Search results for "Simulation"
showing 10 items of 5095 documents
Ab initio determination of the electron affinities of DNA and RNA nucleobases
2008
High-level quantum-chemical ab initio coupled-cluster and multiconfigurational perturbation methods have been used to compute the vertical and adiabatic electron affinities of the five canonical DNA and RNA nucleobases: uracil, thymine, cytosine, adenine, and guanine. The present results aim for the accurate determination of the intrinsic electron acceptor properties of the isolated nucleic acid bases as described by their electron affinities, establishing an overall set of theoretical reference values at a level not reported before and helping to rule out less reliable theoretical and experimental data and to calibrate theoretical strategies. Daniel.Roca@uv.es Manuela.Merchan@uv.es Luis.Se…
Umfrage zum Training laparoskopischer Fertigkeiten in Deutschland
2016
Hintergrund: Das Training fur Laparoskopie an Simulationsmoglichkeiten wie Box-, POP- oder Virtual-Reality-Trainern verbessert nachweislich die intraoperativen Leistungen. In Deutschland ist dieses Training nicht verpflichtend in die Facharztweiterbildung integriert, muss jedoch bspw. in zertifizierten Zentren fur minimalinvasive Chirurgie bereitgestellt werden. Simulatoren sind in Deutschland von Weiterbildern und Weiterzubildenden erwunscht, jedoch laut fruheren Umfragen nicht ausreichend verfugbar. Ziel des Projekts war die strukturierte Erfassung der Moglichkeiten fur Laparoskopietraining in Deutschland sowie deren Nutzung und Finanzierung. Methoden: Es wurde eine Onlineumfrage unter Mi…
Neue Perspektiven der laparoskopischen Simulation: Vom Studententrainingslabor bis zur Stressevaluation
2008
Hintergrund: Die Anwendung eines LapSim®-Trainingsmodells im Studententrainingslabor sowie die objektive Evaluation von Stress in einem virtuellen Operations-Szenario bieten neue Perspektiven der laparoskopischen Simulation. Methodik: Im Studententrainingslabor erfolgte bei 28 Probanden am LapSim® Virtual-Reality (VR)-Simulator in einem Trainingscurriculum, bestehend aus 9 Einheiten, die Erfassung von Lernkurven laparoskopischer Basisfertigkeiten sowie komplexer Prozesse. In einem virtuellen Operations-Szenario wurde des Weiteren bei 18 Chirurgen eine Stressevaluation mittels eines Sympathikografen vorgenommen und dabei die laparoskopische Fehler- und Komplikationsrate erfasst. Hierbei konn…
Mathematical and Mechanical Circulatory Simulators Applied to Heart Replacement Systems
1984
Mathematische und mechanische Kreis!aufSimulatoren werden zur Untersuchung der Beeinflussung der relevanten hamodynamisehen Grosen durch Herzersatzsysteme mit dem Ziel eingesetzt, optimale Ersatzsysteme in toto bzw. Elemente des Ersatzsystems wie z.B. Herzklappen zu entwickeln. Es werden beide Methoden dargestellt und ihr zweckmasiger Einsatz diskutiert.
Virtuelle 3-D-Laparoskopie-Simulation in der chirurgischen Aus- und Weiterbildung – Ergebnisse einer Pilotstudie
2013
Hintergrund: Dem technischen Fortschritt folgend, werden im Operationssaal Module zur 3-dimensionalen Darstellung in der Laparoskopie eingesetzt. Erste Untersuchungen an Box-Trainern haben diskrepante Ergebnisse gezeigt. Fur die Virtual-Reality-Laparoskopie (VRL) fehlen Daten zur 3-dimensionalen Simulation. Material und Methoden: 5 Facharzte fur Chirurgie, 10 chirurgisch tatige Arzte in Weiterbildung und 29 Medizinstudenten fuhrten abstrakte und prozedurale Ubungen am VRL-Simulator im 2-D- und 3-D-Modus durch. Die Reihenfolge der Durchfuhrung (2-D/3-D) wurde randomisiert. Ergebnisse: Fur Arzte und Studenten zeigten sich keine signifikanten Leistungsunterschiede fur Ubungen im 2-D- und 3-D-D…
Optimal selection of touristic packages based on user preferences during sports mega-events
2022
Sport mega-events, such as the Soccer World Cup or Olympic Games, attract many visitors from all over the world. Most of these visitors are also interested in, besides attending the sports events, visiting the host nation and the neighboring countries. In this paper, we focus on the upcoming FIFA World Cup Qatar 2022. As per the schedule of the tournament, a national team can play 7 matches at most. Therefore, a supporter will have six short breaks (of three to five days) between consecutive matches in addition to two longer ones, immediately before and after the tournament, during which they can plan some touris- tic trips. We study the problem faced by a touristic trip provider who wants …
Dosimetric perturbations of a lead shield for surface and interstitial high-dose-rate brachytherapy.
2014
In surface and interstitial high-dose-rate brachytherapy with either (60)Co, (192)Ir, or (169)Yb sources, some radiosensitive organs near the surface may be exposed to high absorbed doses. This may be reduced by covering the implants with a lead shield on the body surface, which results in dosimetric perturbations. Monte Carlo simulations in Geant4 were performed for the three radionuclides placed at a single dwell position. Four different shield thicknesses (0, 3, 6, and 10 mm) and three different source depths (0, 5, and 10 mm) in water were considered, with the lead shield placed at the phantom surface. Backscatter dose enhancement and transmission data were obtained for the lead shields…
Risk assessment of component failure modes and human errors using a new FMECA approach: application in the safety analysis of HDR brachytherapy
2014
Failure mode, effects and criticality analysis (FMECA) is a safety technique extensively used in many different industrial fields to identify and prevent potential failures. In the application of traditional FMECA, the risk priority number (RPN) is determined to rank the failure modes; however, the method has been criticised for having several weaknesses. Moreover, it is unable to adequately deal with human errors or negligence. In this paper, a new versatile fuzzy rule-based assessment model is proposed to evaluate the RPN index to rank both component failure and human error. The proposed methodology is applied to potential radiological over-exposure of patients during high-dose-rate brach…
A generic TG-186 shielded applicator for commissioning model-based dose calculation algorithms for high-dose-rate Ir-192 brachytherapy
2017
PurposeA joint working group was created by the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) with the charge, among others, to develop a set of well-defined test case plans and perform calculations and comparisons with model-based dose calculation algorithms (MBDCAs). Its main goal is to facilitate a smooth transition from the AAPM Task Group No. 43 (TG-43) dose calculation formalism, widely being used in clinical practice for brachytherapy, to the one proposed by Task Group No. 186 (TG-186) for MBDCAs. To do so, in this work a hypothetical, generic high-dose rate (HDR) Ir-19…
Laboratory unraveling of matter accretion in young stars
2017
When matter accretes onto a young star, a shell of dense material can form around the impact, reducing its x-ray emission.