I have no idea of any USB or card reader ports exist for the Nexus 10. I do know Samsung USB and card reader ports for Android tablets, but they work only for Samsung branded Tablets (Galaxy Tabs and Note 10.1). And you won't want to be looking at DSLR raws on those tabs due to lower res screen.
PS:
From the looks of this, looks like there isn't a microSD to microUSB adapter yet
http://www.indiegogo.com/microsdtomicrousb
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