(S (S (NP (BASENP (NNP Burda) (POS 's)) (BASENP (JJ previous) (NN research))) (VP (VBZ involves) (NP (BASENP (JJ naked) (NN mole) (NNS rats)) (COMMA ,) (NP (BASENP (DT a) (JJ small) (JJ blind) (NN mammal) (NN species)) (SBAR (WHNP (WPD whose) (NN behavior)) (S (VP (VBZ indicates) (BASENP (DT an) (JJ internal) (JJ magnetic) (NN compass))))))))) (PERIOD .))