Answer to Question 1
PtD causes designers to think through what workers will actually have to do in constructing the permanent features of a structure. If any aspect of the design creates a hazardous condition the design is altered to eliminate or mitigate the condition.
Answer to Question 2
Heinrich's theory has two central points: 1) Injuries are caused by the action of preceding factors; and 2) removal of the central factor (unsafe act/hazardous condition) negates the action of the preceding factors and, in so doing, prevents accidents and injuries.
The structure of climate diagrams.
Motifs of protein secondary structure
Crystal structure of an adenylate cyclase catalytic domain
Structure of E. coli 30S pre-rRNA
Product safety
Structure of immunoglobulin molecules