Technical University of Dortmund

About: Technical University of Dortmund is a education organization based out in Dortmund, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Large Hadron Collider & Neutrino. The organization has 13028 authors who have published 27666 publications receiving 615557 citations. The organization is also known as: Dortmund University & University of Dortmund.

Search for B→K(*)νν¯ and invisible quarkonium decays

Abstract: We search for the flavor-changing neutral-current decays B→K^(*)νν, and the invisible decays J/ψ→νν and ψ(2S)→νν via B→K^(*)J/ψ and B→K^(*)ψ(2S), respectively, using a data sample of 471×10^6 BB pairs collected by the BABAR experiment. We fully reconstruct the hadronic decay of one of the B mesons in the Υ(4S)→BB decay, and search for the B→K^(*)νν decay in the rest of the event. We observe no significant excess of signal decays over background and report branching fraction upper limits of B(B^+→K^+νν)<3.7×10^(-5), B(B^0→K^0νν)<8.1×10^(-5), B(B^+→K^(*+)νν)<11.6×10^(-5), B(B^0→K^(*0)νν)<9.3×10^(-5), and combined upper limits of B(B→Kνν)<3.2×10-5 and B(B→K^*νν)<7.9×10^(-5), all at the 90% confidence level. For the invisible quarkonium decays, we report branching fraction upper limits of B(J/ψ→νv)<3.9×10^(-3) and B(ψ(2S)→νν)<15.5×10^(-3) at the 90% confidence level. Using the improved kinematic resolution achieved from hadronic reconstruction, we also provide partial branching fraction limits for the B→K^(*)νν decays over the full kinematic spectrum.

Observation of Time-Reversal Violation in the B-0 Meson System

Abstract: Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B^0 or B^0), and J/ψK_L^0 or cc K_S^0 final states (referred to as B_+ or B_-), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B^0→B_- and B_-→B^0, as a function of the time difference between the two B decays. Using 468×10^6 BB pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS_T^+=-1.37±0.14(stat)±0.06(syst) and ΔS_T^-=1.17±0.18(stat)±0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.

Bioorganic synthesis of lipid-modified proteins for the study of signal transduction

Abstract: Biological membranes define the boundaries of the cellular compartments in higher eukaryotes and are active in many processes such as signal transduction and vesicular transport Although post-translational lipid modification of numerous proteins in signal transduction is crucial for biological function, analysis of protein-protein interactions has mainly focused on recombinant proteins in solution under defined in vitro conditions Here we present a new strategy for the synthesis of such lipid-modified proteins It involves the bacterial expression of a carboxy-terminally truncated non-lipidated protein, the chemical synthesis of differently lipidated peptides representing the C terminus of the proteins, and their covalent coupling Our technique is demonstrated using Ras constructs, which exhibit properties very similar to fully processed Ras, but can be produced in high yields and are open for selective modifications These constructs are operative in biophysical and cellular assay systems, showing specific recognition of effectors by Ras lipoproteins inserted into the membrane surface of biosensors and transforming activity of oncogenic variants after microinjection into cultured cells

Improved criteria for clustering based on the posterior similarity matrix

Abstract: In this paper we address the problem of obtaining a single clustering estimate bc based on an MCMC sample of clusterings c (1) ;c (2) :::;c (M) from the posterior distribution of a Bayesian cluster model. Methods to derive b when the number of groups K varies between the clusterings are reviewed and discussed. These include the maximum a posteriori (MAP) estimate and methods based on the posterior similarity matrix, a matrix containing the posterior probabilities that the observations i and j are in the same cluster. The posterior similarity matrix is related to a commonly used loss function by Binder (1978). Minimization of the loss is shown to be equivalent to maximizing the Rand index between esti- mated and true clustering. We propose new criteria for estimating a clustering, which are based on the posterior expected adjusted Rand index. The criteria are shown to possess a shrinkage property and outperform Binder's loss in a simulation study and in an application to gene expression data. They also perform favorably compared to other clustering procedures.