Searches for the Standard Model Higgs Boson with the ATLAS Detector

The most recent results for searches for the Standard Model Higgs boson at a center-of-mass energy of sqrt(s) = 7 TeV using 4.9/fb of data collected with the ATLAS detector at CERNs Large Hadron Collider are presented.Comment: 4 pages, Contribution to the proceedings of the Rencontres de Moriond QCD 201

Quotients of trees for arithmetic subgroups of PGL₂ over a rational function field

In this note we determine the structure of the quotient of the Bruhat-Tits tree of the locally compact group PGL(2)(F-p) with respect to the natural action of its S-arithmetic subgroup PGL(2)(O-{p}), where F is a rational function field over a finite field and p is a place of F

Water Droplets in a Spherically Confined Nematic Solvent: A Numerical Investigation

Recently, it was observed that water droplets suspended in a nematic liquid crystal form linear chains (Poulin et al., Science 275, 1770 (1997)). The chaining occurs, e.g., in a large nematic drop with homeotropic boundary conditions at all the surfaces. Between each pair of water droplets a point defect in the liquid crystalline order was found in accordance with topological constraints. This point defect causes a repulsion between the water droplets. In our numerical investigation we limit ourselves to a chain of two droplets. For such a complex geometry we use the method of finite elements to minimize the Frank free energy. We confirm an experimental observation that the distance d of the point defect from the surface of a water droplet scales with the radius r of the droplet like d = 0.3 * r. When the water droplets are moved apart, we find that the point defect does not stay in the middle between the droplets, but rather forms a dipole with one of them. This confirms a theoretical model for the chaining. Analogies to a second order phase transition are drawn. We also find the dipole when one water droplet is suspended in a bipolar nematic drop with two boojums, i.e., surface defects at the outer boundary. Finally, we present a configuration where two droplets repel each other without a defect between them.Comment: 9 pages, RevTeX, 12 encapsulated postscript figure

Artificial environments for the co-translational stabilization of cell-free expressed proteins

An approach for designing individual expression environments that reduce or prevent protein aggregation and precipitation is described. Inefficient folding of difficult proteins in unfavorable translation environments can cause significant losses of overexpressed proteins as precipitates or inclusion bodies. A number of chemical chaperones including alcohols, polyols, polyions or polymers are known to have positive effects on protein stability. However, conventional expression approaches can use such stabilizing agents only post-translationally during protein extraction and purification. Proteins that already precipitate inside of the producer cells cannot be addressed. The open nature of cell-free protein expression systems offers the option to include single chemicals or cocktails of stabilizing compounds already into the expression environment. We report an approach for systematic screening of stabilizers in order to improve the solubility and quality of overexpressed proteins co-translationally. A comprehensive list of representative protein stabilizers from the major groups of naturally occurring chemical chaperones has been analyzed and their concentration ranges tolerated by cell-free expression systems have been determined. As a proof of concept, we have applied the method to improve the yield of proteins showing instability and partial precipitation during cell-free synthesis. Stabilizers that co-translationally improve the solubility and functional folding of human glucosamine 6-phosphate N-acetyltransferase have been identified and cumulative effects of stabilizers have been studied