Well that DOCTYPE neither has a system id pointing to an external DTD file nor an internal subset so it shouldn't change the parsing, unless your XML parser is using a catalog file to map the public identifier "-//ES//DTD full length article DTD version 4.3.1//EN" to a DTD file. You would need to look into the DTD file to find out whether it has similar namespace declarations as the one you posted earlier.
As an alternative you could write a stylesheet doing
Code:
<xsl:template match="/"><xsl:copy-of select="."/></xsl:template>
and inspect the result, it should show any namespace declarations. Then you need to take them into account, the same way as we showed you for the other file.