Something tells me it is Nbeta.
When you try to draw some of its resonance structures, you can come up with the following(see figure attached) :
In addition to the stabilization due to aromaticity in the figure, the beta N is attached to 2 C=O groups.
I'm definitely not sure, but I thought I'd give it a shot
Oh...and one more thing. How do I attach a figure without having to attach a file?
I mean can I copy a picture from Chemdraw and just paste it here?