The stability of impulsive stochastic Cohen–Grossberg neural networks with mixed delays and reaction–diffusion terms

The global asymptotic stability of impulsive stochastic Cohen–Grossberg neural networks with mixed delays and reaction–diffusion terms is investigated. Under some suitable assumptions and using Lyapunov–Krasovskii functional method, we apply the linear matrix inequality technique to propose some new sufficient conditions for the global asymptotic stability of the addressed model in the stochastic sense. The mixed time delays comprise both the time-varying and continuously distributed delays. The effectiveness of the theoretical result is illustrated by a numerical example.     

北京城市化进程中家庭食物碳消费动态

不可持续的家庭消费是造成全球环境问题的主要原因,食物碳消费研究是促进可持续家庭消费的重要内容。基于政府宏观统计数据,分析北京城市化进程中城市家庭食物碳消费的变化趋势和影响因素。结果表明,与1979年相比,1999年北京城市家庭人均及户均食物消费量分别减少了15.2%和38.6%,而食物碳消费总量增加了28.5%,食物碳消费结构由“以粮食为主”转变成“以粮食和肉类为主”。城市化进程中,以1993年为界,家庭食物人均及户均碳消费量均由明显减少趋势转变为明显增长趋势,变化的主要原因由“食物消费结构变化引起的人均谷物类碳消费量的减少”转变为“人均食物消费量增加引起的人均肉类碳消费量的增加”。北京城市家庭已基本完成食物消费结构的转变,人均食物消费量仍继续增加。GDP指数是影响人均食物碳消费量的主要经济因素,经济的继续增长可能带来人均食物碳消费量的增加,北京城市家庭食物碳消费尚未达到稳定状态。     

Stability of delayed memristive neural networks with time-varying impulses

This paper addresses the stability problem on the memristive neural networks with time-varying impulses. Based on the memristor theory and neural network theory, the model of the memristor-based neural network is established. Different from the most publications on memristive networks with fixed-time impulse effects, we consider the case of time-varying impulses. Both the destabilizing and stabilizing impulses exist in the model simultaneously. Through controlling the time intervals of the stabilizing and destabilizing impulses, we ensure the effect of the impulses is stabilizing. Several sufficient conditions for the globally exponentially stability of memristive neural networks with time-varying impulses are proposed. The simulation results demonstrate the effectiveness of the theoretical results.     

A novel approach for pilot error detection using Dynamic Bayesian Networks

In the last decade Dynamic Bayesian Networks (DBNs) have become one type of the most attractive probabilistic modelling framework extensions of Bayesian Networks (BNs) for working under uncertainties from a temporal perspective. Despite this popularity not many researchers have attempted to study the use of these networks in anomaly detection or the implications of data anomalies on the outcome of such models. An abnormal change in the modelled environment’s data at a given time, will cause a trailing chain effect on data of all related environment variables in current and consecutive time slices. Albeit this effect fades with time, it still can have an ill effect on the outcome of such models. In this paper we propose an algorithm for pilot error detection, using DBNs as the modelling framework for learning and detecting anomalous data. We base our experiments on the actions of an aircraft pilot, and a flight simulator is created for running the experiments. The proposed anomaly detection algorithm has achieved good results in detecting pilot errors and effects on the whole system.     

Cdk5 levels oscillate during the neuronal cell cycle: Cdh1 ubiquitination triggers proteosome-dependent degradation during S-phase

When cell cycle re-activation occurs in post-mitotic neurons it places them at increased risk for death. The cell cycle/cell death association has been reported in many neurodegenerative diseases including Alzheimer disease (AD), yet the mechanisms by which a normal neuron suppresses the cycle remain largely unknown. Recently, our laboratory has shown that Cdk5 (cyclin-dependent kinase 5) is a key player in this protective function. When a neuron is under stress, Cdk5 is transported to the cytoplasm; this eliminates its cell cycle suppression activity and the neuron re-enters S-phase. In the current study we show that a similar principle applies during a normal cell cycle. When a neuronal cell enters S phase, Cdk5 is transported to the cytoplasm where it is ubiquitinated by the E3 ligase APC-Cdh1. Ubiquitinated Cdk5 is then rapidly degraded by the proteasome. The ubiquitination site of Cdk5 appears to be in the p35 binding area; in the presence of high levels of p35, the ubiquitination of Cdk5 was blocked, and the degradation in S phase was attenuated. The data suggest an unsuspected role for Cdk5 during the progression of a normal cell cycle and offer new pharmaceutical targets for regulating neuronal cell cycling and cell death.     

人FGF21原核表达载体的构建及重组蛋白表达

构建人FGF21(fibroblast growth factor,FGF)cDNA的原核表达载体并诱导其重组蛋白表达。提取人肝脏总RNA后,经RT-PCR扩增获得目的片段,构建其T载体进行保存。再构建重组原核表达载体pET-28a(+)-h FGF21,重组质粒转化至大肠杆菌菌株BL21(DE3)中,在IPTG诱导下得到可溶性表达,采用亲和层析法纯化表达产物后,进行Western blot鉴定。成功构建重组质粒pET-28(+)-hFGF21,对其进行可溶性表达后成功纯化出his-hFGF21,经Western blot鉴定该融合蛋白可与FGF21抗体特异性结合。成功构建pET-28(+)-hFGF21,并可溶性表达his-hFGF21蛋白。     

ERK5/KLF2 activation is involved in the reducing effects of puerarin on monocyte adhesion to endothelial cells and atherosclerotic lesion in apolipoprotein E-deficient mice

Puerarin has properties of anti-oxidation and anti-inflammation, which has been demonstrated protective effects in atherosclerosis and other cardiovascular diseases. However, the detail molecular mechanism still remains unclear. Here, we determined whether the atheroprotective effect of puerarin was by reducing monocyte adhesion and explored the underlying mechanism. The results showed that puerarin dose- and time-dependently reduced oxLDL-induced monocyte THP-1 adhesion to HUVECs and the expression of adhesion-related genes such as VCAM-1, ICAM-1, MCP-1 and IL-8 in HUVECs. Puerarin activated ERK5 phosphorylation and up-regulated expressions of downstream KLF2 and its targeted genes endothelial nitric oxide synthase and thrombomodulin. However, the protective effects were reversed by ERK5/KLF2 pathway inhibitor XDM8-92, BIX02189 or KLF2 siRNA suggesting the pathway involved in the function. The ex vivo assay, in which THP-1 adhesion to endothelium isolated from apoE?/? mice received various treatments further confirmed the results from HUVECs. Finally, we found that the atherosclerotic lesions in both cross sections at aortic root and whole aorta were significantly reduced in high fat-diet (HFD) mice with puerarin treatment compared with the HFD-only mice, but were increased respectively by 76% and 71% in XMD8-92 group, and 82% and 73% in BIX02189 group. Altogether, the data revealed that puerarin inhibited the monocyte adhesion in vitro and in vivo and thus reduced atherosclerotic lesions in apoE?/? mice; the protective effects were mediated by activation of ERK5/KLF2 signaling pathway. Our findings advance the understanding of puerarin function in atherosclerosis and point out a way to prevent the disease.     

Event-based exponential synchronization of complex networks

In this paper, we consider exponential synchronization of complex networks. The information diffusions between nodes are driven by properly defined events. By employing the M-matrix theory, algebraic graph theory and the Lyapunov method, two kinds of distributed event-triggering laws are designed, which avoid continuous communications between nodes. Then, several criteria that ensure the event-based exponential synchronization are presented, and the exponential convergence rates are obtained as well. Furthermore, we prove that Zeno behavior of the event-triggering laws can be excluded before synchronization being achieved, that is, the lower bounds of inter-event times are strictly positive. Finally, a simulation example is provided to illustrate the effectiveness of theoretical analysis.     

Exponential input-to-state stability of recurrent neural networks with multiple time-varying delays

In this paper, input-to-state stability problems for a class of recurrent neural networks model with multiple time-varying delays are concerned with. By utilizing the Lyapunov–Krasovskii functional method and linear matrix inequalities techniques, some sufficient conditions ensuring the exponential input-to-state stability of delayed network systems are firstly obtained. Two numerical examples and its simulations are given to illustrate the efficiency of the derived results.