D+ to mu+nu and fD+ from 281 pb-1 at Psi(3770) from CLEO-c
  We report improved measurements of branching fraction and decay constant fD+ in D+ to mu+nu using 281 pb-1 of data taken on the Psi(3770) resonance with the CLEO-c detector. We extract a relatively precise value for the decay constant of the D+ meson by measuring Br(D+ to mu+nu) = (4.40+-0.66+0.09-0.12)x10^-4 and find fD+ = (222.6+-16.7+2.8-3.4) MeV. We also set 90% confidence upper limit on Br(D+ to e+nu) < 2.4x10^-5 which limits contributions from non-Standard Model physics. 
Yongsheng Gao (for CLEO Collaboration)