The application of multiscale modelling to the process of development and prevention of stenosis in a stented coronary artery

The inherent complexity of biomedical systems is well recognized; they are multiscale, multiscience systems, bridging a wide range of temporal and spatial scales. While the importance of multiscale modelling in this context is increasingly recognized, there is little underpinning literature on the methodology and generic description of the process. The COAST (complex autonoma simulation technique) project aims to address this by developing a multiscale, multiscience framework, coined complex autonoma (CxA), based on a hierarchical aggregation of coupled cellular automata (CA) and agent-based models (ABMs). The key tenet of COAST is that a multiscale system can be decomposed into N single-scale CA or ABMs that mutually interact across the scales. Decomposition is facilitated by building a scale separation map on which each single-scale system is represented according to its spatial and temporal characteristics. Processes having well-separated scales are thus easily identified as the components of the multiscale model. This paper focuses on methodology, introduces the concept of the CxA and demonstrates its use in the generation of a multiscale model of the physical and biological processes implicated in a challenging and clinically relevant problem, namely coronary artery in-stent restenosis.

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Flexible composition and execution of high performance, high fidelity multiscale biomedical simulations

Interface Focus ◽

10.1098/rsfs.2012.0087 ◽

2013 ◽

Vol 3 (2) ◽

pp. 20120087 ◽

Cited By ~ 31

Author(s):

D. Groen ◽

J. Borgdorff ◽

C. Bona-Casas ◽

J. Hetherington ◽

R. W. Nash ◽

...

Keyword(s):

High Performance ◽

Multiscale Simulation ◽

High Fidelity ◽

Biomedical Domain ◽

Multiscale Simulations ◽

Total Execution Time ◽

Stent Restenosis ◽

Single Scale ◽

Wide Range ◽

In Stent Restenosis

Multiscale simulations are essential in the biomedical domain to accurately model human physiology. We present a modular approach for designing, constructing and executing multiscale simulations on a wide range of resources, from laptops to petascale supercomputers, including combinations of these. Our work features two multiscale applications, in-stent restenosis and cerebrovascular bloodflow, which combine multiple existing single-scale applications to create a multiscale simulation. These applications can be efficiently coupled, deployed and executed on computers up to the largest (peta) scale, incurring a coupling overhead of 1–10% of the total execution time.

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Developing Rigorous Monitoring Programs: Power and Sample Size Evaluations of a Robust Method for Monitoring Bird Assemblages

Journal of Fish and Wildlife Management ◽

10.3996/042019-jfwm-027 ◽

2019 ◽

Vol 10 (2) ◽

pp. 480-491

Author(s):

Jeremy A. Baumgardt ◽

Michael L. Morrison ◽

Leonard A. Brennan ◽

Tyler A. Campbell

Keyword(s):

Spatial Scales ◽

Monitoring Program ◽

Population Monitoring ◽

Multiscale Model ◽

Ecological Impacts ◽

Management Actions ◽

Monitoring Programs ◽

Wide Range ◽

Unbiased Estimates ◽

Multiple Species

Wildlife population monitoring programs are useful for identifying ecological impacts such as those from local management actions and broader scale influences such as climate change. Increasing the number of species monitored improves robustness of the program towards meeting monitoring objectives. In addition, monitoring at multiple spatial scales should increase the sensitivity of the monitoring program. We developed a monitoring program using unbiased estimates of occupancy at both local and regional scales, and unbiased estimates of density for multiple species of birds with a single protocol. We used transects for sampling ∼1,000-ha pastures that consisted of twelve 200-m radius sampling points. We conducted 10-min point counts and recorded distance to each observation using two independent observers, and resampled each of 30 transects over two study sites in South Texas, for a total of four visits in each of 2015 and 2016. We estimated occupancy at two scales using the multiscale model in Program MARK and estimated density using the Distance package in R. We predicted that it would be possible to detect a 50% decline over 25 y with a power of 0.90 in regional occupancy, local occupancy, and density for 36, 37, and 30 species, respectively, on our larger study site, and for 29, 33, and 12 species, respectively, on our smaller study site using two independent observers and four visits. Our work shows it is possible to monitor numerous species within a complex bird assemblage with a simple field protocol. For those interested in implementing a long-term monitoring program that is sensitive to a wide range of potential stressors at local and regional scales, we suggest considering multiscale occupancy and density monitoring for multiple species of birds.

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In-stent restenosis in the mid-term period after successful coronary arteries chronic total occlusion recanalization by antegrade approach

Proceedings of the National Academy of Sciences of Belarus Medical series ◽

10.29235/1814-6023-2019-16-1-65-76 ◽

2019 ◽

Vol 16 (1) ◽

pp. 65-76

Author(s):

V. I. Stelmashok

Keyword(s):

Coronary Artery ◽

Coronary Arteries ◽

Chronic Total Occlusion ◽

Total Occlusion ◽

Stent Restenosis ◽

Antegrade Approach ◽

Wide Range ◽

The Right ◽

Range Of Values ◽

In Stent Restenosis

The results on the in-stent restenosis in the mid-term period after successful coronary arteries chronic total occlusion (CTO) recanalization by the antegrade approach are assessed. The study included 117 patients who underwent coronary artery CTO recanalization for the period from 2009 to 2012. After 6.1 ± 0.9 months (stage К1) and 12.7 ± 1.6 months (stage К2), all patients were examined by coronary angiography, intravascular ultrasound and optical coherence tomography. During the frst half of the year after the CTO recanalization, there was a more frequent in-stent restenosis rate in the right coronary artery (in 25.6 %) as well as a predominance of focal types of restenosis (59.1 % of the total). The incidence of restenosis depending on the DES type varied over a wide range of values (from 0 to 52.4 % in the frst half of the year and from 0 to 41.2 % in the second half of the year). A signifcant increase in the incidence of restenosis was observed after the trapidil eluting stents implantation (52.4 % in the frst half of the year, 26.3 % in the second half of the year) and sirolimus eluting stents (38.9 % in the frst half, 41.2 % in the second half of the year). Our data show that different types of DES differently determine the changes in the vascular lumen during the medium term period after the successful CTO recanalization.

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Thermohaline layering on the microscale

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.976 ◽

2019 ◽

Vol 862 ◽

pp. 672-695 ◽

Cited By ~ 2

Author(s):

Timour Radko

Keyword(s):

Large Scale ◽

Numerical Models ◽

Spatial Scales ◽

Multiscale Model ◽

Small Scale ◽

Multiscale Approach ◽

Flux Gradient ◽

Gradient Model ◽

Wide Range ◽

Local Background

A theoretical model is developed which illustrates the dynamics of layering instability, frequently realized in ocean regions with active fingering convection. Thermohaline layering is driven by the interplay between large-scale stratification and primary double-diffusive instabilities operating at the microscale – temporal and spatial scales set by molecular dissipation. This interaction is described by a combination of direct numerical simulations and an asymptotic multiscale model. The multiscale theory is used to formulate explicit and dynamically consistent flux laws, which can be readily implemented in large-scale analytical and numerical models. Most previous theoretical investigations of thermohaline layering were based on the flux-gradient model, which assumes that the vertical transport of density components is uniquely determined by their local background gradients. The key deficiency of this approach is that layering instabilities predicted by the flux-gradient model have unbounded growth rates at high wavenumbers. The resulting ultraviolet catastrophe precludes the analysis of such basic properties of layering instability as its preferred wavelength or the maximal growth rate. The multiscale model, on the other hand, incorporates hyperdiffusion terms that stabilize short layering modes. Overall, the presented theory carries the triple advantage of (i) offering an explicit description of the interaction between microstructure and layering modes, (ii) taking into account the influence of non-uniform stratification on microstructure-driven mixing, and (iii) avoiding unphysical behaviour of the flux-gradient laws at small scales. While the multiscale approach to the parametrization of time-dependent small-scale processes is illustrated here on the example of fingering convection, we expect the proposed technique to be readily adaptable to a wide range of applications.

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On the generation of internal waves by river plumes in subcritical initial conditions

Scientific Reports ◽

10.1038/s41598-021-81464-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

R. Mendes ◽

J. C. B. da Silva ◽

J. M. Magalhaes ◽

B. St-Denis ◽

D. Bourgault ◽

...

Keyword(s):

Numerical Modeling ◽

Internal Waves ◽

Coastal Waters ◽

Initial Conditions ◽

Spatial Scales ◽

River Plumes ◽

Wide Range ◽

Near Shore ◽

Generation Mechanisms ◽

Douro River

AbstractInternal waves (IWs) in the ocean span across a wide range of time and spatial scales and are now acknowledged as important sources of turbulence and mixing, with the largest observations having 200 m in amplitude and vertical velocities close to 0.5 m s−1. Their origin is mostly tidal, but an increasing number of non-tidal generation mechanisms have also been observed. For instance, river plumes provide horizontally propagating density fronts, which were observed to generate IWs when transitioning from supercritical to subcritical flow. In this study, satellite imagery and autonomous underwater measurements are combined with numerical modeling to investigate IW generation from an initial subcritical density front originating at the Douro River plume (western Iberian coast). These unprecedented results may have important implications in near-shore dynamics since that suggest that rivers of moderate flow may play an important role in IW generation between fresh riverine and coastal waters.

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Changing paradigm for treatment of heavily calcified coronary artery disease. A complementary role of rotational atherectomy and intravascular lithotripsy with shockwave balloon: a case report

European Heart Journal - Case Reports ◽

10.1093/ehjcr/ytaa456 ◽

2020 ◽

Author(s):

Shana Tehrani ◽

Sudhir Rathore ◽

Vinod Achan

Keyword(s):

Coronary Artery ◽

Interventional Cardiology ◽

Rotational Atherectomy ◽

Stent Restenosis ◽

Case Summary ◽

Stent Expansion ◽

Complementary Role ◽

Artery Disease ◽

Stenotic Lesions

Abstract Background Management of heavily calcified coronary arteries is still a major challenge in interventional cardiology. Inadequate stent expansion in calcific lesions is the single most important predictor of stent thrombosis and in-stent restenosis. Rotational atherectomy (RA) is an important tool to modify the calcium burden but is associated with limitations and requires specific skills. Intravascular lithotripsy (IVL) is a novel technique to treat calcified stenotic lesions and has been proposed as an alternative to RA with promising results. Case summary We report a case of a patient with severely calcified right coronary artery stenosis successfully treated with combination of RA and IVL. Discussion In this case, we demonstrate that the RA and IVL are complementary strategies, not sufficient on their own and not alternative to each other.

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