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This review provides a synthesis of recent work, using computational methods, on the action and inhibition mechanisms of class I ribonucleotide reductase (RNR). This enzyme catalyzes the rate-limiting step of the pathway for the synthesis of DNA monomers and, therefore, has long been regarded as an important target for therapies aiming to control pathologies that depend strongly on DNA replication. In fact, over the last years, several molecules, which are able to impair RNR activity by different mechanisms, have been applied effectively in anti-cancer, anti-viral and anti-parasite therapies. A better understanding of the chemical mechanisms involved in normal catalysis and in inhibition of the enzyme is important for the rational design of more specific and effective inhibitor compounds. To achieve this goal, computational methods, particularly quantum chemical calculations, have been used more and more frequently. The ever-growing capabilities of these methods together with undeniable advantages make it a stimulating area for research purposes.

Abstract
Virtual electronic patient records (VEPR) enable the integration and sharing of healthcare information within large and heterogeneous organizations. The use of wireless technology can improve and fasten healthcare treatment because it brings information to the point of decision allowing also for users' mobility. This use has to comply with security requirements as the wireless technology introduces some specific security problems. The main objective of this work is to model and develop a proposal for a secure wireless architecture in order to access a VEPR. This VEPR is being used within a university hospital by more than 500 doctors, on a daily basis. Its users would greatly benefit if this service would be extended to a wider part of the hospital and not only to their workplace. They would achieve faster and greater mobility in the treatment of their patients. The wireless architecture includes the latest wireless security standards and protocols, and models security requirements according to users and organizations' needs. It provides an extra security layer to the wired system. In this paper we also present an evaluation of the proposed solutions against network attacks and its efficiency in terms of complexity and impact within the network. © 2007 IEEE.

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This paper investigate the fractional-order dynamics during the evolution of a Genetic Algorithm (GA). In order to study the phenomena involved in the GA population evolution, themutation is exposed to excitation perturbations during some generations and the corresponding fitness variations are evaluated. Three similar functions are tested to measure its influence in GA dynamics. The input and output signals are studied revealing a fractional-order dynamic evolution.

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Voltage stability has become a very importante issue of power systems analysis. This paper discusses some important aspects related to voltage stability indices in electric power systems. Some techniques previously studied in the literature are analyzed and a comparison of the performance of several indices is presented. The effectiveness of the analyzed methods are demonstrated through numerical studies in IEEE 14 busbar test system, using several different scenarios of load increase. © 2006 IEEE.

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