从静态字符骨架中提取完整笔划

提出了一个跟踪手写体了字符骨架的新方法,该方法能够从静态字符骨架中提取出由笔落到笔起的完整笔划,也就是说,能够在离线情况下重新获得部分已丧失的书写字符时的动态信息,从而使得字符的离线识别能够采用在线识别的特征,提高离线识别率。     

Southwest monsoon changes indicated by oxygen isotope of ostracode shells from sediments in Qinghai Lake since the late Glacial

The δ 18O records of ostracode shells in sediments of core QH-2000 from Qinghai Lake can be used as a better proxy to reflect monsoon changes. Low monsoon precipitation between 17.5 and 11 cal. ka BP is indicated by positive δ 18O values averaging 2.37‰. A fast shift in δ 18O from positive at 11 cal. ka BP to negative at 10 cal. ka BP indicates sharp increase of monsoon precipitation. An interval of generally high monsoon precipitation is observed between 10 and 6 cal. ka BP with δ 18O values averaging -2.15‰. Decrease of monsoon precipitation between 6 and 2.5 cal. ka BP is indicated by positive δ 18O values. δ 18O keeps positive values averaging 3.0‰ between 2.5 and 0 cal. ka BP suggesting low high monsoon precipitation. The climatic changes indicated by δ 18O records of ostracode shells in sedi- ments of core QH-2000 from Qinghai Lake and our broader regional comparison show that the climate in Qinghai Lake since the late Glacial is probably controlled by southwest monsoon other than southeast monsoon.     

平行四边形内点与边界点的平均距离

针对平面凸域的内点与边界点的平均距离问题,通过对运动公式的特别变形,将平均距离转化为弦幂积分,进而得到平行四边形的平均弦长以及平行四边形内点与边界点的平均距离计算公式。     

一类复系数解析函数族的极值点与支撑点

设Ω={f(z):f(z)在|z|<1内解析,f(z)=z sum from n=2 to ∞(an ibn)zn,an,bn为实数,sum from n=2 to ∞n (a2n bn2)~(1/2)≤1},找出了函数族Ω的极值点与支撑点.     

一类固定系数解析函数的极值点与支撑点

摘要 设Q={f(z):f(z)=z-an+1zn+1-(∞∑k=n+2)akzk},这里an+1=c(n+2)/(n+1)(n+3),ak≥0,∞∑k=n+2k(k+2)/k+1ak≤1-c,0≤c≤1,n∈N,并且f(z)在单位圆盘△={z:| z |＜1}内解析,得到函数族Q的极值点与支撑点.     

Timing of the Last Glacial Maximum from observed sea-level minima

During the Last Glacial Maximum, ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today. But few direct estimates exist of the volume of the ice sheets, or the timing and rates of change during their advance and retreat. Here we analyse four distinct sediment facies in the shallow, tectonically stable Bonaparte Gulf, Australia--each of which is characteristic of a distinct range in sea level--to estimate the maximum volume of land-based ice during the last glaciation and the timing of the initial melting phase. We use faunal assemblages and preservation status of the sediments to distinguish open marine, shallow marine, marginal marine and brackish conditions, and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio-hydro-isostatic modelling. Our results indicate that from at least 22,000 to 19,000 (calendar) years before present, land-based ice volume was at its maximum, exceeding today's grounded ice sheets by 52.5 x 10(6) km. A rapid decrease in ice volume by about 10% within a few hundred years terminated the Last Glacial Maximum at 19,000 +/- 250 years.     

南海海洋真菌Penicillum sp.中的一种新化合物

海洋微生物及其代谢产物的研究在国际上是一个极受重视的新兴领域，发展很快，取得了丰硕成果．近年来，作者开展对南海海洋细菌和真菌活性物质的研究，从中分离出一些结构新颖的，有很好生理活性的化合物．３８６菌是从南海获得的一种海洋真菌，其代谢产物很丰富，以分离出多种结构独特的化合物，其中３８６Ａ是从培养液中分离出的无色晶体，其结构通过波谱数据推导出来．１　实验部分１－１　试剂和仪器　所用试剂均为市售ＡＲ试剂，Ｐｅｎｉｃｉｌｌｕｍｓｐ－（３８６）菌株由香港城市大学Ｖｒｉｊｍｏｅｄ教授提供．所用仪器为ＶＧＺ…     

西藏普兰地区第四纪以来冰锯作用研究

为了验证西藏普兰地区冰川作用对地形演化的影响,选取纳木那尼峰、喜马拉雅山和冈底斯山3个区域,利用数字高程模型(DEM)数据和遥感影像,对现代冰川与末次冰盛期(LGM)古冰川平衡线高度(ELA)、冰川作用区坡度与高程的关系以及冰川分布的高程频谱进行计算和分析。结果显示,研究区内冰川剥蚀作用显著、坡度降低最明显的地带位于LGM古冰川平衡线附近,并在一定程度上限制山脉的高度。根据冰川地貌特征参数和前人研究结果,认为气候是影响冰锯作用的主要因素。冰期时,研究区内西风急流南移,风速增强,降水量增多,为冰川发育创造良好条件,冰锯作用也增强。对于构造抬升强烈的山脉(如纳木那尼峰),虽然冰锯作用得到加强,但是构造抬升增加的山脉高度不会完全被冰锯作用抵消。     

Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice

Dirac points are central to many phenomena in condensed-matter physics, from massless electrons in graphene to the emergence of conducting edge states in topological insulators. At a Dirac point, two energy bands intersect linearly and the electrons behave as relativistic Dirac fermions. In solids, the rigid structure of the material determines the mass and velocity of the electrons, as well as their interactions. A different, highly flexible means of studying condensed-matter phenomena is to create model systems using ultracold atoms trapped in the periodic potential of interfering laser beams. Here we report the creation of Dirac points with adjustable properties in a tunable honeycomb optical lattice. Using momentum-resolved interband transitions, we observe a minimum bandgap inside the Brillouin zone at the positions of the two Dirac points. We exploit the unique tunability of our lattice potential to adjust the effective mass of the Dirac fermions by breaking inversion symmetry. Moreover, changing the lattice anisotropy allows us to change the positions of the Dirac points inside the Brillouin zone. When the anisotropy exceeds a critical limit, the two Dirac points merge and annihilate each other-a situation that has recently attracted considerable theoretical interest but that is extremely challenging to observe in solids. We map out this topological transition in lattice parameter space and find excellent agreement with ab initio calculations. Our results not only pave the way to model materials in which the topology of the band structure is crucial, but also provide an avenue to exploring many-body phases resulting from the interplay of complex lattice geometries with interactions.     

基于关系数据库的专家系统骨架设计

本文提出了一种基于关系数据库的专家系统骨架设计方法，采用关系模式来描述知识库，用数据库操纵语言设计推理机，为设计紧密耦合结构的专家数据库系统提供基础，能克服专家系统不能有效地利用现有的使用常规数据库技术建造起来的数据库的局限。     

屏障条件下Wistar-Imamichi大鼠骨骼生长指标的测定

目的对Wistar-Imamichi大鼠封闭群5～16周龄两性个体骨骼的10个长度指标分别进行了测量,得出了骨骼与周龄的直线回归方程。除雄性颧宽、上臼齿列长两项指标与周龄无相关关系外,颅全长、基长、颅高、眶间宽、上齿隙长、左肱骨长、第3颈椎长、第1腰椎长以及雌性颧宽、上臼齿列长与周龄显著正相关。     

资金流动模型的马尔可夫骨架过程分析

在马尔可夫骨架过程理论的基础上讨论了资金流动模型.通过对此模型进行马尔可夫骨架过程建模并分析其瞬时分布,得出在任一时刻t的账户资金额Q(t)是某一非负线性方程的最小非负解.     

环丙烷骨架赤霉素衍生物的合成及结构鉴定

报道含有9,15-环丙烷结构的赤霉素衍生物(3)的合成.作者所报道的形成9,15-环丙烷结构赤霉素衍生物的方法与原类似方法比较,条件温和,易于操作.所得新化合物(3)的结构除由核磁共振(1H NMR,13C NMR),质谱(MS)及高分辨质谱(HRMS)证实外;还经单晶X-衍射分析得到最后证实.     

Cranial anatomy and implications of Dolichocebus, a late Oligocene ceboid primate

THE very scarce fossil record of Cainozoic New World monkeys(1,2) has contributed little to knowledge of the history of platyrrhine primates, an important element of both the neotropical mammal fauna(3) and the pantropical primates, as a whole. Only the affinities of the Middle Miocene Colombian fossils Neosaimiri, Stirtonia and Cebupithecia seem reasonably well established(4), though not without dissent(5), and these are clearly linked with the modern squirrel, howler and sakiuakari monkeys, respectively. After completion of a survey of the morphology and interrelationships of the platyrrhines, to be detailed elsewhere (A. L. R., in preparation), it is now possible to discuss the evolutionary implications of the terminal Oligocene Dolichocebus gaimanesis of Patagonia, represented by a nearly complete cranium only recently prepared fully, although first described in 1942 (ref. 6). This specimen strongly suggests that Dolichocebus is a member of the Saimiri lineage, which thus becomes the oldest generic lineage known for the primates, dating from about 25 Myr ago(7). Its affinities also imply that the two major monophyletic divisions of Ceboidea were already established by late Oligocene times, as were the marmosets and tamarins.     

Evidence of fire use of late Pleistocene humans from the Huanglong Cave, Hubei Province, China

Since 2004, three excavations have been carried out at a late Pleistocene human fossil site of Huanglong Cave in Yunxi County, Hubei Province of China, which unearthed seven human teeth, dozens of stone tools, mammal fossils and other evidence indicating human activities. During the third excavation in 2006, in the same layer as the human teeth, we found some patches of black materials embedded in the deposit. We doubted that this black deposit layer is the remains of burning or even human use of fire at the cave. To further explore the possibility of human fire use at the Huanglong Cave, we examined samples directly taken from the black deposit layer and compared them with samples taken from several places in the cave using three methods: micromorphology, element content determination and deposit temperature analysis. Our results indicate that the contents of carbon element in the black deposit reach 64.59%―73.29%. In contrast, contents of carbon element of the comparative samples from other parts in the cave are only 5.82%―9.49%. The micromorphology analysis of the black deposit samples reveals a plant structure like axial parenchyma, fibrocyte, uniseriate ray and vessel. High-temperature magnetic susceptibility measurements suggest that the stratum possibly underwent a high temperature in the nature. Based on these lab analyses, we are sure that the black layer in the Huanglong Cave is the remains of fire and combustion did occur in the cave 100000 years ago. Taking other evidence of human activities found in the Huanglong Cave into consideration, we believe that the evidence of fire from the Huanglong Cave was caused by the human activities of controlled use of fire.     

平面上有噪音散乱点集的参数化

散乱点集曲线重建关键步骤是参数化.提出了一种对平面上有噪音散乱点集参数化的新算法.算法中,首先求出点集的Delaunay三角化的最小生成树,继而对最小生成树的最长路径进行参数化.通过把其他点投影到最长路径上,对最长路径以外的点进行参数化.还给出了提高参数化的准确度的方法.以圆盘控制顶点B样条拟合为例展示了该算法的应用.     

Huanglong Cave, a new late Pleistocene hominid site in Hubei Province, China

For the past two decades, the modern human origins debate has received significant interest from both the scientific community and the public. The two hypothe- ses “Out of Africa” and “Mutiregional evolution” are focuses of this debate[1-3]. In partic…     

Identification of a protein associated with circulative transmission of Barley yellow dwarf virus from cereal aphids, Schizaphis graminum and Sitobion avenae

Using 2-D electrophoresis and virus overlay assay,a 50-kDa protein(P50)exhibiting specific binding to purified virus particles of BYDV-GAV was found in the protein extracts from Schizaphis graminum and Sitobion avenae,two aphid species transmiting BYDV-GAV.P50 in the extracts of S.graminum was isolated by preparation electrophoresis and electro-eluted proteins from the gel slices for antiserum preparation.After feeding the antiserum through membrane,the transmission efficiencies of S.graminum and S.avenae for BYDV-GAV decreased significantly.It was suggested that P50 should be related with transmission process.Location of P50 was found at the plasma membrane surrounding the accessory salivary gland(ASG) in the head tissues of S.graminum by immunogold-labelling experiment.The ascertainment of the protein associated with virus transmission has a significance influence on further understanding the transmission mechanism and genetic engineering for resistant to vector transmission.     

First discovery and characterizations of late Cretaceous seep carbonates from Xigaze in Tibet, China

Hydrocarbon seeps,widely occurring in continental margins,have become increasingly focused owing to their close relationships with gas hydrates,strong greenhouse gas methane,and biological resources in extreme environments.Ancient hydrocarbon seeps have already been recognized from Devonian to Quaternary strata worldwide based on seep carbonates or seep-related fossil chemosynthetic assemblages.However,seep-related deposits are rarely found from ancient strata in the mainland China.Here,we report the first discovery of an ancient seep deposit,specifically late Cretaceous seep carbonates from Xigaze in Tibet,China.Xigaze seep carbonates,occurring as nodules,are enclosed in upper Cretaceous turbidite strata in Xigaze forearc basin.These carbonates are composed of authigenic carbonate(56.2% on average),clastic quartz and feldspar(27.3% on average),and clay minerals(chlorite,illite and smectite,16.5% on average).Clotted micrites,peloids and framboid pyrites are frequently observed,all of which are common in modern seep carbonates.The carbonates have negative δ13 C values varying from 27.7‰ to 4.0‰(V-PDB),suggesting that thermogenic methane is the primary carbon source.Ce/Ce* values revised by eliminating La effects show no real Ce anomaly,indicating the carbonates were primarily precipitated in a weak reducing environment.Overall,these features provide unequivocal evidences that the seafloor of Xigaze forearc basin developed hydrocarbon seeps in late Cretaceous.