Mobile, ubiquitous, social and cloud computing have brought an unprecedented amount of information, digitized resources, and computational power—spanning many different devices—to users today. Correspondingly, an increasing amount of work and leisure activity is taking place in this distributed digital computing environment. For example, in a hospital, the medical record and bio-signals of patients are digitized and accessed by multiple stationary, mobile, and wearable devices. At home, digital and social media, email, photo libraries, and the like are accessed on a wide range of devices including laptops, smartphones, TV sets, and other Internet-connected appliances. However, this rapid increase in the diversity and volume of both computational devices and digital content quickly.