Whereas it is the duty of all nations to acknowledge the providence of almighty God, to obey his will, to be grateful for his benefits, and humbly to implore his protection and favor and whereas both houses of Congress have by their joint committee requested me "to recommend to the people of the United States a day of public thanksgiving and prayer to be observed by acknowledging with grateful hearts the many signal favors of Almighty God, especially by affording them an opportunity peaceably to establish a form of government for their safety and happiness."

VOA: special.2009.11.23

The signal comes in the form of molecules which we're going to call throughout the lecture here 'ligands'.

信号通常以分子的形式来传递,在这门课里我们把这种分子叫做配体

耶鲁公开课 - 生物医学工程探索课程节选

In the case of a ligand-receptor, a chemical signal in the form of a concentration of ligand gets converted into a biochemical signal.

在配体-受体系统中,配体浓度这种化学信号,转化为生化信号

耶鲁公开课 - 生物医学工程探索课程节选