Water activity and the challenge for life on early Mars

In situ and orbital exploration of the martian surface has shown that acidic, saline liquid water was intermittently available on ancient Mars. The habitability of these waters depends critically on water activity (aH2O), a thermodynamic measure of salinity, which, for terrestrial organisms, has sharply defined limits. Using constraints on fluid chemistry and saline mineralogy based on martian data, we calculated the maximum aH2O for Meridiani Planum and other environments where salts precipitated from martian brines. Our calculations indicate that the salinity of well-documented surface waters often exceeded levels tolerated by known terrestrial organisms.     

The Opportunity Rover's Athena science investigation at Meridiani Planum, Mars

The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and the nearby plains within Meridiani Planum. The soils consist of fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Wind ripples are common. Underlying the thin soil layer, and exposed within small impact craters and troughs, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts. Small-scale cross-lamination in some locations provides evidence for deposition in flowing liquid water. We interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water, followed by evaporation, exposure, and desiccation. Hematite-rich spherules are embedded in the rock and eroding from them. We interpret these spherules to be concretions formed by postdepositional diagenesis, again involving liquid water.     

In situ evidence for an ancient aqueous environment at Meridiani Planum, Mars

Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features include hematite-rich concretions and crystal-mold vugs. We interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history. The environmental conditions that they record include episodic inundation by shallow surface water, evaporation, and desiccation. The geologic record at Meridiani Planum suggests that conditions were suitable for biological activity for a period of time in martian history.     

Ancient impact and aqueous processes at Endeavour Crater, Mars

The rover Opportunity has investigated the rim of Endeavour Crater, a large ancient impact crater on Mars. Basaltic breccias produced by the impact form the rim deposits, with stratigraphy similar to that observed at similar-sized craters on Earth. Highly localized zinc enrichments in some breccia materials suggest hydrothermal alteration of rim deposits. Gypsum-rich veins cut sedimentary rocks adjacent to the crater rim. The gypsum was precipitated from low-temperature aqueous fluids flowing upward from the ancient materials of the rim, leading temporarily to potentially habitable conditions and providing some of the waters involved in formation of the ubiquitous sulfate-rich sandstones of the Meridiani region.     

Jarosite and hematite at Meridiani Planum from Opportunity's Mossbauer Spectrometer

Mossbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.     

Localization and physical property experiments conducted by Opportunity at Meridiani Planum

The location of the Opportunity landing site was determined to better than 10-m absolute accuracy from analyses of radio tracking data. We determined Rover locations during traverses with an error as small as several centimeters using engineering telemetry and overlapping images. Topographic profiles generated from rover data show that the plains are very smooth from meter- to centimeter-length scales, consistent with analyses of orbital observations. Solar cell output decreased because of the deposition of airborne dust on the panels. The lack of dust-covered surfaces on Meridiani Planum indicates that high velocity winds must remove this material on a continuing basis. The low mechanical strength of the evaporitic rocks as determined from grinding experiments, and the abundance of coarse-grained surface particles argue for differential erosion of Meridiani Planum.     

Pancam multispectral imaging results from the Opportunity Rover at Meridiani Planum

Panoramic Camera (Pancam) images from Meridiani Planum reveal a low-albedo, generally flat, and relatively rock-free surface. Within and around impact craters and fractures, laminated outcrop rocks with higher albedo are observed. Fine-grained materials include dark sand, bright ferric iron-rich dust, angular rock clasts, and millimeter-size spheroidal granules that are eroding out of the laminated rocks. Spectra of sand, clasts, and one dark plains rock are consistent with mafic silicates such as pyroxene and olivine. Spectra of both the spherules and the laminated outcrop materials indicate the presence of crystalline ferric oxides or oxyhydroxides. Atmospheric observations show a steady decline in dust opacity during the mission. Astronomical observations captured solar transits by Phobos and Deimos and time-lapse observations of sunsets.     

Size frequency distribution of martian craters and relative age of light and dark terrains

Light and dark terrains in and around Meridiani Sinus, mapped on the imagery from Mariner 6 and Mariner 7, were found to have significantly different cumulative size frequency distributions of craters. The light terrain on a mosaic of frames 6N11, 6N13, and 6N19 has a greater proportion of large craters and a lesser proportion of smaller craters than the dark terrain on the same frames. The light terrain is interpreted to be generally older than the dark terrain. The filling or partial filling of the smaller craters on the light terrain by surface detritus is suggested. Several wide-angle frames have remarkably similar cumulative crater size frequency distributions that may be representative of a large portion of the martian surface.     

Viscosity of lunar lavas

The viscosity of a synthetic silicate liquid with the composition of a lunar rock has been determined experimentally and found to be lower than that of any previously studied volcanic rock on earth. Course Crystallinity can be a feature of rapidly cooled surface lavas.     

Mineralogy at Meridiani Planum from the Mini-TES Experiment on the Opportunity Rover

The Miniature Thermal Emission Spectrometer (Mini-TES) on Opportunity investigated the mineral abundances and compositions of outcrops, rocks, and soils at Meridiani Planum. Coarse crystalline hematite and olivine-rich basaltic sands were observed as predicted from orbital TES spectroscopy. Outcrops of aqueous origin are composed of 15 to 35% by volume magnesium and calcium sulfates [a high-silica component modeled as a combination of glass, feldspar, and sheet silicates (approximately 20 to 30%)], and hematite; only minor jarosite is identified in Mini-TES spectra. Mini-TES spectra show only a hematite signature in the millimeter-sized spherules. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped from orbit. Bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites. Bright wind streak material matches global dust. Waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering.     

Spectral reflectance and morphologic correlations in eastern Terra Meridiani, Mars

The Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) hyperspectral image data covering eastern Terra Meridiani indicate the ubiquitous presence of molecular water in etched terrain materials that disconformably overlie heavily cratered terrains and underlie the hematite-bearing plains explored by the Opportunity rover. Identification of crystalline water in kieserite (MgSO4.H2O) is linked to materials exposed in a valley and plateau to the north of hematite-bearing plains. The mineralogical similarities between the etched terrain deposits examined with OMEGA data and the layered rocks examined by Opportunity imply that the ancient aqueous environments inferred from analyses of the rover data extend over regional scales.     

Soils of Eagle crater and Meridiani Planum at the Opportunity Rover landing site

The soils at the Opportunity site are fine-grained basaltic sands mixed with dust and sulfate-rich outcrop debris. Hematite is concentrated in spherules eroded from the strata. Ongoing saltation exhumes the spherules and their fragments, concentrating them at the surface. Spherules emerge from soils coated, perhaps from subsurface cementation, by salts. Two types of vesicular clasts may represent basaltic sand sources. Eolian ripples, armored by well-sorted hematite-rich grains, pervade Meridiani Planum. The thickness of the soil on the plain is estimated to be about a meter. The flatness and thin cover suggest that the plain may represent the original sedimentary surface.     

推进新时代古籍工作,加快创新智能化发展

《关于推进新时代古籍工作的意见》的颁布,给古籍典藏保护与整理研究、数字人文创新发展和文化产业提质升级都带来了重大发展机遇。改革开放40余年来,中国古籍事业取得了丰硕成果,为了推进新时代古籍工作,促进古籍事业繁荣发展,让古籍在新时代焕发活力,我刊围绕4个方向组织专题研讨。1）计算人文应成为新时代古籍整理与研究的重要学科方法。充分运用计算人文理论与方法,发挥古籍知识库及其知识服务平台在人文计算、语义出版、文化普及中的优势,可为新时代古籍工作赋予更丰富的资源基础、更便捷的技术支持与更直观的推广形式。2）数智赋能时代的古籍研究和工作必将走向更加繁荣的未来。近年来,随着图像OCR识别、自然语言处理和机器学习技术的进步及其在古籍工作中的成功应用,古籍工作开始从数字化向智能化阶段迈进。3）新技术将促进古籍的共享、传播与利用。虽然古籍工作者长期以来通过建立制度层面上的规范保障、探索借助技术的发展来降低共享的成本和门槛,但在如何取得保藏和利用之间的平衡方面,仍然达不到理想的效果。引入区块链等新技术,非同质化代币等新业务模式,“数字藏品”的产业链将会为古籍数字资源的资产化管理,文创产品开发和古籍数字内容的链上循证提供新的契机。4）古籍的活化利用是新时代古籍工作的新任务。将文本化、数据化、知识化作为新时代古籍资源转化利用的手段,并积极建设“国家古籍数字资源平台”,通过人工智能、VR技术、虚拟现实等智能媒介驱动古籍知识体系建设,让古籍真正“活”起来。     

数字人文视角下的古籍知识关联探析

[目的/意义]数字人文方兴未艾,为古籍知识关联的实现提供了重要现代科技手段。对古籍内容挖掘与知识关联进行研究,有助于提升古籍资源开发水平与服务质量,推动中华优秀传统文化创造性转化、创新性发展。[方法/过程]通过文献综述和网络调研,梳理数字人文视角下古籍知识关联的研究,探讨古籍知识关联的关键环节,通过古籍知识关联应用举例分析古籍知识关联的壁垒。[结果/结论]数字人文视角下,从文献单元层次的组织深入到知识单元层次的组织,借助数据分析技术、机器学习、可视化技术等,可实现古籍知识关联。古籍知识关联起点是文献组织,基础是古籍数据,本质是知识组织。古籍知识关联可进行方志与家谱挖掘、钤印知识网络发现、特定时期与地域学者研究脉络与交往分析等,但在实施中仍面临知识元处理难度大、技术要求高、集成平台少等壁垒。     

将军崖文化遗产与农业崇拜研究

本文以将军崖岩画遗址为切入点,通过对该遗址周边考古遗存、上古神话传说、先秦文献等资料的应用和分析,并结合科技断代的数据,对将军崖岩画中的人面稻米图像、凹穴岩画(星象图)、"石社"进行了重点分析,认为将军崖岩画表征了上古社会的农业崇拜文化;将军崖岩画的主体图像是在农耕文化背景下创作完成的,并与农业文化中的天体崇拜和农业祭祀紧密联系,是苏北鲁南地区上古时期一处规格较高的举行仪式和祭祀的场所。     

浙江省温岭市种子植物区系特点

调查表明,温岭市共有种子植物162科806属1 632种(包括种下等级),分别占浙江省种子植物科、属、种总数的88.04%,59.97%和37.69%。其中裸子植物9科21属38种,被子植物153科785属1 594种,栽培引种植物402种,隶属于264属。对温岭市种子植物区系的组成和地理成分进行了分析,并与南部的泰顺县植物区系以及北面的西天目山植物区系进行比较,认为温岭市植物区系种类较丰富;以小型科、属居多,种类则主要集中于少数大型科、属中;生活型组成以草本植物为主;区系地理成分复杂多样,反映出广布性和地域性的特点;古老原始的类群较多;滨海植物与岩生植物区系发达。表4参14     

Tektite glass in apollo 12 sample

The glassy portion of lunar sample 12013 from Apollo 12 is chemically more like some tektites from Java than like any terrestrial igneous rock. It satisfies all the chemical criteria for a tektite. Tektites are relatively recent and acid rocks, whereas the moon is chiefly ancient and basaltic; hence, tektites are probably ejected volcanically, rather than by impact, from the moon.     

我国古代贮藏物害虫防治的主要策略与方法

根据大量的古籍及相关文献,系统研究了我国古代对贮藏物害虫防治的主要策略和方法,分析了“密封法”、生态因子调控法、利用植物性杀虫物质进行处理、以及采用药物和物理曝晒相结合等方法对害虫控制的原理;探讨现代仓虫防治技术的历史渊源;指出挖掘和深入研究古代储藏害虫防治的措施并加以协调运用,对于开展当今贮藏物害虫的防治有十分重要的意义。     

中国古代的嫁接技艺

通过对中国古籍的考察,发现中国古代嫁接技法的产生可能是受到自然界中“连理枝”现象的启发。嫁接技法应用到生产中的年代不晚于西汉(前206-公元25);古人主要将嫁接技法应用在缩短生产周期,保持物种特异性状和扩大繁殖系数上;古人在生产实践中总结出嫁接“四法”和“六法”,发现砧木和接穗的选择、嫁接时间和嫁接技巧等因素影响着嫁接成活率,提出“气”和“液”的概念来解释嫁接成活机理,并在总结大量远缘嫁接实践的基础上,提出亲缘关系较近的植物嫁接容易成活的观点。参18     

贵州茂兰生物圈保护区尧古布依族村寨旅游开发构想

对茂兰生物圈保护区内的尧古布依族村寨旅游资源进行调查,发现该村寨旅游资源丰富,自然环境优美,村民对旅游开发致富的愿望强烈。与此同时,指出村寨现存主要问题在于建筑破损严重,村寨环境状况较差,文化传承人员缺失。在此基础上,提出了尧古民族村寨开发的总体定位,探讨了其旅游产品开发的构想与布局。强调应依托茂兰生物圈保护区自然风光,以"远古布依,民俗之源"为主题,以"一廊四区"为总体布局,最终实现村寨保护、文化传承、经济发展相统一的民族文化旅游产品开发的目的。