Dr. Mike Walden, North Carolina Cooperative Extension economist in the College of Agriculture and Life Sciences at N.C. State University, responds:

"Well, I think, in a word, the economic slowdown happened. The problems in the economy have, of course, been prompting our Federal Reserve - as people know - to cut interest rates. It's widely expected our Fed will cut interest rates further. But other central banks in the world, like the European central bank and the Bank of England, have not followed suit. Or if they have, in the case of the Bank of England, they have not cut rates as much. What this means is that the interest rate earned by U.S. dollars in the world is much lower than the interest rate earned on the pound - the British pound - or the Euro. Now, international investors are always looking for the best return on their money. So when they are looking around the world and they are saying, 'Ok, what currency should we invest in to get the best return on our money.' What they are finding is they don't want the dollar because the interest rates are very low. They're going to go to the Euro or the pound. And so as they do that, that means they are shunning dollars, and the value of that dollar is going down, just like if for some reason people decided not to buy apples, the price of apples would go down. Now, many economists think that eventually foreign central banks will come around, and they will also lower their interest rates. And if they do, that will help prop up the value of the U.S. dollar."