“微物”的“神”性——论阿兰达蒂·罗伊视野中的贱民形象

印度女作家阿兰达蒂·罗伊的写作聚焦于"权力"二字,但权势重压之处也必有反对强权的力量萌发。这种力量在《微物之神》中表现为:即便是"微物"也有其"神"性。展现了底层民众,尤其是贱民,依靠自身的努力和人格魅力发展自己,展示力量。强调了印度底层民众寻求发展、自由和平等地位的主动性和必然性,反映了作者对整个印度社会发展的期待。

“穷神知化”的生命精神与审美蕴含

"穷神知化"包蕴自然天地的"化"与"变",亦呈现生命活动及"生生"运演的"化"与"变"。其中的"神"既有自然天地之德性内蕴的"神"性,也有人悟解生命实在与精神、德性品质及审美体验所蕴积的"神"性,并通过人的活动(社会、道德及艺术审美)的现实化、对象化而转化不断放射、放大。"穷神"亦呈现由理性的体认去穷究感性、现实事物及生命存在的本根,深测"大化"运行及内外转换的生态轨迹;"知化"也表征着人们通过感悟生命而润化生命,进而品味、悟解审美与艺术生态之妙的机理。中国古代艺术与审美中的"神"也经由自然生态之"神"、生命之"神"向人转化,通向人的精神之"神",以凝化、结晶而成就艺术之"神性"。

Damage effect and mechanisms of cyclophosphamide to human neuroblastoma SH-SY5Y cells

OBJECTIVE To investigate the damage effect and mechanisms of cyclophosphamide(CTX)and its active metabolite derivative 4-hydroperoxycyclophosphamide(4-HC)to human neuroblas⁃toma SH-SY5Y cells.METHODS SH-SY5Y cells were treated with CTX[0(cell control),0.01,0.1,1,5,10,20,40 and 80 mmol·L^(-1)]and 4-HC[0(cell control),0.01,0.1,1,5,10,20,40 and 80μmol·L^(-1)]for 48 h.Cell confluence and morphology were observed by the IncuCyte ZOOM system.Cell viability was assessed by CCK-8 assay.Lactate dehydrogenase(LDH)release was measured by LDH assay kit.SH-SY5Y cells were treated with CTX(0,1,5,10 and 20 mmol·L^(-1))and 4-HC(0,1,5,10 and 20μmol·L^(-1))for 48 h before cell proliferation was analyzed by 5-ethynyl-2′-deoxyuridine(EdU)staining assay.Immunofluorescence was employed to assess the levels of the DNA double-strand break markerγ-H2AX and to evaluate changes in mitochondrial membrane potential.SH-SY5Y cells were treated with CTX(0,1,5 and 10 mmol·L^(-1))and 4-HC(0,1,5 and 10μmol·L^(-1))for 48 h,and the alterations in glycolysis and oxidative phosphorylation levels were analyzed using the Seahorse XFe96 Analyzer.RESULTS Compared with the cell control group,cell confluence and cell viability were significantly reduced in the CTX and 4-HC groups(P<0.01),and the half-maximal inhibitory concentrations(IC50)for CTX and 4-HC were 4.44 mmol·L^(-1) and 4.78μmol·L^(-1),respectively.The release rate of LDH was signif⁃icantly increased while the percentage of EdU+cells was significantly reduced in the CTX and 4-HC groups(P<0.01).The percentage ofγ-H2AX+cells was significantly increased and mitochondrial membrane potential significantly decreased in the CTX and 4-HC group(P<0.05).Treatment with CTX and 4-HC resulted in reduced levels of maximum glycolytic capacity,glycolytic reserve,maximal respi⁃ration,and ATP production(P<0.05).CONCLUSION CTX and 4-HC exert significant cytotoxic effects on SH-SY5Y cells by disrupting cell membrane structure,impeding cell proliferation,and reducing cell viability.The mechanisms underlying these effects may involve intracellular DNA damage,disturbance of energy metabolism and mitochondrial dysfunction.

Autophagy is activated and might protect neurons from degeneration after traumatic brain injury

Objective To investigate changes of autophagy after traumatic brain injury （TBI） and its possible role. Methods Rat TBI model was established by controlled cortical injury system. Autophagic double membrane structure was detected by transmission electronic microscope. Microtubule-associated protein 1 light chain 3 （LC3） and Beclin 1 were also used to investigate the activation of autophagy post-TBI. Double labeling with LC3 and caspase-3, or Beclin 1 and Fluoro-Jade, to show the relationship between autophagy and apoptosis or neuron degeneration after TBI. Results An increase of autophagic double membrane structure was observed in early stage （1 h）, and the increase lasted for at least 32 d post-TBI. LC3 and Beclin 1 proteins also began to elevate at 1 h time point post-TBI in neurons, 3 d later in astrocytes, and peaked at about 8 d post-TBI. In both cell types, LC3 and Beclin l maintained at a high level until 32 d post-TBI. Most LC3 and Beclin 1 positive cells were near the side （including hippocampus）, but not in the core of the injury. In addition, in the periphery of the injury site, not all caspase-3 positive （＋） cells merged with LC3 （＋） cells post-TBI; In hippocampal area, almost all Beclin 1 （＋） neurons did not merge with Fluoro-Jade （＋） neurons from 1 h to 48 h post-TBI. Conclusion Autophagy is activated and might protect neurons from degeneration at early stage post-TBI and play a continuous role afterwards in eliminating aberrant cell components.

Exponential stability criteria on neural networks with continuously distributed delays

The exponential stability of a class of neural networks with continuously distributed delays is investigated by employing a novel Lyapunov-Krasovskii functional. Through introducing some free-weighting matrices and the equivalent descriptor form, a delay-dependent stability criterion is established for the addressed systems. The condition is expressed in terms of a linear matrix inequality （LMI）, and it can be checked by resorting to the LMI in the Matlab toolbox. In addition, the proposed stability criteria do not require the monotonicity of the activation functions and the derivative of a time-varying delay being less than 1, which generalize and improve earlier methods. Finally, numerical examples are given to show the effectiveness of the obtained methods.

Prediction of mechanical properties of A357 alloy using artificial neural network

The workpieces of A357 alloy were routinely heat treated to the T6 state in order to gain an adequate mechanical property.The mechanical properties of these workpieces depend mainly on solid-solution temperature,solid-solution time,artificial aging temperature and artificial aging time.An artificial neural network（ANN） model with a back-propagation（BP） algorithm was used to predict mechanical properties of A357 alloy,and the effects of heat treatment processes on mechanical behavior of this alloy were studied.The results show that this BP model is able to predict the mechanical properties with a high accuracy.This model was used to reflect the influence of heat treatments on the mechanical properties of A357 alloy.Isograms of ultimate tensile strength and elongation were drawn in the same picture,which are very helpful to understand the relationship among aging parameters,ultimate tensile strength and elongation.

Evolving Neural Networks Using an Improved Genetic Algorithm

A novel real coded improved genetic algorithm (GA) of training feed forward neural network is proposed to realize nonlinear system forecast. The improved GA employs a generation alternation model based the minimal generation gap (MGP) and blend crossover operators (BLX α). Compared with traditional GA implemented in binary number, the processing time of the improved GA is faster because coding and decoding are unnecessary. In addition, it needn t set parameters such as the probability value of crossove...

Application of multiple attributes fusion technology in the Su-14 Well Block

In this study area the geological conditions are complicated and the effective sandstone is very heterogeneous.The sandstones are thin and lateral and vertical variations are large.We introduce multi-attribute fusion technology based on pre-stack seismic data, pre-stack P-and S-wave inversion results,and post-stack attributes.This method not only can keep the fluid information contained in pre-stack seismic data but also make use of the high SNR characteristics of post-stack data.First,we use a one-step recursive method to get the optimal attribute combination from a number of attributes.Second,we use a probabilistic neural network method to train the nonlinear relationship between log curves and seismic attributes and then use the trained samples to find the natural gamma ray distribution in the Su-14 well block and improve the resolution of seismic data.Finally,we predict the effective reservoir distribution in the Su-14 well block.

Beneficial effects of moderate voluntary physical exercise and its biological mechanisms on brain health

This article reviewed the beneficial effects of moderate voluntary physical exercise on brain health according to the studies on humans and animals, which includes improving psychological status and cognitive function, enhancing psychological well-being, decreasing the risks of Alzheimer＇s disease （AD） and dementia, and promoting the effects of antidepressant and anxiolytic. The possible underlying neurobiological mechanisms are involved up-active and down-active pathways. The up-active pathway is associated with enhancements of several neurotransmitters systems afferent to hippocampus, including norepinephrine （NE）, serotonin （5-Hydroxytryptamine, 5-HT）, acetylcholine （ACh） and γ-aminobutyric acid （GABA）. The down-active pathway is mainly concerned with up-regulation of the brain-derived neurotrophic factor （BDNF） and neurogenesis. It is suggested that NE activation via β-adrenergic receptors may be essential for exercise-induced BDNF up-regulation. The possible intracellular signaling pathways of NE-mediated BDNF up-expression may be involved in GPCR-MAPK-PI-3K crosstalk and positive feedback.

Overexpression of lentivirus-mediated glial cell line-derived neurotrophic factor in bone marrow stromal cells and its neuroprotection for the PC12 cells damaged by lactacystin

Objective To construct recombinant lentiviral vectors for gene delivery of the glial cell line-derived neurotropnic factor （GDNF）, and evaluate the neuroprotective effect of GDNF on lactacystin-damaged PC12 cells by transfecting it into bone marrow stromal cells （BMSCs）. Methods pLenti6/V5-GDNF plasmid was set up by double restriction enzyme digestion and ligation, and then the plasmid was transformed into Top10 cells. Purified pLenti6/V5-GDNF plasmids from the positive clones and the packaging mixture were cotransfected to the 293FT packaging cell line by Lipofectamine2000 to produce lentivirus, then the concentrated virus was transduced to BMSCs. Overexpression of GDNF in BMSCs was tested by RT-PCR, ELISA and immunocytochemistry, and its neuroprotection for lactacystin-damaged PC12 cells was evaluated by MTT assay. Results Virus stock of GDNF was harvested with the titer of 5.6×10^5 TU/mL. After tmnsduction, GDNF-BMSCs successfully secreted GDNF to supematant with nigher concentration （800 pg/mL） than BMSCs did （less than 100 pg/mL）. The supematant of GDNF-BMSCs could significantly alleviate the damage of PC12 cells induced by lactacystin （10 μmol/L）. Conclusion Overexpression of lentivirus-mediated GDNF in the BMSCs cells can effectively protect PC12 cells from the injury by the proteasome inhibitor.

Fault isolation of air handling unit based on neural network

Aiming at various faults in an air conditioning system,the fault characteristics are analyzed.The influence of the faults on the energy consumption and thermal comfort of the system are also discussed.The simulation results show that the measurement faults of the supply air temperature can lead to the increase in energy consumption.According to the fault characteristics,a data-driven method based on a neural network is presented to detect and diagnose the faults of air handling units.First,the historical data are selected to train the neural network so that it can recognize and predict the operation of the system.Then,the faults can be diagnosed by calculating the relative errors denoting the difference between the measuring values and the prediction outputs.Finally,the fault diagnosis strategy using the neural network is validated by using a simulator based on the TRNSYS platform.The results show that the neural network can diagnose different faults of the temperature,the flow rate and the pressure sensors in the air conditioning system.

Improvement and application of neural network models in development of wrought magnesium alloys

Neural network models of mechanical properties prediction for wrought magnesium alloys were improved by using more reasonable parameters, and were used to develop new types of magnesium alloys. The parameters were confirmed by comparing prediction errors and correlation coefficients of models, which have been built with all the parameters used commonly with training of all permutations and combinations. The application was focused on Mg-Zn-Mn and Mg-Zn-Y-Zr alloys. The prediction of mechanical properties of Mg-Zn-Mn alloys and the effects of mole ratios of Y to Zn on the strengths in Mg-Zn-Y-Zr alloys were investigated by using the improved models. The predicted results are good agreement with the experimental values. A high strength extruded Mg-Zn-Zr-Y alloy was also developed by the models. The applications of the models indicate that the improved models can be used to develop new types of wrought magnesium alloys.

Mechanisms underlying low [Ca^(2+)]_o-induced increased excitability of hippocampal neurons

Objective Concentration of extracellular calcium （[Ca2＋]o） in the central nervous system decreases substantially in different conditions. It results in facilitating neuronal excitability. The goal of this study is to examine the mechanisms of enhanced neuronal excitation in low [Ca2＋]o in order to provide new clues to treat the hyperexcitability diseases in clinic. Methods Whole-cell patch-clamp technique and neuron culture were used in the study. Results The firing threshold of cultured hippocampal neurons decreased markedly in low [Ca2＋]o saline. Unexpectedly, apamine and isoprenaline, antagonists of medium afterhyperpolarization （mAHP） and slow AHP （sAHP） respectively, had no statistic significant effect on excitability of neurons. TTX at a low concentration was sufficient to inhibit/Nap, which blocked the increase of firing frequency in low [Ca2＋]o. It also reduced the number of spikes in normal [Ca2＋]o. Conclusion These results suggest that in cultured hippocampal neurons, modulation of spiking threshold but not AHP may cause the increased excitability in low [Ca2＋]o.

Effect of resuscitation after selective cerebral ultraprofound hypothermia on expressions of nerve growth factor and glial cell line-derived neurotrophic factor in the brain of monkey

Objective To investigate the expression of nerve growth factor （NGF） and glial cell line-derived neurotrophic factor （GDNF） in monkeys of resuscitation after selective cerebral ultraprofound hypothermia and blood flow occlusion. Methods The monkeys were immediately removed brain after death in operation of group A （identical temperature perfusion group） and group B （ultraprofound hypothermia perfusion group）. Immunohistochemical technique was used to determine frontal cellular expression of NGF and GDNF. Statistics were analyzed by ANOVA analyses with significance level at P 〈 0.05. Results The expressions of NGF and GDNF in the group B were significantly higher than those in the group A （P 〈 0.05）. Conclusion NGF and GDNF increased significantly in the monkeys of resuscitation after selective cerebral ultraprofound hypothermia and blood flow occlusion. It may be a protective mechanism for neuron survival and neural function recovery.

Epigenetics and neural stem cell commitment

Neural stem cell is presently the research hotspot in neuroscience. Recent progress indicates that epigenetic modulation is closely related to the self-renewal and differentiation of neural stem cell. Epigenetics refer to the study of mitotical/meiotical heritage changes in gene function that cannot be explained by changes in the DNA sequence. Major epigenetic mechanisms include DNA methylation, histone modification, chromatin remodeling, genomic imprinting, and non-coding RNA. In this review, we focus on the new insights into the epigenetic mechanism for neural stem cells fate.

Isolation and Evaluation of Nerve Growth Factor

Objective: to obtain the high purified and active nerve growth factor (NGF) from mouse submaxillary glands. Methods: NGF was prepared from mouse submaxillary glands by the way of elution with CM 52 column. The molecular weight and purification of NGF were detected by SDS-PAGE polyacrylamide gel electrophoresis. The biological activity of NGF was verified thorough culturing DRG. Results: About 14 kDa stained band was observed on SDS-PAGE and it promoted proliferation of dorsal root gang lia (DRG). Conclusion: Good quality of NGF could be obtained with these methods.

Backlash Nonlinear Compensation of Servo Systems Using Backpropagation Neural Networks

Aim To eliminate the influences of backlash nonlinear characteristics generally existing in servo systems, a nonlinear compensation method using backpropagation neural networks(BPNN) is presented. Methods Based on some weapon tracking servo system, a three layer BPNN was used to off line identify the backlash characteristics, then a nonlinear compensator was designed according to the identification results. Results The simulation results show that the method can effectively get rid of the sustained oscillation(limit cycle) of the system caused by the backlash characteristics, and can improve the system accuracy. Conclusion The method is effective on sloving the problems produced by the backlash characteristics in servo systems, and it can be easily accomplished in engineering.

A Single Neuron with Stochastic Resonance for Noisy Square Pulse Train Signal Transmission

A nonlinear single neuron is demonstrated to exhibit stochastic resonance by theoretical analysis and numerical simulations. This single neuron is used for noisy periodic signal transmission, and significant performance of raising input output SNR gain can be achieved. The research of this paper not only gives a very simple model of neuron with stochastic resonance, but also enlarges the application scope of neuron to the transmission of periodic signals.

Approximation Property of the Modified Elman Network

A new type of recurrent neural network is discussed, which provides the potential for modelling unknown nonlinear systems. The proposed network is a generalization of the network described by Elman, which has three layers including the input layer, the hidden layer and the output layer. The input layer is composed of two different groups of neurons, the group of external input neurons and the group of the internal context neurons. Since arbitrary connections can be allowed from the hidden layer to the context layer, the modified Elman network has more memory space to represent dynamic systems than the Elman network. In addition, it is proved that the proposed network with appropriate neurons in the context layer can approximate the trajectory of a given dynamical system for any fixed finite length of time. The dynamic backpropagation algorithm is used to estimate the weights of both the feedforward and feedback connections. The methods have been successfully applied to the modelling of nonlinear plants.

Identification and Control of Dynamical Systems Using Modified Neural Networks

Aim To study the identification and control of nonlinear systems using neural networks. Methods A new type of neural network in which the dynamical error feedback is used to modify the inputs of the network was employed to reduce the inherent network approximation error. Results A new identification model constructed by the proposed network and stable filters was derived for continuous time nonlinear systems, and a stable adaptive control scheme based on the proposed networks was developed. Conclusion Theory and simulation results show that the modified neural network is feasible to control a class of nonlinear systems.