Production of topological defects at the end of inflation

Hybrid inflation within supersymmetric grand unified theories, as well as inflation through brane collisions within braneworld cosmological models, lead to the formation of one-dimensional defects. Observational data, mainly from the cosmic microwave background temperature anisotropies but also from the gravitational wave background, impose constraints on the free parameters of the models. I review these inflationary models and discuss the constraints from the currently available data.Comment: 9 pages, Invited talk in the Conference "Challenges in Particle Astrophysics" -- 6th Rencontres du Vietnam, Hanoi (Vietnam) 6-12 Aug. 200

Edge Detection, Cosmic Strings and the South Pole Telescope

We develop a method of constraining the cosmic string tension $G\mu$ which uses the Canny edge detection algorithm as a means of searching CMB temperature maps for the signature of the Kaiser-Stebbins effect. We test the potential of this method using high resolution, simulated CMB temperature maps. By modeling the future output from the South Pole Telescope project (including anticipated instrumental noise), we find that cosmic strings with $G\mu > 5.5\times10^{-8}$ could be detected.Comment: 27 pages, 5 figures, reference and minor notes added, discussion of noise expanded, explanation of equation (4) expande

Monomer networking activates recombinases

Recombinases catalyze the DNA strand-exchange reactions of homologous recombination. The regularity of the filaments they form on DNA, though beautiful, does not explain how they work. Functionally important internal interactions now include multiple intermonomer contacts for activation (Galkin et al., 2006)

Mechanistic Insight from Chaos: How RecA Mediates DNA Strand Exchange

Cleverly designed single-molecule FRET experiments reported in this issue of Structure by Ragunathan et al. coax RecA to reveal some of its secrets. Observing individual events identifies intermediate steps and provides clues for how to drive strand exchange forward

Homologous recombination: Down to the wire

AbstractExchange of strands between homologous DNA molecules is catalyzed by evolutionarily conserved recombinases. These proteins can occur in different quaternary arrangements: rings or helical filaments. Recent results reveal that recombinase function follows from the filamentous form