SITUATION EXPLAINED: Aschenbrenner's letter to investors: full responsibility, no more leverage, staying in public equities. • The letter went out last night, he takes "full responsibility," and says the fund will no longer borrow from banks to magnify its bets • It will keep operating in public equities, not converting into a private fund as people had speculated • He compared the dynamics to a bank run, and partly blamed short sellers targeting the fund's positions • New from the FT: when…