We present the design of an authorization service which parallels existing authentication services for distributed systems. Such a service would operate on top of an authentication substrate. There are two distinct ideas underlying our design: (1) The use of a language, called generalized access control list (GACL), as a common representation of authorization requirements. (2) The use of authen...

Ecology can be defined as the study of ecological systems. A system is any set of components, living or nonliving, that are tied together by regular interactions. An ecological system is made up of one or more organisms, together with the nonliving environment with which they interact. Ecological systems exist at several different levels of organization. An ecological system can be a single org...

In this issue and in a recent issue of Cell, Vahedi et al. and Samstein et al. provide new insights into the strategies used to establish an enhancer landscape during development of cell lineages. They report that enhancer landscapes characterizing T cell lineages are pre-established and strongly influenced by environmental stimuli.

The University of the United Arab Emirates (UAEU) commissioned an international panel of experts to devise a model curriculum for their new College of Information Technology. The model has a university core in the freshman year, an IT core in the second year, and a professional concentration in one of seven degree programs in the third and fourth year. The seven degrees are computer science, co...

Empathy is a fundamental competency for daily communication, interaction, and teamwork, thus most relevant future jobs. Nevertheless, educational organizations are limited in providing the necessary conditions students to develop empathy skills, due traditional large-scale distance-learning scenarios. In this paper, we present insights on how design an adaptive learning tool that helps their ab...

Two things are striking about this medieval definition. The first is that it is very close to the modern conception of formal consequence one finds in Bolzano and Tarski3. The second is that although Buridan and the other fourteenth-century logicians state these distinctions with a great deal of precision, they say almost nothing about the point of the distinctions. Why are these distinctions d...