The structural preservation of a titanosaurid (Dinosauria: Sauropoda) vertebral ligament     

《Cretaceous Research》2016

Within the past decade exceptional preservation of original organic components have been reported from several dinosaurian families, including members of Sauropodomorpha. Here we document the partial preservation of a vertebral ligament in the dorsal and sacral series of a titanosaur. Unlike other cases of tissue preservation, this structure does not represent biomineralization of the original organic components. Histology, morphology, and comparative anatomy from extant taxa as well as the preferential placement on the vertebral column suggests that it represents the partial preservation of the nuchal ligament. While preservation of other sauropod connective tissues are known, this case represents the first reported non-biomineralized tissue from a sauropod. In consideration of the location and external and internal morphologies compared to modern vertebral ligaments, we believe this structure to be the micritic replacement of the original tissue via microbially-mediated processes. Along with the suggestive external morphology, internally we interpret some of the unusual structures to represent the remnants of the collagen and elastin fascicles that are strongly overprinted by a clotted, thrombolytic-like fabric recording microbial activity and deposition of micrite prior to lithification. In consideration of the interpreted depositional history, we theorize that post-deposition, bacteria deposited the micrite as a byproduct of metabolization. Subsequently, the recognition of this structure as a vertebral ligament, the largest of such thus documented, substantiates previous findings on the morphological attributes of sauropod vertebral ligaments.  相似文献   

The scientific value of scientific whaling     

《Marine Policy》2016

Scientific whaling has polarized opinion for decades, and its scientific value has been intensely debated. Here, the output of scientific whaling programs is examined by comparing it to the scientific output pertaining to whales of countries that do not practice scientific whaling. Between 1986 and 2013, whaling and non-whaling countries produced, on average, similar total numbers of publications that were directly relevant to the goals of the scientific whaling permits issued by the International Whaling Commission (IWC), and similar numbers of papers that were relevant to whale ecology and conservation but not directly related to IWC goals. Half of the scientific productivity of scientific whaling countries resulted from non-lethal data collection. One-third of publications by whaling countries were published in peer-reviewed outlets, compared to twice as many for non-whaling countries. Publications by whaling countries were cited ~4 times less often than those of non-whaling countries, with no evidence of citation discrimination against whaling countries since the citation rates of papers that did and did not use lethal sampling were similar. These academic criteria suggest that although the overall volume of science produced by scientific whaling countries is similar to that of non-whaling countries, the quality of the science is not. Arguably, academic criteria are not the best way to assess the usefulness of science for management and conservation, but demonstrating links between the science produced by scientific whaling, its integration in management plans and actions, and shifts towards sustainable exploitation or recovery of whale populations is challenging.  相似文献   

Greenhouse gas emissions from Mediterranean agriculture: Evidence of unbalanced research efforts and knowledge gaps     

《Global Environmental Change》2021

Designing effective mitigation policies for greenhouse gas (GHG) emissions from agriculture requires understanding the mechanisms by which management practices affect emissions in different agroclimatic conditions. Agricultural GHG emissions and carbon sequestration potentials have been extensively studied in the Mediterranean biome, which is a biodiversity hot spot that is highly vulnerable to environmental changes. However, the absolute magnitude of GHG emissions and the extent to which research efforts match these emissions in each production system, are unknown. Here, we estimated GHG emissions and potential carbon sinks associated with crop and livestock production systems in the Mediterranean biome, covering 31 countries and assessing approximately 10,000 emission items. The results were then combined with a bibliometric assessment of 797 research publications to compare emissions estimates obtained with research efforts for each of the studied items. Although the magnitude of GHG emissions from crop production and the associated carbon sequestration potential (261 Tg CO₂eq yr⁻¹) were nearly half of those from livestock production (367 Tg CO₂eq yr⁻¹), mitigation research efforts were largely focused on the former. As a result, the relative research intensity, which relates the number of publications to the magnitude of emissions, is nearly one order of magnitude higher for crop production than for livestock production (2.6 and 0.4 papers Tg CO₂eq⁻¹, respectively). Moreover, this mismatch is even higher when crop and livestock types are studied separately, which indicates major research gaps associated with grassland and many strategic crop types, such as fruit tree orchards, fiber crops, roots and tubers. Most life cycle assessment studies do not consider carbon sequestration, although this single process has the highest magnitude in terms of annual CO₂eq. In addition, these studies employ Tier 1 IPCC factors, which are not suited for use in Mediterranean environments. Our analytical results show that a strategic plan is required to extend on-site field GHG measurements to the Mediterranean biome. Such a plan needs to be cocreated among stakeholders and should be based on refocusing research efforts to GHG balance components that have been afforded less attention. In addition, the outcomes of Mediterranean field studies should be integrated into life cycle assessment-based carbon footprint analyses in order to avoid misleading conclusions.  相似文献   

环太平洋成矿带斑岩-矽卡岩型铜矿和与花岗岩有关的锡多金属矿研究现状与展望   总被引：8，自引：6，他引：2  

毛景文  谢桂青  袁顺达  刘鹏  孟旭阳  周振华  郑伟 《岩石学报》2018,34(9):2501-2517

长期以来,斑岩型铜矿是研究和勘查的热点。在20世纪70~90年代,对与花岗岩有关锡矿进行了大量深入研究,近几年,锡被列为一种关键金属,锡矿的研究和勘查又成为新的热点之一。锡矿和铜矿是环太平洋地区乃至全球最重要的两种矿床,但两者的成矿物质和成矿过程相差迥异。环太平洋地区的锡矿和铜矿主要形成于晚中生代至新生代,通常认为与太平洋板块俯冲有关,包括古太平洋板块、伊泽奈岐板块、法拉龙板块以及现今太平洋板块。本文主要综述了环太平洋成矿域的斑岩-矽卡岩铜矿和与花岗岩有关锡矿的时空分布特点、成矿岩体、矿床成因以及成矿环境的研究现状。尽管,目前已经取得了诸多重要进展,但仍然存在一些重要的科学问题亟待解决,例如,1)中国东部平行同时代成对出现的三条锡(钨)成矿带与斑岩铜矿成矿带的形成机制? 2)沿欧亚大陆边缘发育长达一万多公里的巨型铜金锡成矿带,而且绝大多数矿产发育于一系列伸展盆地中,其成矿背景是什么?此外,我们认为开展玻利维亚和大兴安岭南段Sn-Ag成矿系统的对比研究,是推动大兴安岭南段及邻区锡矿找矿取得突破的重要途径。  相似文献   

基于WRF模式的一种台风人造涡旋构建方案     

吴云帆  边旭  吴宝勤  朱先德  王风帆 《海洋科学》2021,45(12):65-76

为了使台风路径的数值预报更加精确,本文对人造(Bogus)涡旋构建方案进行了改进,形成了一种新的Bogus方案.该方案直接采用台风外围的风圈观测信息,并成功地植入到WRF(weather research and forecasting)模式中.本文利用该方案,选取2011年9号台风"梅花"这一典型案例展开讨论,结果表明:1)新构造的台风切向风廓线更加真实地反映了台风风场的实际情况;2)新的Bogus方案对台风中心位置的预报,更有利于对台风路径的预报;3)台风内核风场强度,对其非对称结构起到关键的作用,直接影响对台风路径的预报.  相似文献   

我国夏季暴雨气候学的研究进展与科学问题   总被引：3，自引：2，他引：1  

陈栋  黄荣辉  陈际龙 《气候与环境研究》2015,20(4):477-490

我国夏季暴雨频发并导致洪涝灾害,严重影响着社会和经济的发展。基于对我国夏季降水和暴雨天气学的大量研究,从气候学的角度综述了我国夏季暴雨的研究进展,特别是关于我国暴雨的年际和年代际变化及趋势、与暴雨发生相关联的大尺度环流特征及年际和年代际变化成因以及全球气候变暖背景下今后我国夏季暴雨的演变趋势等方面的主要研究进展。此外,还指出了我国夏季暴雨气候学亟待进一步研究的若干科学问题。  相似文献   

Meta-analyses of case studies: A method for studying regional and global environmental change   总被引：2，自引：0，他引：2  

Thomas K. Rudel   《Global Environmental Change》2008,18(1):18-25

As case studies of global environmental change accumulate over time, ways of summarizing these findings and bringing them to the attention of policymakers become more necessary. In summarized form, these findings might, for example, tell us new things about regional and pan-regional trends in tropical forest cover. This paper proposes a method for analyzing and summarizing the findings from the case studies. It illustrates the method through a meta-analysis of local studies of forest cover change in Mexico, and discusses how the method can produce credible, insightful findings about global environmental change.  相似文献   

我国不同赋存状态烃类气体的研究现状与展望   总被引：5，自引：0，他引：5  

张晓宝  徐永昌 《地球科学进展》1997,12(3):230-235

不同赋存状态烃类气体（包括游离的天然气、吸附气、酸解气、水溶气和油溶气）研究对于烃源岩评价、天然气成因判识、油气复合关系研究，油气源对比和油气勘探均具有十分重要的理论和应用价值。我国经过“六五”、“七五”和“八五”期间组织天然气地学攻关，在该领域内取得了较大进展。综述了我国不同赋存状态烃类气体的研究现状，分析了研究中存在的几个问题，并展望了其理论和应用前景。  相似文献   

生态水文学研究进展   总被引：31，自引：4，他引：31  

严登华  何岩  邓伟  王春梅  侯佑泽  厉彩虹 《地理科学》2001,21(5):467-473

生态水文学是生态学与水文学的交叉学科，它研究不同时空尺度上水文过程与生物动力过程的耦合机制与规律，以期实现水资源的持续管理。它是在水资源问题日益严峻的形势下，于1992年在Dublin国际水与环境大会上正式提出的。虽然生态水文学的产生经历了很长一段时期的孕育，有较为可靠的理论研究背景，但尚未形成完整的理论框架和方法体系，目前的研究仍然是处于基础理论的探求阶段，并且这个阶段还将持续一段时间。当基础理论完善以后，生态水文学可望得到较快的发展。  相似文献   

斑岩铜矿研究的若干进展   总被引：18，自引：0，他引：18  

王奖臻  李朝阳  胡瑞忠 《地球科学进展》2001,16(4):514-519

综述了近年来斑岩铜矿研究领域取得的最新成果，包括6个方面：（1）斑岩铜矿与岩浆的氧化状态有关，只有氧化型岩浆才能形成斑岩铜矿，并提出了确定岩浆氧化状态的新标志；（2）岩浆中硫和氯的含量，存在状态，溶解度等对成矿有重要控制作用；（3）岩浆能否较早达到水过饱和状态，并发生流体相的出溶是成矿的另一个控制因素；（4）俯冲板片释放出的流对对上覆楔形地幔的交代作用是形成含矿岩浆的重要环节；（4）岩浆混合或底侵作用可能在某些斑岩铜矿成矿中起到了重要作用。（5）提出了一些新的成矿及找矿标志，如早期磁铁矿蚀变相。  相似文献