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The ``Cardassian Expansion Scenario'' was recently proposed by Freese and Lewis (2002) as an alternative to a cosmological constant in explaining the current accelerating universe. In this paper we investigate observational constraints on this scenario from recent measurements of the angular size of high-z compact radio sources compiled by Gurvits et al. (1999). We show that the allowed intervals for n and z₄ₐ, the two parameters of the Cardassian model, are heavily dependent on the value of the mean projected linear size l. However, the best fit to the current angular size data prefers the conventional flat \CDM model to this Cardassian expansion proposal, though the latter is cosmologically credible and compatible with the \ - z diagram for some values of l.
Zhu et al. (Tue,) studied this question.