Volume 73, no. 10, p. 6752-6762, 2005. Page 6752, column 2, line 15: (high-MW) (100 to 500) should read (high-MW, 100,000 to 500,000).
Page 6753, column 1, line 8 from bottom: an average MW of ∼100 should read an average MW of ∼100,000).
Column 2, line 19: (average MW, ∼100) should read (average MW, ∼100,000).