Rates inched lower Tuesday as China unexpectedly devalued its currency in an effort to boost its economy. Investors interpreted the move as a sign that China’s economy is slowing more quickly than expected. Stocks fell sharply, boosting mortgage-backed securities. In the U.S., second quarter Productivity rose 1.3%, a bit slower than expected. Results from today’s 3-year Treasury auction will be released at 1:00 PM.