2,553 research outputs found
Search for Rare b-hadron Decays at CDF
We report on searches for B^0_s to \mu^+ \mu^-, B^0_d to \mu^+ \mu^- decays
and b to s \mu^+\mu^- transitions in exclusive decays of B mesons.
Using 2 fb^{-1} of data collected by the CDF II detector we find upper limits
on the branching fractions B(B^0_s to \mu^+ \mu^-) < 5.8 x 10^{-8} and B(B^0_d
to \mu^+ \mu^-) < 1.8 x 10^{-8} at 95% confidence level.
Using 924 pb^{-1} of data we measure the branching fractions B(B^+ to \mu^+
\mu^- K^+) = (0.60 \pm 0.15 \pm 0.04) x 10^{-6}, B(B^0_d to \mu^+ \mu^- K^{*0})
= (0.82 \pm 0.31 \pm 0.10) x 10^{-6} and the limit B(B^0_s to \mu^+ \mu^-
phi)/B(B^0_s to J/\psi\phi) < 2.61(2.30) x 10^{-3} at 95(90)% confidence level.Comment: 3 pages, 5 figures, conference proceedings to the 2007 Europhysics
Conference on High Energy Physics (Manchester, July 2007
An OSI architecture for the deep space network
The flexibility and robustness of a monitor and control system are a direct result of the underlying inter-processor communications architecture. A new architecture for monitor & Control at the Deep Space Network Communications Complexes has been developed based on the Open System Interconnection (OSI) standards. The suitability of OSI standards for DSN M&C has been proven in the laboratory. The laboratory success has resulted in choosing an OSI-based architecture for DSS-13 M&C. DSS-13 is the DSN experimental station and is not part of the 'operational' DSN; it's role is to provide an environment to test new communications concepts can be tested and conduct unique science experiments. Therefore, DSS-13 must be robust enough to support operational activities, while also being flexible enough to enable experimentation. This paper describes the M&C architecture developed for DSS-13 and the results from system and operational testing
CENP-E combines a slow, processive motor and a flexible coiled coil to produce an essential motile kinetochore tether
The mitotic kinesin centromere protein E (CENP-E) is an essential kinetochore component that directly contributes to the capture and stabilization of spindle microtubules by kinetochores. Although reduction in CENP-E leads to high rates of whole chromosome missegregation, neither its properties as a microtubule-dependent motor nor how it contributes to the dynamic linkage between kinetochores and microtubules is known. Using single-molecule assays, we demonstrate that CENP-E is a very slow, highly processive motor that maintains microtubule attachment for long periods. Direct visualization of full-length Xenopus laevis CENP-E reveals a highly flexible 230-nm coiled coil separating its kinetochore-binding and motor domains. We also show that full-length CENP-E is a slow plus end–directed motor whose activity is essential for metaphase chromosome alignment. We propose that the highly processive microtubule-dependent motor activity of CENP-E serves to power chromosome congression and provides a flexible, motile tether linking kinetochores to dynamic spindle microtubules
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