斑竹及各方高人救命啊！！！

最近正在准备和导师联系，不料种种导师的不同称呼让我乱了手脚。请各位大虾们帮帮小妹吧，感激不尽，并且涕零，呜呜......。
  下面是各种头衔：Head of department/associated professor, professor, adjunct associate professor, senior professor, senior specialist.
  该给哪个头衔的人发信联系呢？？