TY  - JOUR
A1  - Staat, Manfred
A1  - Trenz, Eva
A1  - Lohmann, Philipp
A1  - Frotscher, Ralf
A1  - Klinge, Uwe
A1  - Tabaza, Ruth
A1  - Kirschner-Hermanns, Ruth
T1  - New measurements to compare soft tissue anchoring systems in pelvic floor surgery
JF  - Journal of Biomedical Materials Research Part B: Applied Biomaterials
N2  - Suburethral slings as well as different meshes are widely used treating stress urinary incontinence and prolaps in women. With the development of MiniSlings and special meshes using less alloplastic material anchorage systems become more important to keep devices in place and to put some tension especially on the MiniSlings. To date, there are many different systems of MiniSlings of different companies on the market which differ in the structure of the used meshes and anchors. A new objective measurement method to compare different properties of MiniSling systems (mesh and anchor) is presented in this article. Ballistic gelatine acts as soft tissue surrogate. Significant differences in parameters like pull-out strength of anchors or shrinkage of meshes under loading conditions have been determined. The form and size of the anchors as well as the structural stability of the meshes are decisive for a proper integration. The tested anchorings sytems showed markedly different mechanical function at their respective load bearing capacity. As the stable fixation of the device in tissue is a prerequisite for a permanet reinforcement, the proposed test system permits further optimisation of anchor and mesh devices to improve the success of the surgical treatment
Y1  - 2012
U6  - https://doi.org/10.1002/jbm.b.32654
SN  - 1552-4981
VL  - 100B
IS  - 4
SP  - 924
EP  - 933
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Vu, Duc Khoi
T1  - Limit analysis of flaws in pressurized pipes and cylindrical vessels Part II: Circumferential defects
JF  - Engineering Fracture Mechanics ; 97(2013), H. 1
N2  - Upper and lower bound theorems of limit analyses have been presented in part I of the paper. Part II starts with the finite element discretization of these theorems and demonstrates how both can be combined in a primal–dual optimization problem. This recently proposed numerical method is used to guide the development of a new class of closed-form limit loads for circumferential defects, which show that only large defects contribute to plastic collapse with a rapid loss of strength with increasing crack sizes. The formulae are compared with primal–dual FEM limit analyses and with burst tests. Even closer predictions are obtained with iterative limit load solutions for the von Mises yield function and for the Tresca yield function. Pressure loading of the faces of interior cracks in thick pipes reduces the collapse load of circumferential defects more than for axial flaws. Axial defects have been treated in part I of the paper.
Y1  - 2012
U6  - https://doi.org/10.1016/j.engfracmech.2012.05.017
SN  - 0013-7944
VL  - 97
SP  - 314
EP  - 333
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Vu, Duc-Khoi
T1  - An Algorithm for Shakedown Analysis for Materials with Temperature Dependent Yield Stress
JF  - Proceedings in Applied Mathematics and Mechanics (PAMM). 4 (2004), H. 1
Y1  - 2004
SN  - 1617-7061
SP  - 231
EP  - 233
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Vu, Duc-Khoi
T1  - Limit analysis of flaws in pressurized pipes and cylindrical vessels. Part I: Axial defects
JF  - Engineering Fracture Mechanics. 74 (2007), H. 3
Y1  - 2007
SN  - 0013-7944
SP  - 431
EP  - 450
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Vu, Khoi Duc
T1  - Limit loads of circumferentially flawed pipes and cylindrical vessels under internal pressure
JF  - International Journal of Pressure Vessels and Piping. 83 (2006), H. 3
Y1  - 2006
SN  - 0308-0161
SP  - 188
EP  - 196
ER  - 
TY  - JOUR
A1  - Stadler, A.  M.
A1  - Digel, Ilya
A1  - Artmann, Gerhard
A1  - Embs, Jan P.
A1  - Zaccai, Joe
A1  - Büldt, Georg
T1  - Hemoglobin Dynamics in Red Blood Cells: Correlation to Body Temperature
JF  - Biophysical Journal. 95 (2008), H. 11
Y1  - 2008
SN  - 1542-0086
SP  - 5449
EP  - 5461
ER  - 
TY  - JOUR
A1  - Stadler, Andreas M.
A1  - Digel, Ilya
A1  - Embs, Jan P.
A1  - Unruh, Tobias
A1  - Tehei, M.
A1  - Zaccai, G.
A1  - Büldt, G.
A1  - Artmann, Gerhard
T1  - From powder to solution : Hydration dependence of human hemoglobin dynamics correlated to body temperature
JF  - Biophysical Journal. 96 (2009), H. 12
Y1  - 2009
SN  - 0006-3495
SP  - 5073
EP  - 5081
PB  - Cell Press
CY  - Cambridge, Mass.
ER  - 
TY  - JOUR
A1  - Stadler, Andreas M.
A1  - Embs, Jan P.
A1  - Digel, Ilya
A1  - Artmann, Gerhard
A1  - Unruh, Tobias
A1  - Büldt, Georg
A1  - Zaccai, Guiseppe
T1  - Cytoplasmic water and hydration layer dynamics in human red blood cells
JF  - Journal of the American Chemical Society. 50 (2008), H. 130
Y1  - 2008
SN  - 1520-5126
SP  - 16852
EP  - 16853
ER  - 
TY  - CHAP
A1  - Stadler, Andreas M.
A1  - Embs, Jan P.
A1  - Zerlin, Kay
A1  - Digel, Ilya
A1  - Artmann, Gerhard
A1  - Zaccai, Joe
A1  - Büldt, Georg
T1  - Temperature transitions of hemoglobin and cytosolic water diffusion in human red blood cells : [poster]
N2  - Background Hemoglobin interactions in red blood cells Hemoglobin dynamics in human red blood cells Diffusion of H2O in red blood cells
KW  - Erythrozyt
KW  - Hämoglobin
KW  - cytosolic water diffusion
KW  - hemoglobin dynamics
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Stadler, Andreas M.
A1  - Garvey, G. J.
A1  - Bocahut, A.
A1  - Sacquin-Mora, S.
A1  - Digel, Ilya
A1  - Schneider, G. J.
A1  - Natali, F.
A1  - Artmann, Gerhard
A1  - Zaccai, G.
T1  - Thermal fluctuations of haemoglobin from different species : adaptation to temperature via conformational dynamics
JF  - Journal of the Royal Society Interface
N2  - Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 Å at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits.
Y1  - 2012
U6  - https://doi.org/10.1098/rsif.2012.0364
SN  - 1742-5689
VL  - 9
IS  - 76
SP  - 2845
EP  - 2855
PB  - The Royal Society
CY  - London
ER  - 
TY  - JOUR
A1  - Stadler, Andreas M.
A1  - Zerlin, Kay
A1  - Digel, Ilya
A1  - Büldt, Georg
A1  - Zaccai, Guiseppe
A1  - Artmann, Gerhard
T1  - Dynamics and interactions of hemoglobin in red blood cells
JF  - Tissue Engineering Part A. 14 (2008), H. 5
Y1  - 2008
SN  - 1937-3341
N1  - TERMIS EU 2008 Porto Meeting June 22–26, 2008 Porto Congress Center–Alfândega Portugal
SP  - 724
EP  - 724
ER  - 
TY  - JOUR
A1  - Steinseifer, Ulrich
A1  - Kashefi, Ali
A1  - Hormes, Marcus
A1  - Schoberer, Mark
A1  - Orlikowsky, Thorsten
A1  - Behbahani, Mehdi
A1  - Behr, Marek
A1  - Schmitz-Rode, Thomas
T1  - Miniaturization of ECMO Systems : Engineering Challenges and Methods
JF  - Artificial Organs. 33 (2009), H. 5
Y1  - 2009
SN  - 1525-1594
N1  - Fifth International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion Abstracts <May 28, 2009>
SP  - A55
EP  - A55
ER  - 
TY  - JOUR
A1  - Streese, Lukas
A1  - Kotliar, Konstantin
A1  - Deiseroth, Arne
A1  - Infanger, Denis
A1  - Gugleta, Konstantin
A1  - Schmaderer, Christoph
A1  - Hanssen, Henner
T1  - Retinal endothelial function in cardiovascular risk patients: A randomized controlled exercise trial
JF  - Scandinavian Journal of Medicine and Science in Sports
N2  - The aim of this study was to investigate, for the first time, the effects of high-intensity interval training (HIIT) on retinal microvascular endothelial function in cardiovascular (CV) risk patients. In the randomized controlled trial, middle-aged and previously sedentary patients with increased CV risk (aged 58 ± 6 years) with ≥ two CV risk factors were randomized into a 12-week HIIT (n = 33) or control group (CG, n = 36) with standard physical activity recommendations. A blinded examiner measured retinal endothelial function by flicker light-induced maximal arteriolar (ADmax) and venular (VDmax) dilatation as well as the area under the arteriolar (AFarea) and venular (VFarea) flicker curve using a retinal vessel analyzer. Standardized assessments of CV risk factors, cardiorespiratory fitness, and retinal endothelial function were performed before and after HIIT. HIIT reduced body mass index, fat mass, and low-density lipoprotein and increased muscle mass and peak oxygen uptake (VO2peak). Both ADmax (pre: 2.7 ± 2.1%, post: 3.0 ± 2.2%, P = .018) and AFarea (pre: 32.6 ± 28.4%*s, post: 37.7 ± 30.6%*s, P = .016) increased after HIIT compared with CG (ADmax, pre: 3.2 ± 1.8%, post: 2.9 ± 1.8%, P = .254; AFarea, pre: 41.6 ± 28.5%*s, post: 37.8 ± 27.0%*s, P = .186). Venular function remained unchanged after HIIT. There was a significant association between ∆-change VO2peak and ∆-changes ADmax and AFarea (P = .026, R² = 0.073; P = .019, R² = 0.081, respectively). 12-weeks of HIIT improved retinal endothelial function in middle-aged patients with increased CV risk independent of the reduction in classical CV risk factors. Exercise has the potential to reverse or at least postpone progression of small vessel disease in older adults with increased CV risk under standard medication. Dynamic retinal vessel analysis seems to be a sensitive tool to detect treatment effects of exercise interventions on retinal microvascular endothelial function in middle-aged individuals with increased CV risk.
Y1  - 2020
U6  - https://doi.org/10.1111/sms.13560
SN  - 1600-0838
VL  - 30
IS  - 2
SP  - 272
EP  - 280
PB  - Wiley
CY  - Oxford
ER  - 
TY  - CHAP
A1  - Streun, M.
A1  - Al-Kaddoum, R.
A1  - Parl, C.
A1  - Pietrzyk, U.
A1  - Ziemons, Karl
A1  - Waasen, S. van
T1  - Simulation studies of optical photons in monolithic block scintillators
T2  - 2011 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - The interest in PET detectors with monolithic block scintillators is growing. In order to obtain high spatial resolutions dedicated positioning algorithms are required. But even an ideal algorithm can only deliver information which is provided by the detector. In this simulation study we investigated the light distribution on one surface of cuboid LSO scintillators of different size. Scintillators with a large aspect ratio (small footprint and large height) showed significant position information only for a minimum interaction depth of the gamma particle. The results allow a quantitative estimate for a useful aspect ratio.
Y1  - 2012
SN  - 978-1-4673-0120-6 (electronic ISBN)
SN  - 978-1-4673-0118-3 (print ISBN)
U6  - https://doi.org/10.1109/NSSMIC.2011.6154621
SP  - 1380
EP  - 1382
PB  - IEEE
CY  - New York
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  - Streun, M.
A1  - Brandenburg, G.
A1  - Brökel, M.
A1  - Fuss, L.
A1  - Larue, H.
A1  - Parl, C.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - The ClearPET data acquisition
JF  - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5
N2  - Within the Crystal Clear Collaboration a modular system for a small animal PET scanner (ClearPET™) has been developed. The modularity allows the assembly of scanners of different sizes and characteristics in order to fit the specific needs of the individual member institutions. Now a first demonstrator is being completed in Julich. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to multi-channel photomultipliers (PMTs). A free-running ADC digitizes the signal from the PMT and the complete scintillation pulses are sampled by an FPGA and sent with 20 MB/S to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. An advantage of that is that the coincidence window and the dimensions of the field of view can be adjusted easily. The ClearPET™ demonstrator is equipped with 10240 crystals on 80 PMTs. This paper presents an overview of the data acquisition system.
Y1  - 2004
SN  - 1082-3654
SP  - 3097
EP  - 3100
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Khodaverdi, M.
A1  - Larue, H.
A1  - Parl, C.
A1  - Ziemons, Karl
T1  - Timemark correction for the ClearPET™ scanners
JF  - 2005 IEEE Nuclear Science Symposium Conference Record, Vol. 4
N2  - The small animal PET scanners developed by the Crystal Clear Collaboration (ClearPETtrade) detect coincidences by analyzing timemarks which are attached to each event. The scanners are able to save complete single list mode data which allows analysis and modification of the timemarks after data acquisition. The timemarks are obtained from the digitally sampled detector pulses by calculating the baseline crossing of the rising edge of the pulse which is approximated as a straight line. But the limited sampling frequency causes a systematic error in the determination of the timemark. This error depends on the phase of the sampling clock at the time of the event. A statistical method that corrects these errors will be presented
Y1  - 2006
SN  - 1082-3654
SP  - 2057
EP  - 2060
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Parl, C.
A1  - Ziemons, Karl
T1  - The data acquisition system of ClearPET neuro - a small animal PET scanner
JF  - IEEE Transactions on Nuclear Science
N2  - The Crystal Clear Collaboration has developed a modular system for a small animal PET scanner (ClearPET). The modularity allows the assembly of scanners of different sizes and characteristics in order to satisfy the specific needs of the individual member institutions. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to Multichannel Photomultipliers (PMTs). For each PMT a free running 40 MHz ADC digitizes the signal and the complete scintillation pulse is sampled by an FPGA and sent with 20 MB/s to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. The system in Jülich (ClearPET Neuro) is equipped with 10240 crystals on 80 PMTs. The paper will present an overview of the data acquisition system.
Y1  - 2006
SN  - 0018-9499
VL  - 53
IS  - 3
SP  - 700
EP  - 703
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  -