450935.fig.002a
(a)
450935.fig.002b
(b)
450935.fig.002c
(c)
450935.fig.002d
(d)
Figure 2: Contour plots of and : (a) plot of contours of versus and ; (b) plot of contours of versus and ; (c) plot of contours of versus and ; (d) plot of contours of versus and . All other parameters are fixed as follows: , , , , , , , , , , , , and .