One of the issues the researchers had to get around in their study was how to determine gender of the authors of journal articles indexed by Thomson Reuters in the Web of Science. They used a combination of sources to match the name to a gender including social security databases, Wikipedia and even Facebook (the interesting methodology can be read in their supplementary material).
It would be interesting to see the same data normalized for funding. In many cases funding agencies are awarding more money to male scientists than to female scientists (e.g. from the ARC's website for Number of participants on all funded projects Male = 2280 and Female = 622). It would be interesting to know whether perhaps female scientists were achieving "more with less" when it came to publication output compared with funding and opportunity.
While there is no single answer to the problem these researchers are describing they do make a good point about improving the ability for female scientist to travel and collaborate internationally:
"For a country to be scientifically competitive, it needs to maximize its human intellectual capital. Our data suggest that, because collaboration is one of the main drivers of research output and scientific impact, programmes fostering international collaboration for female researchers might help to level the playing field."
Researcher mobility in all fields is a good strategy for any organisation that can afford it - and is certainly critical for any developed nation's research strategic plan.