Re-examining the role of curvature in the slowing down acceleration
  scenario
  By incorporating the curvature $\Omega_k$ as a free parameter, it has been
found that the tension between the high redshift CMB shift parameter
$R(z^{\ast})$ data and the low redshift SNIa and BAO data from the combination
of SDSS and 2dFGRS can be ameliorated, and both SNIa+BAO and SNIa+BAO+CMB favor
that the decelerating parameter $q(z)$ shows a rapid variation in sign at small
redshift. In this paper, with the MCMC method, we re-examine the evolutionary
behavior of $q(z)$ using the latest observational data including the Union2
SNIa, BAO, and CMB data ($R(z^{\ast})$, $l_{A}(z^{\ast})$, $z^{\ast}$) from
WMAP7. For BAO data, four different data sets obtained from the 6dFGS, the
combination of SDSS and 2dFGRS, the WiggleZ dark energy survey and the BOSS,
are used. Except for the spatially flat case constrained by SNIa+ the WiggleZ
BAO data, both SNIa and other BAO+SNIa favor that the present cosmic
acceleration is slowing down irrespective of whether the spatial curvature is
included or not. However, once the WMAP7 CMB data is included, observations
favor strongly the $\Lambda$CDM model, a spatially flat universe, and a
speeding-up of the cosmic acceleration. Therefore, the inclusion of spatial
curvature seems to has no effect on alleviating the tension between SNIa+BAO
and CMB in clear contrast to the previous work in the literature.
