  The spontaneous decay rates of an excited atom placed near a dielectric
cylinder are investigated. A special attention is paid to the case when the
cylinder radius is small in comparison with radiation wavelength (nanofiber or
photonic wire). In this case, the analytical expressions of the transition
rates for different orientations of dipole are derived. It is shown that the
main contribution to decay rates is due to quasistatic interaction of atom
dipole momentum with nanofiber and the contributions of guided modes are
exponentially small. On the contrary, in the case when the radius of fiber is
only slightly less than radiation wavelength, the influence of guided modes can
be substantial. The results obtained are compared with the case of dielectric
nanospheroid and ideally conducting wire.
