Risk analysis via heterogeneous models of SCADA interconnecting Power Grids and Telco Networks

The automation of Power Grids by means of Supervisory Control and Data Acquisition (SCADA) systems has led to an improvement of Power Grid operations and functionalities but also to pervasive cyber interdependencies between Power Grids and Telecommunication Networks. Many power grid services are increasingly depending upon the adequate functionality of SCADA system which in turn strictly depends on the adequate functionality of its Communication infrastructure. We propose to tackle the SCADA risk analysis by means of different and heterogeneous modeling techniques and software tools. We demonstrate the applicability of our approach through a case study on an actual SCADA system for an electrical power distribution grid. The modeling techniques we discuss aim at providing a probabilistic dependability analysis, followed by a worst case analysis in presence of malicious attacks and a real-time performance evaluation. © 2009 IEEE

Prevalence and associated variables of postdialysis fatigue: results of a prospective multicenter study

AIMS: Little is known about postdialysis fatigue (PDF), a debilitating symptom of hemodialysis patients. METHODS: In 5 hemodialysis units of northern-centre Italy, patients were regarded to suffer from PDF if they spontaneously offered this complaint when asked the open-ended question: Do you feel better or worse after dialysis? If worse, please specify in which way. A complaint of fatigue would be probed further with questions directed at its duration, frequency and intensity, allowing creation of a fatigue index of severity (one third of the sum of these three parameters, each rated from 1 to 5). Patients were stratified into three groups according the severity of PDF: 1) score\u2009=\u20090; 2) score\u2009=\u20091-3; 3) score\u2009>\u20093. RESULTS: We studied 271 patients: 164 had PDF and 107 had not. PDF patients had significantly longer time of recovery after dialysis (TIRD). TIRD was significantly associated with PDF duration, intensity, and frequency. Patients with PDF were older and had a lower ADL score. At multivariate analysis, PDF was significantly associated with TIRD. In multivariate model that did not include TIRD, PDF was independently associated with age and ADL. Sixty patients had moderate PDF and 104 severe PDF. In patients with severe PDF, age and dialytic age were higher, ADL and IADL scores were lower, TIRD was longer and the ultrafiltration rate was lower. At multivariate analysis, PDF severity was independently associated with TIRD. In the model without TIRD, PDF severity was associated with ADL only. CONCLUSION: PDF is frequent and associated with age and ADL. Dialytic variables seem unrelated to PDF