AIMS Biophysics最新文献

In this essay, we have presented a fractional numerical model of breast cancer stages with cardiac outcomes. Five compartments were used to build the model, each of which represented a subpopulation of breast cancer patients. Variables A, B, C, D, and E each represent a certain subpopulation. They are levels 1 and 2 (A), level 3 (B), level 4 (C), disease-free (D) and cardiotoxic (E). We have demonstrated that the fractional model has a stable solution. We also discuss how to optimally control this model and numerically simulate the control problem. Using numerical simulations, we computed the results of the dissection. The model's compartment diagram has been completed. A predictor-corrector method has been used to manage the fractional derivatives and produce numerical solutions. The Caputo sense has been used to describe fractional derivatives. The results have been illustrated through numerical simulations. Furthermore, the numerical simulations show that the cancer breast malignant growth fractional order model is easier to model than the traditional integer-order model. To compute the results, we have used mathematical programming. We have made it clear that the numerical method that was applied in this publication to solve this model was not utilized by any other author before that, nor has this method been investigated in the past. Our investigation established this approach.

Cardiac arrhythmias are serious myocardial electrical disturbances that affect the rate and rhythm of heartbeats. Despite the rapidly accumulating data about the pathophysiology and the treatment, new insights are required to improve the overall clinical outcome of patients with cardiac arrhythmias. Three major arrhythmogenic processes can contribute to the pathogenesis of cardiac arrhythmias; 1) enhanced automaticity, 2) afterdepolarization-triggered activity and 3) reentry circuits. The mathematical model of the quantum tunneling of ions is used to investigate these mechanisms from a quantum mechanical perspective. The mathematical model focuses on applying the principle of quantum tunneling to sodium and potassium ions. This implies that these ions have a non-zero probability of passing through the gate, which has an energy that is higher than the kinetic energy of ions. Our mathematical findings indicate that, under pathological conditions, which affect ion channels, the quantum tunneling of sodium and potassium ions is augmented. This augmentation creates a state of hyperexcitability that can explain the enhanced automaticity, after depolarizations that are associated with triggered activity and a reentry circuit. Our mathematical findings stipulate that the augmented and thermally assisted quantum tunneling of sodium and potassium ions can depolarize the membrane potential and trigger spontaneous action potentials, which may explain the automaticity and afterdepolarization. Furthermore, the quantum tunneling of potassium ions during an action potential can provide a new insight regarding the formation of a reentry circuit. Introducing these quantum mechanical aspects may improve our understanding of the pathophysiological mechanisms of cardiac arrhythmias and, thus, contribute to finding more effective anti-arrhythmic drugs.

This study uses laminar and turbulent flow models to investigate the blood flow dynamics in a specific carotid bifurcation. Pulsatile boundary conditions and the rigid carotid artery wall are considered. Three viscosity models describe the non-Newtonian blood behavior. The Fluent solver and the finite volume method solve the equations. Results show a Poiseuille-like flow in the common carotid artery (CCA), unaffected by the flow regime, viscosity model, or boundary conditions. The branching zone exhibits a C-shaped stagnation zone with low velocity and wall shear stress due to the CCA widening and ICA/ECA curvature. Strong secondary flow is observed in the carotid sinus; the flow is directed towards the inner wall with higher velocity in the internal carotid artery. Discrepancies between viscosity models are pronounced in laminar flow, particularly with the natural boundary conditions. The non-Newtonian blood behavior is more apparent in the laminar flow of the external carotid artery, especially with the second set of boundary conditions.

We are devoted to the physical analysis of the habitat area of warm-blooded organisms – humans and many mammals. For this purpose, the establishment of equilibrium distribution of carbon dioxide in aqueous solutions of salts in contact with atmospheric air starting from some time is investigated. More precisely, the relaxation time of carbon dioxide, as a function of temperature and pH, is investigated. It is found that the pH-relaxation time τ_S is a very nontrivial function of temperature, pH values, and NaCl salt concentration. It was assumed that the minimum value of pH relaxation time corresponds to the optimal rate of physical processes in living matter. Using this selection principle and our experimental data, we have shown that the optimal temperature for human and mammalian life activity is close to T_o ≈ 37 °C. The lower and upper temperature limits for their possible activity are close to T_l ≈ 30 °C and T_u ≈ 42 °C, respectively. The optimal value of pH_o, determined by the same selection principle, also becomes true if supplemented by the influence of albumin and other proteins.