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Every excellent ring is both universally catenary and Nagata. How "close" is a universally catenary Nagata ring to being excellent?

Context: I have not worked very much with the notions described above. While I certainly would not turn down a counterexample, I am more interested in getting an idea of how these notions are used in practice, and when it is appropriate to use one versus the other.

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    $\begingroup$ In this article by Christel Rotthaus, she constructs a three-dimensional regular local ring which is Nagata (universally Japanese) but not excellent. Perhaps it will give you some idea of how hard one must work for such examples. gdz.sub.uni-goettingen.de/dms/load/img/?PPN=GDZPPN002418517 $\endgroup$
    – Graham Leuschke
    Commented Dec 2, 2011 at 20:27
  • $\begingroup$ Unfortunately, I don't speak a word of German, but thanks for the reference in any case. $\endgroup$
    – Charles Staats
    Commented Dec 3, 2011 at 2:10

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Nishimura in "A few examples of local rings, I" constructs a two-dimensional normal Nagata domain that is not analytically normal, and hence not excellent (Example 2.5). Since this example is a normal two-dimensional ring, it is Cohen–Macaulay, and therefore is universally catenary by Theorem 17.9 in Matsumura.

Nishimura attributes the construction to Rotthaus, citing the paper referenced by Graham Leuschke in the comments.

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