TY  - JOUR
A1  - Schermutzki, Margret
ED  - Terbuyken, Gregor
T1  - In Modulen lehren, lernen und prüfen
JF  - In Modulen lehren, lernen und prüfen. Herausforderungen an die Hochschuldidaktik
Y1  - 2010
SN  - 978-3-8172-7809-1
N1  - Dokumentation einer Tagung der Evangelischen Akademie Loccum vom 14. bis 16. Dezember 2009 in Kooperation mit der ZEvA Hannover und der Universität Hannover.
SP  - 81
EP  - 106
PB  - Evangelische Akademie Loccum
CY  - Rehburg-Loccum
ER  - 
TY  - JOUR
A1  - Schneider, Bettina
A1  - Schneider, Wilhelm
T1  - Die Konzernrechnungslegung
JF  - Das Wirtschaftsstudium : wisu
Y1  - 2010
SN  - 0340-3084
VL  - 39
IS  - 7
SP  - 938
EP  - 942
PB  - Lange
CY  - Düsseldorf
ER  - 
TY  - JOUR
A1  - Heinrichs, U.
A1  - Pietrzyk, Uwe
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  - Lustfeld, Hans
A1  - Pithan, C.
A1  - Reißel, Martin
T1  - Metallic electrolyte composites in the framework of the brick-layer model
JF  - Journal of the European Ceramic Society
N2  - It is well known that the already large dielectric constants of some electrolytes like BaTiO₃ can be enhanced further by adding metallic (e.g. Ni, Cu or Ag) nanoparticles. The enhancement can be quite large, a factor of more than 1000 is possible. The consequences for the properties will be discussed in the present paper applying a brick-layer model (BLM) for calculating dc-resistivities of thin layers and a modified one (PBLM) that includes percolation for calculating dielectric properties of these materials. The PBLM results in an at least qualitative description and understanding of the physical phenomena: This model gives an explanation for the steep increase of the dielectric constant below the percolation threshold and why this increase is connected to a dramatic decrease of the breakdown voltage as well as the ability of storing electrical energy. We conclude that metallic electrolyte composites like BaTiO₃ are not appropriate for energy storage.
Y1  - 2012
U6  - https://doi.org/10.1016/j.jeurceramsoc.2011.10.017
SN  - 0955-2219
VL  - 32
IS  - 4
SP  - 859
EP  - 864
PB  - Elsevier
CY  - Amsterdam
ER  -