Correlated fluctuations in the exciton dynamics and spectroscopy of DNA

The absorption of ultraviolet light creates excitations in DNA, which subsequently start moving in the helix. Their fate is important for an understanding of photo damage, and is determined by the interplay of electronic couplings between bases and the structure of the DNA environment. We model the effect of dynamical fluctuations in the environment and study correlation, which is present when multiple base pairs interact with the same mode in the environment. We find that the correlations strongly affect the exciton dynamics, and show how they are observed in the decay of the anisotropy as a function of a coherence and a population time in a non-linear optical experiment

The international fight against terrorism and the protection of human rights: with recommendations to the German government and parliament

Die englische Kurzfassung der Studie "Internationale Terrorismusbekämpfung und Menschenrechte" thematisiert wesentliche Entwicklungen der Terrorismusbekämpfung im Rahmen der Vereinten Nationen, der EU und der G8-Staatengruppe in den Jahren 2003 und 2004. Die Studie schließt mit zehn Empfehlungen an die deutsche Außen- und Verteidigungspolitik

Involvement of BMP-2, TGF-ß2 and TGF-ß3 Signaling in Initial and Early Stages of Heterotopic Ossification in a rat Experimental Model

This study focused on the localization and expression of bone morphogenetic protein 2 (BMP-2) and different  isoforms of transforming growth factor s (TGF-s1, TGF-s2 and TGF-s3) in the initial and early stages  of heterotopic ossification (HO) employing an animal model mimicking the situation after total hip arthroplasty  (THA). Bone growth was induced in rats using s-tricalcium phosphate implants immersed either in  osteoinductive rhBMP-2 solution or in saline and implanted at the site where the HO is usually expected  to develop after THA. Implants were removed at 3 or 21 days after the operation and handled according to  stereology principles. mRNA expression and protein staining of growth factors in different types of tissues  was determined by in situ hybridization and immunohistochemistry, respectively. After three days, TGF-s3 content in the undifferentiated mesenchymal-like cells in the rhBMP-2 treated  implants was, as assessed by immunohistochemistry, 49.6% higher compared to the saline treated group  (p=0.024). This was also supported by in situ hybridization of mRNA of TGF-s3, which showed stronger  expression in rhBMP-2 treated group. Immunohistochemical investigation showed that after 21 days the  connective tissue in the rhBMP-2 treated implants contained more TGF-s1, TGF-s2 and TGF-s3, compared  to BMP-2 and osteoblasts contained significantly (27.2%) more TGF-s3 compared to TGF-s1 (p=0.045). In  the formed HO the proportion of the TGF-s2 and TGF-s3 producing bone tissue was increased by 32.1% and  47.8% respectively, compared to the TGF-s1 producing bone tissue (p=0.007 and p=0.006) and although  this difference was not so clear at mRNA level, this suggests that TGF-s2 and TGF-s3 signaling seem to play  an important role during initial and early stages of HO formation.

A haplome alignment and reference sequence of the highly polymorphic Ciona savignyi genome

The high degree of polymorphism in the genome of the sea squirt Ciona savignyi complicated the assembly of sequence contigs, but a new alignment method results in a much improved sequence

Visible-to-telecom quantum frequency conversion of light from a single quantum emitter

Quantum frequency conversion (QFC), a nonlinear optical process in which the frequency of a quantum light field is altered while conserving its non-classical correlations, was first demonstrated 20 years ago. Meanwhile, it is considered an essential tool for the implementation of quantum repeaters since it allows for interfacing quantum memories with telecom-wavelength photons as quantum information carriers. Here we demonstrate efficient (>30%) QFC of visible single photons (711 nm) emitted by a quantum dot (QD) to a telecom wavelength (1,313 nm). Analysis of the first and second-order coherence before and after wavelength conversion clearly proves that important properties, such as the coherence time and photon antibunching, are fully conserved during the frequency translation process. Our findings underline the great potential of single photon sources on demand in combination with QFC as a promising technique for quantum repeater schemes.Comment: 11 pages, 4 figure