arXiv subjects

Sergey Lapin

Publications and source records attributed to Sergey Lapin.

5 recordsLinked to original sources

arXiv2026

Economic Disparities and Their Relationship to Destructive Health Behaviors in Five Western U.S. States

In this paper, we look at the relationships that economic variables have with adverse health outcomes in the western counties of Washington, Idaho, Oregon, California, and Nevada, with specific emphasis on how suicide rate relates to such economic variables. Data was first gathered from Census and County Health Rankings for the entire United States (for website use and usefulness for future research), cleaned and regression-imputed, and then various exploratory data analysis methods were used, such as PCA, clustering, correlation gathering, linear fittings, and LASSO. PCA and clustering suggested that counties may group according to broader state-level economic patterns, although political interpretations would require additional electoral data. Correlation Analysis, along with LASSO and linear fittings, showed us the destructive variables that connected the most with economic variables (in terms of $R^2$ and correlation values seen), the economic variables that are most and least important in predicting suicide rate, and the possible relationships that suicide rate has with these economic variables.

stat.AP↗

arXiv2025

Quantifying the Hemodynamic Effects of Ventricular Fibrillation using a Verified Computational Model

Ventricular Fibrillation (VF) is a malignant cardiac arrhythmia and the leading cause of sudden cardiac death, characterized by disorganized, high-frequency ventricular activity that results in the rapid loss of coordinated pump function and circulatory collapse. While the clinical manifestations of VF are well established, the multiscale mechanisms linking cellular electrophysiology to whole-organ mechanical failure remain challenging to study experimentally. Computational modeling therefore provides a critical platform for mechanistic investigation. This work presents a hierarchical computational study of VF beginning with the implementation and verification of a closed-loop, lumped-parameter (0D) hemodynamic model of the cardiovascular system. The verified model is used to quantify the global circulatory consequences of a prescribed VF state, demonstrating a 62.4% reduction in cardiac output and highlighting the dominant role of impaired ventricular filling and contractile failure. Recognizing the limitations of prescribing arrhythmia dynamics, we then propose a pathway toward an integrated, multiscale framework coupling the 0D hemodynamic core with models of cardiac electrophysiology and autonomic regulation to enable simulation of emergent arrhythmogenic behavior and reflex responses. Finally, we introduce an interactive simulator derived from the verified 0D model, designed to support education, hypothesis testing, and future integration of multiscale components. This work establishes a mechanistic baseline and software foundation for next-generation computational studies of VF and cardiovascular control.

physics.bio-ph↗

arXiv2025

Eye2Heart : a validated lumped-parameter model bridging cardiovascular and ocular dynamics

The cardiovascular and ocular systems are intricately connected, with hemodynamic interactions playing a crucial role in both physiological regulation and pathological conditions. However, existing models often treat these systems separately, limiting the understanding of their interdependence. In this study, we present the Eye2Heart model, a novel closed-loop mathematical framework that integrates cardiovascular and ocular dynamics. Using an electricalhydraulic analogy, the model describes the interactions between the heart and retinal circulation through a system of ordinary differential equations. The model is validated against clinical and experimental data, demonstrating its ability to reproduce key cardiovascular parameters (e.g., stroke volume, cardiac output) and ocular hemodynamics (e.g., retinal blood flow). Additionally, we explore in silico the effects of intraocular pressure (IOP) and left ventricular compliance on both local ocular and global systemic circulation, revealing critical dependencies between cardiovascular and ocular health. The results highlight the model's potential for studying cardiovascular diseases with ocular manifestations, paving the way for patient-specific data integration and expanding applications in personalized medicine.

physics.med-ph↗

arXiv2018

Accuracy of the Muskingum-Cunge method for constant-parameter diffusion-wave channel routing with lateral inflow

Channel routing is important in flood forecasting and watershed modeling. The general constant-parameter Muskingum-Cunge (CPMC) method is second-order accurate and easy to implement. With specific discretizations such that the temporal and spatial intervals maintain a unique relationship, the CPMC method can be third-order accurate. In this paper, we derive the average lateral inflow term in the second- and third-order accuracy CPMC method, and demonstrate that For spatially and temporally variable lateral inflow, the effect of lateral inflow on simulated discharge varies with spatial and temporal discretizations, the value and spatial and temporal variations of lateral inflow, wave celerity, and diffusion coefficient. Comparison of the CPMC solution with the analytical solution shows that both the second- and third-order accuracy schemes are more accurate than the simplified method by which spatial derivatives of lateral inflow are ignored. For small time steps, the third-order accuracy CPMC method results in higher accuracy than the second-order scheme even when the third-order accuracy criterion is not fully met. For large time steps, the temporal and spatial discretization of the third- and second-order scheme becomes the same, but the third-order scheme yields higher accuracy than the second-order scheme because of the third-order accurate estimation of the lateral inflow term.

physics.flu-dyn↗

arXiv2013

Dynamic discrete model for the granular matter formation process

In this paper we introduce 1-$D$ and 2-$D$ discrete models for the dynamic granular matter formation process in the form of a system of difference equations. This approach allows us to differentiate between the influx of the rolling layer coming down from different directions to the corner points of the standing layer. Such points are difficult to adequately describe by means of pde's and their straightforward numerical approximations, typically ``ignoring'' the system's behavior on the sets of zero measure. However, these points are critical for understanding the dynamic formation process when the standing layer is created by the moving front of the rolling matter or when the latter is filling a cavity and/or stops rolling. The existence of distributed (infinite dimensional) limit solutions to our discrete models as the size of mesh tends to zero is also discussed. We illustrate our findings by numerical examples which use our model as a direct algorithm.

math.NA↗