Full-scale unsteady RANSE CFD seakeeping simulations of a high-speed craft

This paper presents a series of RANSE-based seakeeping simulations on a 17m high-speed monohull. The study is performed on the Severn Class all-weather search and rescue lifeboat, designed and operated by the Royal National Lifeboat Institution (RNLI). The Severn is a planing craft with a maximum operational speed of 25 knots, although it often operates at semi-planing and displacement speeds in different situations and weather conditions

Modeling the Cost-Effectiveness for Cement-Less and Hybrid Prosthesis in Total Hip Replacement in Emilia Romagna, Italy

Background. The aim of the present study was to assess the cost-effectiveness of cement-less versus hybrid prostheses in total hip replacement (THR) in patients diagnosed with primary osteoarthritis. Methods. Effectiveness data were obtained from the Emilia-Romagna Regional Registry on Orthopaedic Prosthesis (RIPO), which collects information on all orthopaedic intervention performed in Emilia-Romagna (41,199 total hip replacements performed from 2000 to 2007), and from which we obtained survival curves and transition probabilities for the cement-less and hybrid prostheses, respectively. Conversely, costs were derived from regional databases through a specific procedure, which allowed us to register individual component's costs for both primary and subsequent revision interventions. A specific Markov transition model was constructed in order to consider the 3 types of revisions that an implant could possibly undergo through its life-span: total, cup or stem, head insert or neck. The cost-effectiveness was expressed in terms of cost per "revision-free" life year. Results and conclusions. Considering a 70-y old patient undergoing THR, the cementless strategy resulted more effective but more costly than the hybrid solution, with an incremental cost effectiveness ratio of 2401.63 (sic) per revision-free life year. Following a deterministic sensitivity analysis, hybrid and cementless fixation showed, respectively, a dominance profile for patients older than 83 y and younger than 43 y, whereas for all ages in between, we report a progressive increase in the ICER of cementless prostheses. Our results proved to be robust, as underlined by the probabilistic sensitivity analysis performed using cost distributions. (C) 2011 Elsevier Inc. All rights reserved