Is IPS threading compatible with NPT threading?
According to the Googles, IPS is Iron Pipe Straight thread.  It's meant to seal on a washer-shaped gasket (like the threads the hose for your toilet or faucets attach to).  NPT is a tapered thread, designed to seal on the threads, which is why you put pipe tape on them - to lubricate them and help the threads deform and create a seal.

So, while having no personal experience, I would say no, they will not thread together.  I've been hunting around for adapters, but don't see anything.  Which is weird, because I'd think those arms would be designed to thread into a brass NPTF fitting in the wall/ceiling.