The Audit Logic: Policy Compliance in Distributed Systems

We present a distributed framework where agents can share data along with usage policies. We use an expressive policy language including conditions, obligations and delegation. Our framework also supports the possibility to refine policies. Policies are not enforced a-priori. Instead policy compliance is checked using an a-posteriri auditing approach. Policy compliance is shown by a (logical) proof that the authority can systematically check for validity. Tools for automatically checking and generating proofs are also part of the framework.\u

Evidence for two-electron processes in the mutual neutralization of O- with O+ and N+ at Subthermal Collision Energies

We have measured total absolute cross sections for the Mutual Neutralization (MN) of O- with O+/N+. A fine resolution (of about 50 meV) in the kinetic energy spectra of the product neutral atoms allows unique identification of the atomic states participating in the mutual neutralization process. Cross sections and branching ratios have also been calculated down to 1 meV center-of-mass collision energy for these two systems with a multi-channel Landau-Zener model and an asymptotic method for the ionic-covalent coupling matrix elements. The importance of two-electron processes in one-electron transfer is demonstrated by the dominant contribution of a core-excited configuration of the nitrogen atom in N+ + O- collisions. This effect is partially accounted for by introducing configuration mixing in the evaluation of coupling matrix elements.Comment: 5 pages, 4 figure

X-ray image reconstruction from a diffraction pattern alone

A solution to the inversion problem of scattering would offer aberration-free diffraction-limited 3D images without the resolution and depth-of-field limitations of lens-based tomographic systems. Powerful algorithms are increasingly being used to act as lenses to form such images. Current image reconstruction methods, however, require the knowledge of the shape of the object and the low spatial frequencies unavoidably lost in experiments. Diffractive imaging has thus previously been used to increase the resolution of images obtained by other means. We demonstrate experimentally here a new inversion method, which reconstructs the image of the object without the need for any such prior knowledge.Comment: 5 pages, 3 figures, improved figures and captions, changed titl

Log Analysis for Data Protection Accountability

International audienceAccountability is increasingly recognised as a cornerstone of data protection, notably in European regulation, but the term is frequently used in a vague sense. For accountability to bring tangible benefits, the expected properties of personal data handling logs (used as "accounts") and the assumptions regarding the logging process must be defined with accuracy. In this paper, we provide a formal framework for accountability and show the correctness of the log analysis with respect to abstract traces used to specify privacy policies. We also show that compliance with respect to data protection policies can be checked based on logs free of personal data, and describe the integration of our formal framework in a global accountability process

Factors affecting the survival of patients with oesophageal carcinoma under radiotherapy in the north of Iran

Factors relevant to the survival of patients with oesophageal cancer under radiotherapy have been studied in northern Iran where its incidence is high. We conducted an analytical study using a historical cohort and information from the medical charts of patients with oesophageal cancer. Out of 523 patients referred to the Shahid Rajaii radiotherapy centre in Babolsar from 1992 to 1996, we followed 230 patients for whom an address was available in 1998. The frequency of prognostic factors among those not contacted was very similar to those included in the study. The data were analysed using survival analysis by the nonparametric method of Kaplan Meier and the Cox regression model to determine risk ratios (RR) of prognostic factors. Survival rates were 42% at 1 year, 21% at 2 years, and 8% at 5 years after diagnosis. Patients aged 50–64 were found to have poorer survival compared with those less than 50 (RR = 1.73, P = 0.03); the risk ratio for ages f = 65 was 1.88 (P = 0.03). Females had significantly better survival than males (RR = 0.71, P = 0.02). For each 100 rads dose of radiotherapy, the risk ratio was significantly decreased by 1% (RR = 0.99, P = 0.05); for each session of radiotherapy, the risk ratio was significantly decreased by 4% (RR = 0.96, P = 0.0001); for each square centimetre size of surface under radiotherapy, the risk ratio significantly increased (RR = 1.002, P = 0.04). We did not observe a significant difference on survival by histology, anatomical location of tumours, or type of treatment (P > 0.05). Prognosis is extremely poor. © 2001 Cancer Research Campaign http://www.bjcancer.co

Production of Very Cold, Highly Charged Ions by Synchrotron Radiation: Comparisons of the ''Scalpel'' and ''Hammer'' Methods

Measurements of kinetic energies of highly charged argon ions produced by inner-shell photoionization and by ion-beam impact have been made using time-of-flight techniques. High-charge-state recoil ions produced by beams of approx..5 - 1 MeV/u Cl/sup +5/ are found to have energies one to two orders of magnitude higher than ions of the same charge produced by vacancy cascades following inner-shell photoionization by synchrotron radiation. The results may have application to the development of a very-cold ion source useful for angle-resolved atomic collision studies