Even using an authenticated synchronous broadcast model, the task of unforgeably time-stamping digital documents still presents some problems. It is simply not practical to assume that all participants will record and store everyone else's documents so that creation times can be veri ed. This paper presents a time and space e cient method for accumulation of time-stamped documents. Whenever a q...

Papers published in this report series are preliminary versions of journal articles and not for quotations. Abstract This paper extends the real options literature by discussing an investment problem, where a firm has to determine optimal investment timing and optimal capacity choice at the same time under conditions of irreversible investment expenditures and uncertainty in future demand. Afte...

............................................................................................................................. ii Dedication ......................................................................................................................... iii Acknowledgments ............................................................................................................ iv Tab...

This review deals with computer simulation of biological aging, particularly with the Penna model of 1995. They are based on the mutation accumulation theory of half a century ago. The results agree well with demographical reality, and also with the seemingly contradictory influence of predators on the aging of prey.

Accumulation of contextual data offers new opportunities to improve the preventative health and wellbeing interventions. In this paper, we discuss the importance of understanding the context elements of Behavior Change Support Systems (BCSSs) and present an Event model illustrating the Use, User and Technology Context factors of the Persuasion Context. The model is a conceptual tool for identif...