First Author:   Ana Maria Takahashi University of Utah, US piciorea@economics.utah.edu   Flat 2007 A, Urasa 1014-1 Minamiuonuma, 9497302, Japan   +81-257775127(Phone) +81-257775127(Fax) Second Author: Shingo Takahashi International University of Japan, Japan staka@iuj.ac.jp   International University of Japan Minamiuonuma, 9497277, Japan   +81-257791106(Phone) +81-257775127(Fax)