patterns in daily user activity, infer relationships, identify socially significant locations, and model organizational rhythms.

…Truth [is] being involved in an eternal conversation about things that matter, conducted with passion and discipline…truth is not in the conclusions so much as in the process of conversation itself…if you want to be in truth you must be in conversation. Parker Palmer

This tutorial paper explores the mechanics of protecting computer-stored information from unauthorized use or modification. It concentrates on those architectural structures--whether hardware or software--that are necessary to support information protection. The paper develops in three main sections. Section I describes desired functions, design principles, and examples of elementary protection and authentication mechanisms. Any reader familiar with computers should find the first section to be reasonably accessible. Section II requires some familiarity with descriptor-based computer architecture. It examines in depth the principles of modern protection architectures and the relation between capability systems and access control list systems, and ends with a brief analysis of protected subsystems and protected objects. The reader who is dismayed by either the prerequisites or the level of detail in the second section may wish to skip to Section III, which reviews the state of the art and current research projects and provides suggestions for further reading. Glossary The following glossary provides, for reference, brief definitions for several terms as used in this paper in the context of protecting information in computers. Access The ability to make use of information stored in a computer system. Used frequently as a verb, to the horror of grammarians. Access control list A list of principals that are authorized to have access to some object. Authenticate To verify the identity of a person (or other agent external to the protection system) making a request.

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El Salvador, Guatemala is a, study in black and white. On the left is a collection of extreme Marxist-Leninist groups led by what one diplomat calls “a pretty faceless bunch of people.’ ’ On the right is an entrenched elite that has dominated Central America’s most populous country since a CIA-backed coup deposed the reformist government of Col. Jacobo Arbenz Guzmán in 1954. Moderates of the political center. embattled but alive in E1 Salvador, have virtually disappeared in Guatemala-joining more than 30.000 victims of terror over the last tifteen vears. “The situation in Guatemala is much more serious than in EI Salvador, ” declares one Latin American diplomat. “The oligarchy is that much more reactionary. and the choices are far fewer. “ ‘Zero’: The Guatemalan oligarchs hated Jimmy Carter for cutting off U.S. military aid in 1977 to protest human-rights abuses-and the right-wingers hired marimba bands and set off firecrackers on the night Ronald Reagan was elected. They considered Reagan an ideological kinsman and believed they had a special

Work organizations offer a person far more than merely.a job. Indeed, from the time individuals first enter a workplace to the time they leave their member-ship behind, they experience and often.commit themselves to a distinct way of life complete with its own rhythms, rewards, relationships

Copyright 2013 by the Office of the General Assembly Presbyterian Church (U.S.A.) No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronically, mechanically, photocopying, recording, or otherwise (brief quotations used in magazine or newspaper reviews excepted), without the prior permission of the publisher. The sessions, presbyteries, and synods of the Presbyterian Church (U.S.A.) may use sections of this publication without receiving prior written permission from the publisher.

We are interested in designing systems that support communication and collaboration among large groups of people over computer networks. We begin by asking what properties of the physical world support graceful human-human communication in face-to-face situations, and argue that it is possible to design digital systems that support coherent behavior by making participants and their activities visible to one another. We call such systems “socially translucent systems ” and suggest that they have three characteristics—visibility, awareness, and accountability—which enable people to draw upon their social experience and expertise to structure their interactions with one another. To motivate and focus our ideas we develop a vision of knowledge communities, conversationally based systems that support the creation, management and reuse of knowledge in a social context. We describe our experience in designing and deploying one layer of functionality for knowledge communities, embodied in a working system called “Babble, ” and discuss research issues raised by a socially translucent approach to design. Categories and Subject Descriptors: H.1.2 [Models and Principles]: User/Machine Systems—Human factors; Human information processing; H.5.2 [Information Interfaces and

A fundamental problem in text data mining is to extract meaningful structure from document streams that arrive continuously over time. E-mail and news articles are two natural examples of such streams, each characterized by topics that appear, grow in intensity for a period of time, and then fade away. The published literature in a particular research field can be seen to exhibit similar phenomena over a much longer time scale. Underlying much of the text mining work in this area is the following intuitive premise --- that the appearance of a topic in a document stream is signaled by a "burst of activity," with certain features rising sharply in frequency as the topic emerges.

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