Linear and structural stability of a cell division process model

The paper investigates the linear stability of mammalian physiology time-delayed flow for three distinct cases (normal cell cycle, a neoplasmic cell cycle, and multiple cell arrest states), for the Dirac, uniform, and exponential distributions. For the Dirac distribution case, it is shown that the model exhibits a Hopf bifurcation for certain values of the parameters involved in the system. As well, for these values, the structural stability of the SODE is studied, using the five KCC-invariants of the second-order canonical extension of the SODE, and all the cases prove to be Jacobi unstable

LINEAR AND STRUCTURAL STABILITY OF A CELL DIVISION PROCESS MODEL

The paper investigates the linear stability of mammalian physiology time-delayed flow for three distinct cases (normal cell cycle, a neoplasmic cell cycle, and multiple cell arrest states), for the Dirac, uniform, and exponential distributions. For the Dirac distribution case, it is shown that the model exhibits a Hopf bifurcation for certain values of the parameters involved in the system. As well, for these values, the structural stability of the SODE is studied, using the five KCC-invariants of the second-order canonical extension of the SODE, and all the cases prove to be Jacobi unstable

Factors Associated with Prolonged RT-PCR SARS-CoV-2 Positive Testing in Patients with Mild and Moderate Forms of COVID-19: A Retrospective Study

Background and objectives: This article aims to evaluate the number of days necessary for patients with mild and moderate forms of COVID-19 to reach undetectable levels of SARS-CoV-2 RNA in the upper respiratory tract specimens. As a secondary objective, we sought to establish a correlation between different conditions associated with longer viral load as this could result in a longer period of contagion and infectivity. Materials and Methods: It is a retrospective study. A total of 70 patients with confirmed mild and moderate forms of COVID-19 were enrolled in our study. Results: Number of days with traceable viral load was 25.93 (±6.02) days in patients with mild COVID-19 and 26.97 (±8.30) in moderate form (p = 0.72). Age, male gender, and obesity, along with several chronic conditions (cardiac, liver, renal, and neurological disease), were associated with prolonged positive RT-PCR test from the nasal swab (therefore prolonged viral load). These are in general, risk factors for severe forms of COVID-19. Conclusions: There are several conditions associated with prolonged positive RT-PCR in mild and moderate forms of COVID-19. As to why and what is the significance of it remains to be studied