Complex origins of silicate veinlets in HED meteorites: A case study of Northwest Africa 1109

We report on the petrography and mineralogy of three types of silicate veinlets in the brecciated eucrite Northwest Africa (NWA) 1109. These include Fe‐rich olivine, Mg‐rich olivine, and pyroxene veinlets. The Fe‐rich olivine veinlets mainly infill fractures in pyroxene and also occur along grain boundaries between pyroxene and plagioclase crystals, in both nonequilibrated and equilibrated lithic clasts. The host pyroxene of Fe‐rich olivine veinlets shows large chemical variations between and within grains. The Fe‐rich olivine veinlets also contain fine‐grained Fe³⁺‐bearing chromite, highly calcic plagioclase, merrillite, apatite, and troilite. Based on texture and mineral chemistry, we argue that the formation of Fe‐rich olivine was related to fluid deposition at relatively high temperatures. However, the source of Fe‐rich olivine in the veinlets remains unclear. Magnesium‐rich olivine veinlets were found in three diogenitic lithic clasts. In one of these, the Mg‐rich olivine veinlets only occur in one of the fine‐grained interstitial regions and extend into fractures within surrounding coarse‐grained orthopyroxene. Based on the texture of the interstitial materials, we suggest that the Mg‐rich olivine veinlets formed by shock‐induced localized melting and recrystallization. Pyroxene veinlets were only observed in one clast where they infill fractures within large plagioclase grains and are associated with fine‐grained pyroxene surrounding coarse‐grained pyroxene. The large chemical variations in pyroxene and the fracture‐filling texture indicate that the pyroxene veinlets might also have formed by shock‐induced localized melting and rapid crystallization. Our study demonstrates that silicate veinlets formed by a range of different surface processes on the surface of Vesta.     

Universal reconstruction method for radiometric quality improvement of remote sensing images

The performance of remote sensing images in some applications is often affected by the existence of noise, blurring, stripes and corrupted pixels, as well as the hardware limits of the sensor with respect to spatial resolution. This paper presents a universal reconstruction method that can be used to improve the image quality by performing image denoising, deconvolution, destriping, inpainting, interpolation and super-resolution reconstruction. The proposed method consists of two parts: a universal image observation model and a universal image reconstruction model. In the observation model, most degradation processes in remote sensing imaging are considered in order to relate the desired image to the observed images. For the reconstruction model, we use the maximum a posteriori (MAP) framework to set up the minimization energy equation. The likelihood probability density function (PDF) is constructed based on the image observation model, and a robust Huber–Markov model is employed as the prior PDF. Experimental results are presented to illustrate the effectiveness of the proposed method.     

基于CiteSpace的水生野生保护动物研究可视化分析

水生野生保护动物是水生生态系统中的重要组成部分。文章利用CiteSpace文献可视化软件分析了Web of Science(WoS)核心数据库和中国知网(CNKI)全文数据库中2001—2020年水生野生保护动物相关的文献,对年度发文量、合作机构、国家合作和关键词聚类进行知识图谱分析。研究发现：近20年共发表外文文献634篇,发文量总体呈上升趋势,中文文献128篇,总体呈水平波动趋势;国外发文量最多的机构是美国鱼类及野生动植物管理局,研究机构间合作较为紧密,国内发文量最多的机构是青海省渔业环境监测站,研究机构间的合作分散;美国发文量占比为58.20%,与其他国家交流最为密切,中国发文量占比仅为3.31%,与国际合作关系不紧密;国外的研究热点主要是种群动态分布、栖息地利用和遗传多样性等,海洋与淡水物种均有研究;国内的研究热点主要是区域性保护措施,主要以淡水水生野生保护动物的研究为主,研究范围存在局限性。综合分析认为,我国应增进国内外研究机构间的交流与合作,重视海洋濒危水生野生动物的保护与研究,加强种群动态评估,开展国内对水生野生保护动物栖息地利用与遗传多样性分析的研究,从而实现水生野生保...     

The formation of a gas giant planet in a viscously evolved protoplanetary disk within the core accretion model

The gas giant planets’ formation processes in a viscously evolved protoplanetary disk are studied in the context of the core accretion model. In this paper, we follow the entire formation process of the core accretion model (the three stages). We find that the gas giant planets’ final masses and formation regions have strong dependence on the molecular cloud core’s properties (angular velocity \(\omega \) and mass \(M _{c d}\)) and the \(\alpha _{ \mathit{min} }\) parameter. We find and build the relationship between gas giant planets’ properties and molecular cloud core’s properties. In contrast to the previous works, we find that the formation process can be finished within the protoplanetary disk’s lifetime (4×10⁶ yr) in our disk model. This is because the mass influx produced by the molecular cloud core can provide enough material to the protoplanetary disk. We also find that the gas giant planets’ final masses increase generally with the viscosity coefficient \(\alpha \). This is because most of the gas giant planet’s mass is captured during the rapid gas accretion phase (the third stage of the core accretion model), and furthermore the accretion of gas in this phase is dominated by the “gap limiting case”. And our numerical results can also be compared with the observed data of exoplanet systems.     

Vertical tectonics of the High Plateau region,Manihiki Plateau,Western Pacific,from seismic stratigraphy

The Manihiki Plateau is an elevated oceanic volcanic plateau that was formed mostly in Early Cretaceous time by hotspot activity. We analyze new seismic reflection data acquired on cruise KIWI 12 over the High Plateau region in the southeast of the plateau, to look for direct evidence of the location of the heat source and the timing of uplift, subsidence and faulting. These data are correlated with previous seismic reflection lines from cruise CATO 3, and with the results at DSDP Site 317 at the northern edge of the High Plateau. Seven key reflectors are identified from the seismic reflection profiles and the resulting isopach maps show local variations in thickness in the southeastern part of the High Plateau, suggesting a subsidence (cooling) event in this region during Late Cretaceous and up to Early Eocene time. We model this as a hotspot, active and centered on the High Plateau area during Early Cretaceous time in a near-ridge environment. The basement and Early Cretaceous volcaniclastic layers were formed by subaerial and shallow-water eruption due to the volcanic activity. After that, the plateau experienced erosion. The cessation of hotspot activity and subsequent heat loss by Late Cretaceous time caused the plateau to subside rapidly. The eastern and southern portions of the High Plateau were rifted away following the cessation of hot spot activity. As the southeastern portion of the High Plateau was originally higher and above the calcium carbonate compensation depth, it accumulated more sediments than the surrounding plateau regions. Apparently coeval with the rapid subsidence of the plateau are normal faults found at the SE edge of the plateau. Since Early Eocene time, the plateau subsided to its present depth without significant deformation.     

维生素C、E对镉致毒后中华绒螯蟹抗氧化系统酶活性的影响

通过在饲料中添加不同浓度的维生素C(VC),维生素E(VE)探讨其对镉致毒后中华绒螯蟹(Eriocheirsinensis)肝脏中超氧化物歧化酶(Superoxidedismutase,SOD)、过氧化氢酶(Catalase,CAT)、谷胱甘肽过氧化物酶(Glutathioneperoxidase,GPx)活性变化的影响。结果表明,与镉中毒对照组相比,添加VC组能延缓抗氧化酶活性降低时间,减小其降低幅度。VC添加量增加(0.5%上升到1%),抗氧化酶降低的延缓减小作用随之增加。而投喂添加了VE的饲料,河蟹肝胰腺中SOD,CAT和GPx的变化与投喂VC组相似,表现为SOD、CAT基础活性下降,GPx活性上升,同时也能减慢抗氧化酶活性降低时间,减小其降低幅度。随VE量增加(0.02%增加到0.06%)以上变化呈增强趋势。从实验结果看VC,VE都可在镉致毒初期起到抗氧化保护作用。     

The behavior of deep convective clouds over the warm pool and connection to the Walker circulation

As the deep convective clouds (DCCs) over the western Pacific and Indian Ocean warm pool may play different roles in the climate system, variations in DCC properties over these two sectors are investigated and compared. The DCC intensity and area varies more significantly in the Indian Ocean than the western Pacific sector, while the DCC frequency is comparable in both sectors at the seasonal scale. Although the Indian Ocean sector is strongly dominated by the seasonal evolution, the interannual variations in the two sectors are comparable for all three DCC properties (frequency, intensity, and area). Besides, Walker circulation is closely correlated with the interannual variability of DCCs in both sectors. The Walker circulation strengthens (weakens) as the DCCs shift eastward (westward) over the Indian Ocean sector and westward (eastward) over the western Pacific sector. When more or stronger DCCs occur over the Indian Ocean sector (western Pacific sector), the Walker circulation becomes stronger (weaker) and shifts westward (eastward). Interestingly, the response of the Walker circulation to DCC variability over the warm pool is asymmetry. The asymmetry response of the Walker circulation to the negative and positive DCC anomaly may be related to the non-linearity internal variability of the atmosphere. DCCs over the Indian Ocean sector have a much weaker nonlinear correlation with the Walker circulation than DCCs over the western Pacific sector.     

Stone cover and slope factors influencing hillside surface runoff and infiltration: laboratory investigation

In this study, laboratory rainfall simulation in an extensive area was used to study the infiltration, and interception and storage from surface runoff in points with different stone cover percentages (0, 10, 20 and 30%) and slopes (5°, 10° and 20°). The experimental results of this study showed that the interrelationships among the slope, stone cover percentage, groundwater level, surface runoff amount, and interception and storage of the ponds were varied and irregular. No systematic patterns were detected for the change in the groundwater level, surface runoff amount, and interception and storage of the ponds with different stone cover percentages at different slopes and no threshold values were apparent. For a 5° slope, if the stone cover percentage was increased, the amount of surface runoff was reduced, the infiltration and the groundwater level experienced no significant change, and the interception and storage of the ponds increased. For a 10° slope, if the stone cover percentage was increased, the amount of surface runoff increased, the infiltration decreased, the groundwater level experienced no significant change or decreased slightly at certain points, and the interception and storage of the ponds increased. For a 20° slope, if the stone cover percentage was increased, the amount of runoff increased, the infiltration decreased, the groundwater level experienced no significant change or decreased slightly at certain points, and the interception and storage of the ponds increased. With or without stone cover, when the hydraulic conductivity of the top material is close to that of fine sand or laterite, an increase in the slope gradient decreased the amount of surface runoff and increased the storage amount of the ponds. As for the stone distribution, an interlaced style showed better performance in the interception and storage of ponds than that of a regular style. There was no significant change in the groundwater level. Copyright © 2000 John Wiley & Sons, Ltd.     

大连石庙鲍育苗池冬!春季底栖藻类组成初探

对大连石庙鲍育苗池冬,春季底栖藻类的组成作了调研,共发现藻类５７种（含变种）,其中有２４种及变种为辽宁省新记录。藻类组成有如下特点：硅藻种类比较丰富;冬、春季藻类群落组成有一定的主次,演替表现十分明显,种类的重现率不高。     

基于气温的浮冰侧向融化速率参数化方案实验研究

为定量探究影响冰层侧向融化的主导因素,并简化冰层侧向融化速率参数化方案,在实验室模拟了无风、静水、无辐射、纯热力学条件下纯水冰的融化过程,测量了冰层的侧向融化量,并记录了融化期间实验室气温、冰面皮温、水温及冰温等要素。观测结果表明,无辐射纯热力学条件下冰层侧向融化整体较均匀,侧向上层和下层融化速率相对中间层较快;相关性分析结果表明,气温与水温、冰温、冰面皮温之间都有很好的线性相关;信息流结果表明,气温是影响冰层侧向融化的最主要因素;最后通过拟合建立了用气温表征冰层侧向融化速率的参数化方案,并与前人的方案进行了比较,结果显示本文参数化方案模拟效果较好,所得标准偏差最小,为0.08 mm/h,达到了简化参数的目的。