Now as you all know I'm, something of a Jack the Ripper buff, have all the books fiction and non,seen all the movies, watched all the documentaries, have a picture of Mary Kelly in my photo album.
While this article is very interesting and has some valid points I must point out five of my own observations.
1) A woman in this day and age would not have the opportunity to study medicine
2)A woman wandering around White Chapel, especially rich would stand out and someone would have seen her.
3) Serial killer females by statistics do not kill and mutilate other women. They kill men. If they do kill women it's because they were a)hired to do so or b)in a fit of passion
4) Women in this era did not "work out" they were kept beautiful and pliant. So no woman unless she were a supernatural creature would have had the upper body strength needed to cut through all the layers of tissue and fat to bleed their victim out.
5) The letters sent to police have never been proven, and in fact most historians believe they are fake, to be from "Jack The Ripper." Handwriting experts have been documented in saying the hand writing is too different to be the same person. Just because a woman licked the envelopes doesn't mean that a woman was Jack the Ripper and the invention of envelopes with Mechanised gumming (where you have to lick them shut rather than seal with wax or something else) didn't come around until 1890-1900's.
So on conclusion (besides the fact that viable DNA after 118 years in almost non existent and unbelievable) if it were a woman she would have to be a vampire/shapesifter/demon/sidhe/witch to pull off these killings. Though on a personal level I believe that it was probably something supernatural.
That is all. :)