What does “them” refer to here?

Please consider the following sentence.

I summarize these topics in the conclusions, with hopes that others will research them further.

Does “them” refer to the “topics,” or does it refer to the “conclusions”? It is supposed to refer to the former. Am I forced to write it more verbosely, as follows?

I summarize these topics in the conclusions, with hopes that others will research the topics further.

I think there are three ways to analyze this, two of which have been suggested.

The first is with a naive application of the rule of the nearest antecedent. "Conclusions" is separated from "them" by fewer words than "topics," so "conclusions" must be the antecedent.

The second is with a highbrow application of the rule of the nearest antecedent. (I am applying a theory here that I was exposed to only in passing a long time ago, so forgive any injustice I might do to it and my lack of attribution.) Consider this pseudo-diagram of your sentence:

(I) (summarize) (these topics)
     ├ (in (the conclusions))
     └ (with (the hope)) 
              └ (that (others) (will research) (them)
                                └ (further)

"Them" occurs in a clause that ultimately modifies "summarize," so any route to the antecedent passes through that word. From "summarize," it is one syntactic step to "topics," whereas it is two steps to "conclusions" (one step to the "in" phrase, then another into that phrase). Additionally, "these topics" is restrictive--and therefore semantically integral--but "in the conclusions" is not. Therefore, "topics" is the syntactically nearer antecedent and it must be the one intended.

The third is a semantic analysis, as suggested in an earlier answer. If you are suggesting that others research your conclusions, then you are in effect asking your reader to check your math, and that doesn't speak well of your confidence in your own scholarly abilities. Furthermore, by summarizing the topics, you're already suggesting that further work could be done.

In conclusion, I think the risk of confusion is low, and the effect of any confusion is minimal; if a reader is going to hold against you any miscue this sentence causes, he will likely have other, more substantive criticisms of your work.

That said, no one will misunderstand, "My conclusions include a summary of these topics for those who would research them further." Your hopes are less than relevant in serious writing; further research will be driven by the importance of the topics, not a future scholar's worry that you'll be saddened by unfulfilled hopes.

I took "them" to refer to the "topics", not the "conclusions", in your first version.

I do not know if there is a general rule (such as that a subordinate clause will be presumed to refer to the object or direct object of the main clause of the sentence). At least part of reason for my reading the sentence that way semantic: You don't generally research a conclusion, though you may research the reasoning behind it. Topics can be researched, while conclusions can be disputed or confirmed by further research.

The pronoun (according to my high-school English teacher) refers to the nearest preceding noun, so it refers to "conclusions" in your sentence. But that doesn't make sense. It is confusing, however slightly. To remove all doubt, you might want to rephrase your sentence along the lines of:

"In the conclusions, I summarize these topics with hopes that others will research them further."