Search results for "COMPUTATION"
showing 10 items of 7362 documents
Impact of Thoracic Endografting on the Hemodynamics of the Native Aorta: Pre- and Postoperative Assessments of Wall Shear Stress and Vorticity Using …
2021
Purpose To quantify the hemodynamic consequences of thoracic endovascular aortic repair (TEVAR) by comparing the preoperative and postoperative wall shear stress (WSS) and vorticity profiles on computational fluid dynamics (CFD) simulations. Materials and Methods The pre- and postoperative computed tomography (CT) scans from 20 consecutive patients (median age 69 years, range 20–87) treated for different thoracic aortic pathologies (11 aneurysms, 5 false aneurysms, 3 penetrating ulcers, and 1 traumatic aortic rupture) were segmented to construct patient-specific CFD models using a meshless code. The simulations were run over the cardiac cycle, and the WSS and vorticity values measured at th…
A Single-Channel Algorithm for Land-Surface Temperature Retrieval From ASTER Data
2010
This letter presents an adaptation to Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data of the generalized single-channel (SC) algorithm developed by JimE?nez-MuN?oz and Sobrino, also adapted to the Landsat thermal-infrared (TIR) channel (band 6) later by JimE?nez-MuN?oz The SC algorithm relies on the concept of atmospheric functions (AFs), which are dependent on atmospheric transmissivity, upwelling, and downwelling atmospheric radiances. These AFs are fitted versus the atmospheric water-vapor content for operational purposes, despite the fact that other computation options are also possible. The SC algorithm has been adapted to ASTER TIR bands 13 (10.659 ?m) and …
InCREDulity in Artificial Societies
2021
This paper describes an artificial society in which the simulated agents behave and interact based on a computational architecture informed by insights from one of the leading social psychological theories in the scientific study of secularization and religion: “credibility-enhancing displays” (or CREDs) theory. After introducing the key elements of the theory and outlining the computational architecture of our CRED model, we present some of our initial simulation results. These efforts are intended to advance the quest within social simulation for more authentic artificial societies and more plausible human-like agents with complex interactive and interpretative capacities.
Modeling Radicalization and Violent Extremism
2020
Given public anxiety about radicalization and violent extremism, it is not surprising that these topics have grabbed the attention of so many scholars in recent years. However, some have expressed concern over the fact that only a few studies in this relatively new field contain empirical data or systematic data analysis or develop causal models of the mechanisms generating these phenomena. We believe that computational modeling and simulation techniques can make a significant contribution to this scientific literature and eventually provide new tools for improving policy analysis. Here we briefly describe (1) an integrative theory of violent extremism proposed by Kruglanski and colleagues …
Modelling terror management theory: computer simulations of the impact of mortality salience on religiosity
2017
ABSTRACTThis article outlines the development – and reports on the experimental findings – of two computational models designed to simulate the dynamic systems and behavioural patterns identified and clarified by research on terror management theory. The causal architectures of these models are informed by empirical research on the effects of mortality salience on “religiosity” (and vice versa). They are also informed by research on the way in which perception of personal and environmental hazards activate evolved cognitive and coalitional precautionary systems that can intensify anxiety-alleviating behaviours such as imaginative engagement with supernatural agents postulated within a relig…
Computational Science of Religion
2021
This article provides a basic overview of the most common methods of computer modelling and simulation that are currently being used to study religion. It focuses on the use (and illustrates the value) of system dynamics models, agent-based models, including game theory and multi-agent artificial intelligence models, and artificial neural networks. General use case examples are provided, and considerations for future research are discussed. We conclude by encouraging scholars interested in religion and related fields to incorporate techniques from the computational science of religion into their collaborative methodological toolkits.
A Full-Scale Agent-Based Model to Hypothetically Explore the Impact of Lockdown, Social Distancing, and Vaccination During the COVID-19 Pandemic in L…
2021
Background The COVID-19 outbreak, an event of global concern, has provided scientists the opportunity to use mathematical modeling to run simulations and test theories about the pandemic. Objective The aim of this study was to propose a full-scale individual-based model of the COVID-19 outbreak in Lombardy, Italy, to test various scenarios pertaining to the pandemic and achieve novel performance metrics. Methods The model was designed to simulate all 10 million inhabitants of Lombardy person by person via a simple agent-based approach using a commercial computer. In order to obtain performance data, a collision detection model was developed to enable cluster nodes in small cells that can b…
Up-Regulation of leucocytes Genes Implicated in Telomere Dysfunction and Cellular Senescence Correlates with Depression and Anxiety Severity Scores
2012
BACKGROUND: Major depressive disorder (MDD) is frequently associated with chronic medical illness responsible of increased disability and mortality. Inflammation and oxidative stress are considered to be the major mediators of the allostatic load, and has been shown to correlate with telomere erosion in the leucocytes of MDD patients, leading to the model of accelerated aging. However, the significance of telomere length as an exclusive biomarker of aging has been questioned on both methodological and biological grounds. Furthermore, telomeres significantly shorten only in patients with long lasting MDD. Sensitive and dynamic functional biomarkers of aging would be clinically useful to eval…
Expression of Toll-Like Receptors in the Developing Brain
2012
Toll-like receptors (TLR) are key players of the innate and adaptive immune response in vertebrates. The original protein Toll in Drosophila melanogaster regulates both host defense and morphogenesis during development. Making use of real-time PCR, in situ hybridization, and immunohistochemistry we systematically examined the expression of TLR1-9 and the intracellular adaptor molecules MyD88 and TRIF during development of the mouse brain. Expression of TLR7 and TLR9 in the brain was strongly regulated during different embryonic, postnatal, and adult stages. In contrast, expression of TLR1-6, TLR8, MyD88, and TRIF mRNA displayed no significant changes in the different phases of brain develop…
A simplified framework to optimize MRI contrast preparation
2018
PURPOSE This article proposes a rigorous optimal control framework for the design of preparation schemes that optimize MRI contrast based on relaxation time differences. METHODS Compared to previous optimal contrast preparation schemes, a drastic reduction of the optimization parameter number is performed. The preparation scheme is defined as a combination of several block pulses whose flip angles, phase terms and inter-pulse delays are optimized to control the magnetization evolution. RESULTS The proposed approach reduces the computation time of B 0 -robust preparation schemes to around a minute (whereas several hours were required with previous schemes), with negligible performance loss. …