There’s a quiet memorial in San Francisco’s Golden Gate Park, cradled between groves of hardy trees topped with quilted canopies. Sunlight pierces through their verdant veils, casting dappled light...

Michael Slater, 27, presents his Truvada pill - a medication that prevents HIV by 99 percent. Photos by Martin Bustamante By Carlos Mendoza Two and a half years ago Michael Slater, a 26-year-old homosexual,...