verbs - "has been raised" or "was raised" in an academic journal

The first line in my research is the following:

Since the May 6, 2010 ``Flash Crash’’ event, the following question
has been raised several times: Does High-Frequency Trading increase
the likelihood of long tail and chaotic events in financial markets?

Should I say

Since the May 6, 2010 ``Flash Crash’’ event, the following question
was raised several times: Does High-Frequency Trading increase the
likelihood of long tail and chaotic events in financial markets?

I have been told that I have to avoid "has been" and even "was" in academic journals. Is there a better way for me to improve my sentence?

Answer

If your intention was to tie the raising of said question to the event, it's possible to phrase it like this:

The May 6, 2010 ``Flash Crash’’ event provoked much questioning along the following lines: does High-Frequency Trading increase the likelihood of long tail and chaotic events in financial markets?

or alternatively (and I think it is better this way, without the question directly asked; more noticeably professional than any exclusion of "has been" or "was" would denote):

The May 6, 2010 ``Flash Crash’’ event caused many to question whether High-Frequency Trading increases the likelihood of long tail and chaotic events in financial markets.

I have to say, however, that I have never come across such a prohibition of "has been" or "was" in journals, and you should not feel like you have to abide strictly by such a restriction where it makes writing more awkward. Communication is the goal, after all.