و قد كان "Andrew" يجري بحوثه حول الموضوع و من الأشياء التي قيلت له و التي تعلمها خلال مراجعاته الأدبية هو وجود عائق كبير.
And Andrew had been doing his own bits of research, and one of the things that he had been told and that he'd learned from studying the literature was that there's actually a big bottleneck.