草地生物量是高寒草甸生态系统功能状态与生产效益的基础指标.然而,青藏高原冬半年非生育期,包括生物量在内的牧草要素观测全面中止,使得冬季成为牧草观测的一个空白期.通过2020年8月—2021年4月在青海海北高寒草地逐月牧草参数与高光谱野外同步观测试验,进行了牧草不同月份、不同衰减状态下生物量、表观状态、光谱特征的观测及其动态变化过程分析.结果表明,高寒冬季牧草生物量总体呈迅速下降和相对稳定两个阶段.8—10月牧草生物量处于迅速衰减下降阶段,牧草生物量由8月的9225kg/hm2急剧下降至10月的3536kg/hm2,降幅近160％,11月—次年4月则进入总体稳定阶段.利用衰减过程牧草生物量与反射光谱间关系,提出了一种修订的归一化枯草植被指数(R-DGVI),该指数在低覆盖与高覆盖植被区均表现出较好的枯草识别能力,具有相比NDVI更强的枯草识别能力与更宽的阈值范围.在此基础上,建立的中分辨率成像光谱仪(MODIS)卫星冬季枯草生物量遥感估算模型R2达到0.5627(P<0.01),进一步,通过给出5个等级枯草生物量遥感估算的R-DGVI阈值指标,实现了枯草生物量的卫星遥感的较好估算.研究工作为揭示冬季枯草衰减规律以及构建冬季枯草遥感监测业务提供了关键参数与可行的技术方法.

Background:Neuroimaging studies have identified altered brain structures and functions in women with primary dysmenorrhea (PDM). However, previous studies focused on either structural or functional changes in specific brain regions rather than combining structural and functional analysis. Therefore, this prospective cross-sectional study aimed to investigate the changes in whole brain structure, and functional variation along with structural abnormalities in women with PDM during menstruation.Methods:In all, 31 patients with PDM (PTs) and 31 healthy controls (HCs) were recruited. Voxel-based morphometry (VBM) and surface-based morphometry (SBM) analyses were applied to investigate structural changes based on high-resolution T1-weighted magnetic resonance images. Functional connectivity (FC) analysis was performed to evaluate functional variations related to the brain regions that showed structural group differences. Pearson correlation analysis was performed to assess the relationship between neuroimaging changes and clinical measures.Results:Compared to HCs, PTs had reduced gray matter volume (GMV) in the right superior temporal gyrus (STG) and reduced thickness in the bilateral orbitofrontal cortex (OFC), left postcentral gyrus (PoCG), and left superior occipital gyrus (SOG). Among these areas, the STG and PoCG are responsible for altered resting-state FC patterns in PTs. Results showed decreased FC between the STG and the left cerebellar posterior lobe (poCb), the right dorsolateral prefrontal cortex (DLPFC), and the left precentral gyrus (PrCG). Results also showed decreased FC between the PoCG and the right precuneus and the right DLPFC. We also found greater FCs between the PoCG and the bilateral poCb, the left middle temporal gyrus (MTG), and the left angular gyrus. In addition, the FCs between the STG and poCb, and DLPFC in PTs were positively correlated with history and Cox menstrual symptom scale (CMSS) scores, respectively, while the FCs between STG and PrCG were negatively correlated with the onset age of PDM.Conclusions:Our research found structural abnormalities and related FC changes in several brain regions that were mainly involved in the emotional and sensory aspects of menstrual pain in PDM. These findings could help us understand the occurrence of PDM from a neuroimaging perspective.

目的 采用多频段局部一致性(regional homogeneity,ReHo)的方法探索原发性痛经(primary dysmenorrhea,PDM)患者自发性区域神经活动异常与特定频段的相关性,并探讨ReHo值的变化是否与临床指标相关.材料与方法 纳入32例PDM患者和36例健康对照(healthy controls,HC).所有受试者均接受静息态功能磁共振成像检查.计算常规频段(0.010～0.080 Hz)、慢-4频段(0.027～0.073 Hz)和慢-5频段(0.010～0.027 Hz)的ReHo值.采用两样本t检验比较两组间的ReHo值,并采用皮尔逊相关分析探索PDM患者ReHo值与临床指标的关系.结果 与HC相比,PDM患者在常规频段及慢-4频段上,右侧海马旁回、颞极颞上回、基底核及前扣带回ReHo值增加,左侧颞中回、颞下回及岛叶的ReHo值减低,而在慢-5频段,PDM患者右侧额中回的ReHo值增加,左侧小脑8区的ReHo值减低(体素水平P＜0.001,团块水平P＜0.05,FWE校正).相关性分析表明PDM患者的COX1评分与常规频段左侧颞中回的ReHo值正相关.结论 本研究揭示了PDM中频率特异性的ReHo改变,其中,常规频段发现的与疼痛传入、情绪和记忆有关的脑区活动改变与慢-4频段基本一致,而慢-5频段则可能会提供额外的发现,为PDM的神经生物学机制提供了新的见解.

青藏高原积雪监测在地球辐射平衡、全球气候变化和生态环境等方面有重要作用,对气候预测、雪灾预测等具有重要意义.FY-4(风云4号)卫星数据具有高时空分辨率的优势,基于FY-4A(风云4号A星)构建积雪监测方法与模型,不仅拓展了静止卫星应用领域,也丰富了积雪监测应用的手段.FY-4的高时间分辨率为积雪监测的研究提供了分钟级数据,对积雪与云的变化掌握的更为细致,但用于积雪监测的波段,因分辨率不高容易导致错判与漏判.本文基于2020年小时级野外地面雪深观测数据、风云3号D星积雪覆盖产品(FY-3D_SNC)数据,构建了基于归一化积雪指数(Normalized Difference Snow Index,NDSI)的FY-4A卫星积雪判识方法,提出了雪深监测模型与等级划分指标.结果表明:NDSI≥0.20是青藏高原地区FY-4A卫星积雪判识的适用阈值,无论有云或无云条件,其漏判率均低于8.0％.地面站点验证结果表明,积雪判识准确率达83.33％以上.空间范围内直接剔除云区后,积雪判识经混淆矩阵验证准确率在82.48％以上.因此,FY-4A卫星在青藏高原地区具有积雪监测的能力.虽然FY-4A卫星对超过10 cm以上雪深不具备区分能力,但可以较好地识别10 cm以下浅雪雪深,相关系数达到0.745,通过了0.001显著性水平检验.据此建立的FY-4A卫星0～10 cm雪深等级指标,总体分级精度达到87.50％.FY-4A卫星雪深反演方法在青藏高原地区对0～10 cm浅雪雪深有较好的估算能力.

冬季枯草是遥感监测服务的一个空白领域,通过揭示枯草的独特光谱特征、建立高寒冬季枯草监测技术方法等一系列针对高寒冬季枯草的研究,可推动高寒地区冬季牧草遥感监测新的服务领域与服务时段的发展,为青藏高原生态环境保护与管理提供创新性技术支持.基于2016年8月和11月青藏高原三江源腹地的玉树隆宝自然保护区两次野外观测试验,获取了 72个鲜草与枯草样方的地面高光谱实测数据.枯草光谱特征的分析发现,在350-1 350 nm的可见光至近红外波段,枯草反射光谱呈显著的线性分布特征,其反射率自350 nm处的1.5％线性增长至1 350 nm附近约38％.枯草与鲜草光谱存在显著的差异性,枯草完全丧失了绿色植被红光强吸收、绿光强反射的光谱特征,其红光波段反射率约为鲜草的4.9倍,而绿光波段反射率也接近1.4倍,760-1 350 nm近红外波段一致的高反射也不复存在.基于枯草独特的光谱特征,建立了基于MODIS卫星波段5与波段3归一化的枯草指数DGVI(Dead Grass Vegetation Index).地面样本和卫星数据的验证表明,DGVI可有效识别枯草,其估算值与实测值相关系数达到0.68(P＜0.05),且明显优于现有的常用植被指数,可用于冬季高寒枯草的遥感识别与生物量监测.

Grassland, as an important part of the ecosystem in the Qinghai-Tibet Plateau, plays an ecological indicator role. However, during the non-growing season, it generally didn't monitor or observe alpine grass in winter. It could be a great gap to develop the methods of grassland monitoring and its application in winter. PROSAIL, a physical radiation model, can quantitatively describe the relationship between various vegetation parameters and canopy reflectance spectra. In this study, the latest version of the PROSAIL-D model and ground observed data were applied to explore the thresholds of critical range for 10 parameters of withered grass affected by reflectance spectrum. Based on the reflectance spectrums and the corresponding character' s parameters of withered grass that were obtained in the field, 15 000 possible withered grass spectrums were simulated by the PROSAIL model. Compared to the difference of reflectance spectra between withered grass and green grass observed in winter and summer respectively, it is found that a clear difference displayed on visible and near-infrared bands and with a significant linear in 400 similar to 1 300 nm spectral range for withered grass in winter in Qinghai-Tibet Plateau. On that basis, we proposed a method to distinguish the withered and green grass using the difference between red and green spectral reflections. It can be considered as a withered grass spectrum while the difference is greater than 0. Furthermore, a dataset of potential withered grass spectrum was established by two-steps identification from 15 000 possible spectrums based on the methods described above. The potential withered grass spectrums are correlated closely to the observed spectrums with a whole range of 400 similar to 2 500 nm, and the R-2 of all the simulated spectrum lines was between 0. 904 and 0. 994. By EFAST method and global sensitivity analysis, the brown pigment, carotenoid, anthocyanin, leaf structure and hot spot were identified as non-sensitive factors that respond to the withered grass spectrum. Finally, PROSAIL model was run again in OFAT (One Factor at a Time) with 99% confidence interval as the criterion and cosine distance as the evaluation function. The parameter threshold intervals of the sensitive factors of withered grass are estimated as : leaf area index of 0. 2-0. 89, chlorophyll content in 0 similar to 1. 29 mu g . cm(2), the average leaf angle between 11 degrees similar to 90 degrees, equivalent water thickness from 0. 000 1 to 0. 005 cm, dry matter content within 0. 008 similar to 0. 05 g . cm(2). The results provide some important parameters and further understanding of grass characteristics in winter, and it will strongly promote the application in remote sensing monitoring.

Pharmacophore models of glycogen synthase kinase-3 inhibitors were developed with using 3D QSAR Pharmacophore program of Discovery Stutio with a training set of 30 small compounds(IC50 values from 0.08 to 100 000 nmol·L-1) containing eight different kinds of structures.The optimal pharmacophore model(Correl=0.900,Config=13.962,Δcost=90.725) was selected by one hydrogen-bond acceptor unit,one hydrogen-bond donor unit,a hydrophobic unit,a ring aromatic unit and a excluded volume unit.The model was evaluated by other 490 inhibitors as a test set and ligand-receptor docking.The results indicate that the pharmacophore model exhibits good predictive ability,and it is able to provide helpful guidelines for designing new lead compounds of glycogen synthase kinase-3 Inhibitors.

This study was aimed to compare the proportion of endothelial cells (EC) in human bone marrow mesenchymal stem cell (BM-MSC) and human umbilical cord mesenchymal stem cells (UC-MSC), and to investigate the influence of vascular endothelial growth factor (VEGF) on proportion of EC in MSC. Flow cytometry was used to detect the proportion of CD34(+)CD133(+) and vWF(+)CD31(+) double positive cells in MSC. Wright's staining was employed to observe the influence of VEGF on morphology of MSC. The expressions of CD34, CD133, CD31, vWF were detected by immunofluorescence. qRT-PCR was performed to detect the influence of VEGF on EC marker genes' expression of MSC. The results showed that there were a small amount of EC and endothelial progenitor cells (EPC) in obtained BM-MSC and UC-MSC. After exposed to VEGF 10 ng/ml for 24 h, aspect ratio of MSC and the proportion of EC increased, while proportion of EPC decreased. Expression of EC related marker genes such as Tie-2 and ecNOS up-regulated, especially in UC-MSC. It is concluded that small amount of EC and EPC exists in cultured BM-MSC and UC-MSC, VEGF can enhance the proportion and function of EC in MSC.

In recent years the environmental pollutions, especially NH4+-N pollution in livestock and poultry wastewater were becoming increasingly serious with the rapid development of the large-scale farms in China. NH4+-N removal rate from livestock and poultry farming wastewater was investigated by using nitrification reactor. Firstly, the nitrifying bacteria was cultivated in nitrification reactor, and then continuous experiment, the batch experiment were conducted to study the Ammonia removal effect and the influence of several operating parameters. The results showed that when the temperature, pH, DO, HRT and influent NH4+-N concentration were 25 ℃, 6～7, 4～6 mg·L-1, 12 h and 200 mg·L-1 respectively, the effluent NH4+-N concentration was about 1 mg·L-1 ,and NH4+-N removal efficiency neared to 100%.

Stromal cells are the important part of the bone marrow microenvironment. They provide a suitable environment for the self-renewal, proliferation and differentiation of the hematopoietic stem cells. Stromal cells include dendritic cells, macrophages, fibroblasts, endothelial cells and adipocytes. They secrete cytokines,extracellular matrix and provide direct cellular contaction to regulate hematopoiesis. Dysfunction of the stromal cells will lead to all kinds of hemopathy and immune system diseases directly.

The paper analyzes financial leverage,operating leverage and combined leverage of listed companies in real estate industry,and finds that the microeconomic leverage is ineffective to some extent,which is embodied in the following aspects: financial leverage is too weak to produce the intended effect;there is a positive correlation between operating leverage and financial leverage,which indicates that listed companies don't control risks by means of balance of leverage;and listed companies don't give consideration to risk control and leverage effect but pay more attention to risks.