of resistance within the minute range to the exposure until the maximum concentration of 6.9% v/v H2O2. At operating temperatures below 450 °C the corresponding sensor response to a concentration of 4.1% v/v increases. The sensor shows a good reproducibility of the signal at different measurements. CuO seems to be a suitable candidate for the detection of H2O2 vapour at high concentrations.

Resistance behaviour of the sensor under exposure to H2O2 vapours between 2.3 and 6.9% v/v at an operating temperature of 450 °C.
Y1  - 2013
U6  - https://doi.org/10.1002/pssa.201200775
SN  - 1862-6319
VL  - 210
IS  - 5
SP  - 859
EP  - 863
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Reisert, Steffen
A1  - Schneider, Benno
A1  - Geissler, Hanno
A1  - Gompel, Matthias van
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - Multi-sensor chip for the investigation of different types of metal oxides for the detection of H2O2 in the ppm range
JF  - physica status solidi (a)
N2  - In this work, a multi-sensor chip for the investigation of the sensing properties of different types of metal oxides towards hydrogen peroxide in the ppm range is presented. The fabrication process and physical characterization of the multi-sensor chip are described. Pure SnO2 and WO3 as well as Pd- and Pt-doped SnO2 films are characterized in terms of their sensitivity to H2O2. The sensing films have been prepared by drop-coating of water-dispensed nano-powders. A physical characterization, including scanning electron microscopy and X-ray diffraction analysis of the deposited metal-oxide films, was done. From the measurements in hydrogen peroxide atmosphere, it could be shown, that all of the tested metal oxide films are suitable for the detection of H2O2 in the ppm range. The highest sensitivity and reproducibility was achieved using Pt-doped SnO2.

Calibration plot of a SnO2, WO3, Pt-, and Pd-doped SnO2 gas sensor for H2O2 concentrations in the ppm range.
Y1  - 2013
SN  - 1862-6319
VL  - 210
IS  - 5
SP  - 898
EP  - 904
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Hanssen, Henner
A1  - Eberhardt, Karla
A1  - Vilser, Walthard
A1  - Schmaderer, Christoph
A1  - Halle, Martin
A1  - Heemann, Uwe
A1  - Baumann, M.
T1  - Retinal pulse wave velocity in young male normotensive and mildly hypertensive subjects
JF  - Microcirculation
Y1  - 2013
SN  - 1549-8719
N1  - Accepted Article (Accepted, unedited articles published online and citable. The final edited and typeset version of record will appear in future.)
PB  - Wiley
CY  - Malden
ER  - 
TY  - JOUR
A1  - Feucht, Nikolaus
A1  - Schönbach, Etienne Michael
A1  - Lanzl, Ines
A1  - Kotliar, Konstantin
A1  - Lohmann, Chris Patrick
A1  - Maier, Mathias
T1  - Changes in the foveal microstructure after intravitreal bevacizumab application in patients with retinal vascular disease
JF  - Clinical Ophthalmology
Y1  - 2013
SN  - 1177-5483
VL  - 7
SP  - 173
EP  - 178
PB  - Dove Medical Press
CY  - Auckland, New Zealand
ER  - 
TY  - JOUR
A1  - Heinzel, Alexander
A1  - Schäfer, Ralf
A1  - Müller, Hans-Wilhelm
A1  - Schieffer, Andre
A1  - Ingenhag, Ariane
A1  - Eickhoff, Simon B.
A1  - Northoff, Georg
A1  - Franz, Matthias
A1  - Hautzel, Hubertus
T1  - Increased Activation of the Supragenual Anterior Cingulate Cortex during Visual Emotional Processing in Male Subjects with High Degrees of Alexithymia: An Event-Related fMRI Study
JF  - Psychotherapy and Psychosomatics
N2  - Background: One of the most prominent neurobiological models of alexithymia assumes an altered function of the anterior cingulate cortex (ACC) as the crucial neural correlate of alexithymia. So far functional imaging studies have yielded inconclusive results. Therefore, we tested this hypothesis in healthy alexithymics and nonalexithymics in an event-related fMRI study.
Methods: Thirty high- and 30 low-alexithymic right-handed male subjects (selected by the 20-item Toronto Alexithymia Scale, TAS-20) were investigated with event-related fMRI using a picture viewing paradigm. The stimuli consisted of happy, fearful and neutral facial expressions (Ekman-Friesen) as well as positive, negative and neutral pictures from the International Affective Picture System.
Results: Contrasting the high-alexithymic with the low-alexithymic group we observed increased activation of the supragenual ACC for different emotional valences as well as for different emotional stimuli. Moreover, there was a positive correlation of the ACC with the individual TAS-20 scores but no correlations with the individual Beck Depression Inventory scores. Additionally, there was no difference in activity of the amygdala. 
Conclusions: We demonstrated that the supragenual ACC is constantly activated more strongly in alexithymic subjects and that this activation is related to the symptoms of alexithymia and not to associated symptoms such as depression. Therefore, our findings support the hypothesis of an altered function of the ACC in alexithymia.
Y1  - 2010
U6  - https://doi.org/10.1159/000320121
SN  - 0033-3190
VL  - 79
IS  - 6
SP  - 363
EP  - 370
PB  - Karger
CY  - Basel
ER  - 
TY  - JOUR
A1  - Heinzel, Alexander
A1  - Schäfer, Ralf
A1  - Müller, Hans-Wilhelm
A1  - Schieffer, Andre
A1  - Ingenhag, Ariane
A1  - Northoff, Georg
A1  - Franz, Matthias
A1  - Hautzel, Hubertus
T1  - Differential modulation of valence and arousal in high-alexithymic and low-alexithymic individuals
JF  - Neuroreport
N2  - High-alexithymic individuals are characterized by an impaired ability to identify and communicate emotions whereas low-alexithymic individuals have a wide-ranging ability to deal with emotions. This study examined the hypothesis that valence and arousal modifications of emotional stimuli differentially modulate cortical regions in high-alexithymic and low-alexithymic individuals. To this end, 28 high-alexithymic and 25 low-alexithymic individuals were investigated with event-related fMRI using visual emotional stimuli. We found differential neural activations in the dorsal anterior cingulate, the insula and the amygdala. We suggest that these differences may account for the impaired ability of high-alexithymic individuals to appropriately handle emotional stimuli.
Y1  - 2010
U6  - https://doi.org/10.1097/WNR.0b013e32833f38e0
SN  - 1473-558X
VL  - 21
IS  - 15
SP  - 998
EP  - 1002
PB  - Lippincott Williams & Wilkins
CY  - London
ER  - 
TY  - JOUR
A1  - Nomdedeu, Mar Monsonis
A1  - Willen, Christine
A1  - Schieffer, Andre
A1  - Arndt, Hartmut
T1  - Temperature-dependent ranges of coexistence in a model of a two-prey-one-predator microbial food web
JF  - Marine Biology
N2  - The objective of our study was to analyze the effects of temperature on the population dynamics of a three-species food web consisting of two prey bacteria (Pedobacter sp. and Acinetobacter johnsonii) and a protozoan predator (Tetrahymena pyriformis) as model organisms. We assessed the effects of temperature on the growth rates of all three species with the objective of developing a model with four differential equations based on the experimental data. The following hypotheses were tested at a theoretical level: Firstly, temperature changes can affect the dynamic behavior of a system by temperature-dependent parameters and interactions and secondly, food web response to temperature cannot be derived from the single species temperature response. The main outcome of the study is that temperature changes affect the parameter range where coexistence is possible within all three species. This has significant consequences on our ideas regarding the evaluation of effects of global warming.
Y1  - 2012
U6  - https://doi.org/10.1007/s00227-012-1966-x
SN  - 1432-1793
VL  - 159
IS  - 11
SP  - 2423
EP  - 2430
PB  - Springer
CY  - Berlin
ER  - 
TY  - THES
A1  - Schieffer, Andre
T1  - Studies on diversity and coexistence in an experimental microbial community
N2  - Biodiversity and the coexistence of species have puzzled and fascinated biologists since decades and is a hotspot in todays’ natural sciences. Preserving this biodiversity is a great challenge as habitats and environments underlying tremendous changes like climate change and the loss of natural habitats, which are mainly due to anthropogenic influences. The coexistence of numerous species even in homogeneous environments is a stunning feature of natural communities and has been summarized under the term ‘paradox of plankton’. Up to now, there are several mechanisms discussed, which may contribute to local and global diversity of organisms. Several interspecific trade offs have been identified maintaining the coexistence of species like their abilities regarding competition and predator avoidance, their capability to disperse in space and time, and their ability to exploit variable resources. Further, micro-evolutionary dynamics supporting the coexistence of species have been added to our knowledge, and deriving from theoretical deterministic models, non-linear dynamics which describe the temporal fluctuation of abundances of organisms. Whereas competition and predation seem to be clue structural elements within interacting organisms, the intrinsic dynamic behavior – by means of temporal changes in abundance - plays an important role regarding coexistence within a community. The present work sheds light on different factors affecting the coexistence of species using experimental microbial model systems consisting of a bacterivorous ciliate as the predator and two bacteria strains as prey organism. Additionally, another experimental setup consisting of two up to five bacteria species competing for one limiting resource was investigated. Highly controllable chemostat systems were established to exclude extrinsic disturbances. According to theoretical analyses I was able to show - experimentally and theoretically - that phenotypic plasticity of one species within a microbial one-predator-two-prey food web enlarges the range of possible coexistence of all species under different dynamic conditions, compared to a food web without phenotypic plasticity. This was accompanied by non-linear (chaotic) population dynamics within all experimental systems showing phenotypic plasticity. The experiments on the interplay of competition, predation and invasion showed that all aspects have an influence on species coexistence. Under undisturbed controlled conditions all aspects were analyzed in detail and in combination. Populations showed oscillations which were shown by quasi-chaotic attractors in phase space diagrams. Competition experiments with two up to five bacteria species competing for one limiting resource showed that all organisms were able to coexist which was mediated by species oscillations entering a regime of chaos. Besides that fact it was found, that the productivity (biomass) as well as the total cell numbers – under the same nutrition supply – increased by an increasing number of species in the experimental systems. Up to now, the occurrence of non-linear dynamics in well controlled experimental studies has been recognized several times and this phenomenon seemed to be more common in natural systems than generally assumed.
N2  - Biodiversität und die Koexistenz von Arten fasziniert und verblüfft Biologen seit Jahr-zehnten und stellen einen Schwerpunkt in der heutigen Umweltforschung dar. Der Schutz und die Konservierung dieser Mannigfaltigkeit stellen eine große Herausfor-derung dar, da die natürlichen Lebensräume sowie die Umwelt enormen Verände-rungen unterworfen sind, welche meist in einem anthropogenen Ursprung wurzeln. Die Koexistenz vieler Arten, auch in relativ homogenen Habitaten ist ein faszinieren-des Charakteristikum natürlicher Lebensgemeinschaften und wird als ‚Paradox des Planktons‘ bezeichnet. Gegenwärtig werden diverse Ursachen diskutiert, welche vermutlich zur lokalen und globalen Diversität von Organismen beitragen. Einige die-ser möglichen Ursachen, die zur Aufrechterhaltung der Koexistenz der Arten beitra-gen, wurden identifiziert: Das Vermögen der Konkurrenz- und Prädationsvermeidung, die Fähigkeit räumlicher sowie zeitlicher Verteilung, sowie das Vermögen variable Ressourcen zu nutzen. Des Weiteren wurden mikro-evolutionäre Phänomene und Dynamiken identifiziert, sowie, von theoretischen deterministischen Modellen ausge-hend, nichtlineare Dynamiken, welche die zeitlichen Schwankungen der Abundanzen von Organismen beschreiben. Diese Aspekte stellen die Schlüsselkomponenten zwi-schen interagierenden Organismen dar, wobei das intrinsiche, nicht lineare dynami-sche Verhalten in Form von zeitlichen Veränderungen in Abundanzen eine zusätzli-che entscheidende Rolle bezüglich der Koexistenz von Arten spielen kann. Einige dieser Aspekte wurden in der vorliegenden Arbeit untersucht. In Anlehnung an theoretische Analysen konnte experimentell sowie theoretisch gezeigt werden, dass phänotypische Plastizität in einer Bakterienart in einem mikrobiellen Ein-Räuber-zwei-Beute-Nahrungsgewebe den Bereich der möglichen Koexistenz unter sich än-dernden experimentellen Bedingungen (Änderungen der Durchflussraten der Chemostate) – im direkten Vergleich zu einem experimentellen Nahrungsgewebe ohne phänotypische Plastizität – erweitern kann. Dies wurde begleitet durch nicht lineare Abundanzschwankungen in den Populationen aller untersuchten Versuchs-ansätze. In weiteren Untersuchungen wurde das Zusammenspiel von Konkurrenz, Prädation und Invasion in einer experimentellen mikrobiellen Gemeinschaft untersucht. Unter kontrollierten Bedingungen konnten diese Aspekte detailliert untersucht werden und es konnten Aufschlüsse darüber gewonnen werden, welche Reaktionen (Interaktionen) innerhalb der untersuchten Gemeinschaften stattfinden. Im Versuchsverlauf wurden Veränderungen in den Abundanzen sowie chaotische Schwankungen der Zellzahlen festgestellt. In Konkurrenzexperimenten von zwei bis zu fünf um eine limitierende Ressource konkurrierende Bakterienarten konnte gezeigt werden, dass alle Arten – vermittelt durch chaotische Abundanzschwankungen – nebeneinander koexistieren konnten. Begleitend dazu wurde herausgefunden, dass die Produktivität (Biomasse) sowie die Gesamtzellzahl bei gleicher Nahrungsverfügbarkeit der experimentellen Systeme mit steigender Artenzahl zunehmen. Gegenwärtig ist das Auftreten von Chaos in gut kontrollierten experimentellen Studien vereinzelt beobachtet worden, wobei dieses Phänomen jedoch häufiger in der Natur aufzutreten scheint als generell vermutet.
Y1  - 2012
N1  - Köln, Univ., Diss., 2012
ER  - 
TY  - CHAP
A1  - Uibel, Thomas
A1  - Blaß, Hans Joachim
T1  - Load Carrying Capacity of Joints with Dowel Type Fasteners in Solid Wood Panels
T2  - Proceedings. CIB-W18 Meeting 2006, Florence, Italy 2006
Y1  - 2006
SN  - 0945-6996
N1  - Paper 39-7-5
SP  - 1
EP  - 10
ER  - 
TY  - JOUR
A1  - Mosset, J.-B.
A1  - Devroede, O.
A1  - Krieguer, M.
A1  - Rey, M.
A1  - Vieira, J.-M.
A1  - Jung, J. H.
A1  - Kuntner, C.
A1  - Streun, M.
A1  - Ziemons, Karl
A1  - Auffray, E.
A1  - Sempere-Roldan, P.
A1  - Lecoq, P.
A1  - Bruyndonckx, P.
A1  - Loude, J.-F.
A1  - Tavernier, S.
A1  - Morcel, C.
T1  - Development of an optimized LSO/LuYAP phoswich detector head for the Lausanne ClearPET demonstrator
JF  - IEEE Transactions on Nuclear Science
N2  - This paper describes the LSO/LuYAP phoswich detector head developed for the ClearPET small animal PET scanner demonstrator that is under construction in Lausanne within the Crystal Clear Collaboration. The detector head consists of a dual layer of 8×8 LSO and LuYAP crystal arrays coupled to a multi-anode photomultiplier tube (Hamamatsu R7600-M64). Equalistion of the LSO/LuYAP light collection is obtained through partial attenuation of the LSO scintillation light using a thin aluminum deposit of 20-35 nm on LSO and appropriate temperature regulation of the phoswich head between 30°C to 60°C. At 511keV, typical FWHM energy resolutions of the pixels of a phoswich head amounts to (28±2)% for LSO and (25±2)% for LuYAP. The LSO versus LuYAP crystal identification efficiency is better than 98%. Six detector modules have been mounted on a rotating gantry. Axial and tangential spatial resolutions were measured up to 4 cm from the scanner axis and compared to Monte Carlo simulations using GATE. FWHM spatial resolution ranges from 1.3 mm on axis to 2.6 mm at 4 cm from the axis.
Y1  - 2006
SN  - 0018-9499
VL  - 53
IS  - 1
SP  - 25
EP  - 29
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Beer, S.
A1  - Hombach, T.
A1  - Jahnke, S.
A1  - Khodaverdi, M.
A1  - Larue, H.
A1  - Minwuyelet, S.
A1  - Parl, C.
A1  - Roeb, G.
A1  - Schurr, U.
A1  - Ziemons, Karl
T1  - PlanTIS: A positron emission tomograph for imaging 11C transport in plants
JF  - 2007 IEEE Nuclear Science Symposium Conference Record, Vol. 6
N2  - Plant growth and transport processes are highly dynamic. They are characterized by plant-internal control processes and by strong interactions with the spatially and temporally varying environment. Analysis of structure- function relations of growth and transport in plants will strongly benefit from the development of non-invasive techniques. PlanTIS (Plant Tomographic Imaging System) is designed for non-destructive 3D-imaging of positron emitting radiotracers. It will permit functional analysis of the dynamics of carbon distribution in plants including bulky organs. It will be applicable for screening transport properties of plants to evaluate e.g. temperature adaptation of genetically modified plants. PlanTIS is a PET scanner dedicated to monitor the dynamics of the 11C distribution within a plant while or after assimilation of 11CO2. Front end electronics and data acquisition architecture of the scanner are based on the ClearPETTM system [1]. Four detector modules form one of two opposing detector blocks. Optionally, a hardware coincidence detection between the blocks can be applied. In general the scan duration is rather long (~ 1 hour) compared to the decay time of 11C (20 min). As a result the count rates can vary over a wide range and accurate dead time correction is necessary.
Y1  - 2008
SN  - 1082-3654
SP  - 4110
EP  - 4112
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Bruyndonckx, P.
A1  - Perez, J. M.
A1  - Pietrzyk, U.
A1  - Rato, P.
A1  - Tavernier, S.
T1  - Beyond ClearPET: Next Aims
JF  - 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro Symposium Proceedings ISBI 2008
N2  - The CRYSTAL CLEAR collaboration, in short CCC, is a consortium of 12 academic institutions, mainly from Europe, joining efforts in the area of developing instrumentation for nuclear medicine and medical imaging. In the framework of the CCC a high performance small animal PET system, called ClearPET, was developed by using new technologies in electronics and crystals in a phoswich arrangement combining two types of lutetium- based scintillator materials: LSO:Ce and LuYAP:Ce. Our next aim will be the development of hybrid image systems. Hybrid MR-PET imaging has many unique advantages for brain research. This has sparked a new research line within CCC for the development of novel MR-PET compatible technologies. MRI is not as sensitive as PET but PET has poorer spatial resolution than MRI. Two major advantages of PET are sensitivity and its ability to acquire metabolic information. To assess these innovations, the development of a 9.4T hybrid animal MR-PET scanner is proposed based on an existing 9.4T MR scanner that will be adapted to enable simultaneous acquisition of MR and PET data using cutting- edge technology for both MR and PET.
Y1  - 2008
SN  - 978-1-4244-2003-2
SP  - 1421
EP  - 1424
ER  - 
TY  - JOUR
A1  - Jahnke, Siegfried
A1  - Menzel, Marion I.
A1  - Dusschoten, Dagmar van
A1  - Roeb, Gerhard W.
A1  - Bühler, Jonas
A1  - Minwuyelet, Senay
A1  - Blümler, Peter
A1  - Temperton, Vicky M.
A1  - Hombach, Thomas
A1  - Streun, Matthias
A1  - Beer, Simone
A1  - Khodaverdi, Maryam
A1  - Ziemons, Karl
A1  - Coenen, Heinz H.
A1  - Schurr, Ulrich
T1  - Combined MRI–PET dissects dynamic changes in plant structures and functions
JF  - The Plant Journal
N2  - Unravelling the factors determining the allocation of carbon to various plant organs is one of the great challenges of modern plant biology. Studying allocation under close to natural conditions requires non-invasive methods, which are now becoming available for measuring plants on a par with those developed for humans. By combining magnetic resonance imaging (MRI) and positron emission tomography (PET), we investigated three contrasting root/shoot systems growing in sand or soil, with respect to their structures, transport routes and the translocation dynamics of recently fixed photoassimilates labelled with the short-lived radioactive carbon isotope 11C. Storage organs of sugar beet (Beta vulgaris) and radish plants (Raphanus sativus) were assessed using MRI, providing images of the internal structures of the organs with high spatial resolution, and while species-specific transport sectoralities, properties of assimilate allocation and unloading characteristics were measured using PET. Growth and carbon allocation within complex root systems were monitored in maize plants (Zea mays), and the results may be used to identify factors affecting root growth in natural substrates or in competition with roots of other plants. MRI–PET co-registration opens the door for non-invasive analysis of plant structures and transport processes that may change in response to genomic, developmental or environmental challenges. It is our aim to make the methods applicable for quantitative analyses of plant traits in phenotyping as well as in understanding the dynamics of key processes that are essential to plant performance.
Y1  - 2009
SN  - 1365-313X
VL  - 59
IS  - 4
SP  - 634
EP  - 644
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wedrowski, M.
A1  - Bruyndonckx, P.
A1  - Tavernier, S.
A1  - Zhi, L.
A1  - Dang, J.
A1  - Mendes, P. R.
A1  - Perez, J. M.
A1  - Ziemons, Karl
T1  - Robustness of neural networks algorithm for gamma detection in monolithic block detector, positron emission tomography
JF  - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - The monolithic scintillator block approach for gamma detection in the Positron Emission Tomography (PET) avoids estimating Depth of Interaction (DOI), reduces dead zones in detector and diminishes costs of detector production. Neural Networks (NN) are very efficient to determine the entrance point of a gamma incident on a scintillator block. This paper presents results on the robustness of the spatial resolution as a function of the random fraction in the data, temperature and HV fluctuations. This is important when implementing the method in a real scanner. Measurements were done with two Hamamatsu S8550 APD arrays, glued on a 20 × 20 × 10 mm3 monolithic LSO crystal block.
Y1  - 2009
SN  - 1082-3654
SP  - 2625
EP  - 2628
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Larue, H.
A1  - Parl, C.
A1  - Ziemons, Karl
T1  - A compact PET detector readout using charge-to-time conversion
JF  - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - The readout of gamma detectors is considerably simplified when the event intensity is encoded as a pulse width (Pulse Width Modulation, PWM). Time-to-Digital-Converters (TDC) replace the conventional ADCs and multiple TDCs can be realized easily in one PLD chip (Programmable Logic Device). The output of a PWM stage is only one digital signal per channel which is well suited for transport so that further processing can be performed apart from the detector. This is particularly interesting for large systems with high channel density (e.g. high resolution scanners). In this work we present a circuit with a linear transfer function that requires a minimum of components by performing the PWM already in the preamp stage. This allows a very compact and also cost-efficient implementation of the front-end electronics.
Y1  - 2009
SN  - 1082-3654
SP  - 1868
EP  - 1870
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Pulse recording by free-running sampling
JF  - IEEE Transactions on Nuclear Science
N2  - Pulses from a position-sensitive photomultiplier (PS-PMT) are recorded by free-running ADCs at a sampling rate of 40 MHz. A four-channel acquisition board has been developed which is equipped with four 12-bit ADCs connected to one field programmable gate array (FPGA). The FPGA manages data acquisition and the transfer to the host computer. It can also work as a digital trigger, so a separate hardware trigger can be omitted. The method of free-running sampling provides a maximum of information, besides the pulse charge and amplitude also pulse shape and starting time are contained in the sampled data. This information is crucial for many tasks such as distinguishing between different scintillator materials, determination of radiation type, pile-up recovery, coincidence detection or time-of-flight applications. The absence of an analog integrator allows very high count rates to be dealt with. Since this method is to be employed in positron emission tomography (PET), the position of an event is also important. The simultaneous readout of four channels allows localization by means of center-of-gravity weighting. First results from a test setup with LSO scintillators coupled to the PS-PMT are presented here
Y1  - 2001
SN  - 0018-9499
VL  - 48
IS  - 3
SP  - 524
EP  - 526
ER  - 
TY  - JOUR
A1  - Heinrich, U.
A1  - Blum, A.
A1  - Bussmann, N.
A1  - Engels, R.
A1  - Kemmerling, G.
A1  - Weber, S.
A1  - Ziemons, Karl
T1  - Statistical studies on the light output and energy resolution of small LSO single crystals with different surface treatments combined with various reflector materials
JF  - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - The optimization of light output and energy resolution of scintillators is of special interest for the development of high resolution and high sensitivity PET. The aim of this work is to obtain statistically reliable results concerning optimal surface treatment of scintillation crystals and the selection of reflector material. For this purpose, raw, mechanically polished and etched LSO crystals (size 2×2×10 mm3) were combined with various reflector materials (Teflon tape, Teflon matrix, BaSO4) and exposed to a 22Na source. In order to ensure the statistical reliability of the results, groups of 10 LSO crystals each were measured for all combinations of surface treatment and reflector material. Using no reflector material the light output increased up to 551±35% by mechanical polishing the surface compared to 100±5% for raw crystals. Etching the surface increased the light output to 441±29%. The untreated crystals had an energy resolution of 24.6±4.0%. By mechanical polishing the surface it was possible to achieve an energy resolution of 13.2±0.8%, by etching of 14.8±0.7%. In combination with BaSO4 as reflector material the maximum increase of light output has been established to 932±57% for mechanically polished and 895±61% for etched crystals. The combination with BaSO4 also caused the best improvement of the energy resolution up to 11.6±0.2% for mechanically polished and 12.2±0.3% for etched crystals. Relating to the light output there was no significant statistical difference between the two surface treatments in combination with BaSO4. In contrast to this, the statistical results of the energy resolution have shown the combination of mechanical polishing and BaSO4 as the optimum.
Y1  - 2002
SN  - 0168-9002
N1  - Proceedings of the 6th International Conference on Inorganic Scin tillators and their Use in Scientific and Industrial Applications
VL  - 486
IS  - 1-2
SP  - 60
EP  - 66
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - A PET system with free running ADCs
JF  - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - A small PET system has been built up with two multichannel photomultipliers, which are attached to a matrix of 64 single LSO crystals each. The signal from each multiplier is being sampled continuously by a 12 bit ADC at a sampling frequency of 40 MHz. In case of a scintillation pulse a subsequent FPGA sends the corresponding set of samples together with the channel information and a time mark to the host computer. The data transfer is performed with a rate of 20 MB/s. On the host all necessary information is extracted from the data. The pulse energy is determined, coincident events are detected and multiple hits within one matrix can be identified. In order to achieve a narrow time window the pulse starting time is refined further than the resolution of the time mark (=25 ns) would allow. This is possible by interpolating between the pulse samples. First data obtained from this system will be presented. The system is part of developments for a much larger system and has been created to study the feasibility and performance of the technique and the hardware architecture.
Y1  - 2002
SN  - 0168-9002
N1  - Proceedings of the 6th International Conference on Inorganic Scin tillators and their Use in Scientific and Industrial Applications
VL  - 486
IS  - 1-2
SP  - 18
EP  - 21
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Coincidence detection by digital processing of free-running sampled pulses
JF  - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - Coincident events in two scintillator crystals coupled to photomultipliers (PMT) are detected by processing just the digital data of the recorded pulses. For this purpose the signals from both PMTs are continuously sampled by free-running ADCs at a sampling rate of 40 MHz. For each sampled pulse the starting time is determined by processing the pulse data. Even a fairly simple interpolating algorithm results in a FWHM of about 2 ns.
Y1  - 2002
SN  - 0168-9002
VL  - 487
IS  - 3
SP  - 530
EP  - 534
ER  - 
TY  - JOUR
A1  - Khodaverdi, M.
A1  - Pauly, F.
A1  - Schroder, G.
A1  - Ziemons, Karl
A1  - Sievering, R.
A1  - Halling, H.
T1  - Preliminary studies of a micro-CT for a combined small animal PET/CT scanner
JF  - 2001 IEEE Nuclear Science Symposium Conference Record, Vol. 3
N2  - We are developing an X-ray computed tomography (CT) system which will be combined with a high resolution animal PET system. This permits acquisition of both molecular and anatomical images in a single machine. In particular the CT will also be utilized for the quantification of the animal PET data by providing accurate data for attenuation correction. A first prototype has been built using a commercially available plane silicon diode detector. A cone-beam reconstruction provides the images using the Feldkamp algorithm. First measurements with this system have been performed on a mouse. It could be shown that the CT setup fulfils all demands for a high quality image of the skeleton of the mouse. It is also suited for soft tissue measurements. To improve contrast and resolution and to acquire the X-ray energy further development of the system, especially the use of semiconductor detectors and iterative reconstruction algorithms are planned.
Y1  - 2002
SN  - 1082-3654
SP  - 1605
EP  - 1606
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - A PET system based on data processing of free-running sampled pulses
JF  - 2001 IEEE Nuclear Science Symposium Conference Record, Vol. 2
N2  - Within the developments for the Crystal Clear small animal PET project (CLEARPET) a dual head PET system has been established. The basic principle is the early digitization of the detector pulses by free running ADCs. The determination of the γ-energy and also the coincidence detection is performed by data processing of the sampled pulses on the host computer. Therefore a time mark is attached to each pulse identifying the current cycle of the 40 MHz sampling clock. In order to refine the time resolution the pulse starting time is interpolated from the samples of the pulse rise. The detector heads consist of multichannel PMTs with a single LSO scintillator crystal coupled to each channel. For each PMT only one ADC is required. The position of an event is obtained separately from trigger signals generated for each single channel. An FPGA is utilized for pulse buffering, generation of the time mark and for the data transfer to the host via a fast I/O-interface.
Y1  - 2002
SN  - 1082-3654
SP  - 693
EP  - 694
ER  - 
TY  - JOUR
A1  - Heinrichs, U.
A1  - Pietrzyk, U.
A1  - Ziemons, Karl
T1  - Design optimization of the PMT-ClearPET prototypes based on simulation studies with GEANT3
JF  - 2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3
N2  - Within the Crystal Clear Collaboration four centres are developing 2nd generation high performance small animal PET scanners for different kinds of animals and medical applications. The first prototypes are PMT-based systems including depth of interaction (DOI) detection by using a phoswich layer of LSO and LuYAP. The aim of these simulation studies is to optimize sensitivity and spatial resolution of given designs, which vary in FOVs caused by different detector configurations (ring/octagon) and sizes. For this purpose the simulation tool GEANT3 (CERN) was used. The simulations have shown that all PMT designs with one-to-one coupling of crystals have a very nonlinear axial sensitivity profile. By shifting every other PMT 1/4 of a PMT length in axial direction the sampling of the FOVs became more homogeneous. At an energy threshold of 350keV the regression coefficient increases from 0.818 for the non-shifted to 0.993 for the shifted design. Simulations of a point source centred in the FOV (threshold: 350keV) resulted in sensitivities of 4.2% for a 4×20PMT (LSO/LuYAP a 10mm) and 3.8% for a 4×16PMT (LSO/LuYAP a 8mm) ring design. The 3D-MLEM reconstruction of a point source shows the enormous improvement of resolution using a crystal double layer with DOI (3.1mm at 40mm from CFOV) instead of a 20mm single layer (11.9mm).
Y1  - 2003
SN  - 1082-3654
SP  - 682
EP  - 686
ER  - 
TY  - JOUR
A1  - Heinrichs, U.
A1  - Pietrzyk, U.
A1  - Ziemons, Karl
T1  - Design optimization of the PMT-ClearPET prototypes based on simulation studies with GEANT3
JF  - IEEE Transactions on Nuclear Science
N2  - Within the Crystal Clear Collaboration (CCC), four centers are developing second generation high performance small animal positron emission tomography (PET) scanners for different kinds of animals and medical applications. The first prototypes are photomultiplier tube (PMT)-based systems including depth of interaction (DOI) detection by using a phoswich layer of lutetium oxyorthosilicate (LSO) and lutetium yttrium aluminum perovskite (LuYAP). The aim of these simulation studies is to optimize sensitivity and spatial resolution of given designs, which vary in fields of view (FOVs) caused by different detector configurations (ring/octagon) and sizes. For this purpose the simulation tool GEANT3 (CERN, Geneva, Switzerland) was used.
Y1  - 2003
SN  - 0018-9499
VL  - 50
IS  - 5
SP  - 1428
EP  - 1432
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Saleh, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Pulse shape discrimination of LSO and LuYAP scintillators for depth of interaction detection in PET
JF  - 2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3
N2  - A feasible way to gain the depth of interaction information in a PET scanner is the use of phoswich detectors. In general the layer of interaction is identified front the pulse shape of the corresponding scintillator material. In this work pulses from LSO and LuYAP crystals were investigated in order to find a practical method of distinguishing. It turned out that such a pulse processing could he kept simple due to an additional slow component in the light decay of the LuYAP pulse. At the same time the short decay time guarantees that the major amount of the light output is still collected within a short pulse recording time.
Y1  - 2003
SN  - 1082-3654
SP  - 1636
EP  - 1639
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Saleh, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Pulse shape discrimination of LSO and LuYAP scintillators for depth of interaction detection in PET
JF  - IEEE Transactions on Nuclear Science
N2  - A feasible way to gain the depth of interaction information in a positron emission tomography scanner is the use of phoswich detectors. In general, the layer of interaction is identified from the pulse shape of the corresponding scintillator material. In this work, pulses from LSO and LuYAP crystals were investigated in order to find a practical method of distinguishing. It turned out that such a pulse processing could be kept simple because of an additional slow component in the light decay of the LuYAP pulse. At the same time, the short decay time guarantees that the major amount of the light output is still collected within a short pulse recording time.
Y1  - 2003
SN  - 0018-9499
VL  - 50
IS  - 3
SP  - 344
EP  - 347
ER  - 
TY  - JOUR
A1  - Khodaverdi, M.
A1  - Chaziioannou, A. F.
A1  - Weber, S.
A1  - Ziemons, Karl
A1  - Halling, H.
A1  - Pietrzyk, U.
T1  - Investigation of different microCT scanner configurations by GEANT4 simulations
JF  - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4
N2  - This study has been performed to design the combination of the new ClearPET TM (ClearPET is a trademark of the Crystal Clear Collaboration), a small animal Positron Emission Tomography (PET) system, with a microComputed Tomography (microCT) scanner. The properties of different microCT systems have been determined by simulations based on GEANT4. We demonstrate the influence of the detector material and the X-ray spectrum on the obtained contrast. Four different detector materials (selenium, cadmium zinc telluride, cesium iodide and gadolinium oxysulfide) and two X-ray spectra (a molybdenum and a tungsten source) have been considered. The spectra have also been modified by aluminum filters of varying thickness. The contrast between different tissue types (water, air, brain, bone and fat) has been simulated by using a suitable phantom. The results indicate the possibility to improve the image contrast in microCT by an optimized combination of the X-ray source and detector material.
Y1  - 2004
SN  - 1082-3654
SP  - 2989
EP  - 2993
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Auffray, E.
A1  - Barbier, R.
A1  - Brandenburg, G.
T1  - The ClearPET TM LSO/LuYAP phoswich scanner: a high performance small animal PET system
JF  - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 3
N2  - A 2nd generation high performance small animal PET scanner, called ClearPET™, has been designed and a first prototype is built by working groups of the Crystal Clear Collaboration (CCC). In order to achieve high sensitivity and maintain good uniform spatial resolution over the field of view in high resolution PET systems, it is necessary to extract the depth of interaction (DOI) information and correct for spatial degradation. The design of the first ClearPET™ Demonstrator based on the use of the multi-anode photomultiplier tube (Hamamatsu R7600-M64) and a LSO/LuYAP phoswich matrix. The two crystal layers of 8*8 crystals (2*2*10 mm3) are stacked on each other and mounted without light guide as one to one on the PMT. A unit of four PMTs arranged in-line represents one of 20 sectors of the ring design. The opening diameter of the crystal ring is 137 mm, the axial detector length is 110 mm. The PMT pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the pulse arrival time. Single gamma interactions are recorded and coincidences are found by software. The gantry allows rotation of the detector modules around the field of view. The measurements have been done using the first LSO/LuYAP detector cassettes.
Y1  - 2004
SN  - 1082-3654
SP  - 1728
EP  - 1732
ER  -