3,556 research outputs found
QCD Approach to B->D \pi Decays and CP Violation
The branching ratios and CP violations of the decays, including
both the color-allowed and the color-suppressed modes, are investigated in
detail within QCD framework by considering all diagrams which lead to three
effective currents of two quarks. An intrinsic mass scale as a dynamical gluon
mass is introduced to treat the infrared divergence caused by the soft
collinear approximation in the endpoint regions, and the Cutkosky rule is
adopted to deal with a physical-region singularity of the on mass-shell quark
propagators. When the dynamical gluon mass is regarded as a universal
scale, it is extracted to be around MeV from one of the
well-measured decay modes. The resulting predictions for all
branching ratios are in agreement with the current experimental measurements.
As these decays have no penguin contributions, there are no direct
asymmetries. Due to interference between the Cabibbo-suppressed and the
Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the
decays to be consistent with the experimental data at
1- level. More precise measurements will be helpful to extract weak
angle .Comment: 21pages,5 figures,3 tables, typos corrected and numerical result for
one of decay channels is improve
Active cooling control of the CLEO detector using a hydrocarbon coolant farm
We describe a novel approach to particle-detector cooling in which a modular
farm of active coolant-control platforms provides independent and regulated
heat removal from four recently upgraded subsystems of the CLEO detector: the
ring-imaging Cherenkov detector, the drift chamber, the silicon vertex
detector, and the beryllium beam pipe. We report on several aspects of the
system: the suitability of using the aliphatic-hydrocarbon solvent PF(TM)-200IG
as a heat-transfer fluid, the sensor elements and the mechanical design of the
farm platforms, a control system that is founded upon a commercial programmable
logic controller employed in industrial process-control applications, and a
diagnostic system based on virtual instrumentation. We summarize the system's
performance and point out the potential application of the design to future
high-energy physics apparatus.Comment: 21 pages, LaTeX, 5 PostScript figures; version accepted for
publication in Nuclear Instruments and Methods in Physics Research
LST1 promotes the assembly of a molecular machinery responsible for tunneling nanotube formation
Carefully orchestrated intercellular communication is an essential prerequisite for the development
of multicellular organisms. In recent years, tunneling nanotubes (TNT) have emerged as a novel
and widespread mechanism of cell-cell communication. However, the molecular basis of their
formation is still poorly understood. In the present study we report that the transmembrane MHC
class III protein LST1 induces the formation of functional nanotubes and is required for endogenous
nanotube generation. Mechanistically, we found LST1 to induce nanotube formation by recruiting
the small GTPase RalA to the plasma membrane and promoting its interaction with the exocyst
complex. Furthermore, we determined LST1 to recruit the actin-crosslinking protein filamin to the
plasma membrane and to interact with M-Sec, myosin and myoferlin. These results allow us to
suggest a molecular model for nanotube generation. In this proposal LST1 functions as a membrane
scaffold mediating the assembly of a multimolecular complex, which controls the formation of
functional nanotubes
Molecular classification of the placebo effect in nausea
In this proof-of-concept study, we tested whether placebo effects can be monitored and predicted by plasma proteins. In a randomized controlled design, 90 participants were exposed to a nauseating stimulus on two separate days and were randomly allocated to placebo treatment or no treatment on the second day. Significant placebo effects on nausea, motion sickness, and (in females) gastric activity could be verified. Using label-free tandem mass spectrometry, 74 differentially regulated proteins were identified as correlates of the placebo effect. Gene ontology (GO) enrichment analyses identified acute-phase proteins and microinflammatory proteins to be involved, and the identified GO signatures predicted day-adjusted scores of nausea indices in the placebo group. We also performed GO enrichment analyses of specific plasma proteins predictable by the experimental factors or their interactions and identified 'grooming behavior' as a prominent hit. Finally, Receiver Operator Characteristics (ROC) allowed to identify plasma proteins differentiating placebo responders from non-responders, comprising immunoglobulins and proteins involved in oxidation reduction processes and complement activation. Plasma proteomics is a promising tool to identify molecular correlates and predictors of the placebo effect in humans
Neutrino Mass Limit from Galaxy Cluster Number Density Evolution
Measurements of the evolution with redshift of the number density of massive
galaxy clusters are used to constrain the energy density of massive neutrinos
and so the sum of neutrino masses . We consider a spatially-flat
cosmological model with cosmological constant, cold dark matter, baryonic
matter, and massive neutrinos. Accounting for the uncertainties in the
measurements of the relevant cosmological parameters we obtain a limit of 2.4 eV (95 % C.L.).Comment: 6 pages, 2 figures and references added, accepted for publication in
Phys. Rev.
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