To probe into pulsar's interior through gravitational waves
  The gravitational radiation from compact pulsar-like stars depends on the state of dense matter at supranuclear densities, i.e., the nature of pulsar (e.g., either normal neutron stars or quark stars). The solid quark star model is focused for the nature of pulsar-like compact objects. Possible gravitational emission of quark stars (either fluid or solid) during the birth and later lifetime is discussed. Several observational features to distinguish various models for pulsar-like stars are proposed. It is suggested that the gravitational wave behaviors should be mass-dependent. Based on the data from the second LIGO science run, the upper limits of R.theta^{1/5} and thus M.theta^{3/5} (M: mass, R: radius, and theta: wobble angle) are provided for those targets of millisecond pulsars. 
R. X. Xu (PKU)