Pliocene eclogite exhumation at plate tectonic rates in eastern Papua New Guinea

As lithospheric plates are subducted, rocks are metamorphosed under high-pressure and ultrahigh-pressure conditions to produce eclogites and eclogite facies metamorphic rocks. Because chemical equilibrium is rarely fully achieved, eclogites may preserve in their distinctive mineral assemblages and textures a record of the pressures, temperatures and deformation the rock was subjected to during subduction and subsequent exhumation. Radioactive parent-daughter isotopic variations within minerals reveal the timing of these events. Here we present in situ zircon U/Pb ion microprobe data that dates the timing of eclogite facies metamorphism in eastern Papua New Guinea at 4.3 +/- 0.4 Myr ago, making this the youngest documented eclogite exposed at the Earth's surface. Eclogite exhumation from depths of approximately 75 km was extremely rapid and occurred at plate tectonic rates (cm yr(-1)). The eclogite was exhumed within a portion of the obliquely convergent Australian-Pacific plate boundary zone, in an extending region located west of the Woodlark basin sea floor spreading centre. Such rapid exhumation (> 1 cm yr(-1)) of high-pressure and, we infer, ultrahigh-pressure rocks is facilitated by extension within transient plate boundary zones associated with rapid oblique plate convergence.     

Mantle compensation of active metamorphic core complexes at Woodlark rift in Papua New Guinea

In many highly extended rifts on the Earth, tectonic removal of the upper crust exhumes mid-crustal rocks, producing metamorphic core complexes. These structures allow the upper continental crust to accommodate tens of kilometres of extension, but it is not clear how the lower crust and underlying mantle respond. Also, despite removal of the upper crust, such core complexes remain both topographically high and in isostatic equilibrium. Because many core complexes in the western United States are underlain by a flat Moho discontinuity, it has been widely assumed that their elevation is supported by flow in the lower crust or by magmatic underplating. These processes should decouple upper-crust extension from that in the mantle. In contrast, here we present seismic observations of metamorphic core complexes of the western Woodlark rift that show the overall crust to be thinned beneath regions of greatest surface extension. These core complexes are actively being exhumed at a rate of 5-10 km Myr(-1), and the thinning of the underlying crust appears to be compensated by mantle rocks of anomalously low density, as indicated by low seismic velocities. We conclude that, at least in this case, the development of metamorphic core complexes and the accommodation of high extension is not purely a crustal phenomenon, but must involve mantle extension.     

New ages for human occupation and climatic change at Lake Mungo,Australia

Australia's oldest human remains, found at Lake Mungo, include the world's oldest ritual ochre burial (Mungo III) and the first recorded cremation (Mungo I). Until now, the importance of these finds has been constrained by limited chronologies and palaeoenvironmental information. Mungo III, the source of the world's oldest human mitochondrial DNA, has been variously estimated at 30 thousand years (kyr) old, 42-45 kyr old and 62 +/- 6 kyr old, while radiocarbon estimates placed the Mungo I cremation near 20-26 kyr ago. Here we report a new series of 25 optical ages showing that both burials occurred at 40 +/- 2 kyr ago and that humans were present at Lake Mungo by 50-46 kyr ago, synchronously with, or soon after, initial occupation of northern and western Australia. Stratigraphic evidence indicates fluctuations between lake-full and drier conditions from 50 to 40 kyr ago, simultaneously with increased dust deposition, human arrival and continent-wide extinction of the megafauna. This was followed by sustained aridity between 40 and 30 kyr ago. This new chronology corrects previous estimates for human burials at this important site and provides a new picture of Homo sapiens adapting to deteriorating climate in the world's driest inhabited continent.     

Pleistocene dates for the human occupation of New Ireland, northern Melanesia

Pleistocene dates from three cave sites indicate the human capacity to colonise across two oceanic straits to the east of a former Tasmania-Australia-New Guinea continent by 33 kyr BP. The sites demonstrate exploitation of costal marine and lowland tropical forest resources. They extend Pleistocene occupation into island Melanesia and demonstrate that the large islands of northern Melanesia have an antiquity of human occupation of the same order as the adjacent Greater Australian continent.     

New evidence for human occupation of the northern Tibetan Plateau, China during the Late Pleistocene

The described stone artifacts are recovered from the 70 m-high terrace (4600 m a.s.l.) at the southeastern shore of the Siling Co on the northern Tibetan Plateau. The terrace was formed during the Interstadial period before the LGM, ca. 40-30 ka B.P. based on paleoenvironmental research. The Paleoliths from the Siling Co provide evidence for early human occupation of the northern Tibetan Plateau. They show technological and typological affinities with the European Middle Paleolithic suggesting that the early human occupation here might relate to migratory waves during the Late Pleistocene that dispersed humans across the Old World.     

公路工程工地实验室管理浅析

工地试验室是公路工程质量管理必不可少的系统工程。本文结合榆神高速公路工程建设实践,对工地试验室管理工作的重点和难点进行了全面分析,并结合自身的实践提出了工地实验室管理的改进建议。为其他同类工程提供参考和借鉴。     

Research on the relationship between site function and environment at the site of Zhongba,Chongqing City, China

The Zhongba site has been demonstrated to be a location of salt production based on multi-disciplinary research including salt archaeology,environmental archaeology,zooarchaeology,paleobotany,and other natural science examinations.The continuity of salt production from the Han Dynasty to the present day as understood primarily from ancient texts can now be traced back to even earlier times. Based on the characteristics of cultural layer deposits,features,and artifacts,Zhongba can be clearly distinguished from known settlements,and from bronze,iron,pottery and porcelain workshops.According to various natural science examinations,the major impurities in local salt brine are also found in floor features,brine troughs,and rounded bottom pots at the site even though NaCl itself was not preserved.These traces were left over from the salt production process rather than being naturally deposited.Zhongba and its constituent features and artifacts share many common characters with other salt production sites around the world.Consequently,the Zhongba site can be confidently identified as a salt production site where activity continued for several thousand years.The formation of the site cannot be separated from salt production,and it is also highly related to its natural environment.     

一种快速可靠的豚鼠心室肌细胞分离法

报道一种快速的豚鼠心室肌细胞分离方法。该方法可获得杆状、清晰边缘的耐Ca^2 的单个心室肌细胞。     

哥德巴赫猜想的新尝试

本文提出两个猜想:(Y)猜想和弱(Y)猜想,证明了(Y)猜想的正确性蕴涵哥德巴赫猜想的正确性;弱(Y)猜想的正确性蕴涵弱型哥德巴赫问题的一个新命题:一切偶数都可以表示为至多四个素数之和。     

“课程定义”新论

现有的课程定义有五大硬伤.希冀得到课程的公认定义,首先必须明了公认定义的标准,其次必须采用新的研究方法.所谓课程,简而言之就是主体创建的具有教育意义的项目;预设性、服务性、教育性、创新性、系统性是其特征所在.     

A preliminary report on the newly found Tianyuan Cave, a Late Pleistocene human fossil site near Zhoukoudian

The Tianyuan Cave is the only human fossil-bearing site containing rich mammalian fossils found in the last decades near Zhoukoudian. Up to now more than 34 specimens of the human body have been recovered, and the mammalian fossils can be put into 29 species. Cervids dominate the fauna, and carnivores are very rare. Based on the primary examination, the human fossils can be attributed to the species Homo sapiens. All the mammalian fossils, except one between tooth of Crocuta belong to the species that still exist today. But some of them are the first records in fossil form north of the Yellow River, such as Arctonyx and Capricornis. Based on the mammalian fauna study, it seems that the Tianyuan Cave can be correlated with the Upper Cave.Sixty-three percent of the species of the mammalian fauna from the Tianyuan Cave are also present in the Upper Cave.The characters of the deposits also share some similarities between the Tianyuan Cave and the Upper Cave; both of them are mainly composed of breccia without cement. The dating using the U-series method on deer tooth samples indicates that the geological age of the new site is around 25 thousand years B.P. This is the first discovery of human sites outside the core area of the Peking Man Site at Zhoukoudian,which throws new light onto this world famous site complex.     

Heat treatment and associated early modern human behaviors in the Late Paleolithic at the Shuidonggou site

Unearthed artifacts and cultural relics from the Shuidonggou site revealed extensive information and insights regarding the activities of early modern humans.A series of experimental research and physical analysis suggest that stone artifacts from Locality 2 and Locality 12 have undergone heat treatment.The utilization ratio and knapping properties of raw materials were consequently enhanced.Heat treatment technology reflects the production capacities and the survival strategies in the Upper Paleolithic period.This discovery indicates the earliest existence of this technology in the East Asia and thus confirms a wider geographic distribution of this technology which provides new perspectives and evidence for understanding the associated early modern human behaviors.     

试论高校学风建设

加强高校的学风建设是高校自身发展过程中的一项内在的客观要求,是高等教育改革和发展的一个永恒主题.良好学风的养成不能靠顺其自然,需要外力加以引导和推动.形成优良学风需要学校领导、教师和学生长期的努力,需要在校内倡导一个学风养成的良好环境,也需要有利于学风建设的社会大环境.     

Further geological and palaeoanthropological investigations at the Maludong hominin site, Yunnan Province, Southwest China

Three-dimensional mapping and section work undertaken by us in 2008 have identified 11 stratigraphic units at Maludong site. AMS radiocarbon dating of charcoal established an accurate and internally consistent age profile for the sequence of 17.8±0.2 ka to 13.2±0.1 ka. Archaeomagnetic analysis showed changes in externally derived pedogenically enhanced material consistent with a warming in climate between the cold period of Henrich Event 1 and the Blling-AllerCd interstadial. Human remains recovered during the 1989 excavation were derived from a deposit dating to this interstadial, or between 14.3±0.3 ka and 13.5±0.1 ka. An- thropogenic features, including burnt rocks, baked sediment and thick charcoal and ash layers, were identified and examined through archaeomagnetic analysis. Two monkey fossils are described here, one of them being reassigned from Macaca robustus to M. aft＇. M. assamensis. They confirm the young age of the site and also show signs of anthropogenic alteration in the form of burning. Additional human cranial remains are reported for the first time and new data are provided for some specimens described previously. A range of new features is identified that strengthen the affinities of the Maludong remains to archaic humans. The presence of this globally unique mosaic of archaic and modern features raises important questions about human evolutionary his- tory in East Asia during the Late Upper Pleistocene.     

A位的Sm掺杂对La0.67Sr0.33MnO3体系磁电性质的影响

通过实验研究了La0.67-xSmxSr0.33MnO3(x=0.00,0.10,0.20,0.30)体系的M-T曲线、ESR曲线、ρ-T曲线和MR-T曲线.实验结果表明:随着Sm掺杂的增加,体系从长程铁磁有序向自旋团簇玻璃态和反铁磁状态转变,Sm掺杂引起的磁结构变化和额外磁性耦合将导致CMR效应.     

海上安全人为因素研究概述

阐述了人为因素是影响海上安全的主要因素的观点，集中反映了目前上对其研究的现状，重点讨论了海上安全中人为因素研究对航运产生的影响，积极倡导在我国应大力开展人为因素对海上安全的影响的研究。     

一种分析有丝分裂期蛋白的新方法

介绍了一种分析细胞有丝分裂任一时期蛋白质组成及各时期蛋白动态变化的方法,该法将细胞的显微分离,微量蛋白电泳和银染结合起来,通过显微分离可以获得无期它时期细胞污染的任一时期细胞,通过微量蛋白电泳和银染,可以分析其蛋白组成,并通过显微分离100个小麦根尖末期细胞证明了其可行性。     

一种新的截尾分布模型

从机械零,构件的所有设计变量都不服从理论分布这一事实出发,提出了两端截尾分布模型。以零构件的寿命为例,给出了可靠性设计中常用的两端截尾分布的概率密度和可靠度的计算公式。     

生态观下数学课堂教学中几个问题的探讨

数学课堂是进行数学教育活动的主要场所,传统的数学课堂存在诸多生态失衡问题,新课程理念下的数学课堂应从几个方面建立生态平衡:(1)建立多维互动的数学课堂教学模式;(2)注重生态个体的差异性;(3)注重生态系统的开放性,让学生的数学学习走出教室;(4)建立良好的数学课堂生态环境。     

New evidence on the earliest human presence at high northern latitudes in northeast Asia

The timing of early human dispersal to Asia is a central issue in the study of human evolution. Excavations in predominantly lacustrine sediments at Majuangou, Nihewan basin, north China, uncovered four layers of indisputable hominin stone tools. Here we report magnetostratigraphic results that constrain the age of the four artefact layers to an interval of nearly 340,000 yr between the Olduvai subchron and the Cobb Mountain event. The lowest layer, about 1.66 million years old (Myr), provides the oldest record of stone-tool processing of animal tissues in east Asia. The highest layer, at about 1.32 Myr, correlates with the stone tool layer at Xiaochangliang, previously considered the oldest archaeological site in this region. The findings at Majuangou indicate that the oldest known human presence in northeast Asia at 40 degrees N is only slightly younger than that in western Asia. This result implies that a long yet rapid migration from Africa, possibly initiated during a phase of warm climate, enabled early human populations to inhabit northern latitudes of east Asia over a prolonged period.