have you written any interesting papers lately regarding bitcoin? It's a topic that I havent seen a lot of substantial academic research on.
No, nothing formally published yet.
I only started to write a tech report on how a mining cartel with majority hashpower can force a change in the protocol, such as postponing the next halving, in spite of opposition by the "economic majority" -- by sabotaging the old chain while mining the new one. But, after countless forum discussions, that attack is now well known, and I haven't got enough motivation to finish it.
(1)Other than that, the closest to a technical article I wrote is
this post about bitcoin price bubbles.
(2)(1) Critics have two arguments to dismiss it. First, they claim that any such attempt would cause a drop in the price that would negate the cartel's expected payoff. Second, they say that developers could change the PoW algorithm so as to render ASICs useless, and all users would shun the CartelCoin and use only the DevCoin. I don't accept either argument, but since they depend on predicting the behavior of people, we have no way of proving our positions...
(2) That sum-of-bubbles model is less satisfactory after the Dec/2014 crash, unfortunately. The most prominent "bubbles" became almost rectangular pulses: a sudden rise, a plateau, then a sudden drop. In 2015 the price became even more irregular: there were three apparent bubbles (in February, June, and September) but their shapes were more complicated than the model that worked before 2014...