Using dashes, ellipses

From Slate: "Dashes — useful and lovely though they are — are not … ellipses. They excel at representing interruptions, trains of thought abruptly shorn off. Meanwhile, an ellipsis trails away gradually, delicately, all hesitance and apprehension. If a dash indicates the sudden arrival of a fiend in a Bram Stoker novel ('The curtains flutter strangely in the moonlight, I hear a noise —'), an ellipsis means the monster has come and gone, and things aren't looking good for the victim. ('It had … fangs … my neck … ow.')"