  At a next-to-leading order calculation, the initial-state energy loss of the
quark is investigated by means of the Drell-Yan experimental data including the
new E906 measurements. Furthermore, the incoming gluon energy loss effect
embedded in the Compton scattering subprocess of the nuclear Drell-Yan process
is also examined. The next-to-leading order computations for Drell-Yan ratios
are carried out with the SW quenching weights (provided by Salgado and
Wiedemann to evaluate the probability distribution that quark (gluon) loses the
energy), as well as the nuclear parton distributions (obtained by only fitting
the existing experimental data on nuclear structure functions). It is found
that the obtained calculations that consider the incoming quark energy loss
agree well with the experimental data particularly for E906 data. In addition,
the incoming gluon energy loss embodied in the primary next-to-leading order
Compton scattering subprocess is not obvious, which may be due to the form of
the Drell-Yan differential cross section ratio as a function of the quark
momentum fraction ($R_{A_{1}/A_{2}}(x_{1},x_{2},x_{F})$) minimizes the
influence of the QCD next-to-leading order correction.
