Spatial and Temporal Variations in Earthquake Stress Drops between the 2008 Wenchuan and 2013 Lushan Earthquakes

As a case study of spatial and temporal variations in earthquake stress drops between the 2008 Ms 8.0 Wenchuan and 2013 Ms 7.0 Lushan earthquakes,we computed 1828 stress-drop values for earthquakes with magnitudes 1.7≤ML≤5.0 during an eight-year time span before and after major earthquakes.We divide the study area into three subregions(the southern segment of the Longmen Shan fault zone;the southwestern junction of the Longmen Shan and Sichuan Basin;and the southwestern margin of the Sichuan Basin)and calculate individual event stress drops in each.The results show that regions of alternating high and low stress drop are found on either side of the southwestern segment of the Longmen Shan fault zone.During the two-year period after the 2008 Ms 8.0 Wenchuan earthquake,the stress state of the southern Longmen Shan fault shows no significant change.A marked increase in stress level appears about 18 months before the 2013 Ms 7.0 Lushan earthquake near the Lushan hypocenter zone.Two months after the Ms 7.0 event,the stress drops suddenly attenuate,with significantly less seismic energy release per event.We find that changes in the patterns of high and low stress drop values are consistent with the process of stress accumulation or transfer from the pre-mainshock to postmainshock periods.The results indicate that major earthquakes are the dominant cause of temporal and spatial evolution in stress levels.Stress drop variations show obvious temporal and spatial patterns that may suggests subtle changes in the character of stress fields on faults and spatial variations related to local intense compression and tectonic effects.

Stress spatial evolution law and rockburst danger induced by coal mining in fault zone

In order to explore the influence of coal mining disturbance on the rockburst occurring in fault zone, this research constructed a mechanical model for the evolution of fault stress, and analyzed the influence of the ratio of horizontal stress to vertical stress on the stability of fault, and the spatial distribution of the stress in fault zone as well as its evolution rule. Furthermore, the rockburst danger at different spatial areas of fault zone was predicated. Results show that: when both sides of the working face are mined out, the fault zone in the working face presents greater horizontal and vertical stresses at its boundaries but exhibits smaller stresses in its middle section; however, the ratio of horizontal stress to vertical stress is found to be greater at middle section and smaller at boundaries. As the working face advances towards the fault, the horizontal and vertical stresses of the fault firstly increases and then decreases; conversely,the ratio of horizontal stress to vertical stress keeps decreasing all the time. Therefore, if the fault zones are closer to the goaf and the coal wall, the stress ratio will be smaller, and the fault slip will be more prone to occur, therefore rockburst danger will be greater. This research results provide guidance for the rockburst prevention and hazard control of the coal mining in fault zone.

Analysis of stress and natural frequencies of high-speed spatial parallel mechanism

In order to grasp the dynamic behaviors of 4-UPS-UPU high-speed spatial parallel mechanism, the stress of driving limbs and natural frequencies of parallel mechanism were investigated. Based on flexible multi-body dynamics theory, the dynamics model of 4-UPS-UPU high-speed spatial parallel mechanism without considering geometric nonlinearity was derived. The stress of driving limbs and natural frequencies of 4-UPS-UPU parallel mechanism with specific parameters were analyzed. The relationship between the basic parameters of parallel mechanism and its dynamic behaviors, such as stress of driving limbs and natural frequencies of parallel mechanism, were discussed. The numerical simulation results show that the stress and natural frequencies are relatively sensitive to the section parameters of driving limbs, the characteristic parameters of material on driving limbs, and the mass of moving platform. The researches can provide important theoretical base of the analysis of dynamic behaviors and optimal design for high-speed spatial parallel mechanism.

On temporal and spatial distribution of seismic apparent stresses in Yunnan area

The method of radiation energy （ER） of the earthquake wave measured by the peak velocity （r·v） of the ground motion is applied to a detailed study on the temporal and spatial distribution of the seismic apparent stresses （σa） for the moderate and small earthquakes and two aftershock sequences in Yunnan area. The results show that there exists an obvious non-homogeneity for the seismic apparent stresses in the spatial distribution. The concentrated regions of the high apparent stresses are related to the active places of the moderate and small earthquakes. Before the Dayao M=6.2 earthquake, there was a period in which the apparent stresses were high and the value was 5 times of the average value, 0.25 MPa. The relatively high values of apparent stresses distribute around the epicentral area of the major shock and nearby. It indicates that the variation characteristics of the apparent stresses can be taken as a new kind of criterion for the earthquake-risk forecast. Usually the ratio of the apparent stresses of the aftershock sequence σaA to the ones σaM of main shock is less than 1.0.

Stress Analysis of Spatial Non-Concurrent Tubular Joints

The formulations of analytic-numerical method for the stress analysis of non-concurrent spatial tubular joints are introduced in the paper. The spatial DT joints with different eccentricity in the vertical diametrical plane of chord are computed. Finally the influence of eccentricity on the stress at possible hot spots is discussed.

Astragaloside Ⅳ Protects Against Aβ1-42-induced Oxidative Stress, Neuroinflammation and Cognitive Impairment in Rats

Objective To investigate the neuroprotective action of astragaloside Ⅳ(AS-Ⅳ) on spatial learning and memory impairment induced by amyloid-beta 1-42(Aβ1-42) in rats and elucidate its underlying molecular mechanisms.Methods Adult-male Sprague-Dawley rats(230-250 g) were divided into six groups randomly: control, Aβ1-42, AS-Ⅳ, Aβ1-42 plus 5 mg/kg·d AS-Ⅳ, Aβ1-42 plus 25 mg/kg·d AS-Ⅳ, and Aβ1-42 plus 50 mg/kg·d AS-Ⅳ groups. Aβ1-42 were delivered by intracerebroventricular injection under the guidance of a brain stereotaxic apparatus. The Morris water maze test(hidden platform test, probe trials, visible platform test) was performed one week after Aβ1-42 injection to obtain the ability of rat spatial learning and memory. AS-Ⅳ(5, 25 and 50 mg/kg·d) was administrated intraperitoneally once per day from the 8 th day after Aβ1-42 injection for 5 consecutive days. Average escape latencies, distances for searching for the platform under water and the percentage of total time elapsed and distance swam in the right quadrant after removing platform were determined by behavior softwaresystem. The vision and swim speeds of rats were also determined to exclude the effect of these factors on the parameters of learning and memory. After behavioral tests, the rats were sacrificed immediately by decapitation. Hippocampus were collected. The enzyme activities of superoxide dismutase(SOD), glutathione peroxidase(GSH-px) and catalase(CAT) in the hippocampus obtained from different-treated rat brain were measured by following the manufacturer’s instructions. The levels of interleukin-1 beta(IL-1β) and tumor necrosis factor-alpha(TNF-α) in tissue lysates were assayed with ELISA.Results The water maze test results indicated that chronic treatments with AS-Ⅳ effectively protected the rats from Aβ1-42-induced spatial learning and memory impairment. Furthermore, the activities of SOD, GSH-px and CAT decreased by Aβ1-42 were also restored by AS-Ⅳ treatment in the hippocampus of rats. In addition, AS-Ⅳ significantly decreased the levels of IL-1β and TNF-α in the hippocampus of Aβ1-42-induced amnesia’s rats. Conclusion Our findings suggest that AS-Ⅳ might be a useful chemical in improving the spatial memory and relieving the oxidative stress and neuroinflammation in Alzheimer patients.

Effects of the Spatial Coupling of Water and Fertilizer on the Chlorophyll Fluorescence Parameters of Winter Wheat Leaves

Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol （Cinnamon soil）, with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence （F0） of leaves was higher in the dry treatment （0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity） compared to the wet treatment （entire soil column at 75-80% of field capacity）. The maximal fluorescence （Fm）, the variable fluorescence （Fv）, the photochemical efficiency （Fv/Fm） and potential activites （Fv/F0） of photosystem 2 （PS2） were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased FJFm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 em of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and F,fFm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants FJFm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.

2-Methyl-5H-benzo[d]pyrazolo[5,1-b][1,3]oxazin-5-imine, an edaravone analog, exerts neuroprotective effects against acute ischemic injury via inhibiting oxidative stress

Oxidative stress plays an indispensable role in the pathogenesis of cerebral ischemia.Inhibiting oxidative stress has been considered as an effective approach for stroke treatment.Edaravone,a free radical scavenger,has been shown to prevent cerebral ischemic injury.However,the clinical efficacy of edaravone is limited because it has a low scavenging activity for superoxide anions（O_2-（·-））.Here,we report that 2-methyl-5 H-benzo[d]pyrazolo[5,1-b][1,3]oxazin-5-imine,a novel small-molecule compound structurally related to edaravone,showed a stronger inhibitory effect on oxidative stress in vitro.In vivo,2-methyl-5 H-benzo[d]pyrazolo[5,1-b][1,3]oxazin-5-imine reversed transient middle cerebral artery occlusion-induced dysfunctions of superoxide dismutases and malondialdehyde,two proteins crucial for oxidative stress,suggesting a strengthened antioxidant system.Moreover,2-methyl-5 H-benzo[d]pyrazolo[5,1-b][1,3]oxazin-5-imine decreased blood brain barrier permeability.Then,we found that 2-methyl-5 Hbenzo[d]pyrazolo[5,1-b][1,3]oxazin-5-imine had a stronger neuroprotective effect than edaravone.More importantly,2-methyl-5 H-benzo[d]pyrazolo[5,1-b][1,3]oxazin-5-imine decreased not only infarct size and neurological deficits in the acute phase but also modified neurological severity score and escape latency in Morris water maze task in the delayed period,indicating enhanced neuroprotection,sensorimotor function and spatial memory.Together,these findings suggest that 2-methyl-5 H-benzo[d]pyrazolo[5,1-b][1,3]oxazin-5-imine could be a preferable option for stroke treatment.

Spatial Patterns of Irrigation Water Withdrawals in China and Implications for Water Saving

By considering numerical features, spatial variation, and spatial association, the spatial patterns of China's irrigation water withdrawals in 2001 and 2010 were explored at the regional, provincial, and prefectural scales. In addition, an overlay analysis was used to develop specific water-saving guidance for areas under different levels of water stress and with different degrees of irrigation water withdrawals. It was found that at the regional scale, irrigation water withdrawals were highest in the Middle-Lower Yangtze River region in both years, while at the provincial scale, the largest irrigation water withdrawals occurred in Xinjiang. During 2001–2010, the total of irrigation water withdrawals decreased; however, in the Northeast region, especially in Heilongjiang Province, it experienced a dramatic increase. The spatial variation was largest at the prefectural scale, with an apparent effect. The spatial association was globally negative at the provincial scale, and Xinjiang was the only significant high-low outlier. In contrast, the association displayed a significant positive relationship at the prefectural scale, and several clusters and outliers were detected. Finally, it was found that the water stress in the northern part of China worsened and water-saving irrigation techniques urgently need to be applied in the Northeast region, the Huang-Huai-Hai Plain region, and Gansu-Xinjiang region. This study verified that a multi-scale and aspect analysis of the spatial patterns of irrigation water withdrawals were essential and provided water-saving advice for different areas.

大跨环形矮塔斜拉桥主塔力学性能分析

以大跨度环形矮塔斜拉桥的主塔为研究对象,借助大型有限元程序midas进行了静力及地震动时程分析,通过提取杆系模型中的最不利内力,对索塔锚固区及下塔柱钢混结合段空间应力进行分析。结果表明:1)钢塔在静力及地震工况下强度及稳定均满足要求;2)索塔锚固区及钢混结合段应力状态良好、构造细节处理较为合理。

大跨度斜拉桥索塔侧壁锚固区受力性能分析

以大跨度斜拉桥主塔索塔锚固区为研究对象,采用Midas FEA NX软件建立索塔锚固区实体有限元模型,并对索塔锚固区空间应力进行分析。结果表明:1)主塔在挂索前后、运营阶段及断索工况下,塔壁横桥向、纵桥向应力均为压应力,预应力配束较为安全合理;2)长索锚固齿块的正上方区域锚后牵拉效应较为突出,设计过程中应加强该区域的配筋,限制其开裂。

A spatiotemporal signal processing technique for wafer-scale IC thermomechanical stress monitoring by an infrared camera

In this paper, we describe a new silicon-die thermal monitoring approach using spatiotemporal signal processing technique for Wafer-Scale IC thermome- chanical stress monitoring. It is proposed in the context of a wafer-scale-based (WaferICTM) rapid prototyping platform for electronic systems. This technique will be embedded into the structure of the WaferIC, and will be used as a preventive measure to protect the wafer from possible damages that can be caused by excessive thermomechanical stress. The paper also presents spatial and spatiotemporal algorithms and the experimental results from an IR images collection campaign conducted using an IR camera.

Research on Frequency of the Aftershock Sequence of the Wenchuan Earthquake Based on Coseismic Coulomb Stress Change

By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "aftershocks of the Wenchuan earthquake related to coseismic static Coulomb stress changes in its aftershock zone and the areas nearby.It shows that the frequency is significantly lower than the truth in the main rupture zone,especially in the southern rupture zone,due to the decrease of stress level on the rupture plane of the main shock resulting from coseismic Coulomb stress change.The study also shows that the effect of the Coulomb stress change on the duration of aftershock activity is associated with the lower limit magnitude.The duration is about 15-16 months for aftershocks above ML4.0,and close to 60 months for aftershocks above ML3.5.In this period,the ratio of the"direct"aftershocks caused by coseismic Coulomb stress change ranges between 44.7% to48.6%,which suggests that,even in the "effective"period of coseismic Coulomb stress changes,about half of the aftershocks on the main shock rupture plane are independent of coseismic Coulomb stress changes.It is pointed out that those aftershocks may be related to the afterslip or the viscoelastic relaxation,which are time dependent cases.

NR2A特异性拮抗剂NVP-AAM077对大鼠海马空间学习和记忆能力的影响

目的基于经典水迷宫空间记忆行为范式,观察大鼠学习记忆前后N-甲基-D-天冬氨酸受体(N-methyl-D-aspartic acid receptor,NMDAR)2A亚单位(NR2A)变化,通过海马齿状回微量注射NVP-AAM077(NR2A拮抗剂)探讨其神经药理学作用及可能机制。方法3月龄♂SD大鼠随机分为行为学训练(Training)和未训练(Non-training)两大组,再分别分为对照和齿状回注射NVP-AAM077(NVP)组。Western blot检测齿状回的NR2A、p-eIF2α、ATF4和脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)表达;向NVP组大鼠齿状回注射整合应激反应抑制剂ISRIB,观察齿状回的p-eIF2α水平、ATF4表达及空间记忆能力。结果与Non-training比较,行为学训练促进大鼠齿状回的NR2A和BDNF表达;Training-NVP大鼠齿状回的NR2A和BDNF表达明显减少,p-eIF2α和ATF4表达增加;ISRIB明显抑制ATF4表达,并翻转注射NVP引起的大鼠空间记忆损伤。结论齿状回注射NVP抑制NR2A通路激活并损害大鼠空间记忆,这种作用主要与海马整合应激反应有关。

数字经济对水资源压力的影响及空间效应

利用2010—2020年中国30个省份(因数据缺失未统计西藏自治区和港澳台地区)的面板数据,通过构建评价指标体系对数字经济发展水平进行测算,基于水足迹测算方法,从水量和水质视角研究水资源压力及其时空变化,并采用基准回归模型和空间计量模型分析数字经济对水资源压力的影响。结果表明:研究期内水资源压力指数、基于蓝水足迹的水量压力和基于灰水足迹的水质压力整体上均呈现逐渐上升的趋势,东、中部地区水资源压力指数普遍高于西部地区。数字经济发展会显著降低区域水资源压力指数、水量压力及水质压力,且对区域整体水资源压力的影响存在区域异质性,数字经济对水资源压力的影响在东、中部地区显著,但在西部地区不显著。空间杜宾模型检验结果显示,数字经济发展不仅会降低本省份水资源压力指数,也会对周围省份的水资源压力有负向溢出作用。

1800 MHz电磁辐射对豚鼠空间记忆及听觉系统影响的初步研究

目的研究1800 MHz急性电磁辐射(electromagnetic radiation,EMR)对豚鼠听阈、记忆、海马及听皮层超微结构的影响。方法32只豚鼠随机分为假辐射组(Sham)8只、2 w/kg组(E2A)8只、4 w/kg组(E4A)8只、10 w/kg组(E10A)8只。Sham组、E2A组、E4A组、E10A组分别暴露于比吸收率(specific absorption rate,SAR)为0、2、4、10 w/kg的辐射源中连续48 h。比较辐射前后听性脑干反应(auditory brainstem response,ABR)检测阈值变化;辐射后Morris水迷宫观察空间记忆能力;活性氧簇(reactive oxygen species,ROS)含量变化;海马、听觉皮层组织超微结构改变。结果辐射后,Sham组、E2A组、E4A组、E10A组ABR阈值与本组辐射前比较,差异无统计学意义(P>0.05);E4A组、E10A组中央活动路程缩短;辐射组氧化应激水平升高;辐射组神经元损伤及线粒体结构破坏,E10A组最明显。结论1800 MHz急性电磁辐射不影响豚鼠听阈,随着辐射强度的增强,超微结构损伤和氧化应激水平逐渐加重,可能影响空间记忆能力。

光肩星天牛胁迫声及种内空间运动行为

为了利用行为调制手段防治害虫,以光肩星天牛(Anoplophora glabripennis)为研究对象,在实验室内对光肩星天牛雌雄两性胁迫声进行录制和分析,分别在光周期和暗周期对光肩星天牛进行行为生测,分析胁迫声对光肩星天牛空间运动行为的影响。结果表明:光肩星天牛雄性胁迫声音组持续时间短于雌性、频率明显高于雌性,但雌雄胁迫声对空间运动行为的影响没有差异。在光周期,胁迫声对天牛向上爬行及水平运动均没有影响;对雄性起飞行为有抑制作用,但对雌性起飞行为没有影响。在暗周期,胁迫声对雌雄两性水平爬行有驱离作用,降低了天牛趋光爬行的活性;对雄性起飞行为没有影响,但对雌性起飞行为有促进作用。光肩星天牛胁迫声对种内个体具有警戒信号作用,这种作用与光周期相关并对雌雄两性的行为影响有所不同。

慢性社交挫败应激模型小鼠纹状体脑区空间转录组的变化

目的通过空间转录组技术探索慢性社交挫败应激(CSDS)模型小鼠纹状体转录组的变化,揭示其在抑郁症发生发展中的作用。方法应用CSDS实验范式建立抑郁样小鼠模型,通过悬尾、强迫游泳、糖水偏爱和社会交互实验分别检测行为绝望、快感缺乏和社交障碍抑郁样指标。选取正常对照小鼠和抑郁样行为明显的CSDS模型小鼠进行纹状体脑区的空间转录组测序,筛选高表达基因,采用DAVID数据库进行KEGG和GO富集分析。结果CSDS模型小鼠行为绝望、快感缺乏和社交回避行为显著增加(P<0.05,P<0.01)。纹状体空间转录组测序结果显示,正常小鼠筛选得到193个纹状体高表达基因;KEGG和GO分析结果显示,高表达基因与纹状体发育、运动行为和药物成瘾行为调节相关,并与环磷酸腺苷信号通路、环磷酸鸟苷/蛋白激酶G信号通路、钙信号、Ras相关蛋白1和丝裂原活化蛋白激酶信号通路高度相关,同时与γ-氨基丁酸能神经元和多巴胺能神经元突触相关。与正常对照小鼠相比,抑郁样行为明显的CSDS模型小鼠纹状体差异基因298个,高度富集于亨廷顿病、阿尔茨海默病和帕金森病等多种神经退行性疾病相关信号通路。结论空间转录组技术能够在空间水平揭示正常小鼠和CSDS模型小鼠纹状体脑区的转录组特征,纹状体可能与抑郁导致神经退行性疾病的病理过程相关。

唐山地区地震视应力时空变化特征

利用唐山地区2009年以来的地震波形资料,基于Brune圆盘模型反演得到105个M_(L)≥3.0地震的震源参数。根据震源参数定标关系可知,各参数与震级均呈现较好的正相关性;视应力值在0.29×10^(5)~18.97×10^(5)Pa之间,平均值为3.08×10^(5)Pa。视应力时空变化特征分析结果表明,随着唐山地区中强地震的发生,视应力出现显著的震前上升-震后下降的变化特征,反映了区域应力场的演化过程。丰南M_(S)4.5和唐山M_(S)5.1地震不仅发生于高视应力集中区边缘,而且处于归准化视应力高低值分界附近,推测高视应力和低视应力的过渡区可能是中强地震孕育的场所之一。

基于多源遥感数据的耕地生态系统稳定性评价——以汾河流域为例

从汾河流域耕地外源胁迫视角出发,基于多源遥感数据获取土壤侵蚀、沙化、盐渍化、污染、遥感生态指数和植被生产力等监测指标.构建胁迫—抵抗—响应框架下动态稳定性评价模型,分析耕地生态系统稳定性的时空演变特征.运用两维图论聚类对耕地进行分区,并提出相应调控措施.结果显示:(1)2011~2021年,晋中盆地及其东北部所属的部分县区受土壤污染、盐渍化程度加重的影响较大,外源胁迫值略微上升,其他地区则以外源胁迫值降低为主,占耕地总面积的91.66%;抵抗值上升明显,98.69%的耕地处于上升状态,在空间格局上基本形成以晋中盆地和临汾盆地为双核心的增长区;83.13%的耕地处于响应值上升状态,下降区则集中在晋中盆地及东北部.(2)耕地生态系统稳定性总体明显上升,99.06%的耕地处于稳定性增加状态,晋中盆地以稳定性略微上升为主,下游临汾盆地及河谷地区则以显著上升为主,区域之间的稳定性差异逐渐缩小,核心原因是生态环境质量的提高.(3)基于稳定性及其内涵指标,将研究区划分为黄土丘陵—核心治理区、晋中盆地—都市农业区、灵霍山峡—生态保障区、临汾盆地—保育缓冲区和河谷平原—稳产增产区,据此提出差异化的耕地保护管理措施.研究结果可为提升耕地生态系统稳定性提供科学依据.