  Using dynamic light scattering, we measure for the first time the
temperature-dependent elastic moduli and associated orientational viscosity
coefficients of the nematic phase in a self-assembled lyotropic chromonic
liquid crystal. The bend K3 and splay K1 moduli are an order of magnitude
higher than the twist K2 constant. The ratio K3/K1 shows an anomalous increase
with temperature; we attribute this to the shortening of the aggregates as
temperature increases. The viscosity coefficients also show a significant
anisotropy, as well as a strong temperature dependence; in particular, the bend
viscosity is three orders of magnitude smaller than the splay and twist
viscosities.
