Buruli ulcer (BU), a necrotizing skin disease caused by Mycobacterium ulcerans, remains a neglected tropical disease with complex environmental and vector-mediated transmission dynamics. Motivated by the potential interaction between chronic BU infection, environmental contamination, and cancer-associated immunosuppression, this study develops an integrated mathematical model describing the coupled dynamics of Buruli ulcer and BU–cancer co-infection. The proposed framework incorporates dual transmission pathways, an environmental infectious reservoir, and immunosuppression-mediated progression to the co-infected class. The basic reproduction number [Formula: see text] is derived using the next-generation matrix approach, and the local and global stability properties of the disease-free and endemic equilibria are investigated. Bifurcation analysis is performed to examine threshold behavior near [Formula: see text], while numerical simulations are used to illustrate the qualitative dynamics of the model under representative baseline parameter values. Global sensitivity analysis based on the Latin Hypercube Sampling–Partial Rank Correlation Coefficient (LHS–PRCC) method identifies the environmental contamination rate, Buruli ulcer recovery rate, and progression to the co-infected compartment as the parameters exerting the greatest influence on disease dynamics. The proposed framework provides theoretical insights into the interaction between environmental persistence, Buruli ulcer transmission, and cancer-associated immunosuppression, and may serve as a basis for future epidemiological investigations and model refinement.
Early screening is essential for improving the prognosis of colorectal cancer (CRC), for which fecal occult blood testing (FOBT) remains one of the most widely adopted noninvasive screening approaches. However, conventional FOBT methods often exhibit insufficient sensitivity and limited reliability when handling complex fecal matrices, largely due to nonspecific fouling and cumbersome sample pretreatment procedures. Herein, we report a surface plasmon resonance biosensor integrating a self-assembled anti-fouling interface with DNA aptamer-mediated molecular recognition for sensitive hemoglobin detection in fecal samples. The engineered sensing surface exhibits high interfacial stability and resistance to nonspecific adsorption, enabling direct analysis of fecal samples without complicated pretreatment. The proposed platform achieved a detection limit of 1 nM and a diagnostic accuracy of 97.6%. This study demonstrates the feasibility of SPR-based hemoglobin detection in complex fecal samples using an antifouling sensing interface and highlights its potential as a promising optical biosensing strategy for noninvasive colorectal cancer screening.
Background: The lutetium-177 (177Lu) radioisotope has been proposed for use in radio-immunotherapy. Nowadays, 177Lu is mostly generated through neutron activation in nuclear reactors, although cyclotron-based production may also be utilized. Methods: In this study, a small cyclotron located in Karaj city of Iran with a maximum deuteron energy of 14[Formula: see text]MeV was simulated to produce 177Lu through 176Yb target by using SRIM and TALYS codes. In addition to estimating the cross-section values, the production yield of the reaction [Formula: see text]Yb(d,p)[Formula: see text]Yb*[Formula: see text]Lu was calculated at different deuteron energies. Here, the combination model of optical model parameters (OMP) and back-shifted Fermi gas model (BSFGM) with RIPL-3 parameters was performed to estimate the energy level density for the compound nucleus [Formula: see text]Yb, which is particularly important for cross-sections near the threshold. Results: The computed cross-section values of the reaction (d,p) and its competing reaction (d,x) were compared with other published reports. The maximum cross-section value for the (d,p) reaction was estimated to be 125[Formula: see text]mb at 10.5[Formula: see text]MeV, and for the (d,x) reaction to be 121[Formula: see text]mb at 9.5[Formula: see text]MeV. The production yields determined by Pade fitting were 118 and 315[Formula: see text]MBq/[Formula: see text] [Formula: see text]A.h, respectively, at deuteron energies of 10.5 and 14[Formula: see text]MeV. This corresponds to a yield of 318 MBq/[Formula: see text] [Formula: see text]A and 272 MBq/[Formula: see text] [Formula: see text]A for 1[Formula: see text]h of irradiation, respectively. Conclusion: The BSFGM may not provide accurate predictions of the [Formula: see text]Lu/[Formula: see text]Lu branching ratios in isomer estimates. Due to pre-equilibrium contributions, the (d,p) reaction exhibits significant direct/semi-direct components that optical models may not fully capture. Besides, using [Formula: see text]Yb-specific parameters ignores contributions from other Yb isotopes in natural targets, which affects the target’s isotopic purity. A drawback of the model is the underestimation of level densities for highly deformed nuclei. Although RIPL-3 provides the best results, uncertainties can be substantial for nuclei with limited data. This parameter uncertainty necessitates a fixed functional form; the exponential form may not capture all effects of nuclear structure.
This study presents a novel extension of the classical Rosenzweig–MacArthur predator–prey model by incorporating two predator species and an Allee effect in the prey population, along with an eco-epidemiological interaction between the predators. The resulting system captures complex trophic dynamics where the intermediate predator is suppressed by both direct predation on the prey and a parasitic or infection-like pressure from the top predator. The prey population is subject to Allee-type depensation, influencing its ability to recover at low densities a biologically relevant feature in many real ecosystems. Mathematically, the model is formulated through a set of nonlinear ordinary differential equations, analyzed for equilibrium behavior, local and global stability, and bifurcations. The system is nondimensionalized to reduce parameter redundancy and emphasize key ecological mechanisms. Stability and bifurcation analyses are performed to uncover critical thresholds where the system shifts from stable coexistence to periodic or chaotic behavior. We then examine the spatially explicit system and evaluate the Turing instability conditions for the resulting spatio-temporal dynamics. Numerical simulations, including bifurcation diagrams and Lyapunov exponent computations, validate the analytical findings and demonstrate rich dynamical regimes including stable nodes, limit cycles, and strange attractors. Biologically, the model emphasizes the role of Allee effects, predator interference, and infection-like interactions in shaping population persistence and ecosystem stability. The results underscore the importance of managing interspecies interactions and mortality rates to prevent extinction and chaotic outbreaks. This work contributes to the understanding of nonlinear eco-epidemiological systems and provides a basis for future studies incorporating spatial dynamics or stochasticity.
In this paper, we extend the classical Hastings–Powell tri-trophic food chain model by incorporating two ecologically realistic mechanisms: predator-induced fear in prey and a weak Allee effect. A rigorous mathematical analysis is carried out, including positivity, boundedness, dissipativeness, and persistence of solutions, followed by a detailed investigation of all equilibrium points and their local and global stability properties. Through bifurcation analysis, we identify that govern system transitions. Sensitivity analysis using Partial Rank Correlation Coefficients (PRCC) highlights the most influential parameters for prey, predator, and top predator dynamics. Numerical simulations, conducted via MATLAB and MATCONT, further reveal complex dynamical regimes. In particular, variation of the prey-handling time parameter [Formula: see text] drives the system into chaos, as confirmed by a positive maximum Lyapunov exponent (MLE). Importantly, we demonstrate that chaos can be suppressed by strengthening the weak Allee effect ([Formula: see text]) and predator-induced fear ([Formula: see text]). Two-parameter bifurcation diagrams for [Formula: see text], [Formula: see text], and [Formula: see text] provide deeper insights into the combined ecological effects of these parameters. The results, supported with ecological interpretations, show how behavioral responses and Allee effects can regulate chaotic oscillations and promote system stability, offering useful theoretical insights for ecological management and conservation.
