Dynamics of a diffusive predator–prey model with herd behavior

This paper is devoted to considering a diffusive predator–prey model with Leslie–Gower term and herd behavior subject to the homogeneous Neumann boundary conditions. Concretely, by choosing the proper bifurcation parameter, the local stability of constant equilibria of this model without diffusion and the existence of Hopf bifurcation are investigated by analyzing the distribution of the eigenvalues. Furthermore, the explicit formula for determining the direction of Hopf bifurcation and the stability of the bifurcating periodic solutions are also derived by applying the normal form theory. Next, we show the stability of positive constant equilibrium, the existence and stability of periodic solutions near positive constant equilibrium for the diffusive model. Finally, some numerical simulations are carried out to support the analytical results

Entropy regulation in LaNbO4-based fergusonite to implement high-temperature phase transition and promising dielectric properties

High-entropy effect is a novel design strategy to optimize properties and explore novel materials. In this work, (La1/5Nd1/5Sm1/5Ho1/5Y1/5)NbO4 (5RNO) high-entropy microwave dielectric ceramics were successfully prepared in the sintering temperature (S.T.) range of 1210–1290 ℃ via a solid-phase reaction route, and medium-entropy (La1/3Nd1/3Sm1/3)NbO4 and (La1/4Nd1/4Sm1/4Ho1/4)NbO4 (3RNO and 4RNO) ceramics were compared. The effects of the entropy (S) on crystal structure, phase transition, and dielectric performance were evaluated. The entropy increase yields a significant increase in a phase transition temperature (from monoclinic fergusonite to tetragonal scheelite structure). Optimal microwave dielectric properties were achieved in the high-entropy ceramics (5RNO) at the sintering temperature of 1270 ℃ for 4 h with a relative density of 98.2% and microwave dielectric properties of dielectric permittirity (εr) = 19.48, quality factor (Q×f) = 47,770 GHz, and resonant frequency temperature coefficient (τf) = –13.50 ppm/℃. This work opens an avenue for the exploration of novel microwave dielectric material and property optimization via entropy engineering

Amyloid-beta/Fyn–Induced Synaptic, Network, and Cognitive Impairments Depend on Tau Levels in Multiple Mouse Models of Alzheimer’s Disease

Alzheimer\u27s disease (AD), the most common neurodegenerative disorder, is a growing public health problem and still lacks effective treatments. Recent evidence suggests that microtubule-associated protein tau may mediate amyloid-β peptide (Aβ) toxicity by modulating the tyrosine kinase Fyn.Weshowed previously that tau reduction prevents, and Fyn overexpression exacerbates, cognitive deficits in human amyloid precursor protein (hAPP) transgenic mice overexpressing Aβ. However, the mechanisms by which Aβ, tau, and Fyn cooperate in AD-related pathogenesis remain to be fully elucidated. Here we examined the synaptic and network effects of this pathogenic triad. Tau reduction prevented cognitive decline induced by synergistic effects of Aβ and Fyn. Tau reduction also prevented synaptic transmission and plasticity deficits in hAPP mice. Using electroencephalography to examine network effects, we found that tau reduction prevented spontaneous epileptiform activity in multiple lines of hAPP mice. Tau reduction also reduced the severity of spontaneous and chemically induced seizures in mice overexpressing both Aβ and Fyn. To better understand these protective effects, we recorded wholecell currents in acute hippocampal slices from hAPP mice with and without tau. hAPP mice with tau had increased spontaneous and evoked excitatory currents, reduced inhibitory currents, and NMDA receptor dysfunction. Tau reduction increased inhibitory currents and normalized excitation/inhibition balance and NMDA receptor-mediated currents in hAPP mice. Our results indicate that Aβ, tau, and Fyn jointly impair synaptic and network function and suggest that disrupting the copathogenic relationship between these factors could be of therapeutic benefit

MicroRNA Let-7f Inhibits Tumor Invasion and Metastasis by Targeting MYH9 in Human Gastric Cancer

BACKGROUND: MicroRNAs (miRNAs) are important regulators that play key roles in tumorigenesis and tumor progression. A previous report has shown that let-7 family members can act as tumor suppressors in many cancers. Through miRNA array, we found that let-7f was downregulated in the highly metastatic potential gastric cancer cell lines GC9811-P and SGC7901-M, when compared with their parental cell lines, GC9811 and SGC7901-NM; however, the mechanism was not clear. In this study, we investigate whether let-7f acts as a tumor suppressor to inhibit invasion and metastasis in gastric cancers. METHODOLOGY/PRINCIPAL: Real-time PCR showed decreased levels of let-7f expression in metastatic gastric cancer tissues and cell lines that are potentially highly metastatic. Cell invasion and migration were significantly impaired in GC9811-P and SGC7901-M cell lines after transfection with let-7f-mimics. Nude mice with xenograft models of gastric cancer confirmed that let-7f could inhibit gastric cancer metastasis in vivo after transfection by the lentivirus pGCsil-GFP- let-7f. Luciferase reporter assays demonstrated that let-7f directly binds to the 3'UTR of MYH9, which codes for myosin IIA, and real-time PCR and Western blotting further indicated that let-7f downregulated the expression of myosin IIA at the mRNA and protein levels. CONCLUSIONS/SIGNIFICANCE: Our study demonstrated that overexpression of let-7f in gastric cancer could inhibit invasion and migration of gastric cancer cells through directly targeting the tumor metastasis-associated gene MYH9. These data suggest that let-7f may be a novel therapeutic candidate for gastric cancer, given its ability to reduce cell invasion and metastasis

Common Fixed Point Theorems for Contractive Mappings of Integral Type in G-Metric Spaces and Applications

Two common fixed point theorems for weakly compatible mappings satisfying contractive conditions of integral type in G-metric spaces are demonstrated. The results obtained in this paper generalize and differ from a few results in the literature and are used to prove the existence and uniqueness of common bounded and continuous solutions for certain functional equations and nonlinear Volterra integral equations. A nontrivial example is included

Hexagonal cyclical network structure and operating mechanism of the social-ecological system

Research on the social-ecological system unifies society, the economy, resources and the environment and provides an integrated and systematic research framework through which to study complex earth system problems, such as climate change, globalization, land use/cover change and population growth. This research aims to provide support for the excavation of the deep-seated coupling mechanism of the social-ecological system by revealing the basic structure of this system to answer the following three questions. What are the elements of the social-ecological system? What are the correlations between elements? How does the system work? The results are as follows. (1) The social-ecological system consists of six basic elements—population, capital, facility, management, resource, and environment—the first four of which constitute the social subsystem, and the last two of which constitute the ecological subsystem. (2) The basic material circulation and social production chains formed by the six basic elements through specific material and information flow are interrelated; they are fed to each other to form a unit social-ecological system, and a hexagonal network structure is formed through the networking of flow elements. (3) The essential feature of the operation of the hexagonal network structure is circulation. The basic social production chain is nested in the basic material circulation chain; that is, the ecological subsystem provides raw materials and services for social production, then starts the next cycle after absorbing the waste generated by the social subsystem during the production and consumption process. This research reveals that the social-ecological system structure is not only a static geometric network with stability and elasticity formed layer by layer due to multiple factors but also a dynamic circular network based on the circular movement of factors, which can distinguish flow and stock

Evaluation for Appropriate Tillage of Sandy Land in Arid Sandy Area Based on Limitation Factor Exclusion Method

Investigating and evaluating the quantity and spatial distribution of arable sandy land in arid and semiarid sandy areas is of great significance for the sustainable development and utilization of sandy land resources and the maintenance of the stability of the structure and function of regional ecosystems. Based on the characteristics of sandy soil, being without structure and susceptible to wind erosion, this study used the limiting factor exclusion method to investigate and evaluate arable sandy land in arid and semiarid areas. All sandy soils were taken as the evaluation objects of arable sandy land (including visible sandy land and invisible sandy land). On the basis of following the principle of ecological protection, the evaluation indicators and limiting factor exclusion evaluation methods of arable sandy land were determined. The results of Hangjin Banner are as follows: the total area of the visible sandy land and the recessive sandy land was 1.2 × 106 hm2; the visible sandy land accounted for 42.6%, and the invisible sandy land accounted for 57.5%. However, only 7.7% of the sandy land was suitable for farming, which is the current cultivated land of bare sand and sandy soil, extremely-low-coverage grassland, inland tidal flats, and other saline-alkali land. Even if these arable sandy lands are to be used sustainably after reclamation, reasonable ecological protection, irrigation engineering measures, and field protective farming measures must be taken. It is hoped that this study can provide a valuable reference for the sustainable development and utilization of arable sandy land and desertification control in arid and semiarid areas

Evaluation for Appropriate Tillage of Sandy Land in Arid Sandy Area Based on Limitation Factor Exclusion Method

Investigating and evaluating the quantity and spatial distribution of arable sandy land in arid and semiarid sandy areas is of great significance for the sustainable development and utilization of sandy land resources and the maintenance of the stability of the structure and function of regional ecosystems. Based on the characteristics of sandy soil, being without structure and susceptible to wind erosion, this study used the limiting factor exclusion method to investigate and evaluate arable sandy land in arid and semiarid areas. All sandy soils were taken as the evaluation objects of arable sandy land (including visible sandy land and invisible sandy land). On the basis of following the principle of ecological protection, the evaluation indicators and limiting factor exclusion evaluation methods of arable sandy land were determined. The results of Hangjin Banner are as follows: the total area of the visible sandy land and the recessive sandy land was 1.2 × 106 hm2; the visible sandy land accounted for 42.6%, and the invisible sandy land accounted for 57.5%. However, only 7.7% of the sandy land was suitable for farming, which is the current cultivated land of bare sand and sandy soil, extremely-low-coverage grassland, inland tidal flats, and other saline-alkali land. Even if these arable sandy lands are to be used sustainably after reclamation, reasonable ecological protection, irrigation engineering measures, and field protective farming measures must be taken. It is hoped that this study can provide a valuable reference for the sustainable development and utilization of arable sandy land and desertification control in arid and semiarid areas