Search results for "computer simulation"
showing 10 items of 1054 documents
Production and detection of atomic hexadecapole at Earth's magnetic field
2007
Anisotropy of atomic states is characterized by population differences and coherences between Zeeman sublevels. It can be efficiently created and probed via resonant interactions with light, the technique which is at the heart of modern atomic clocks and magnetometers. Recently, nonlinear magneto-optical techniques have been developed for selective production and detection of higher polarization moments, hexadecapole and hexacontatetrapole, in the ground states of the alkali atoms. Extension of these techniques into the range of geomagnetic fields is important for practical applications. This is because hexadecapole polarization corresponding to the $\Delta M=4$ Zeeman coherence, with maxim…
A computational study of the lowest singlet and triplet states of neutral and dianionic 1,2-substituted icosahedral and octahedralo-carboranes
2006
This work introduces a calibrated B3LYP/6-31G(d) study on the electronic structure of singlet and triplet neutral species of 1,2-substituted icosahedral 1,2-R(2)-1,2-C(2)B(10)H(10) and octahedral 1,2-R(2)-1,2-C(2)B(4)H(4) molecules with R = {H, OH, SH, NH(2), PH(2), CH(3), SiH(3)} and their respective dianions formed by proton removal on each R group. A variety of small adiabatic singlet-triplet gaps DeltaE(ST) are obtained from these systems ranging from 2.93 eV (R = NH(2)) <or= DeltaE(ST) <or= 3.98 eV (R = SiH(3)) for the icosahedral neutrals and 1.56 eV (R = NH(2)) <or= DeltaE(ST) <or= 4.13 eV (R = SiH(3)) for the octahedral neutrals, these gaps being globally smaller for the dianionic s…
Anti-inflammatory and tight junction protective activity of the herbal preparation STW 5-II on mouse intestinal organoids
2021
Abstract Background Irritable bowel syndrome (IBS) is a functional bowel disorder, in which recurrent abdominal pain is associated with defecation or a change in bowel habits. STW 5-II is a combination of six medicinal herbs with a clinically proven efficacy in managing IBS. Aim This study aims to establish an in vitro IBS model using mouse intestinal organoids and to explore the anti-inflammatory and tight junction protective activities of the multi-herbal preparation STW 5-II. Methods Intestinal organoids were cultured in 1:1 Matrigel™ and medium domes. Inflammation and tight junction disruption were induced by a cocktail of cytokines (TNFα, IFNγ, IL-1β, IL-6) and bacterial proteins (LPS,…
A membrane computing simulator of trans-hierarchical antibiotic resistance evolution dynamics in nested ecological compartments (ARES)
2015
In this article, we introduce ARES (Antibiotic Resistance Evolution Simulator) a software device that simulates P-system model scenarios with five types of nested computing membranes oriented to emulate a hierarchy of eco-biological compartments, i.e. a) peripheral ecosystem; b) local environment; c) reservoir of supplies; d) animal host; and e) host's associated bacterial organisms (microbiome). Computational objects emulating molecular entities such as plasmids, antibiotic resistance genes, antimicrobials, and/or other substances can be introduced into this framework and may interact and evolve together with the membranes, according to a set of pre-established rules and specifications. AR…
QuBiLs-MAS method in early drug discovery and rational drug identification of antifungal agents
2015
The QuBiLs-MAS approach is used for the in silico modelling of the antifungal activity of organic molecules. To this effect, non-stochastic (NS) and simple-stochastic (SS) atom-based quadratic indices are used to codify chemical information for a comprehensive dataset of 2478 compounds having a great structural variability, with 1087 of them being antifungal agents, covering the broadest antifungal mechanisms of action known so far. The NS and SS index-based antifungal activity classification models obtained using linear discriminant analysis (LDA) yield correct classification percentages of 90.73% and 92.47%, respectively, for the training set. Additionally, these models are able to correc…
Computer Modeling for the Prediction of Thoracic Aortic Stent Graft Collapse
2011
OBJECTIVE: To assess the biomechanical implications of excessive stent protrusion into the aortic arch in relation to thoracic aortic stent graft (TASG) collapse by simulating the structural load and quantifying the fluid dynamics on the TASG wall protrusion extended into a model arch. METHODS: One-way coupled fluid-solid interaction analyses were performed to investigate the flow-induced hemodynamic and structural loads exerted on the proximal protrusion of the TASG and aortic wall reconstructed from a patient who underwent traumatic thoracic aortic injury repair. Mechanical properties of a Gore TAG thoracic endoprosthesis (W. L. Gore and Assoc, Flagstaff, Ariz) were assessed via experimen…
Comparison of hemodynamic and structural indices of ascending thoracic aortic aneurysm as predicted by 2-way FSI, CFD rigid wall simulation and patie…
2018
Patient-specific computational modeling is increasingly being used to predict structural and hemodynamic parameters, especially when current clinical tools are not accessible. Indeed, pathophysiology of ascending thoracic aortic aneurysm (ATAA) has been simulated to quantify the risk of complications by novel prognostic parameters and thus to improve the clinical decision-making process related to the intervention of ATAAs. In this study, the relevance of aneurysmal wall elasticity in determining parameters of clinical importance, such as the wall shear stress (WSS), is discussed together with the significance of applying realistic boundary conditions to consider the aortic stretch and twis…
Calculation of the pH and the titratable acidity in clinically used infusion solutions.
2006
Clinically used infusion solutions are complex aqueous mixtures composed of a variety of different salts, acids, and non-electrolytes, and are characterized by composition, initial pH, and titratable acidity (TA). By rigorous treatment as a multi-composed acid-base system, pH and TA were calculated from proton dissociation equilibria, mass balance equations and electroneutrality condition. Nine were arbitrarily chosen as model solutions in which pH and TA were experimentally determined. From composition, and based on a set of apparent acidity constants (pK values) at 37 degrees C and total ionic strength 0.155 mol/l, pH was calculated by iteration. In the model solutions, measured pH was in…
Modeling the insect mushroom bodies: application to a delayed match-to-sample task.
2013
Despite their small brains, insects show advanced capabilities in learning and task solving. Flies, honeybees and ants are becoming a reference point in neuroscience and a main source of inspiration for autonomous robot design issues and control algorithms. In particular, honeybees demonstrate to be able to autonomously abstract complex associations and apply them in tasks involving different sensory modalities within the insect brain. Mushroom Bodies (MBs) are worthy of primary attention for understanding memory and learning functions in insects. In fact, even if their main role regards olfactory conditioning, they are involved in many behavioral achievements and learning capabilities, as …
A Simple Cardiovascular Model for the Study of Hemorrhagic Shock
2020
Hemorrhagic shock is the number one cause of death on the battlefield and in civilian trauma as well. Mathematical modeling has been applied in this context for decades; however, the formulation of a satisfactory model that is both practical and effective has yet to be achieved. This paper introduces an upgraded version of the 2007 Zenker model for hemorrhagic shock termed the ZenCur model that allows for a better description of the time course of relevant observations. Our study provides a simple but realistic mathematical description of cardiovascular dynamics that may be useful in the assessment and prognosis of hemorrhagic shock. This model is capable of replicating the changes in mean …