Study on evolution of a predator–prey model in a polluted environment

In this paper, we investigate the effects of pollution on the body size of prey about a predator–prey evolutionary model with a continuous phenotypic trait in a pulsed pollution discharge environment. Firstly, an eco-evolutionary predator–prey model incorporating the rapid evolution is formulated to investigate the effects of rapid evolution on the population density and the body size of prey by applying the quantitative trait evolutionary theory. The results show that rapid evolution can increase the density of prey and avoid population extinction, and with the worsening of pollution, the evolutionary traits becomes smaller gradually. Next, by employing the adaptive dynamic theory, a long-term evolutionary model is formulated to evaluate the effects of long-term evolution on the population dynamics and the effects of pollution on the body size of prey. The invasion fitness function is given, which reflects whether the mutant can invade successfully or not. Considering the trade-off between the intrinsic growth rate and the evolutionary trait, the critical function analysis method is used to investigate the dynamics of such slow evolutionary system. The results of theoretical analysis and numerical simulations conclude that pollution affects the evolutionary traits and evolutionary dynamics. The worsening of the pollution leads to a smaller body size of prey due to natural selection, while the opposite is more likely to generate evolutionary branching

Fatigue Life Simulation and Analysis of Aluminum Alloy Sheet Self-piercing Riveting

The fatigue life prediction model of self-piecing riveting components of aluminum alloy is established and the effects of roughness and residual stress on fatigue life of self-piercing riveting components is analyzed by the model. Finite element software ABAQUS and fatigue analysis software FE-SAFE are used to study the effects of roughness and residual stress on the fatigue life of self-piecing riveting components through finite element simulation and mathematical statistics multivariate orthogonal regression experiment. The quantitative relations between fatigue life and three variables (roughness, residual stress and maximum stress) are fitted, and the variation trend of fatigue life with roughness and residual stress is obtained. The order of influence of roughness, residual stress, maximum stress and two interactions on fatigue life is as follows: residual stress, interaction between roughness and residual stress, roughness. When the maximum stress is fixed, the fatigue life decreases with the increase of roughness with a certain residual stress, and the fatigue life decreases with the increase of roughness with a certain residual stress. The average error between the fatigue experiment results and the simulation results is 9.74%, which proves that the simulation results are reliable

Gas migration at the granite-bentonite interface under semi-rigid boundary conditions in the context of HLRW disposal

The corrosion of waste canisters in the deep geological disposal facilities (GDFs) for high-level radioactive waste (HLRW) can generate gas, which can escape from the engineered barrier system. Such escape can happen through the interfaces between the bentonite buffer blocks and the host rock, and also at the interfaces between the bentonite blocks. This paper presents new insights and a quantitative assessment of the impact of the interface between clay and host rock on gas transport through a series of water infiltration and gas breakthrough experiments on granite and on granite-bentonite specimens with smooth and grooved interfaces.The water permeability values from water infiltration tests on granite and granite-bentonite samples (10-19 ~ 10-20 m2) were found to be slightly higher than that of bentonite. The gas permeability of the mock-up samples with smooth interface was one order of magnitude larger than that of the mock-up with grooved interfaces. The gas results of breakthrough pressures for the granite and the granite-bentonite mock-up samples indicated significantly lower pressures than that of bentonite. The results highlight the potential existence of preferential gas migration channels between the rock and bentonite buffer which require further considerations in the safety case assessment.<br/

Methane emissions and microbial communities as influenced by dual cropping of <em>Azolla</em> along with early Rice

Azolla caroliniana Willd. is widely used as a green manure accompanying rice, but its ecological importance remains unclear, except for its ability to fix nitrogen in association with cyanobacteria. To investigate the impacts of Azolla cultivation on methane emissions and environmental variables in paddy fields, we performed this study on the plain of Dongting Lake, China, in 2014. The results showed that the dual cropping of Azolla significantly suppressed the methane emissions from paddies, likely due to the increase in redox potential in the root region and dissolved oxygen concentration at the soil-water interface. Furthermore, the floodwater pH decreased in association with Azolla cultivation, which is also a factor significantly correlated with the decrease in methane emissions. An increase in methanotrophic bacteria population (pmoA gene copies) and a reduction in methanogenic archaea (16S rRNA gene copies) were observed in association with Azolla growth. During rice cultivation period, dual cropping of Azolla also intensified increasing trend of 1/Simpson of methanogens and significantly decreased species richness (Chao 1) and species diversity (1/Simpson, 1/D) of methanotrophs. These results clearly demonstrate the suppression of CH(4) emissions by culturing Azolla and show the environmental and microbial responses in paddy soil under Azolla cultivation

Severe Maternal Hyperglycemia Exacerbates the Development of Insulin Resistance and Fatty Liver in the Offspring on High Fat Diet

Background. Adverse maternal environments may predispose the offspring to metabolic syndrome in adulthoods, but the underlying mechanism has not been fully understood. Methods. Maternal hyperglycemia was induced by streptozotocin (STZ) injection while control (CON) rats received citrate buffer. Litters were adjusted to eight pups per dam and then weaned to standard diet. Since 13 weeks old, a subset of offspring from STZ and CON dams were switched to high fat diet (HFD) for another 13 weeks. Glucose and insulin tolerance tests (GTT and ITT) and insulin secretion assay were performed; serum levels of lipids and leptin were measured. Hepatic fat accumulation and islet area were evaluated through haematoxylin and eosin staining. Results. STZ offspring exhibited lower survival rate, lower birth weights, and growth inhibition which persisted throughout the study. STZ offspring on HFD showed more severe impairment in GTT and ITT, and more profound hepatic steatosis and more severe hyperlipidemia compared with CON-HFD rats. Conclusions. Offspring from diabetic dams would be prone to exhibit low birth weight and postnatal growth inhibition, but could maintain normal glucose tolerance and insulin sensitivity. HFD accelerates development of insulin resistance in the offspring of diabetic dams mainly via a compensatory response of islets

Influence of snake rolling on metal flow in hot rolling of aluminum alloy thick plate

Most asymmetrical rolling conditions should not appear in regular rolling processes, but for obtaining large deformations inside aluminium alloy thick plates, the asymmetrical rolling process is the most effective method. Snake rolling is adopted for promoting more deformation inside the plates. For exploring the deformation inside an aluminium alloy thick plate, a finite element model for simulating the process of snake rolling is established and the key influence factors are set as initial thickness, speed ratio and offset distance. The results show that deformation inside of the plate increases obviously while the thickness of plate is less than 300 mm after snake rolling. The speed ratio has a positive effect on promoting deformation partly inside of the plate. On the contrary, the offset distance has a negative influence by affecting the exit thickness. A formula for calculating the exit thickness after snake rolling is proposed and validated by data from the finite element models. Thus, snake rolling is suggested to be used in the downstream pass of hot rough rolling considering that the influence of thickness and the offset distance should be controlled in a reasonable range

Emotional processing of sadness and disgust evoked by disaster scenes

Abstract Objective Disaster scenes produce long‐term negative feelings in those who experience them. Previous studies have focused on mitigating disaster impacts through directed forgetting or conscious suppression. However, the initial emotional processing of disaster scenes is not fully understood, hindering the comprehension of long‐term disaster impacts. This study aims to investigate how pictures of disaster scenes evoking disgust and sadness are processed via cortical electrical activity. Methods Pictures of grief and mutilation from disasters were used to evoke sadness and disgust, respectively. Event‐related desynchronization (ERD) and event‐related potentials (ERPs) were used to quantify the intensity and time‐course of emotional processing. Results The information processing of emotional pictures was stronger than neutral pictures, represented by greater declines of alpha ERD. In the posterior ERP components of N1 and EPN, amplitudes for emotional pictures were larger than those for neutral pictures, which reflected the effects of arousal on visual perception. In the anterior ERP components of P2, P3, and LPP, disgust pictures showed higher attention attraction and enhanced encoding memory processing. Conclusions Disgust disaster scenarios induced long‐term prominent LPP, which may correspond with the long‐term negative impacts of the disaster

Analysis and Control of the Singular System Model of Aphid Ecosystems

Considering the change of the parameter related to the natural enemy population and the impact on the aphid populations in the fold catastrophe manifold, the singular system model of aphid ecosystems is proposed. Combining singular system theory with catastrophe theory, the corresponding dynamics behaviors and the existence conditions of the impasse points are given by using the qualitative analysis. The biological significance of the analytical results is also discussed. The controllers are designed to make the aphid populations stabilize the refuge level by releasing natural enemy. Some numerical simulations are carried out to prove the results