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Eibenberger E.,Friedrich - Alexander - University, Erlangen - Nuremberg | Eibenberger E.,International Max Planck Research | Angelopoulou E.,Friedrich - Alexander - University, Erlangen - Nuremberg
Proceedings - International Conference on Image Processing, ICIP | Year: 2010

The neutral interface reflection (NIR) assumption is a widely accepted theory in computer vision. According to the NIR the color of specularities of dielectric materials is the color of the incident illumination and the influence of the Fresnel reflectance is neglected. We show, that there is a material- and geometry-dependent shift between the color of the specularity and the color of the incident light due to the Fresnel effect which for human skin can be up to approximately 5.8%. As the NIR concept is often the core idea of specularity-based illuminant-color estimation techniques, the ignored Fresnel effect introduces a systematic error in the estimation result. We thus propose a material-dependent rectification method for correcting this color shift. Our experiments on human skin regions show an average improvement of the illuminant color estimation of about 30%. © 2010 IEEE. Source

Barkauskaite E.,Paterson Institute for Cancer Research | Jankevicius G.,Ludwig Maximilians University of Munich | Ladurner A.G.,Ludwig Maximilians University of Munich | Ladurner A.G.,International Max Planck Research | And 3 more authors.
FEBS Journal | Year: 2013

Poly(ADP-ribosyl)ation is involved in the regulation of a variety of cellular pathways, including, but not limited to, transcription, chromatin, DNA damage and other stress signalling. Similar to other tightly regulated post-translational modifications, poly(ADP-ribosyl)ation employs 'writers', 'readers' and 'erasers' to confer regulatory functions. The generation of poly(ADP-ribose) is catalyzed by poly(ADP-ribose) polymerase enzymes, which use NAD+ as a cofactor to sequentially transfer ADP-ribose units generating long polymers, which, in turn, can affect protein function or serve as a recruitment platform for additional factors. Historically, research has focused on poly(ADP-ribose) generation pathways, with knowledge about PAR recognition and degradation lagging behind. Over recent years, several discoveries have significantly furthered our understanding of poly(ADP-ribose) recognition and, even more so, of poly(ADP-ribose) degradation. In this review, we summarize current knowledge about the protein modules recognizing poly(ADP-ribose) and discuss the newest developments on the complete reversibility of poly(ADP-ribosyl)ation. Poly(ADP-ribosyl)ation is an evolutionary conserved dynamic post-translational modification involved in a variety of biological functions. Poly(ADP-ribose) has a short half-life and the cellular levels of poly(ADP-ribose) are tightly regulated by both its production and degradation. In this review, we discuss the current knowledge of the protein modules that recognize poly(ADP-ribose) and summarize the newest developments on the degradation of poly(ADP-ribose). © 2013 FEBS. Source

Sardana N.,Martin Luther University of Halle Wittenberg | Sardana N.,International Max Planck Research | Heyroth F.,Martin Luther University of Halle Wittenberg | Schilling J.,Martin Luther University of Halle Wittenberg
Journal of the Optical Society of America B: Optical Physics | Year: 2012

Nanoporous gold films are prepared using a dealloying method and form a sponge type bicontinuous network. As the structure sizes are below 50 nm, the material forms an effective medium with a negative dielectric constant for near infrared light. The dispersion relation of the propagating surface plasmons on the air/nanoporous gold interface is determined from reflection measurements in the Kretschmann configuration. A characteristic red-shift by ca. 0.85 eV compared to surface plasmons on solid gold layers is observed. The results are compared with calculated dispersion relations applying the Bruggeman effective medium theory for the nanoporous gold films. © 2012 Optical Society of America. Source

Bose P.,Martin Luther University of Halle Wittenberg | Bose P.,International Max Planck Research | Zahn P.,Martin Luther University of Halle Wittenberg | Henk J.,Max Planck Institute of Microstructure Physics | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We report on systematic ab initio investigations of Co and Cr interlayers embedded in Fe(001)/MgO/Fe(001) magnetic tunnel junctions, focusing on the changes in the electronic structure and the transport properties with interlayer thickness. The results of spin-dependent ballistic transport calculations reveal options to specifically manipulate the tunnel magnetoresistance ratio. The resistance-area products and the tunnel magnetoresistance ratios show a monotonous trend with distinct oscillations as a function of the Cr thickness. These modulations are directly addressed and interpreted by means of magnetic structures in the Cr films and by complex band-structure effects. The characteristics for embedded Co interlayers are considerably influenced by interface resonances which are analyzed by the local electronic structure. © 2010 The American Physical Society. Source

Saka S.K.,Sensory Medical | Saka S.K.,International Max Planck Research | Honigmann A.,Max Planck Institute for Biophysical Chemistry | Eggeling C.,Weatherall Institute of Molecular Medicine | And 3 more authors.
Nature Communications | Year: 2014

Most proteins have uneven distributions in the plasma membrane. Broadly speaking, this may be caused by mechanisms specific to each protein, or may be a consequence of a general pattern that affects the distribution of all membrane proteins. The latter hypothesis has been difficult to test in the past. Here, we introduce several approaches based on click chemistry, through which we study the distribution of membrane proteins in living cells, as well as in membrane sheets. We found that the plasma membrane proteins form multi-protein assemblies that are long lived (minutes), and in which protein diffusion is restricted. The formation of the assemblies is dependent on cholesterol. They are separated and anchored by the actin cytoskeleton. Specific proteins are preferentially located in different regions of the assemblies, from their cores to their edges. We conclude that the assemblies constitute a basic mesoscale feature of the membrane, which affects the patterning of most membrane proteins, and possibly also their activity. © 2014 Macmillan Publishers Limited. Source

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