1 Subjects: “...gravel grain shape...”

2 Subjects: “...gravel beaches...”

3 Subjects: “...,Oil prices,Debt,Trade,Green Deal,Alternative data,Dynamic Capabilities,Technology,Travel barriers...”

4 “... of geographical borders as well as the individuals who travel between them and those who live in border regions...”

5 “..., including large increases in international travel, threats posed by emerging infections, and the movement...”

6 “... to travel, ease of communication and technology, and civil unrest and conflicts. Global populations have...”