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Algorithm Selection for Resource-Constrained Project Scheduling Problems: A Graph Neural Network Approach
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A comprehensive numerical approach to coil placement in cerebral aneurysms: mathematical modeling and in silico occlusion classification
No full textEndovascular coil embolization is one of the primary treatment techniques for cerebral aneurysms. Although it is a well-established and minimally invasive method, it bears the risk of suboptimal coil placement which can lead to incomplete occlusion of the aneurysm possibly causing recurrence. One of the key features of coils is that they have an imprinted natural shape supporting the fixation within the aneurysm. For the spatial discretization, our mathematical coil model is based on the discrete elastic rod model which results in a dimension-reduced 1D system of differential equations. We include bending and twisting responses to account for the coils natural curvature and allow for the placement of several coils having different material parameters. Collisions between coil segments and the aneurysm wall are handled by an efficient contact algorithm that relies on an octree based collision detection. In time, we use a standard symplectic semi-implicit Euler time stepping method. Our model can be easily incorporated into blood flow simulations of embolized aneurysms. In order to differentiate optimal from suboptimal placements, we employ a suitable in silico Raymond–Roy-type occlusion classification and measure the local packing density in the aneurysm at its neck, wall region and core. We investigate the impact of uncertainties in the coil parameters and embolization procedure. To this end, we vary the position and the angle of insertion of the micro-catheter, and approximate the local packing density distributions by evaluating sample statistics
Graphbasierter Ansatz zur Analyse von BIM-Raumbeziehungen
No full textEs gibt bereits viele Formate und Wege, um Gebäude so zu modellieren und abzubilden, dass auch Computer diese Modelle vollständig oder zumindest teilweise verarbeiten und prüfen können. Diese Analysen beschränken sich aber meist auf das, was tatsächlich modelliert wurde, da der Maschine die Möglichkeit fehlt, Dinge zu interpretieren und Schlussfolgerungen zu ziehen. In dieser Arbeit wird deshalb das Prinzip Linked Data genutzt, um bereits in frühen Leistungsphasen mögliche Probleme mit der Gebäudetechnik oder anderen Verknüpfungen zwischen Räumen zu erkennen, obwohl noch keine einzige Leitung explizit modelliert wurde. Dafür wird eine Ontologie entworfen, mit der es möglich ist, Relationen verschiedener Arten zwischen zwei Räumen abzubilden. Die Ontologie baut auf der Building Topology Ontology auf und ist auch mit ifcOWL und den weiteren LBD-Ontologien kompatibel. Es werden Competency Questions definiert und anschließend mittels SPARQL-Abfragen und Beispielen gezeigt, dass die Ontologie diese erfüllt. Darüber hinaus, werden Möglichkeiten entwickelt, die entsprechenden nötigen Informationen aus IFC-Dateien in einen RDF-Graph zu überführen
Statistische Methoden für erste MADMAX Messungen von Axionen als dunkle Materie und darüber hinaus
No full textThe axion could resolve key issues in physics: the lack of CP-violating strong interactions and the nature of dark matter. This thesis presents a first MADMAX axion dark matter search, setting world-leading limits on axion-photon couplings at high axion masses. It also provides improved theory predictions for the photon couplings of non-minimal QCD axions, creating a systematic catalogue for DFSZ-type axions, and proposes a method for unbiased parameter inference in case of an axion detection.Diese Arbeit präsentiert die erste MADMAX-Suche nach Dunkler Materie Axionen und setzt weltweit führende Limits für Axion-Photon-Kopplungen bei hohen Axion-Massen. Theoretische Vorhersagen für die Photonenkopplungen nicht-minimaler QCD-Axionen werden verbessert, indem ein systematischer Katalog für Axionen des DFSZ-Typs erstellt wird. Außerdem wird eine Methode für eine unverzerrte Parameterinferenz im Fall einer Entdeckung von Axionen vorgeschlagen
Systematic Exploration of Optimization Potentials for the MGLET Pressure-Solver on Heterogeneous Hardware
No full textMost computational science and engineering problems in domains such as computational fluid dynamics, thermodynamics, and electronics require solving large, sparse linear systems derived from discretizing partial differential equations. Due to the highly computationally expensive nature, many numerical algorithms and libraries implementing these algorithms have been developed through decades of research. PETSc (Portable Extensible Toolkit for Scientific Computing) is a widely used library due to the large pool of numer- ical solvers and preconditioners and the support for the rapidly advancing computing platforms. However, selecting the most suitable solver and preconditioner for solving the linear system is not straightforward. It would need extensive knowledge and experience in numerical mathematics, domain expertise, and reading through many literature. Attempts have been made to ease the process using machine learning techniques, which this study tries to follow to find the best solver-preconditioner pair for the pressure Poisson solver of the MGLET computational fluid dynamics code and extend the finding to heterogenous computing architectures involving GPUs
Dynamic monitoring of viral gene expression reveals rapid antiviral effects of CD8 T cells recognizing the HCMV-pp65 antigen.
No full textINTRODUCTION: Human Cytomegalovirus (HCMV) is a betaherpesvirus that causes severe disease in immunocompromised transplant recipients. Immunotherapy with CD8 T cells specific for HCMV antigens presented on HLA class-I molecules is explored as strategy for long-term relief to such patients, but the antiviral effectiveness of T cell preparations cannot be efficiently predicted by available methods.
METHODS: We developed an Assay for Rapid Measurement of Antiviral T-cell Activity (ARMATA) by real-time automated fluorescent microscopy and used it to study the ability of CD8 T cells to neutralize HCMV and control its spread. As a proof of principle, we used TCR-transgenic T cells specific for the immunodominant HLA-A02-restricted tegumental phosphoprotein pp65. pp65 expression follows an early/late kinetic, but it is not clear at which stage of the virus cycle it acts as an antigen. We measured control of HCMV infection by T cells as early as 6 hours post infection (hpi).
RESULTS: The timing of the antigen recognition indicated that it occurred before the late phase of the virus cycle, but also that virion-associated pp65 was not recognized during virus entry into cells. Monitoring of pp65 gene expression dynamics by reporter fluorescent genes revealed that pp65 was detectable as early as 6 hpi, and that a second and much larger bout of expression occurs in the late phase of the virus cycle by 48 hpi. Since transgenic (Tg)-pp65 specific CD8 T cells were activated even when DNA replication was blocked, our data argue that pp65 acts as an early virus gene for immunological purposes.
DISCUSSION: ARMATA does not only allow same day identification of antiviral T-cell activity, but also provides a method to define the timing of antigen recognition in the context of HCMV infection
Lipid metabolism in B cell biology.
No full textIn recent years, the field of immunometabolism has solidified its position as a prominent area of investigation within the realm of immunological research. An expanding body of scientific literature has unveiled the intricate interplay between energy homeostasis, signalling molecules, and metabolites in relation to fundamental aspects of our immune cells. It is now widely accepted that disruptions in metabolic equilibrium can give rise to a myriad of pathological conditions, ranging from autoimmune disorders to cancer. Emerging evidence, although sometimes fragmented and anecdotal, has highlighted the indispensable role of lipids in modulating the behaviour of immune cells, including B cells. In light of these findings, this review aims to provide a comprehensive overview of the current state of knowledge regarding lipid metabolism in the context of B cell biology
