A central question in drug policy is how control efforts should be divided among enforcement, treatment, and prevention. Of particular interest is how the mix should vary dynamically over the course of an epidemic. Recent work considered how various pairs of these interventions interact. This paper considers all three simultaneously in a dynamic optimal control framework, yielding some surprisi...

Recently, XACML is a popular access control policy language that is used widely in many applications. Policies in XACML are built based on many components over distributed resources. Due to the expressiveness of XACML, it is not trivial for policy administrators to understand the overall effect and consequences of XACML policies they have written. In this paper we show a mechanism and a tool ho...

The world population is aging rapidly, which poses a greater challenge for the institutions involved which, in turn, require new public health policies that include the prevention of falls. The objective of this study was to assess the risk of falls in the elderly. This epidemiological, cross-sectional study was performed at a family health unit, using a quantitative approach. The sample consis...

The decentralized and anonymous characteristics of P2P environments, necessitates the need for an access control model, based on trust and recommendation. Since peers are heterogeneous, some peers might be malicious and in the absence of a centralized authority to punish such peers, mechanisms for trust and recommendation can help to distinguish between good and bad peers. In this paper we prop...

Most organizations use several security policies to control different systems and data, comprising in this way a global complex policy. These security policies are often scattered over different environments, each one with its own security model and domain of administration, making them difficult to administer and understand. Moreover, some applications (e.g. workflow), often need to cross seve...

For at least the past decade, political leaders and policy makers have stressed how important it is for Africa to harness technology, leapfrog development, and take part in the global knowledge economy. In numerous initiatives aimed at realizing these goals, education is a primary target, viewed as a mechanism through which information and communication technologies (ICT) can em­ power societie...

In this paper, we investigate pollutant reduction policies under uncertainty. We assume that when an agent reduces quantity of a pollutant, it incurs costs. We consider two kinds of policies distinguished by their costs. One policy incurs proportional reduction cost (Case 1) and the other incurs fixed and proportional reduction costs (Case 2). To solve these problems, we formulate the agent’s p...