Search results for "SIMULATION"

Probing a Polar Cluster in the Retinal Binding Pocket of Bacteriorhodopsin by a Chemical Design Approach

2012

Bacteriorhodopsin has a polar cluster of amino acids surrounding the retinal molecule, which is responsible for light harvesting to fuel proton pumping. From our previous studies, we have shown that threonine 90 is the pivotal amino acid in this polar cluster, both functionally and structurally. In an attempt to perform a phenotype rescue, we have chemically designed a retinal analogue molecule to compensate the drastic effects of the T90A mutation in bacteriorhodopsin. This analogue substitutes the methyl group at position C(13) of the retinal hydrocarbon chain by and ethyl group (20-methyl retinal). We have analyzed the effect of reconstituting the wild-type and the T90A mutant apoprotein…

Fluorine Scan of Inhibitors of the Cysteine Protease Human Cathepsin L: Dipolar and Quadrupolar Effects in the π-Stacking of Fluorinated Phenyl Rings…

2016

The π-stacking of fluorinated benzene rings on protein backbone amide groups was investigated, using a dual approach comprising enzyme-ligand binding studies complemented by high-level quantum chemical calculations. In the experimental study, the phenyl substituent of triazine nitrile inhibitors of human cathepsin L (hCatL), which stacks onto the peptide amide bond Gly67-Gly68 at the entrance of the S3 pocket, was systematically fluorinated, and differences in inhibitory potency were measured in a fluorimetric assay. Binding affinity is influenced by lipophilicity (clog P), the dipole and quadrupole moments of the fluorinated rings, but also by additional interactions of the introduced fluo…

On critical behaviour in systems of Hamiltonian partial differential equations

2013

Abstract We study the critical behaviour of solutions to weakly dispersive Hamiltonian systems considered as perturbations of elliptic and hyperbolic systems of hydrodynamic type with two components. We argue that near the critical point of gradient catastrophe of the dispersionless system, the solutions to a suitable initial value problem for the perturbed equations are approximately described by particular solutions to the Painlevé-I (P $$_I$$ I ) equation or its fourth-order analogue P $$_I^2$$ I 2 . As concrete examples, we discuss nonlinear Schrödinger equations in the semiclassical limit. A numerical study of these cases provides strong evidence in support of the conjecture.

New developments in simulation-based harbour crane training

2011

This paper presents the efforts that have been made during the development of a set of harbour training simulators to improve their quality. The paper focuses on two main research lines: the improvement of complex physical systems involved in the simulation and the analysis of hardware architecture solutions. Cable-based hoist systems and bulk materials are systems present in different harbour equipment and are usually simulated with poor quality due to their complexity. In this paper physics-based models for the interactive simulation of these systems are proposed and applied to real cases. Also, different hardware simulator architectures are analysed and different approaches are proposed …

Hazards That Can Affect CNC Machine Tools during Operation—An AHP Approach

2020

CNC (computer numerically controlled) machine tools are highly advanced technological systems, used to machine parts by means of metal cutting processes. Their structure and kinematics are very complex, involving accurate coordinated motions on three to five axes. Operating CNC machine tools is a complicated process, which can easily be affected by errors. Nowadays, safety systems and devices are developed in order to make this process safer and more user friendly. Modern CNC controllers are designed to deal with obvious sources of hazards, such as overloads (by means of various sensor systems) and collisions (by checking the NC code syntax and simulating it on the machine). However, despit…

A morphology-based approach to the evaluation of atrial fibrillation organization.

2007

SIeSTA: From Concept Board to Concept Desktop

2011

Recently published social protection and dependence reports reaffirm that the elderly, the disabled, or those in situations of dependency objectively benefit from continuing to live at home with the assistance from direct family. Currently in Spain - amongst the elderly, or people in a situation of dependency - 8 out of every 10 people stay at home. The end result is that the direct family relations have the responsibility of performing 76% of the tasks during the daily routine where aid is needed. Associations for people with disabilities, however, not only report a lack of adequate aid services, but a lack of direct-family assistance as well. It is necessary, therefore, for an "evolution"…

Molecular docking and oxidation kinetics of 3-phenyl coumarin derivatives by human CYP2A13.

2021

CYP2A13 enzyme is expressed in human extrahepatic tissues, while CYP2A6 is a hepatic enzyme. Reactions catalysed by CYP2A13 activate tobacco-specific nitrosamines and some other toxic xenobiotics in lungs.To compare oxidation characteristics and substrate-enzyme active site interactions in CYP2A13 vs CYP2A6, we evaluated CYP2A13 mediated oxidation characteristics of 23 coumarin derivatives and modelled their interactions at the enzyme active site.CYP2A13 did not oxidise six coumarin derivatives to corresponding fluorescent 7-hydroxycoumarins. The Km-values of the other coumarins varied 0.85-97 µM, Vmax-values of the oxidation reaction varied 0.25-60 min-1, and intrinsic clearance varied 26-…

Measuring the Rate of Information Transfer in Point-Process Data: Application to Cardiovascular Interactions

2021

We present the implementation to cardiovascular variability of a method for the information-theoretic estimation of the directed interactions between event-based data. The method allows to compute the transfer entropy rate (TER) from a source to a target point process in continuous time, thus overcoming the severe limitations associated with time discretization of event-based processes. In this work, the method is evaluated on coupled cardiovascular point processes representing the heartbeat dynamics and the related peripheral pulsation, first using a physiologically-based simulation model and then studying real point-process data from healthy subjects monitored at rest and during postural …

High Degree of Realism in Teaching Percutaneous Coronary Interventions by Combining a Virtual Reality Trainer With a Full Scale Patient Simulator

2008

The virtual reality coronary angiography simulator "CATHI" (Catheter Instruction System, Mannheim, Germany) simulates coronary arteries with implemented vessel lesions in virtual patients. Like similar systems the software model runs on common PC systems, which are linked to the mechanical device for manual training. We combined the advantages of this skill trainer with the near to reality assembly of a cardiac catheterization laboratory (Cath-lab) by connecting it to a full scale simulator (HPS, METI, Sarasota, FL). We present two methods of synchronizing the heartbeat between both simulation devices. Method A-the hardware solution-uses the electrocardiogram-synchronization signal of the H…