Security Policy Specification Using a Graphical Approach

A security policy states the acceptable actions of an information system, as the actions bear on security. There is a pressing need for organizations to declare their security policies, even informal statements would be better than the current practice. But, formal policy statements are preferable to support (1) reasoning about policies, e.g., for consistency and completeness, (2) automated enforcement of the policy, e.g., using wrappers around legacy systems or after the fact with an intrusion detection system, and (3) other formal manipulation of policies, e.g., the composition of policies. We present LaSCO, the Language for Security Constraints on Objects, in which a policy consists of two parts: the domain (assumptions about the system) and the requirement (what is allowed assuming the domain is satisfied). Thus policies defined in LaSCO have the appearance of conditional access control statements. LaSCO policies are specified as expressions in logic and as directed graphs, giving a visual view of policy. LaSCO has a simple semantics in first order logic (which we provide), thus permitting policies we write, even for complex policies, to be very perspicuous. LaSCO has syntax to express many of the situations we have found to be useful on policies or, more interesting, the composition of policies. LaSCO has an object-oriented structure, permitting it to be useful to describe policies on the objects and methods of an application written in an object-oriented language, in addition to the traditional policies on operating system objects. A LaSCO specification can be automatically translated into executable code that checks an invocation of a program with respect to a policy. The implementation of LaSCO is in Java, and generates wrappers to check Java programs with respect to a policy.Comment: 28 pages, 22 figures, in color (but color is not essential for viewing); UC Davis CS department technical report (July 22, 1998

The evidence of published papyrus fragments for the text of fifth century drama at Athens

The aim of this work is to provide a comprehensive and documented catalogue of the published papyrus texts from Graeco-Roman, Egypt which coincide with extant mediaeval sources of Fifth Century Athenian Drama. To facilitate comparison, the papyrus evidence is accompanied" by a parallel modem recension; for the fully extant dramas the Oxford Classical Texts of Aeschylus, Sophocles, Euripides and Aristophanes have been, used and for the "fragmenta" the texts of Nauck (ed. altera) and Kock. The evidence of the papyri has been presented' as a simple transcript or "Abschrift". This form allows the continued use of one standard parallel text irrespective of the deviations of individual papyri from the textus receptus. At the same time prejudicing suppletions are avoided', and editorial symbols reduced to a minimum. Variant readings of the papyri and mss, and characteristic features of the papyri are recorded in the apparatus criticus. Significant textual material is discussed: in the commentary. All new variants and readings of the papyri which support existing presumptive variants have been noted, and, if necessary, evaluated. Where the surviving evidence indicates that the papyrus text diverged from the mediaeval mss tradition editorial reconstructions have been considered; im at least four instances the differences appear to be less extensive than hitherto assumed. Certain corruptions in the papyri indicate the previous existence of readings not extant in the mediaeval mss; the probable nature of such lost variants has been explored. An index of new variants is appended, and the frequency of these analysed in selected plays of differing mss representation. It is apparent that papyri of the Romans and Byzantine periods maintain a fairly constant standard, and any appreciable increase in the proportion: of new variants in these papyri may normally be associated with peculiarities in the later transmission of individual plays. The proportion of new variants in texts immediately before the Alexandrian recension is three times greater than in the subsequent papyri, indicating the need for greater reserve in the consideration of Ptolemaic variants

Fault tolerant architectures for integrated aircraft electronics systems

Work into possible architectures for future flight control computer systems is described. Ada for Fault-Tolerant Systems, the NETS Network Error-Tolerant System architecture, and voting in asynchronous systems are covered

Fault tolerant architectures for integrated aircraft electronics systems, task 2

The architectural basis for an advanced fault tolerant on-board computer to succeed the current generation of fault tolerant computers is examined. The network error tolerant system architecture is studied with particular attention to intercluster configurations and communication protocols, and to refined reliability estimates. The diagnosis of faults, so that appropriate choices for reconfiguration can be made is discussed. The analysis relates particularly to the recognition of transient faults in a system with tasks at many levels of priority. The demand driven data-flow architecture, which appears to have possible application in fault tolerant systems is described and work investigating the feasibility of automatic generation of aircraft flight control programs from abstract specifications is reported

Techniques for the realization of ultrareliable spaceborne computers Interim scientific report

Error-free ultrareliable spaceborne computer

Design of a fault tolerant airborne digital computer. Volume 1: Architecture

This volume is concerned with the architecture of a fault tolerant digital computer for an advanced commercial aircraft. All of the computations of the aircraft, including those presently carried out by analogue techniques, are to be carried out in this digital computer. Among the important qualities of the computer are the following: (1) The capacity is to be matched to the aircraft environment. (2) The reliability is to be selectively matched to the criticality and deadline requirements of each of the computations. (3) The system is to be readily expandable. contractible, and (4) The design is to appropriate to post 1975 technology. Three candidate architectures are discussed and assessed in terms of the above qualities. Of the three candidates, a newly conceived architecture, Software Implemented Fault Tolerance (SIFT), provides the best match to the above qualities. In addition SIFT is particularly simple and believable. The other candidates, Bus Checker System (BUCS), also newly conceived in this project, and the Hopkins multiprocessor are potentially more efficient than SIFT in the use of redundancy, but otherwise are not as attractive

Thyroid dysfunction in the elderly

The International Society for Burns Injuries (ISBI) has published guidelines for the management of multiple or mass burns casualties, and recommends that 'each country has or should have a disaster planning system that addresses its own particular needs.' The need for a national burns disaster plan integrated with national and provincial disaster planning was discussed at the South African Burns Society Congress in 2009, but there was no real involvement in the disaster planning prior to the 2010 World Cup; the country would have been poorly prepared had there been a burns disaster during the event. This article identifies some of the lessons learnt and strategies derived from major burns disasters and burns disaster planning from other regions. Members of the South African Burns Society are undertaking an audit of burns care in South Africa to investigate the feasibility of a national burns disaster plan. This audit (which is still under way) also aims to identify weaknesses of burns care in South Africa and implement improvements where necessary

Tungsten resonance integrals and Doppler coefficients Third quarterly report, Jan. - Mar. 1966

Reactivities, Doppler coefficients, and resonance integrals for tungsten isotope