Editor’s note: Twelve months on from the killing of George Floyd, The Economist is publishing a series of articles, films, podcasts, data visualisations and guest contributions on the theme of race in America. Policies can be reworked to help manage borders and protect those in genuine need, says Barham Salih, the UN’s refugees commissioner Demanding that China revalue the yuan gets both the diagnosis and the cure wrong, write Gita Gopinath, Pierre-Olivier Gourinchas and Hélène Rey