Periodic oscillation and fine structure of wedge-induced oblique detonation waves

An oblique detonation wave for a Mach 7 inlet flow over a long enough wedge of 30 turning angle is simulated numerically using Euler equation and one-step rection model.The fifth-order WENO scheme is adopted to capture the shock wave.The numerical results show that with the compression of the wedge wall the detonation wave front structure is divided into three sections：the ZND model-like strcuture,single-sided triple point structure and dual-headed triple point strucuture.The first structure is the smooth straight,and the second has the characteristic of the triple points propagating dowanstream only with the same velocity,while the dual-headed triple point structure is very complicated.The detonation waves facing upstream and downstream propagate with different velocities,in which the periodic collisions of the triple points cause the oscillation of the detonation wave front.This oscillation process has temporal and spatial periodicity.In addition,the triple point trace are recorded to obtain different cell structures in three sections.

An Observational Study of the 30-50 Day Atmospheric Oscillations Part I: Structure and Propagation

Features of structure and propagation of the 30 to SO day atmospheric oscillations are investigated using the ECMWF analysis of 1980-1983. Evidence is provided to confirm the characteristics of the oscillation in the equatorial region. Those in the mid-high latitudes, however, are revealed to be very different from the tropics and pose a strong barotropic structure. Horizontal coherence shows teleconnection patterns which can be identified as EAP and PNA. The wind field of the specified time scale of the oscillation appears as long-lived vortices and vortex pairs. Mid-latitude perturbations propagate clearly westwards, especially during the winter season. In the high latitudes, they propagate westwards in the winter but eastwards in the summer. Meridional propagations are rather different from region to region.

Bifurcation of Nonlinear Kelvin Wave-CISK with ConditionalHeating in a Truncated Spectral Model: A PossibleMechanism of 30-60-Day Oscillation at the Equator

In this paper, the nonlinear Kelvin wave equations with 'positive-only' nonlinear (conditional) heating at the equator are reduced to a sixth-order nonlinear ordinary differential equation by using the Galerkin spectral truncated method. The stability analysis indicates that when the heating parameter increases, the supercritical pitchfork and Hopf bifurcations can occur for the prescribed three heating profiles. Numerical calculations are made with the help of the fourth-order Rung-Kutta method. It is found that the convection heating-related Hopf bifurcation can lead to limit cycle and chaotic solutions. In a wide range of heating parameter, the solutions possess 30-60-day periods, and are dominated by wavenumbers one and two, especially by wavenumber-one. In addition, the zonal winds of the low-frequency solutions have a phase reversal between the upper and lower tropospheres. Thus, it appears that the convection heating-related Hopf bifurcation might be a possible mechanism of 30-60-day oscillation in the tropical atmosphere.

A Further Inquiry on the Mechanism of 30-60 Day Oscillation in the Tropical Atmosphere

In a simple semi-geostropic model on the equatorial β-plane, the theoretical analysis on the 30-60 day oscillation in the tropical atmosphere is further discussed based on the wave-CISK mechanism. The convection heating can excite the CISK-Kelvm wave and CISK-Rossby wave in the tropical atmosphere and they are all the low-frequency modes which drive the activities of 30-60 day oscillation in the tropics. The most favorable conditions to excite the CISK-Kelvin wave and CISK-Rossby wave are indicated: There is convection heating but not very strong in the atmosphere and there is weaker disturbance in the lower troposphere.The influences of vertical shearing of basic flow in the troposphere on the 30-60 day oscillation in the tropics are also discussed.

An Observational Study of the 30-50 Day Atmospheric Oscillations Part II: Temporal Evolution and Hemispheric Interaction across the Equator

In this part, the temporal evolution and interaction across the equator of 30-50 day oscillation in the atmosphere are investigated further. The annual variation of 30-50 day oscillation is quite obvious in the mid-high latitudes. In the tropical atmosphere, the obvious interannual variation is an important property for temporal evolution of 30-50 day oscillation. The low-frequency wavetrain across the equator over the central Pacific and central Atlantic area, the movement of the long-lived low-frequency system across the equator and the meridional wind component across the equator will obviously show the interaction of 30-50 day oscillation in the atmosphere across the equator.

CISK-rossby wave and the 30-60 Day Oscillation in the Tropics

The 30-60 day oscillation is an important aspect of the atmospheric variance in the tropical area. A number of works have been done on this phenomenon, this article is a further one. A quasi-geostrophic linear model that consists of a two-layer free atmosphere and a well-mixed boundary layer is used to investigate the instability of intraseasonal oscillation, its propagation and vertical structures. Results show that the dynamical coupling and interaction between the barotropic and baroclinic components via boundary layer convergence / divergence are responsible for the appearance of a new kind of low-frequency wave. Such wave is very different from the traditional tropical Rossby wave. It can propagate westward and eastward. Some behaviours of it appear to resemble the observed 30-60 day oscillation mode in many aspects, such,as vertical structures, zonal and meridional propagations. Now many researchers emphasize the direct relationship between CISK-Kelvin mode and the tropical atmospheric 30-60 oscillation. It is considered that CISK-Rossby mode should not be neglected.

The Characteristics of 30-60 Day Oscillation and Its Relations to the Interannual Oscillations

The characteristics of 30-60 day oscillation (hereafter called LFO ) of the outgoing longwave radiation data (OLR) and its relations to the interannual oscillations of the sea surface temperature (SST) are investigated by using the daily OLR data for the period from January, 1979 to December, 1987 and the corresponding monthly SST data. It is found that the LFO the band the interannual oscillations of the SST monthly anomaly (SSTA) interact each other and they all relate to the occurrence and development of El Nino events closely. Before El Nino event happens, it contributes to the SST's wanning up and to the SST's quasi-biennial oscillation (called QBO for brevity) and three and half years oscillation (called SO for short) being in warm water phase in the equatorial central and eastern Pacific (ECP and EEP) that the LFO in the equatorial western Pacific (EWP) enhances and propagates eastward; When El Nino event takes place, the LFO, SSTA and SSTA's QBO and SO in the EEP interact and strengthen each other; But the warmer SST and the SSTA's QBO and SO in the warm water phase in the EEP contribute to the LFO's weakening in the equatorial Pacific. Moreover, these contribute to the SST in the EEP becoming cold and the SSTA's QBO and SO in the EWP being in cold water phase and then impel the El Nino event to end.

STUDY ON DYNAMICS OF TROPICAL CISK-ROSSBY WAVES AND MECHANISM OF 30-50 DAY OSCILLATIONS

To add to the growing mature research on the tropical 30-50 day oscillations from a new prospective, the current work bases on dynamic analysis of baroclinic quasi-geostrophic models to discuss dynamic mechanisms for the generation and propagation of CISK-Rossby waves, and to understand restraints and effects of different wave structures and thermodynamic forcing on the 30-50 day oscillations in the tropical atmosphere. Some important properties of the oscillation propagation have been explained and, in detail, with respect to its meridional propagation and vertical "baroclinic" structure. The work has come up with some new opinions and viewpoints. New opinions about the propagation and energy dispersion are to be proved by more observations and study.

IMPACT OF ATMOSPHERIC LOW-FREQUENCY OSCILLATION ON THE IMMIGRATION OF NILAPARVATA LUGENS(STL) IN HUNAN AND JIANGXI PROVINCES

Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration.

Theta Oscillations Support Prefrontal-hippocampal Interactions in Sequential Working Memory

The prefrontal cortex and hippocampus may support sequential working memory beyond episodic memory and spatial navigation.This stereoelectroencephalography(SEEG)study investigated how the dorsolateral prefrontal cortex(DLPFC)interacts with the hippocampus in the online processing of sequential information.Twenty patients with epilepsy(eight women,age 27.6±8.2 years)completed a line ordering task with SEEG recordings over the DLPFC and the hippocampus.Participants showed longer thinking times and more recall errors when asked to arrange random lines clockwise(random trials)than to maintain ordered lines(ordered trials)before recalling the orientation of a particular line.First,the ordering-related increase in thinking time and recall error was associated with a transient theta power increase in the hippocampus and a sustained theta power increase in the DLPFC(3–10 Hz).In particular,the hippocampal theta power increase correlated with the memory precision of line orientation.Second,theta phase coherences between the DLPFC and hippocampus were enhanced for ordering,especially for more precisely memorized lines.Third,the theta band DLPFC→hippocampus influence was selectively enhanced for ordering,especially for more precisely memorized lines.This study suggests that theta oscillations may support DLPFC-hippocampal interactions in the online processing of sequential information.

A hyperbolic Lindstedt-Poincare method for homoclinic motion of a kind of strongly nonlinear autonomous oscillators

A hyperbolic Lindstedt-Poincare method is presented to determine the homoclinic solutions of a kind of nonlinear oscillators, in which critical value of the homoclinic bifurcation parameter can be determined. The generalized Lienard oscillator is studied in detail, and the present method＇s predictions are compared with those of Runge-Kutta method to illustrate its accuracy.

Effects of Intraseasonal Oscillation on the Anomalous East Asian Summer Monsoon During 1999

The 1999 East Asian summer monsoon was very unusual for its weak northward advance and remarkably anomalous climate conditions. The monsoonal southwesterly airflow and related rain belt in East Asia were blocked south of the Yangtze River Valley. The monsoonal airflow and major moisture transport conduct shifted eastward and turned northward to Japan from the tropical western Pacific rather than to East China from the South China Sea （SCS） as in normal years. Severe and prolonged drought occurred over extensive areas of North China and heavy precipitation in South China and Japan. The investigation on the possible intrinsic mechanisms related to such an anomalous monsoon year has shown that the unique behavior of intraseasonal oscillation may play an essential role during this process. During this year, the northward propagation of 30-60-day anomalous low-level cyclone/anticyclone collapsed in the region around 20°N and did not extend beyond the latitudes of the Yangtze River basin due to the barrier of strong cold air intrusion from the mid-latitudes. The southwesterly moisture flux on the northwestern flank of the anticyclonic moisture transport system in the western North Pacific, which was regulated by the northward shift of 30-60-day cyclonic/anticyclonic moisture transport, also did not reach the region north of 30°N as well. Under this circumstance, the weak northward advance of the monsoon westerlies and associated northward moisture transport could not arrive in North China and led to the severe droughts there in 1999. The SCS and South China were mostly affected by the airflow in the southern and northern flanks of the same 30-60-day cyclones or anticyclones, respectively, and thus controlled by the nearly reverse zonal wind and moisture convergent/divergent conditions. The rainfall in the SCS and South China showed out-of-phase oscillation through the transient local Hadley circulation, with the rainfall maximum occurring in the SCS （South China） when the 30-60-day anticyclone （cyclone） reached its peak phase.

Low noise,continuous-wave single-frequency 1.5-μm laser generated by a singly resonant optical parametric oscillator

We report a low noise continuous-wave （CW） single-frequency 1.5-μm laser source obtained by a singly resonant optical parametric oscillator （SRO） based on periodically poled lithium niobate （PPLN）. The SRO was pumped by a CW single-frequency Nd：YVO4 laser at 1.06μm. The 1.02 W of CW single-frequency signal laser at 1.5 μm was obtained at pump power of 6 W. At the output power of around 0.75 W, the power stability was better than ±l.5% and no mode-hopping was observed in 30 min and frequency stability was better than 8.5 MHz in 1 min. The signal wavelength could be tuned from 1.57 to 1.59 μm by varying the PPLN temperature. The 1.5-μm laser exhibits low noise characteristics, the intensity noise of the laser reaches the shot noise limit （SNL） at an analysis frequency of 4 MHz and the phase noise is less than 1 dB above the SNL at analysis frequencies above 10 MHz.

RELATIONSHIP BETWEEN THE 30 TO 60 DAY OSCILLATION OF ATMOSPHERIC HEAT SOURCE AND THE DROUGHT AND FLOOD EVENTS IN JUNE IN THE SOUTH OF CHINA

Based on the NCEP/NCAR reanalysis data and the observed precipitation data in the south of China from 1958 to 2000,the impact of 30 to 60 day oscillation of atmospheric heat sources on the drought and flood events in June in the south of China is discussed.During the flood(drought) events,there exists an anomalous low-frequency anticyclone(cyclone) at the low level of the troposphere over the South China Sea and the northwestern Pacific,accompanied with anomalous low-frequency heat sinks(heat sources),while there exists an anomalous low-frequency cyclone(anticyclone) with anomalous heat sources(sinks) over the area from the south of China to the south of Japan.On average,the phase evolution of the low-frequency in drought events is 7 to 11 days ahead of that in flood events in May to June in the south of China.In flood events,low-frequency heat sources and cyclones are propagated northward from the southern South China Sea,northwestward from the warm pool of the western Pacific and westward from the northwestern Pacific around 140°E,which have very important impact on the abundant rainfall in June in the south of China.However,in drought events,the northward propagations of the low-frequency heat sources and cyclones from the South China Sea and its vicinity are rather late compared with those in flood events,and there is no obvious westward propagation of the heat sources from the northwestern Pacific.The timing of the low-frequency heat source propagation has remarkable impact on the June rainfall in the south of China.

2,5-二甲氧基-4-碘苯丙胺对卡巴胆碱诱导的小鼠离体海马CA3区γ振荡的作用

目的探究5-羟色胺2A受体(5-HT_(2A)R)激动剂2,5-二甲氧基-4-碘苯丙胺(DOI)对卡巴胆碱(CCh)诱发的小鼠离体海马CA3区γ振荡的作用。方法制备C57BL/6J小鼠离体海马脑片,用人工脑脊液(ACSF)灌流,用离体脑片电生理法记录海马CA3区局部场电位(LFP),用NeuroExplorer软件分析LFP功率,用Matlab软件分析θ振荡和γ振荡的相位振幅耦合。离体海马脑片给予CCh 5μmol·L^(-1),记录给药前后海马CA3区LFP的变化,并给予荷包牡丹碱(Bic)5μmol·L^(-1)验证γ振荡的诱发。在CCh诱导产生γ振荡后给予DOI 10μmol·L^(-1),分析DOI对γ振荡功率的影响,计算θ振荡和γ振荡的相位振幅耦合调制指数(MI)。结果离体海马脑片给予CCh 5μmol·L^(-1)后,海马CA3区LFP功率较给药前显著升高(P<0.01);在此基础上给予Bic 5μmol·L^(-1)后,LFP功率较给Bic前显著降低(P<0.01),表明γ振荡诱发成功。给予DOI 10μmol·L^(-1)后,CCh诱发的γ振荡功率较给DOI前显著增加(P<0.05),θ振荡功率及θ振荡与γ振荡相位振幅耦合MI较给DOI前无显著差异。结论DOI可能是通过增加海马CA3区γ振荡功率,而非通过影响θ振荡或θ振荡与γ振荡相位振幅耦合发挥影响认知的药理学作用。

Expression of miR-9-5p and RHOA in aluminum-induced rat cognitive dysfunction

Objective:To investigate the possible mechanism of microRNA-9-5p(miR-9-5p)and Ras homologous gene family A(RHOA)in aluminum-induced cognitive dysfunction in rats.Methods:According to the principle of randomization,48 Wistar rats were randomly divided into four groups(n=12)of blank control,low dose,medium dose and high dose.The blank control group was gavaged daily saline,and the other three dose groups were given daily gavage AlCl3 aqueous solution at three doses of 25 mg/kg,50 mg/kg,and 100 mg/kg to create a rat model of cognitive impairment for three months.The water maze(MWM)positioning navigation experiment was used to record the time t(s),namely,the incubation period,on the platform of rats,and the incubation period of each group was used to determine whether the rats in the infected group had learning and memory impairment.Hematoxylin-eosin(HE)and Nissl stains observed the pathological changes of nerve cells in the hippocampus of the four groups.Western blot detected the protein expression levels of RHOA and cranial neurotrophic factor(BDNF)in fresh rat hippocampal tissues.RT-qPCR detected the mRNA expression of miR-9-5p,RHOA,and BDNF in rat hippocampal tissues.Results:The results of Morris water maze positioning navigation test showed that the incubation period of each group was calculated on the 1st,3rd and 5th days of the experiment,and the motor incubation period of the infected group was higher than that of the control group.The results of HE staining showed that the rat nerve cells in the control group were morphologically intact,the staining was clear,the nucleus was clearly visible,and the edge of the cell membrane was sharp.The rat neurons in the infected group were damaged to varying degrees,the nucleus gradually dissolved,the cytoplasmic staining became deeper,the edges of the cell membrane were blurred and disordered,and the cells were deformed and arranged disordered.The results of Nissl staining showed that the well-stained Nissl body particles were visible in the nerve cells of rats in the control group,and the dissipation of Nissl bodies in the nerve cells of the infected group was reduced,and the staining was shallow.The results of RT-qPCR showed that compared with the control group,the mRNA expression of miR-9-5p and BDNF was decreased in the infected group,and the mRNA expression of RHOA was increased(P<0.05 or P<0.001).The Western blot results showed that compared with the control group,the relative expression of BDNF in the three infected groups was decreased,and the relative expression of RHOA increased(P<0.05).Conclusion:In aluminum-induced cognitive impairment,miR-9-5p is downregulated and RHOA is upregulatd.

Quantization of the 1-D Forced Harmonic Oscillator in the Space (<i>x</i>, <i>v</i>)

The quantization of the forced harmonic oscillator is studied with the quantum variable (x, v∧), with the commutation relation , and using a Schrödinger’s like equation on these variable, and associating a linear operator to a constant of motion K (x, v, t) of the classical system, The comparison with the quantization in the space (x, p) is done with the usual Schrödinger’s equation for the Hamiltonian H(x, p, t), and with the commutation relation . It is found that for the non-resonant case, both forms of quantization bring about the same result. However, for the resonant case, both forms of quantization are different, and the probability for the system to be in the exited state for the (x, v∧) quantization has fewer oscillations than the (x, p∧) quantization, the average energy of the system is higher in (x, p∧) quantization than on the (x, v∧) quantization, and the Boltzmann-Shannon entropy on the (x, p∧) quantization is higher than on the (x, v∧) quantization.

GABAergic Interneurons are Required for Generation of Slow CA1 Oscillation in Rat Hippocampus

Neuronal oscillations are fundamental to hip- pocampal function. It has been shown that GABAergic interneurons make an important contribution to hippocampal oscillations, but the underlying mechanism is not well understood. Here, using whole-cell recording in the complete hippocampal formation isolated from rats at postnatal days 14-18, we showed that GABAA receptormediated activity enhanced the generation of slow CA1 oscillations. In vitro, slow oscillations （0.5-1.5 Hz） were generated in CA1 neurons, and they consisted primarily of excitatory rather than inhibitory membrane-potential changes. These oscillations were greatly reduced by blocking GABAA receptor-mediated activity with bicuculline and were enhanced by increasing such activity with midazolam, suggesting that interneurons are required for oscillation generation. Consistently, CA1 fast-spiking interneurons were found to generate action potentials usually preceding those in CA1 pyramidal cells. These findings indicate a GABAA receptor-based mechanism for the generation of the slow CA1 oscillation in the hippocampus.

强直电刺激嗅内皮质-海马环路诱发CA1神经元的癫痫同步性膜电位振荡行为

目的和方法 :4 0 0～ 5 0 0 μm大鼠水平脑切片含有封闭的EC 海马环路。强直电刺激 (60Hz ,2s)海马Schaeffer侧支诱发癫痫放电 ,全细胞记录CA1胞体层单个神经元电活动 ,同步记录相应树突区细胞外场电位 ,探讨单个神经元膜电位振荡特性与细胞外癫痫电活动之间的关系。结果 :①强直电刺激诱发CA1神经元膜电位后放性振荡行为呈宽频特征 (3～ 10 0Hz)。以θ节律多见 ,跟随在刺激引起的膜电位去极化或超极化偏移 (paroxysmaldepolarizingorhyperpolaringshift,PDSorPHS)之后 ,振荡波的上升支和下降支分别由膜电位去极化 超极化或超极化 去极化成分构成 ;②逐渐增强的IPSP构成了膜电位振荡的起搏成分 ,继而反弹形成锋电位和阈下振荡 ,与细胞外癫痫样电活动同步 ,并促成癫痫放电由紧张性向阵挛性形式转变 ;③发现了电偶联电位 (spikelets)以及细胞之间的染料偶联现象。结论 :单个神经元作为振荡器可以启动群体神经元超同步化癫痫样电活动 ;缝隙连接可能参与了膜电位振荡的启动与场电位癫痫样电活动的同步作用。

MiR-214-3p Prevents the Development of Perioperative Neurocognitive Disorders in Elderly Rats

Objective:This study aimed to identify microRNAs(miRNAs)involved in the development of perioperative neurocognitive disorders(PND).Methods:Plasma exosomal miRNA expression was examined in patients before and after cardiopulmonary bypass(CPB)using microarray and qRT-PCR and these patients were diagnosed as PND later.Elderly rats were subjected to CPB,and the cognitive functions were examined.Bioinformatics analysis was conducted to predict the targets of miR-214-3p.Rats were administered rno-miR-214-3p agomir before or after CPB to investigate the role of miR-214-3p in PND development.Results:We identified 76 differentially expressed plasma exosomal miRNAs in PND patients after surgery(P<0.05,|log2FC|>0.58),including the upregulated hsa-miR-214-3p(P=0.002399392).Prostaglandin-endoperoxide synthase 2(PTGS2)was predicted as a miR-214-3p target.In rats,CPB reduced the platform crossing numbers and target quadrant stay time,accompanied with hippocampal neuronal necrosis.The rno-miR-214-3p level was significantly increased in plasma exosomes but decreased in rat hippocampus after surgery,exhibiting a negative correlation(P<0.001,r=-0.762).A negative correlation between miR-214-3p and PTGS2 protein expression was also observed in the hippocampus after surgery.Importantly,rno-miR-214-3p agomir treatment,before or after surgery,significantly increased the platform crossing numbers(P=0.035)and target quadrant stay time(P=0.029)compared with negative control.Hippocampal PTGS2 protein level was increased in the untreated surgery group and decreased in response to rno-miR-214-3p agomir treatment before or after surgery(both P<0.05 vs.negative control).Conclusion:These data suggest that miR-214-3p/PTGS2 signaling contributes to the development of PND,serving as a potential therapeutic target for PND.