Approximation anatomischer Strukturen und biomedizinischer Prozesse zur rechnergestützten Untersuchung der Hämodynamik in Aneurysmen

Arterien des Menschen können Aneurysmen aufweisen, deren Ruptur zu lebensbedrohenden inneren Blutungen wie Schlaganfällen führen kann. Ein Therapieansatz ist das Einsetzen von sogenannten Stents. Eine Ruptur oder der Einfluss eines Stents kann mit dem momentanen Stand der Technik nicht exakt vorhergesagt werden. Für eine optimale Behandlung von Patienten wäre dies allerdings eine wichtige Zusatzinformation für den behandelnden Arzt. Zur Bestimmung dieser Zusatzinformation sollen zukünftig Simulationen der Hämodynamik in pathologischen Arterien eingesetzt werden. In dieser Arbeit werden Strömungsgeschwindigkeiten in Arterien ohne beziehungsweise mit Einbringung von Einbauten wie Stents berechnet und die entstehenden Wandscherspannungen im Hinblick auf eine Rupturvorhersage untersucht. Weiterhin wird der Massentransfer zwischen Arterie und Aneurysma charakterisiert und eine Analyse des Thrombosierungsverhaltens unter Strömungseinfluss vorgenommen. Bei letztgenanntem Thema werden insbesondere der Verschluss von Aneurysmen durch Thromben, die Ortseindämmung der Thrombenbildung und das Verhalten von wandanhaftenden Thromben auch in Bezug auf eine Ablösung untersucht. Um hierfür geeignete Simulationen durchführen zu können, wird eine Analyse der biomedizinischen Grundlagen durchgeführt. Für die Untersuchung der komplexen Dynamik sind aus methodischer Sicht zwei grundlegende Aspekte zu bearbeiten: die geometrische und die funktionelle Approximation. Die funktionelle Approximation biomedizinischer Prozesse umfasst die Untersuchung der Blutströmung, des Transports von passiven Stoffen und der Thrombosierung. Hierfür werden entsprechende Modelle identifiziert, in entsprechende Lattice-Boltzmann-Verfahren umgewandelt, simuliert und untersucht. Durch die Erarbeitung geeigneter Konzepte für eine Umsetzung der hier beschriebenen Simulationen auf einzelnen oder mehreren, miteinander kommunizierenden Grafikprozessoren kann eine effiziente Simulation der gekoppelten Multi-Physik-Probleme mit Lattice-Boltzmann-Verfahren erreicht werden. Insgesamt stellt diese Vorgehensweise ein Novum dar und unterstreicht die Praktikabilität der Methode. Die geometrische Approximation anatomischer Strukturen wird in dieser Arbeit mit Level-Set-Darstellungen gelöst. Mit ihnen können vielfältige Problemstellungen im Umfeld der Simulation bearbeitet werden, dies umfasst beispielsweise die Konstruktion einer Simulationsdomäne aus unterschiedlichen Tomographiedaten und die Einbringung von Einbauten wie Stents in das Untersuchungsgebiet. Durch die Kombination mit der Lattice-Boltzmann-Methode können Vorteile gegenüber dem Stand der Technik erreicht werden, etwa bei der effizienten Berechnung der Wandscherspannungen. Eine Validierung der Strömungs- und Transportsimulationen wird mit hochaufgelöster Magnetresonanztomographie vorgenommen. Dazu wird ein Modell des Aufnahmevorgangs unter Einfluss von Radiofrequenz-Magnetfeldern und Gradienten erstellt und der Magnetisierungstransport sowie die Relaxation simuliert. Die bestimmten Abweichungen zwischen Simulation und Messung sind insgesamt gering. Für die Messexperimente werden erstmals 3D-Druckverfahren für die Konstruktion von physischen Modellen eingesetzt und deren Güte untersucht. Durch die Ergebnisse dieser Arbeit steht eine effiziente und umfassende Verarbeitungspipeline für Blutströmungs-, Transport- und Thrombosierungsprozesse für weitere Untersuchungen bereit. Sie kann ebenfalls leicht um neue Modelle erweitert werden. Die Simulation der Magnetresonanztomographie für Flussbildgebung ermöglicht ebenfalls zukünftige Anwendungen im Bereich der Sequenzentwicklung

Interactive editing of virtual chordae tendineae for the simulation of the mitral valve in a decision support system

Purpose: Decision support systems for mitral valve disease are an important step toward personalized surgery planning. A simulation of the mitral valve apparatus is required for decision support. Building a model of the chordae tendineae is an essential component of a mitral valve simulation. Due to image quality and artifacts, the chordae tendineae cannot be reliably detected in medical imaging. Methods: Using the position-based dynamics framework, we are able to realistically simulate the opening and closing of the mitral valve. Here, we present a heuristic method for building an initial chordae model needed for a successful simulation. In addition to the heuristic, we present an interactive editor to refine the chordae model and to further improve pathology reproduction as well as geometric approximation of the closed valve. Results: For evaluation, five mitral valves were reconstructed based on image sequences of patients scheduled for mitral valve surgery. We evaluated the approximation of the closed valves using either just the heuristic chordae model or a manually refined model. Using the manually refined models, prolapse was correctly reproduced in four of the five cases compared to two of the five cases when using the heuristic. In addition, using the editor improved the approximation in four cases. Conclusions: Our approach is suitable to create realistically parameterized mitral valve apparatus reconstructions for the simulation of normally and abnormally closing valves in a decision support system

Project Status of the Polish Synchrotron Radiation Facility Solaris

Abstract in Undetermined The Polish synchrotron radiation facility Solaris is being built at the Jagiellonian University in Krakow. The project is based on an identical copy of the 1.5 GeV storage ring being concurrently built for the MAX IV project in Lund, Sweden. A general description of the facility is given together with a status of activities. Unique features associated with Solaris are outlined, such as infrastructure, the injector and operational characteristics

A systematic review of the psychometric properties of self-report research utilization measures used in healthcare

<p>Abstract</p> <p>Background</p> <p>In healthcare, a gap exists between what is known from research and what is practiced. Understanding this gap depends upon our ability to robustly measure research utilization.</p> <p>Objectives</p> <p>The objectives of this systematic review were: to identify self-report measures of research utilization used in healthcare, and to assess the psychometric properties (acceptability, reliability, and validity) of these measures.</p> <p>Methods</p> <p>We conducted a systematic review of literature reporting use or development of self-report research utilization measures. Our search included: multiple databases, ancestry searches, and a hand search. Acceptability was assessed by examining time to complete the measure and missing data rates. Our approach to reliability and validity assessment followed that outlined in the <it>Standards for Educational and Psychological Testing</it>.</p> <p>Results</p> <p>Of 42,770 titles screened, 97 original studies (108 articles) were included in this review. The 97 studies reported on the use or development of 60 unique self-report research utilization measures. Seven of the measures were assessed in more than one study. Study samples consisted of healthcare providers (92 studies) and healthcare decision makers (5 studies). No studies reported data on acceptability of the measures. Reliability was reported in 32 (33%) of the studies, representing 13 of the 60 measures. Internal consistency (Cronbach's Alpha) reliability was reported in 31 studies; values exceeded 0.70 in 29 studies. Test-retest reliability was reported in 3 studies with Pearson's <it>r </it>coefficients > 0.80. No validity information was reported for 12 of the 60 measures. The remaining 48 measures were classified into a three-level validity hierarchy according to the number of validity sources reported in 50% or more of the studies using the measure. Level one measures (n = 6) reported evidence from any three (out of four possible) <it>Standards </it>validity sources (which, in the case of single item measures, was all applicable validity sources). Level two measures (n = 16) had evidence from any two validity sources, and level three measures (n = 26) from only one validity source.</p> <p>Conclusions</p> <p>This review reveals significant underdevelopment in the measurement of research utilization. Substantial methodological advances with respect to construct clarity, use of research utilization and related theory, use of measurement theory, and psychometric assessment are required. Also needed are improved reporting practices and the adoption of a more contemporary view of validity (<it>i.e.</it>, the <it>Standards</it>) in future research utilization measurement studies.</p

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

Peer reviewe

Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

Peer reviewe

Search for anomalous couplings in boosted WW/WZ -> l nu q(q)over-bar production in proton-proton collisions at root s=8TeV

Peer reviewe

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe