Competitive exclusion and coexistence in a stoichiometric chemostat model

In this paper, we incorporate stoichiometry into a competition model in chemostat culture. We first discuss the dynamics of this stoichiometric chemostat model for single algae species. We obtain the uniform persistence and find that an increase of phosphorus input or a slow dilution rate facilitates the algal persistence. Then, we consider a stoichiometric chemostat model in which two species competing for single nutrient, investigate how stoichiometry, dilution rate and concentration of phosphorus input affect the result of competition between algae species. Competitive exclusion and coexistence of two competing algae species are explored by discussing the existence, local stability of all feasible equilibria. Previous studies suggested that competitive exclusion holds in general chemostat models with two species competing for one limiting nutrient. Our theoretical and numerical results demonstrate that stoichiometry brings the coexistence of two competing algae species. Moreover, under low phosphorus input or fast dilution rate, competitive exclusion still holds. High phosphorus input or slow dilution rate facilitates the coexistence of multiple species

Dynamical analysis of a network-based SIR model with saturated incidence rate and nonlinear recovery rate: an edge-compartmental approach

A new network-based SIR epidemic model with saturated incidence rate and nonlinear recovery rate is proposed. We adopt an edge-compartmental approach to rewrite the system as a degree-edge-mixed model. The explicit formula of the basic reproduction number $\mathit{\boldsymbol{R_{0}}}$ is obtained by renewal equation and Laplace transformation. We find that \mathit{\boldsymbol{R_{0}}} < 1 is not enough to ensure global asymptotic stability of the disease-free equilibrium, and when \mathit{\boldsymbol{R_{0}}} > 1 , the system can exist multiple endemic equilibria. When the number of hospital beds is small enough, the system will undergo backward bifurcation at $\mathit{\boldsymbol{R_{0}}} = 1$. Moreover, it is proved that the stability of feasible endemic equilibrium is determined by signs of tangent slopes of the epidemic curve. Finally, the theoretical results are verified by numerical simulations. This study suggests that maintaining sufficient hospital beds is crucial for the control of infectious diseases

Release of Perfluoroalkyl Substances From Melting Glacier of the Tibetan Plateau: Insights Into the Impact of Global Warming on the Cycling of Emerging Pollutants

The Tibetan Plateau (TP) has encountered rapid warming, with more than 50% of lakes expanding and 80% of glaciers retreating. Melting glaciers are known as a secondary source of pollutants, but the dynamics and release features of water‐soluble emerging chemicals have not been studied in the TP. Glacial ice and snow, meltwater runoff, rain, and lake water were collected in Nam Co basin, in the central TP. The total concentrations of perfluoroalkyl acids (PFAAs) were 1,413 pg/L for glacial ice, followed by 1,277 pg/L for meltwater runoff, 980 pg/L for lake water, and 616 pg/L for rain. Perfluorobutanoic acid is dominant in runoff and glacial ice, while lake water contained high proportions of perfluorobutane sulfonate and perfluorooctane sulfonate. During the melting season, meltwater runoff generally had greater PFAAs concentrations, and the PFAAs release fluxes were strongly related to the glacial melt intensity. Due to the direct input of PFAAs by melted glaciers, south shore of Lake Nam Co contained higher PFAAs concentrations. The estimated input fluxes of PFAAs to the lake by rain and glacial and nonglacial runoff were 1,425, 1,342, and 2,192 mg/day, respectively. Taken together, these evidences suggest that melting glaciers are sources of PFAAs, while the lake is the receptor. Given the continuity of glacial melt and high concentrations of water‐soluble emerging pollutants in glacier, the melting process will increase the risks of emerging pollutants to freshwater sources and should be of great concern.Post-print / Final draf

dsRNA Virus Model Molecule and the Mechanism of PRRs and its Research Progress in Female Reproductive Tract Infections

Female animal genital tract opening on the body surface, prone to bacterial, viral, parasitic, and other pathogenic microorganism infections, leading to genital tract infectious diseases, such as endometritis, cervicitis, vaginitis, etc. Severe infection can lead to infertility, abortion, and even fetal death. Double-stranded RNA (dsRNA) is an important model molecule, which is widely present in the genome of viruses and generated in the process of virus replication. In mammals, dsRNA is considered to be an innate immune response signal for viral infection, which binds to the corresponding pattern-recognition receptors (PRRs) In vivo and then exerts biological functions. This review summarizes the signal transduction pathway induced by the binding of dsRNA model molecules to PRRs, research status of female genital tract infections and research progress of dsRNA in simulating viral infection in the female genital tract

Deep learning-based edge caching for multi-cluster heterogeneous networks

© 2019, Springer-Verlag London Ltd., part of Springer Nature. In this work, we consider a time and space evolution cache refreshing in multi-cluster heterogeneous networks. We consider a two-step content placement probability optimization. At the initial complete cache refreshing optimization, the joint optimization of the activated base station density and the content placement probability is considered. And we transform this optimization problem into a GP problem. At the following partial cache refreshing optimization, we take the time–space evolution into consideration and derive a convex optimization problem subjected to the cache capacity constraint and the backhaul limit constraint. We exploit the redundant information in different content popularity using the deep neural network to avoid the repeated calculation because of the change in content popularity distribution at different time slots. Trained DNN can provide online response to content placement in a multi-cluster HetNet model instantaneously. Numerical results demonstrate the great approximation to the optimum and generalization ability

Serum retinol binding protein as a novel marker for clearance and dosage optimization: pharmacokinetics study of voriconazole in a cirrhosis population

Background and ObjectiveVoriconazole (VRC) exhibits nonlinear pharmacokinetic (PK) characteristics and a narrow therapeutic window. Consequently, standardized dosage regimens are insufficient to achieve the targeted therapeutic exposure in patients with cirrhosis. While numerous population pharmacokinetic (PPK) studies on VRC have been conducted, data on the cirrhosis demographic remain limited.This study aimed to explore the PK characteristics of VRC and its covariates in a cirrhosis population, with the objective of recommending individualized dosing regimens.MethodsData collected from routine therapeutic drug monitoring (TDM) of patients with recorded VRC plasma concentrations during a period of therapy between September 2022 and August 2024 were included. A population pharmacokinetic (PPK) model was constructed using nonlinear mixed-effects modeling (NONMEM). Monte Carlo simulation was used to predict the target trough concentrations of VRC under steady-state conditions based on the final model parameters, thereby facilitating tailored dosage recommendations.ResultsA total of 151 trough concentrations were obtained from 78 patients enrolled in the PPK study of VRC. A one-compartment model featuring first-order absorption and first-order elimination was optimal in describing the PK characteristics, additionally incorporating Child-Pugh grades and retinol-binding protein (RBP) as covariates affecting the central ventricular clearance rate (CL) of VRC. In the final model, the CL was determined as 6.96 L/h. For patients classified as Child-Pugh A and B with RBP ≥25 mg/L, the recommended dosages were 400 mg/d and 200 mg/d, respectively. At RBP levels &lt;25 mg/L, the recommended dosages for Child-Pugh A and C patients were 200 mg/d and 100 mg/d, respectively, while for Child-Pugh B patients, both 200 mg/d and 100 mg/d were recommended.ConclusionOur results support the utility of RBP as a novel marker associated with VRC clearance. This biomarker may offer a practical option for VRC dosage optimization. The clinical dosage of VRC could be tailored according to the Child-Pugh grades and RBP levels of patients. While numerous unexplained factors potentially influence the pharmacokinetic properties of VRC, the application of PPK model-guided TDM is crucial for achieving precision in individualized medication regimens

Visible emission and energy transfer in Tb³⁺/Dy³⁺ co-doped phosphate glasses

In this work, we systematically study the spectroscopic properties of Tb3+/Dy3+ co-doped phosphate glasses in the visible spectral region and explore the sensitization role of Dy3+ in the enhancement of visible fluorescence of Tb3+ ions. Judd-Ofelt parameters Ω2 and Ω4/Ω6 of the phosphate glass as host for Tb3+ are calculated as 21.60 × 10-20 cm2 and 0.73, respectively, based on the measured spectral absorption. Multiple energy transfer (ET) routes from Dy3+ to Tb3+ and their efficiencies are characterized, and the enhanced fluorescence properties of Tb3+ are investigated, including the emission spectral strength and the spontaneous emission lifetime as functions of Dy3+ doping concentration. The efficient nonradiative ET processes between Dy3+ and Tb3+ allow a moderate concentration level of Tb3+ to achieve favorably stronger spectral absorption at blue and ultraviolet wavelengths. Tb3+/Dy3+ co-doped phosphate glass shows promising potential for phosphors and lasing operation at visible wavelengths.</p

Progressive collapse resistance mechanism of RC frame structure considering reinforcement corrosion

Corrosion causes reduction in cross-sectional area of reinforcement, deterioration of mechanical properties, and degradation of bonding properties between reinforced concrete, which are the most important factors leading to the degradation of structural service performance. In order to investigate the progressive collapse mechanism of a corroded reinforced concrete frame structure, the failure modes, characteristics of the vertical displacement, and load capacity are studied using the finite element method. Based on existing experimental research, the established model is verified, and the influence of different influencing factors on the progressive collapse mechanism is analyzed. The results show that the corrosion of the reinforcement affects the yield load, peak load, and ultimate load of the reinforced concrete substructure. As the corrosion rate increases, the tensile arch action shows a particularly severe deterioration. The variation of concrete strength and the height–span ratio affects the substructure’s load-bearing capacity much more significantly than the stirrup spacing

Psychometric evaluation of the cardiac rehabilitation adherence scale in patients with coronary heart disease: an observational study

BackgroundCardiac rehabilitation has showed the potential to improve health outcomes of patients with coronary heart disease. However, the adherence of patients participating in cardiac rehabilitation is unsatisfactory due to some barriers. The quantitative instrument for measuring cardiac rehabilitation adherence is scarce. Hence, the purpose of this study was to develop a scientific tool and assess its psychometric properties in patients with coronary heart diseaseMaterial and MethodsThe psychometric properties of the revised scale were tested with 509 patients. Item analysis was conducted to evaluate the discrimination and homogeneity of the scale. Content validity was evaluated by content validity index and Exploratory factor analyses and confirmatory factor analyses were used to examine the factor structure of the scale. Reliability was evaluated by Cronbach's coefficients and split-half reliability coefficients.ResultsA scale covering five dimensions and thirty-three items was developed for evaluating cardiac rehabilitation adherence. The content validity index of the scale was 0.96. In exploratory factor analysis, a five-factor structure model was confirmed, explaining 71.255% of the total variation. In confirmatory factor analysis, the five- factor structure was supported by appropriate fitting indexes. In terms of reliability, the Cronbach's α coefficient of the scale was 0.909 and the spilt-half reliability coefficient of the scale was 0.765.ConclusionThe newly developed self-completion scale is reliable and valid. It appears to be a sound instrument for nurses and a broader range of healthcare professionals to effectively evaluate the cardiac rehabilitation adherence