Can I use a past participle clause after a noun without a relative pronoun or conjunction?
For instance, is it correct just to place "graduated" after "doctor" in the below example without using "who" or "and"? It feels a bit awkward to place "who" when I refer to myself, however, I am not sure about the use of "and".
I am a doctor graduated from Harvard University in 2022.
Either of your suggestions is correct:
I am a doctor who graduated from Harvard University in 2022.
I am a doctor and graduated from Harvard University in 2022.
I agree that the second version sounds much better.
Most readers will infer that your 2022 Harvard degree was your doctorate, but (as another answer noted) that's not 100% certain. Something like this would therefore be clearer (and more concise):
I received my doctorate from Harvard University in 2022.
Finally, I'll note that some sticklers insist that "graduate" is a transitive verb meaning "to grant a degree or diploma to". Those sticklers were not uncommon when I was growing up (decades ago in the Northeast U.S.) but seem to be quite rare nowadays.
It reads very awkwardly without anything there, although I think "and" is better than "who", as "who" makes it sound like you are talking about someone else, not yourself. Although even then, the "and" could make it sound like two separate events, you are a doctor, and you graduated from Harvard in 2022, but that graduation may have been for something completely different, or a different degree entirely.
To make it completely clear you could say something like "I am a doctor, and received my doctorate from Harvard University in 2022".
Yes, you can use a past-participle clause after a noun (see "Whiz deletion"), but when a past participle is used as a participle (as opposed to when it is used in a perfect construction), it is always passive in meaning.
As Marcin says, there is authority for using graduate transitively, but it is rare. Most people use it only intransitively (what the student does, rather than what the institution does), so it does not have a passive, and cannot be used in this construction.
