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Recent Techniques (recent + techniques)
Selected AbstractsThe History of Sclerosing FoamsDERMATOLOGIC SURGERY, Issue 5 2004Jan-Christoph G. R. Wollmann MD Background. The use of foamed sclerosants in phlebology is undergoing a renaissance. The use of foam sclerotherapy was relaunched only a few years ago. Despite this, the early developments, pioneer findings, and improvements, especially in foaming techniques, are not widely recognized. Objective. The objective of this study was to give an overview from the very beginnings of foam sclerotherapy until the most recent and progressive techniques, as described by Tessari or the double syringe system technique. Results. The publications found after a thorough research for literature about foam sclerotherapy allow us to examine what has been invented between Orbach's work in 1944 and now and,surprisingly,even before 1944. The contributions of greatly reputed and also of unknown colleagues, such as Orbach, Sigg, Mayer, or Flückiger, are presented, giving a historical overview from the very beginnings of foam sclerotherapy until the most recent techniques. Basically, the literature shows that remarkable work was carried out in the field of noncommercial foam sclerotherapy and that sclerosing foams have been used by numerous doctors continuously for the past six decades, especially for the treatment of varicose veins of the lower limbs. Conclusion. The use of foamed sclerosing agents in therapy of large or small varicose veins is not new. It started as early as 1939 and has continuously been improved in the past decades. [source] Robust fault estimation of uncertain systems using an LMI-based approachINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 18 2008Euripedes G. Nobrega Abstract General recent techniques in fault detection and isolation (FDI) are based on H, optimization methods to address the issue of robustness in the presence of disturbances, uncertainties and modeling errors. Recently developed linear matrix inequality (LMI) optimization methods are currently used to design controllers and filters, which present several advantages over the Riccati equation-based design methods. This article presents an LMI formulation to design full-order and reduced-order robust H, FDI filters to estimate the faulty input signals in the presence of uncertainty and model errors. Several cases are examined for nominal and uncertain plants, which consider a weight function for the disturbance and a reference model for the faults. The FDI LMI synthesis conditions are obtained based on the bounded real lemma for the nominal case and on a sufficient extension for the uncertain case. The conditions for the existence of a feasible solution form a convex problem for the full-order filter, which may be solved via recently developed LMI optimization techniques. For the reduced-order FDI filter, the inequalities include a non-convex constraint, and an alternating projections method is presented to address this case. The examples presented in this paper compare the simulated results of a structural model for the nominal and uncertain cases and show that a degree of conservatism exists in the robust fault estimation; however, more reliable solutions are achieved than the nominal design. Copyright © 2008 John Wiley & Sons, Ltd. [source] Shortest paths on dynamic graphsINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 5 2008Giacomo Nannicini Abstract Among the variants of the well-known shortest path problem, those that refer to dynamically changing graphs are theoretically interesting, as well as computationally challenging. Application-wise, there is an industrial need for computing point-to-point shortest paths on large-scale road networks whose arcs are weighted with a travelling time that depends on traffic conditions. We survey recent techniques for dynamic graph weights as well as dynamic graph topology. [source] Methods for prenatal assessment of fetal cardiac functionPRENATAL DIAGNOSIS, Issue 13 2009Tim Van Mieghem Abstract Fetal cardiac function is increasingly recognized as a marker of disease severity and prognosis in selected fetal conditions. Magnetic resonance imaging (MRI) has been used in experimental (animal) fetal cardiology but the lack of a noninvasive fetal electrocardiogram (ECG) to trigger image acquisition remains a major limiting factor precluding its application in humans. Fetal medicine specialists are therefore limited to ultrasound to evaluate human fetal cardiac function. In this review, we aim to provide a complete overview of the different ultrasound techniques that can be used for fetal cardiac function assessment and we discuss their (theoretical) strengths and shortcomings. Conventional methods include M-mode assessment of ventricular contractility and Doppler assessment of the precordial veins and cardiac output (CO). More recent techniques such as the measurement of the myocardial performance index (MPI), myocardial motion analysis with tissue Doppler, speckle tracking and three-dimensional (3D) ultrasound techniques are also discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Recent developments in classical density modificationACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2010Kevin Cowtan Classical density-modification techniques (as opposed to statistical approaches) offer a computationally cheap method for improving phase estimates in order to provide a good electron-density map for model building. The rise of statistical methods has lead to a shift in focus away from the classical approaches; as a result, some recent developments have not made their way into classical density-modification software. This paper describes the application of some recent techniques, including most importantly the use of prior phase information in the likelihood estimation of phase errors within a classical density-modification framework. The resulting software gives significantly better results than comparable classical methods, while remaining nearly two orders of magnitude faster than statistical methods. [source] Reduction of postoperative morbidity and mortality in patients with rectal cancer following the introduction of a colorectal unitBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 2 2001Dr K. Smedh Background: Surgery for rectal cancer is associated with high morbidity and mortality rates. The reason for this has been much debated. This population-based study reports the findings on postoperative morbidity and mortality after rectal cancer surgery following the introduction of a centralized colorectal unit in a county central hospital, supervised by a colorectal surgeon using the most recent techniques. Methods: All consecutive patients with rectal cancer who underwent surgery at four county hospitals in the Västmanland county in Sweden during 1993,1996 (n = 133) were compared with patients who underwent surgery at the new colorectal unit in the county central hospital from 1996 to 1999 (n = 144). Results: The number of operating surgeons was reduced from 26 to four. The postoperative mortality rate decreased from 8 to 1 per cent (P = 0·002) and the total postoperative complication rate was reduced from 57 to 24 per cent (P < 0·001). Surgical complications dropped from 37 to 11 per cent (P < 0·001). The relaparotomy rate fell from 11 to 4 per cent (P < 0·05). Postoperative stay in hospital was reduced from a median of 13 to 9 days (P < 0·001). Conclusion: The new organization, with centralized rectal cancer surgery using modern techniques, reduced postoperative mortality and overall morbidity rates to less than half. © 2001 British Journal of Surgery Society Ltd [source] | ||||||||||