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Laila Al Shaer,1 Ranjita Sharma,2 Mahera AbdulRahman2 1College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, UAE; 2Dubai Health Authority, Dubai, UAE Background: To ensure an adequate and safe blood supply, it is crucial to select suitable donors according to stringent eligibility criteria. Understanding the reasons for donor deferral can help in planning more efficient recruitment strategies and evaluating donor selection criteria. This study aims to define donor pre-donation deferral rates, causes of deferral, and characteristics of deferred donors in Dubai.Materials and methods: This retrospective study was conducted on all donors who presented for allogeneic blood donation between January 1, 2010, until June 30, 2013, in Dubai Blood Donation Centre, accredited by the American Association of Blood Banks. The donation and deferral data were analyzed to determine the demographic characteristics of accepted and deferred donors, and frequency analyses were also conducted.Results: Among 142,431 individuals presenting during the study period, 114,827 (80.6%) were accepted for donation, and 27,604 (19.4%) were deferred. The overall proportion of deferrals was higher among individuals less than 21 years old (35%, P

Policy comparison is useful for a variety of applications, including policy validation and policy-aware service selection. While policy comparison is somewhat natural for policy languages based on description logics, it becomes rather difficult for rule-based policies. When policies have recursive rules, the problem is in general undecidable. Still most policies require some form of recursion to model - say - subject and object hierarchies, and certificate chains. In this paper, we show how policies with recursion can be compared by adapting query optimization techniques developed for the relational algebra. We prove soundness and completeness of our method, discuss the compatibility of the restrictive assumptions we need w.r.t. our reference application scenarios, and report the results of a preliminary set of experiments to prove the practical applicability of our approach.