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At present, some control strategies have been applied to bifurcation control, but these control strategies are flawed. For instance, some new equilibrium are likely to emerge in the controlled system by the state feedback control and proportional–derivative control. The time-delay feedback control and hybrid control may force the controlled system to have discontinuous stable intervals. In consideration of these defects, this article is the first to design a time-delay feedback control strategy with distributed characteristics. The designed controller may not only remain the invariance of the quantity and position of equilibriums, but also ensure the continuity of stability intervals on the controlled system. It is observed that under the specific control parameters, the designed controller can be weakened to the state feedback controller. The bifurcation threshold of the controlled object can be effectively improved. Finally, numerical simulation results verify the validity of the designed controller and illustrate the variations of dynamic performance for the controlled object. Some comparative experiments are directly rendered to reveal the superiority of the designed control strategy.

Recently, the dynamics of delayed neural networks has always incurred the widespread concern of scholars. However, they are mostly confined to some simplified neural networks, which are only made up of a small amount of neurons. The main cause is that it is difficult to decompose and analyze generally high-dimensional characteristic matrices. In this article, for the first time, we can solve the computing issues of high-dimensional eigenmatrix by employing the formula of Coates flow graph, and the dynamics is considered for a bidirectional neural network with super-ring structure and multiple delays. Under certain circumstances, the characteristic equation of the linearized network can be transformed into the equation with integration element. By analyzing the equation, we find that the self-feedback coefficient and the delays have significant effects on the stability and Hopf bifurcation of the network. Then, we achieve some sufficient conditions of the stability and Hopf bifurcation on the network. Furthermore, the obtained conclusions are applied to design a standardized high-dimensional network with bidirectional ring structure, and the scale of the standardized high-dimensional network can be easily extended or reduced. Afterward, we propose some designing schemes to expand and reduce the dimension of the standardized high-dimensional network. Finally, the results of theories are coincident with that of experiments. [ABSTRACT FROM AUTHOR]

In this paper, a fractional-order Proportional-Derivative (PD) control policy of variable order is initially designed in solving the problems of Hopf bifurcation and optimal control on the integer-order small-world network. Firstly, the time delay of the network as a key parameter is selected as the bifurcation parameter. Meanwhile, the impact of it is considered on dynamics of the controlled network. In order to analyse the dynamics of the controlled network, two methods are used to make the equivalent transformation for it and the analysis shows that transformed networks have similar linear features near the equilibrium point when variable order is a rational number. Then, through implementing the eigenvalue analysis for the characteristic equations of transformed networks, we are able to acquire some control conditions which can enable the controlled network to be stable or occur Hopf bifurcation. The finding represents that the bifurcation dynamics of the controlled network are effectively optimized by tuning the control parameters. Finally, numerical simulation results are illustrated to prove the availability of the designed control strategy and provide some diagrams between the bifurcation threshold and the control parameters. The diagrams indicate that there is an optimal order to maximize the bifurcation threshold of the controlled network under the fixed control gains. [ABSTRACT FROM AUTHOR]

In this paper, we address the problem of bifurcation control for a delayed neuron system. By introducing a new fractional-order Proportional-Derivative (PD) feedback controller, this paper aims to control the stability and Hopf bifurcation through adjusting the control gain parameters. The order chosen in PD controller is different with that of the integer-order neuron system. Sufficient conditions for guaranteeing the stability and generating Hopf bifurcation are constructed for the controlled neuron system. Finally, numerical simulation results are illustrated to verify our theoretical derivations and the relationships between the onset of the Hopf bifurcation and the gain parameters are obtained.

This study investigates the effects of soybean lecithin (SL) on the growth, fatty acid composition, lipid metabolism, and gonadal development of rice field eels. Fourteen-month-old eels were fed either fish oil diets or varying levels of dietary soybean lecithin (0%, 1.4%, and 2.8%) for 10 weeks. Dietary SL had no significant impact on growth, whereas 1.4% SL led to a significant decrease in moisture content and an increase in crude protein content in eels. The content of both saturated and polyunsaturated fatty acids increased in muscles fed the higher SL diet, with a concurrent decline in saturated fatty acids and an increase in polyunsaturated fatty acids detected in the liver. The expression levels of genes related to lipid synthesis, including accαand PPARγ, and genes related to polyunsaturated fatty acid synthesis, such as pla2g4a, fad2and scd, were significantly increased in the liver of eels fed with 1.4% SL diet. SL supplementation enhances lipid transport and antioxidant capacity in the liver, reduces fat deposition, and protects the liver from damage. Hepatosomatic index of fish in the SL1.4% and SL2.8% groups decreased. Supplementation of the diet with 1.4% SL led to a significant decrease in the content of saturated fatty acids and an increase in the content of polyunsaturated fatty acids in the gonads, with a significant increase in arachidonic acid levels. The gonadosomatic index also increased with increasing dietary SL content. Rice field eels fed diets containing SL exhibited elevated serum levels of E2, delayed ovary-to-testis transition, and a preference for retaining the female state. In conclusion, dietary supplementation with SL increased the proportion of highly unsaturated fatty acids in the tissues, enhanced lipid metabolism in the liver, and improved antioxidant capacity. Furthermore, SL supplementation has been demonstrated to promote ovarian development and delay sex reversal in rice field eels.

10-week dietary arachidonic acid (ARA) feeding trials were conducted in 14-month-old swamp eel (Monopterus albus) to evaluate the effects on growth performance, gonadal development, tissue fatty acid profile, and gene expression related to lipid metabolism. The results showed that swamp eels fed diets supplemented with 1.4% or 2.8% ARA had a significantly higher weight gain rate (WGR) and specific growth rate (SGR) than those fed the control diet. Dietary supplementation with ARA improved oocyte development and maturation. Higher gonadosomatic index (GSI) was detected in 1.4% and 2.8% ARA groups. ARA supplementation delayed sexual reversal in females. The ARA content in the muscle, liver and gonads increased with increasing dietary ARA concentration; however, ARA supplementation significantly reduced the transcriptional expression of lipid metabolism-related genes in the gonads, such as fad2, pla2g4a, and elovl5. Serum alanine aminotransferase (ALT) levels in the ARA 1.4% group were significantly lower than those in the control and ARA 2.8% groups. Total cholesterol (T-CHO) and triglyceride (TG) levels were significantly lower in the 1.4% and 2.8% ARA groups than in the control group. Catalase (CAT) and high-density lipoprotein cholesterol (HDL-C) increased with dietary ARA concentrations. This study found that dietary ARA is important for improving growth, Ovarian development, and antioxidant capacity in swamp eels.

N6-methyladenosine (m6A), catalyzed by Mettl3 methyltransferase, is a highly conserved epigenetic modification in eukaryotic messenger RNA (mRNA). Previous studies have implicated m6A modification in multiple biological processes, but the in vivofunction of m6A has been difficult to study, because mettl3mutants are embryonic lethal in both mammals and plants. In this study, we have used transcription activator-like effector nucleases and generated viable zygotic mettl3mutant, Zmettl3m/m, in zebrafish. We find that the oocytes in Zmettl3m/madult females are stalled in early development and the ratio of full-grown stage (FG) follicles is significantly lower than that of wild type. Human chorionic gonadotropin-induced ovarian germinal vesicle breakdown in vitroand the numbers of eggs ovulated in vivoare both decreased as well, while the defects of oocyte maturation can be rescued by sex hormone in vitroand in vivo. In Zmettl3m/madult males, we find defects in sperm maturation and sperm motility is significantly reduced. Further study shows that 11-ketotestosterone (11-KT) and 17β-estradiol (E2) levels are significantly decreased in Zmettl3m/m, and defective gamete maturation is accompanied by decreased overall m6A modification levels and disrupted expression of genes critical for sex hormone synthesis and gonadotropin signaling in Zmettl3m/m. Thus, our study provides the first in vivoevidence that loss of Mettl3 leads to failed gamete maturation and significantly reduced fertility in zebrafish. Mettl3 and m6A modifications are essential for optimal reproduction in vertebrates.

γ-Aminobutyric acid (GABA) is a major amino acid neurotransmitter in the vertebrate brain. To provide detailed information on the distribution of the GABA in zebrafish (Danio rerio), neurons were labeled with mCherry driven by the glutamic acid decarboxylase 67 (gad67) promoter. In the transgenic line Tg(gad67:mCherry), mCherry-positive gad67 cell bodies were predominantly localized to the olfactory bulb, pallial zones, subpallium zones, parvocellular preoptic nucleus, periventricular gray zone of optic tectum, torus semicircularis, posterior tuberculum, medial longitudinal fascicle, caudal zone of periventricular hypothalamus, and oculomotor nucleus. mCherry-positive fibers were widely distributed in the olfactory bulbs, subpallium, thalamus, ventral hypothalamic zone, tectum opticum, mesencephalon, and rhombencephalon. mCherry-positive neurons were also observed in the retina and the spinal cord. The anatomical relationships between GABAergic and gonadotrophin-releasing hormone 3 (GnRH3) neurons were investigated by crossing Tg(gad67:mCherry) fish with the previously established Tg(gnrh3:EGFP) transgenic line. GnRH3 cell bodies and fibers were contacted by GABAergic fibers directly in the ventral telencephalon and anterior tuberal nucleus. A subpopulation of GnRH3 neurons in the ventral telencephalic area was also labeled with mCherry, so some GnRH3 neurons are also GABAergic. GABAB receptor agonist (baclofen) and antagonist (CGP55845) treatments indicated that GABAB receptor signaling inhibited gnrh3 expression in larval fish but was stimulatory in adult fish. The expression of pituitary lhβ and fshβ was stimulated by intraperitoneal injection of baclofen in adult fish. We conclude that GABA via GABAB receptors regulates GnRH3 neurons in a developmentally dependent manner in zebrafish.

The optimal control of dynamics is a popular topic for small-world networks. In this paper, we address the problem of improving the behavior of Hopf bifurcations in an integer-order model of small-world networks. In this study, the time delay is used as the bifurcation parameter. We add a fractional-order proportional-derivative (PD) scheme to an integer-order Newman-Watts (N-W) small-world model to better control the Hopf bifurcation of the model. The most important contribution of this paper involves obtaining the stability of the system and the variation of the conditions of the Hopf bifurcation after a fractional PD controller is added to the integer-order small-world model. The results demonstrate that the designed PD controller can be used to restrain or promote the occurrence of Hopf bifurcations by setting appropriate parameters. We also describe several simulations to verify our research results.

• We firstly introduce a fractional-order PD scheme to control the Hopf bifurcation caused embedded in congestion control system. • The condition of stability, the criterion of Hopf bifurcation and the range of periodic oscillations for the congestion control system are derived. • The initiation of the inherent Hopf bifurcation can be effectively delayed or advanced by setting appropriate proportional and differential gain parameters. In this paper, we consider the control of nonlinear dynamic in a congestion control system. A novel fractional-order proportional-derivative (PD) feedback law is firstly designed to control the Hopf bifurcation caused by the system. The proposed P D 1 n controller has the different order with the original congestion system. Meanwhile, the communication delay is elected as the bifurcation parameter to study the stability, bifurcations and periodic oscillations of the controlled congestion system. By the stability mechanism of fractional-order systems, we can obtain the criteria for satisfying the stability and Hopf bifurcation. It has been discovered that the Hopf bifurcation point can be delayed or advanced under the adjustment of appropriate control gain parameters and the order. Therefore, the congestion system becomes controllable and the desirable behaviors can be realized. Finally, numerical simulations are presented to demonstrate the validity of the main results and the efficiency of the control strategy in the designed fractional-order PD controller. [ABSTRACT FROM AUTHOR]

Small-world networks have been of increasing interest because of their high similarity with complex networks in reality. Achievements about controlling the propagation and evolution of small world networks have been highlighted, but little is known about the tipping mechanism and control of such network. In this paper, a novel dynamic delayed feedback scheme is put forward and applied to successfully control the tipping phenomenon in small-world networks. Firstly, the linear characteristic equation of the controlled system is analyzed and the conditions for stability and the occurrence of bifurcation-induced tipping are given. Then, the direction of Hopf bifurcation, which reveals the further evolution mechanism of tipping, is analyzed by using the normal form theory and center manifold reduction. Finally, the numerical simulations are provided to support the theoretical analysis and to verify the effectiveness of the proposed dynamic delayed feedback controller for the small-world network. • We propose a novel delayed feedback controller with a washout filter and apply it to the small-world network for the first time. Moreover, we add higher-order terms to make the controller further have the nonlinear control capability. • The condition for the occurrence of bifurcation-induced tipping is given, and the property of bifurcation direction is analyzed. It is proved that by choosing the controller parameters appropriately, we can increase or decrease the tipping threshold to meet the system requirements. • By adopting simulations, we reveal that the tipping threshold can be increased by 18.9% at the highest and reduced by 14.4% at the lowest. The advantages of delayed feedback control are carried out by comparing with the state feedback controller. [ABSTRACT FROM AUTHOR]