R help - Feb 2007 - 2 axes in an coordinate system

Hello sir: 
I wanna get such kind of plot: 

x : location of chromosome
y_left: p value 
y_right: logratio 

In other words,On the left side of plot,y is p value;On the right side of plot,y
is logratio How can I do it via R command?

Thanks a lot! My best!