Exploring unique dynamics in a predator-prey model with generalist predator and group defense in prey.

In the current paper, we consider a predator-prey model where the predator is modeled as a generalist using a modified Leslie-Gower scheme, and the prey exhibits group defense via a generalized response. We show that the model could exhibit finite-time blow-up, contrary to the current literature [Patra et al., Eur. Phys. J. Plus 137(1), 28 (2022)]. We also propose a new concept via which the predator population blows up in finite time, while the prey population quenches in finite time; that is, the time derivative of the solution to the prey equation will grow to infinitely large values in certain norms, at a finite time, while the solution itself remains bounded. The blow-up and quenching times are proved to be one and the same. Our analysis is complemented by numerical findings. This includes a numerical description of the basin of attraction for large data blow-up solutions, as well as several rich bifurcations leading to multiple limit cycles, both in co-dimension one and two. The group defense exponent p is seen to significantly affect the basin of attraction. Last, we posit a delayed version of the model with globally existing solutions for any initial data. Both the ordinary differential equation model and the spatially explicit partial differential equation models are explored.

Stability and bifurcation analysis of a two-patch model with the Allee effect and dispersal.

In the current manuscript, a two-patch model with the Allee effect and nonlinear dispersal is presented. We study both the ordinary differential equation (ODE) case and the partial differential equation (PDE) case here. In the ODE model, the stability of the equilibrium points and the existence of saddle-node bifurcation are discussed. The phase diagram and bifurcation curve of our model are also given as a results of numerical simulation. Besides, the corresponding linear dispersal case is also presented. We show that, when the Allee effect is large, high intensity of linear dispersal is not favorable to the persistence of the species. We further show when the Allee effect is large, nonlinear diffusion is more beneficial to the survival of the population than linear diffusion. Moreover, the results of the PDE model extend our findings from discrete patches to continuous patches.

The effect of "fear" on two species competition.

Non-consumptive effects such as fear of depredation, can strongly influence predator-prey dynamics. There are several ecological and social motivations for these effects in competitive systems as well. In this work we consider the classic two species ODE and PDE Lotka-Volterra competition models, where one of the competitors is "fearful" of the other. We find that the presence of fear can have several interesting dynamical effects on the classical competitive scenarios. Notably, for fear levels in certain regimes, we show novel bi-stability dynamics. Furthermore, in the spatially explicit setting, the effects of several spatially heterogeneous fear functions are investigated. In particular, we show that under certain integral restrictions on the fear function, a weak competition type situation can change to competitive exclusion. Applications of these results to ecological as well as sociopolitical settings are discussed, that connect to the "landscape of fear" (LOF) concept in ecology.

Modeling and Simulation of Tin Sulfide (SnS)-Based Solar Cell Using ZnO as Transparent Conductive Oxide (TCO) and NiO as Hole Transport Layer (HTL).

This paper describes the simulation by Solar Cell Capacitance Simulator-1D (SCAPS-1D) software of ZnO/CdS/SnS/NiO/Au solar cells, in which zinc oxide (ZnO) is used as transparent conductive oxide (TCO) and nickel oxide (NiO) is used as a hole transport layer (HTL). The effects of absorber layer (SnS) thickness, carrier concentration, SnS defect density, NiO HTL, ZnO TCO, electron affinity and work function on cell performance have been evaluated. The effect of interface defect density of SnS/CdS on the performance of the heterojunction solar cell is also analysed. As the results indicate, a maximum power conversion efficiency of 26.92% was obtained.

Design and Simulation of Efficient SnS-Based Solar Cell Using Spiro-OMeTAD as Hole Transport Layer.

In the present paper, the theoretical investigation of the device structure ITO/CeO2/SnS/Spiro-OMeTAD/Mo of SnS-based solar cell has been performed. The aim of this work is to examine how the Spiro-OMeTAD HTL affects the performance of SnS-based heterostructure solar cell. Using SCAPS-1D simulation software, various parameters of SnS-based solar cell such as work function, series and shunt resistance and working temperature have been investigated. With the help of Spiro-OMeTAD, the suggested cell's open-circuit voltage was increased to 344 mV. The use of Spiro-OMeTAD HTL in the SnS-based solar cell resulted in 14% efficiency increase, and the proposed heterojunction solar cell has 25.65% efficiency. The cell's performance is determined by the carrier density and width of the CeO2 ETL (electron transport layer), SnS absorber layer and Spiro-OMeTAD HTL (hole transport layer). These data reveal that the Spiro-OMeTAD solar cells could have been a good HTL (hole transport layer) in regards to producing SnS-based heterojunction solar cell with high efficiency and reduced cost.

Brownian dynamics simulations for the narrow escape problem in the unit sphere.

The narrow escape problem is a first-passage problem that concerns the calculation of the time needed for a Brownian particle to leave a domain with localized absorbing boundary traps, such that the measure of these traps is asymptotically small compared to the domain size. A common model for the mean first-passage time (MFPT) as a function of particle's starting location in a given domain with constant diffusivity is given by a Poisson partial differential equation subject to mixed Dirichlet-Neumann boundary conditions. The primary objective of this work is to perform direct numerical simulations of multiple particles undergoing Brownian motion in a three-dimensional spherical domain with boundary traps, compute MFPT values by averaging Brownian escape times, and compare these with explicit asymptotic results obtained previously by approximate solution of the Poisson problem. A close agreement of MFPT values is observed already at 10^{4} particle runs from a single starting point, providing a computational validation of the Poisson equation-based continuum model. Direct Brownian dynamics simulations are also used to study additional features of particle dynamics in narrow escape problems that cannot be captured in a continuum approach, such as average times spent by particles in a thin layer near the domain boundary, and effects of isotropic vs anisotropic near-boundary diffusion.

A rare case of Balo concentric sclerosis showing unusual clinical improvement and response with oral prednisolone.

The present report is a rare case of Balo Concentric Sclerosis. Most cases have either been diagnosed post mortem or have succumbed to the disease after being diagnosed ante mortem. In our case, the patient showed a dramatic response to treatment, and after a one-year follow-up, he was asymptomatic, with no relapses or residual effect of the illness.

Determinants of intravascular resistance in Indian diabetic nephropathy patients: a hospital-based study.

Aims and Objectives. Metabolic dysregulation has failed to explain clinical variability of patients with diabetic nephropathy and hence a renewed interest emerged in haemodynamic factors as determinant of progression and development of diabetic nephropathy. We therefore studied for various factors which can correlate with raised renal vascular resistance in diabetic nephropathy. Material and Methods. Renal vascular resistance was measured in patients with established and incipient diabetic nephropathy and compared with controls using noninvasive color Doppler examinations of intrarenal vasculature. Results. Renal vascular resistance correlated with age, duration of disease, GFR, serum creatinine, and stage of retinopathy. Renal vascular resistance was significantly reduced in patients on treatment with RAAS inhibitors and insulin, than those on OHA and antihypertensives other than RAAS inhibitors. Conclusion. The study implies that renal vascular resistance may help identify diabetics at high risk of developing nephropathy, and these set of patients could be candidates for RAAS inhibition and early insulin therapy even in patients without albuminuria.