Strontium isotope evidence for landscape use by early hominins

Ranging and residence patterns among early hominins have been indirectly inferred from morphology, stone-tool sourcing, referential models and phylogenetic models. However, the highly uncertain nature of such reconstructions limits our understanding of early hominin ecology, biology, social structure and evolution. We investigated landscape use in Australopithecus africanus and Paranthropus robustus from the Sterkfontein and Swartkrans cave sites in South Africa using strontium isotope analysis, a method that can help to identify the geological substrate on which an animal lived during tooth mineralization. Here we show that a higher proportion of small hominins than large hominins had non-local strontium isotope compositions. Given the relatively high levels of sexual dimorphism in early hominins, the smaller teeth are likely to represent female individuals, thus indicating that females were more likely than males to disperse from their natal groups. This is similar to the dispersal pattern found in chimpanzees, bonobos and many human groups, but dissimilar from that of most gorillas and other primates. The small proportion of demonstrably non-local large hominin individuals could indicate that male australopiths had relatively small home ranges, or that they preferred dolomitic landscapes.     

Early hominid diets from quantitative image analysis of dental microwear

The dietary habits of the early hominids Australopithecus and Paranthropus have long been debated. Robinson argued that the two species differed in the proportions of meat and vegetables consumed. More recently it has been suggested that Paranthropus, with its presumably larger body size, simply processed greater amounts of the same foods eaten by Australopithecus to maintain 'functional equivalence'. Microscopic dental wear patterns are related to the dietary habits of extant mammals, and quantification of these patterns is useful in distinguishing among primates with different diets. Nevertheless, few attempts have been made to use microwear in the reconstruction of early hominid diets, and only very recently has the quantification of such data been initiated. While microwear fabrics can be reduced to individual elements (for example, scratches and pits), there is some disagreement over exactly how they should be defined and measured. Fourier transforms have been applied successfully in the study of a variety of physical and biological patterns, and recently they have been used to characterize and distinguish different tooth wear patterns more objectively. Here we report the first combined use of image processing and other quantitative techniques to analyse the dental microwear of early hominids. Our results suggest that Paranthropus ate substantially more hard food items than Australopithecus.     

The diet of Australopithecus sediba

Specimens of Australopithecus sediba from the site of Malapa, South Africa (dating from approximately 2 million years (Myr) ago) present a mix of primitive and derived traits that align the taxon with other Australopithecus species and with early Homo. Although much of the available cranial and postcranial material of Au. sediba has been described, its feeding ecology has not been investigated. Here we present results from the first extraction of plant phytoliths from dental calculus of an early hominin. We also consider stable carbon isotope and dental microwear texture data for Au. sediba in light of new palaeoenvironmental evidence. The two individuals examined consumed an almost exclusive C(3) diet that probably included harder foods, and both dicotyledons (for example, tree leaves, fruits, wood and bark) and monocotyledons (for example, grasses and sedges). Like Ardipithecus ramidus (approximately 4.4 Myr ago) and modern savanna chimpanzees, Au. sediba consumed C(3) foods in preference to widely available C(4) resources. The inferred consumption of C(3) monocotyledons, and wood or bark, increases the known variety of early hominin foods. The overall dietary pattern of these two individuals contrasts with available data for other hominins in the region and elsewhere.     

First fossil chimpanzee

There are thousands of fossils of hominins, but no fossil chimpanzee has yet been reported. The chimpanzee (Pan) is the closest living relative to humans. Chimpanzee populations today are confined to wooded West and central Africa, whereas most hominin fossil sites occur in the semi-arid East African Rift Valley. This situation has fuelled speculation regarding causes for the divergence of the human and chimpanzee lineages five to eight million years ago. Some investigators have invoked a shift from wooded to savannah vegetation in East Africa, driven by climate change, to explain the apparent separation between chimpanzee and human ancestral populations and the origin of the unique hominin locomotor adaptation, bipedalism. The Rift Valley itself functions as an obstacle to chimpanzee occupation in some scenarios. Here we report the first fossil chimpanzee. These fossils, from the Kapthurin Formation, Kenya, show that representatives of Pan were present in the East African Rift Valley during the Middle Pleistocene, where they were contemporary with an extinct species of Homo. Habitats suitable for both hominins and chimpanzees were clearly present there during this period, and the Rift Valley did not present an impenetrable barrier to chimpanzee occupation.     

自动权值的马尔科夫彩色图像纹理分割方法

为准确获得目标图像,提出一种自动权值的马尔科夫彩色图像纹理分割方法。在HSV颜色空间中以颜色直方图作为颜色特征．设计Gabor滤波器提取图像纹理特征,对马尔科夫算法进行研究．设计自动权值算法。实验证明．该方法能有效降低算法复杂度,减少了分割过程中人为设置参数的主观性．较好地屏蔽图像噪声影响,可以很好地提取出目标图像。     

东海宽体舌鳎年龄与生长的研究

本文研究了东海宽体舌鳎的鳞片形态、年轮特征及其生长规律。结果表明：宽体舌鳎直至５龄生长尚未停止，但２龄前生长最快，以后生长速度逐渐降低，并且在各年龄阶段全长、体高、体厚的生长是不同步的，由此导致了各年龄阶段鱼体型的变化，高龄鱼比低龄鱼更肥胖、宽厚。     

Multiplex amplification of the mammoth mitochondrial genome and the evolution of Elephantidae

In studying the genomes of extinct species, two principal limitations are typically the small quantities of endogenous ancient DNA and its degraded condition, even though products of up to 1,600 base pairs (bp) have been amplified in rare cases. Using small overlapping polymerase chain reaction products, longer stretches of sequences or even whole mitochondrial genomes can be reconstructed, but this approach is limited by the number of amplifications that can be performed from rare samples. Thus, even from well-studied Pleistocene species such as mammoths, ground sloths and cave bears, no DNA sequences of more than about 1,000 bp have been reconstructed. Here we report the complete mitochondrial genome sequence of the Pleistocene woolly mammoth Mammuthus primigenius. We used about 200 mg of bone and a new approach that allows the simultaneous retrieval of multiple sequences from small amounts of degraded DNA. Our phylogenetic analyses show that the mammoth was more closely related to the Asian than to the African elephant. However, the divergence of mammoth, African and Asian elephants occurred over a short time, corresponding to only about 7% of the total length of the phylogenetic tree for the three evolutionary lineages.     

Anisotropy of nickel-based superalloy K418 fabricated by selective laser melting

Selective laser melting (SLM) is a promising additive manufacturing (AM) technology for fabricating the near net-shaped parts by selectively melting and solidifying a thin powder layer with a high-intensity laser beam according to the CAD data for arbitrary components. In this work, Ni-based superalloy K418 samples were fabricated by selective laser melting (SLM). To evaluate the anisotropic mechanical behavior of the SLM processed K418 samples with layer-by-layer melting, the samples were manufactured parallel (transverse specimens) and vertical (longitudinal specimens) to the building direction on the substrate. The microstructural anisotropy analysis was performed by optical microscopy (OM) and scanning electron microscopy (SEM). Electron backscatter diffraction (EBSD) analysis was used to identify their crystallographic preferred orientation (texture) and to correlate the anisotropy of the mechanical strength with the texture of the material. The results showed that the transverse specimens had slightly higher yield strength, but much significantly higher ductility than that of the transverse specimens with the elongated columnar grains along the building direction.     

静态地图符号视觉变量的分类及作用

以多年地图设计实践经验和实验观察资料为依据,对静态地图符号视觉变量的应用效果作了分析和评价.在此基础上,对传统视觉变量类型作了重新整合,删除了一些不合理的类型,建立了新的视觉变量分类体系.将一级变量分为图形和色彩两种类型,图形变量又分为形状、尺寸、纹理三种二级类型,色彩变量又分为色相、纯度、亮度三种二级类型,还将二级变量分为三级类型.此外,对各种视觉变量的作用作了深入分析.在表达地图内容系统性特征方面,形状、纹理、色相变量可用于更好地表达分类信息,尺寸、亮度、纯度变量可用于表达内容的等级、层次、数量的对比信息.在表征地理事物的个体属性方面,视觉变量能用于表达客体的色彩、肌理、质地、冷暖、重量等外在和内在的物理属性信息,还能用于象征各种社会经济属性信息.     

近红外图像纹理分析叶片含水率的初步研究

利用水分子对９６０ｎｍ附近的近红外光有较强的吸收这一特性,通过图像处理技术中的纹理分析方法,对三种作物（苞菜、青菜及生菜）叶片的近红外图像进行纹理分析,找寻图像的纹理特征量与叶片的干基含水率之间的关系,为应用图像处理技术获取作物生理信息作初步的研究采用纹理分析的直方图统计特征法、灰度—梯度共生矩阵法分别对叶片的近红外图像求出各自的特征量特征量与叶片干基含水率之间的线性关系不仅和特征量有关,而且和拍摄图像时的实验因素（如摄像头的工作距离、光圈、光强等）有关灰度—梯度共生矩阵法还取决于梯度图像灰度级的数目     

斯万特·帕博：因人类进化遗传学研究获2022诺贝尔生理学或医学奖

因“在已灭绝的古人类的基因组和人类演化方面的发现”，斯万特·帕博获得2022年诺贝尔生理学或医学奖。回顾了人类起源的长久之问、生物测序技术的突破发展和帕博团队的科研历程，明确了其源于兴趣、攻坚克难的古DNA领域探索之路和丰硕成果：首次实现了对已灭绝古人类尼安德特人的全基因组测序，发现了未知古人类丹尼索瓦人，为人类的进化遗传学提供了新证据。帕博对人类进化遗传中基因流动探索的科研历程，展现了严谨的科学精神以及理想的科研生态；他的科研成果和理念，实现了古基因组学跨越学科与时代的价值，也引起了人类未来将去往何方的进一步思考。     

裂缝的分形分析方法

从裂缝的分形分布出发,对裂缝的分布、裂缝的有效截面积、裂缝的强度、裂面的粗糙度和裂缝的各向异性度,提出了分形分析方法。根据裂缝分形分布特点,提出了基本裂缝分布模型,对这些模型做相应的分形对比,来阐明裂缝的分形和特征。裂缝的分形分析方法改变了以往单一的裂缝性质分析方法,而从裂缝的分形分布结构上全面地进行定量分析,不仅反映裂缝的平均效果,而且反映了裂缝分布的非均匀性及其发育程度的差异。     

Large Mesozoic mammals fed on young dinosaurs

Mesozoic mammals are commonly portrayed as shrew- or rat-sized animals that were mainly insectivorous, probably nocturnal and lived in the shadow of dinosaurs. The largest known Mesozoic mammal represented by substantially complete remains is Repenomamus robustus, a triconodont mammal from the Lower Cretaceous of Liaoning, China. An adult individual of R. robustus was the size of a Virginia opossum. Here we report a new species of the genus, represented by a skeleton with most of the skull and postcranium preserved in articulation. The new species is 50% larger than R. robustus in skull length. In addition, stomach contents associated with a skeleton of R. robustus reveal remains of a juvenile Psittacosaurus, a ceratopsian dinosaur. Our discoveries constitute the first direct evidence that some triconodont mammals were carnivorous and fed on small vertebrates, including young dinosaurs, and also show that Mesozoic mammals had a much greater range of body sizes than previously known. We suggest that Mesozoic mammals occupied diverse niches and that some large mammals probably competed with dinosaurs for food and territory.     

超纯铁素体不锈钢的组织、织构及深拉伸性能

重点研究了冷轧压下率对冷轧、再结晶织构的影响.结果表明:当终轧温度为750℃时,热轧带退火后以{111}再结晶织构为主.随着冷轧压下量的增加,γ织构减弱,α织构增强,{111}再结晶织构明显增强.当冷轧压下率为84%时,{111}再结晶组分的体积分数达到64.5%,退火板的平均塑性应变比(-R)高达1.69,平面各向异性(ΔR)仅为-0.17,深拉伸性能优良.     

第二相粒子与织构对高强Cu--Ni--Si系合金薄板各向异性的影响

利用利用X射线衍射、电子背散射衍射和透射电子显微镜等手段研究了Cu-Ni-Si系合金在不同固溶温度下第二相与织构对其平面各向异性的影响.结果表明:随固溶温度的升高,合金强度和伸长率均出现先升高后降低的趋势,且存在明显的各向异性;800℃固溶时,Cu'和S'为主织构,部分形变晶粒诱发少量Brass、Goss和{011}〈511〉取向的形成,使得合金各向异性减弱;高温固溶时(≥850℃),晶粒发生完全再结晶,Cu'和S'织构强度显著增加,Brass等织构减弱甚至消失,各向异性增强;850℃固溶时效后形成δ-Ni2Si析出相,并与基体满足[001]Cu//[110]δ,(010)Cu//(001)δ位向关系,温度进一步增加,第二相析出体积分数降低,有利于改善材料的各向异性.     

二步冷轧对铁素体不锈钢深冲性能和织构的影响

比较了一步冷轧和二步冷轧对铁素体不锈钢深冲性能和织构的影响.结果显示,采用一步冷轧(冷轧压下率90%)后,获得了高的平均r值(rm=1.92),且45°方向的r值要大于轧向和横向的r值,导致了材料的Δr呈负值(Δr=-0.31);在总压下率一定的情况下,采用二步冷轧后,薄板的平均r值变化不大(rm=1.90),但材料的平面各向异性很小(Δr=0.14).对两种工艺的再结晶织构分析表明,一步冷轧后薄板生成了强烈的γ织构,但是织构的峰值明显偏离了{111}轴,位于{223}〈582〉处;二步冷轧后薄板则生成了均匀的γ再结晶织构.     

基于纹理结构引导自适应的改进Criminisi算法

针对缺损图像修复时容易产生纹理紊乱、边界残缺等问题,基于Criminisi算法提出一种纹理结构引导的自适应图像修复算法。首先对决定合成顺序的优先级进行改进,在数据项中加入结构张量,使图像修复从结构区域向无结构区域填充;其次根据原图像区域纹理结构信息自适应地改变模板块的尺寸,这在一定程度上避免了纹理块过小或过大带来的弊端,从而使合成效果更为自然。实验结果表明,本文提出的改进算法不仅保证了修复图像结构信息的合理填充,还较好地保持了修复边界的完整性,图像修复后具有较佳视觉效果。     

云南金线鲃属一新种——版纳金线鲃

描记采于云南省西双版纳勐腊县罗梭江的金线鲃属一新种,命名版纳金线鲃Sinocyclocheilus bannaensis sp. nov.,该新种曾被误订为狭孔金线鲃S. angustiporus Zheng et Xie 1985,但背鳍条iii-8 vs iii-7,侧线鳞47 vs 68~89两特征可明显区别.新种外形更像粗壮金线鲃S. robustus Chen et Zhao 1988,但背鳍条iii-8 vs iii-7,侧线鳞47 vs 72亦可区别.     

基于灰色关联支持向量机的中国粮食产量预测模型

研究我国粮食生产系统的变动规律,做好粮食产量科学预测不仅是制定农业政策的重要依据,而且对于保证我国的粮食安全具有重要意义。鉴于粮食生产系统的复杂性和信息不完全性,在对粮食生产系统灰色关联分析的基础上,确定出影响粮食产量的主要因子,然后根据支持向量机回归原理,建立了基于灰色关联支持向量机的预测模型。预测结果表明该模型具有较高的预测精度,为粮食产量预测提供了一条新的途径。     

HDDR钕铁硼材料各向异性产生的机制

研究了NdFeB铸态粉末及HDDR工艺处理过程中不同阶段材料的显微结构、磁性能和各向异性产生的机理. 发现NdFeB铸态粉末的各向异性均大于HDDR NdFeB材料的各向异性. 随歧化时间延长HDDR NdFeB材料的各向异性单调下降,最终消失,说明HDDR NdFeB材料的各向异性来源于对铸态粉末各向异性的继承;短时间的歧化处理有助于材料获得各向异性;柱状歧化组织作为各向异性的传递介质,以位向关系的方式,将各向异性由铸态粉末传递到了经HDDR处理后的NdFeB粉末.