New fossil seeds of Eurya (Theaceae) from East Asia and their paleobiogeographic implications

AbstractEurya has an excellent fossil record in Europe, but it has only a few fossil occurrences in East Asia though this vast area houses the highest modern diversity of the genus. In this study, three-dimensionally preserved fossil seeds of Eurya stigmosa (Ludwig) Mai from the late Pliocene of northwestern Yunnan, southwestern China are described. The seeds are compressed and flattened, slightly campylotropous, and nearly circular to slightly angular in shape. The surface of the seeds is sculptured by a distinctive foveolate pattern, consisting of funnel-shaped and finely pitted cells. Each seed valve contains a reniform or horseshoe-shaped embryo cavity, a characteristic condyle structure and an internal raphe. These fossil seeds represent one of the few fossil records of Eurya in East Asia. This new finding therefore largely extends the distributional ranges of Eurya during Neogene. Fossil records summarized here show that Eurya persisted in Europe until the early Pleistocene, but disappeared thereafter. The genus might have first appeared in East Asia no later than the late Oligocene, and dispersed widely in regions such as Japan, Nepal, and southwestern China

Warming induced growth decline of Himalayan birch at its lower range edge in a semi-arid region of Trans-Himalaya, central Nepal

Changes in the position of altitudinal treelines and timberlines are considered useful indicators of climatic changes on tree growth and forest dynamics. We sought to determine if recent warming is driving contrasting growth responses of Himalayan birch, at moist treeline (Lete Lekh) and semi-arid timberline (Chimang Lekh) sites in the Trans-Himalayan zone of central Nepal. We used dendrochronological techniques to measure tree ring width (TRW) and basal area increment (BAI) of birch trees from climatically contrasting but nearby sites. The TRW series were correlated with climate records from nearby meteorological stations, and BAI was compared between populations to explore growth trends over recent decades. We found contrasting precipitation trends between nearby sites such that the wet site (Lete) is getting warmer and wetter, and the dry site (Chimang) is getting warmer and drier in recent decades. The radial growth of birch in both moist and semi arid sites are positively correlated to spring (March-May) rainfall, and negatively correlated to mean and maximum temperature for the same period. The growth climate analysis indicated that moisture availability in early growing season is crucial for birch growth at these locations. The BAI of birch is declining more rapidly at the dry timberline than at the moist treelines in the recent decades, indicating that climatic warming might negatively impact birch radial growth where warming interacts with increasing spring drought in the region. Our work highlights contrasting growth response of birch to climate change at moist and semi-arid forests indicating that local climatic variation must be accounted for when assessing and forecasting regional patterns of tree growth in topographically complex regions like Trans-Himalaya, in order to make accurate predictions of vegetation responses to climate change

MAT: Mask-Aware Transformer for Large Hole Image Inpainting

Recent studies have shown the importance of modeling long-range interactions in the inpainting problem. To achieve this goal, existing approaches exploit either standalone attention techniques or transformers, but usually under a low resolution in consideration of computational cost. In this paper, we present a novel transformer-based model for large hole inpainting, which unifies the merits of transformers and convolutions to efficiently process high-resolution images. We carefully design each component of our framework to guarantee the high fidelity and diversity of recovered images. Specifically, we customize an inpainting-oriented transformer block, where the attention module aggregates non-local information only from partial valid tokens, indicated by a dynamic mask. Extensive experiments demonstrate the state-of-the-art performance of the new model on multiple benchmark datasets. Code is released at https://github.com/fenglinglwb/MAT.Comment: Accepted to CVPR2022 Ora

Tracing the Evolution of Plant Diversity in Southwestern China

Biodiversity hotspots are key regions for understanding the evolutionary history of biodiversity as well as the processes initiating and maintaining it [...

SPHR-SAR-Net: Superpixel High-resolution SAR Imaging Network Based on Nonlocal Total Variation

High-resolution is a key trend in the development of synthetic aperture radar (SAR), which enables the capture of fine details and accurate representation of backscattering properties. However, traditional high-resolution SAR imaging algorithms face several challenges. Firstly, these algorithms tend to focus on local information, neglecting non-local information between different pixel patches. Secondly, speckle is more pronounced and difficult to filter out in high-resolution SAR images. Thirdly, the process of high-resolution SAR imaging generally involves high time and computational complexity, making real-time imaging difficult to achieve. To address these issues, we propose a Superpixel High-Resolution SAR Imaging Network (SPHR-SAR-Net) for rapid despeckling in high-resolution SAR mode. Based on the concept of superpixel techniques, we initially combine non-convex and non-local total variation as compound regularization. This approach more effectively despeckles and manages the relationship between pixels while reducing bias effects caused by convex constraints. Subsequently, we solve the compound regularization model using the Alternating Direction Method of Multipliers (ADMM) algorithm and unfold it into a Deep Unfolded Network (DUN). The network's parameters are adaptively learned in a data-driven manner, and the learned network significantly increases imaging speed. Additionally, the Deep Unfolded Network is compatible with high-resolution imaging modes such as spotlight, staring spotlight, and sliding spotlight. In this paper, we demonstrate the superiority of SPHR-SAR-Net through experiments in both simulated and real SAR scenarios. The results indicate that SPHR-SAR-Net can rapidly perform high-resolution SAR imaging from raw echo data, producing accurate imaging results

A primitive honey bee from the Middle Miocene deposits of southeastern Yunnan, China (Hymenoptera, Apidae)

While fossils of honey bees (Apini: Apis Linnaeus) are comparatively abundant in European Oligocene and Miocene deposits, the available material from Asia is scant and represented by only a handful of localities. It is therefore significant to report a new deposit with a fossil honey bee from southern China. Apis (Synapis) dalica Engel & Wappler, sp. n., is described and figured from Middle Miocene sediments of Maguan County, southeastern Yunnan Province, China. This is the first fossil bee from the Cenozoic of southern China, and is distinguished from its close congeners present at the slightly older locality of Shanwang, Shandong in northeastern China. The species can be distinguished on the basis of wing venation differences from other Miocene Apis.This research was supported by the National Natural Science Foundation of China (41572010, 41622201, 41688103, U1502231)the Chinese Academy of Sciences (XDPB05)King Saud University through ISPP #0083 (M.S.E. and A.S.A.)T.W. was supported by the German Research Foundation (WA 1496/6-1, Heisenberg grant WA 1496/8-1

A new positive relationship between pCO2 and stomatal frequency in Quercus guyavifolia (Fagaceae): a potential proxy for palaeo-CO2 levels

Background and Aims The inverse relationship between atmospheric CO2 partial pressure (pCO2) and stomatal frequency in many species of plants has been widely used to estimate palaeoatmospheric CO2 (palaeo-CO2) levels; however, the results obtained have been quite variable. This study attempts to find a potential new proxy for palaeo-CO2 levels by analysing stomatal frequency in Quercus guyavifolia (Q. guajavifolia, Fagaceae), an extant dominant species of sclerophyllous forests in the Himalayas with abundant fossil relatives. Methods Stomatal frequency was analysed for extant samples of Q. guyavifolia collected from17 field sites at altitudes ranging between 2493 and 4497 m. Herbarium specimens collected between 1926 and 2011 were also examined. Correlations of pCO2-stomatal frequency were determined using samples from both sources, and these were then applied to Q. preguyavaefolia fossils in order to estimate palaeo-CO2 concentrations for two late-Pliocene floras in south-western China. Key Results In contrast to the negative correlations detected for most other species that have been studied, a positive correlation between pCO2 and stomatal frequency was determined in Q. guyavifolia sampled from both extant field collections and historical herbarium specimens. Palaeo-CO2 concentrations were estimated to be approx. 180-240 ppm in the late Pliocene, which is consistent with most other previous estimates. Conclusions A new positive relationship between pCO2 and stomatal frequency in Q. guyavifolia is presented, which can be applied to the fossils closely related to this species that are widely distributed in the late-Cenozoic strata in order to estimate palaeo-CO2 concentrations. The results show that it is valid to use a positive relationship to estimate palaeo-CO2 concentrations, and the study adds to the variety of stomatal density/index relationships that available for estimating pCO2. The physiological mechanisms underlying this positive response are unclear, however, and require further researc

Uplift, Climate and Biotic Changes at the Eocene-Oligocene Transition in Southeast Tibet

The uplift history of southeastern Tibet is crucial to understanding processes driving the tectonic evolution of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernisation of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly-collected plant fossil archives, we quantify the surface height of part of Tibet’s southeastern margin of Tibet in the latest Eocene (~34 Ma) to be ~3 km and rising, possibly attaining its present elevation (3.9 km) in the early Oligocene. We also find that the Eocene-Oligocene transition in southeastern Tibet witnessed leaf size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that by the latest Eocene floral modernization on Tibet had already taken place implying modernization was deeply-rooted in the Paleogene

Graphene Quantum Dots Enhanced Electrochemical Performance of Polypyrrole as Supercapacitor Electrode

通过将吡咯单体在低温下与石墨烯量子点进行原位聚合，获得一种全新的聚吡咯/石墨烯量子点（PPY/GQD）复合材料. 实验中采用了扫描电子显微镜（SEM）、原子力显微镜（AFM）、X射线衍射(XRD)、红外（FT-IR）和热重（TGA）对复合物的表面形貌、结构进行表征. 结果表明，吡咯单体以石墨烯量子点为软模板，以化学键的方式在石墨烯量子点的表面聚合生长成片状聚吡咯. 通过机械冷压法将粉末状PPY/GQD复合物压成圆片电极，电极的电化学测试结果表明，PPY和GQD质量比为50:1所制得的复合物的电容量为485 F·g-1，同时在两千次循环之后电容量只降低了大约2%. 通过与同比例的PG（聚吡咯/石墨烯复合材料）以及纯PPY对比，发现聚吡咯/石墨烯量子点的高比容量及优异的循环稳定性将会使其在电化学超级电容器领域中具有的潜在的应用价值.With an objective to develop electrode materials with high specific capacitance and good stability, a completely new nanocomposite of Polypyrrole (PPY) and graphene quantum dots (GQD) was successfully obtained through in-situ polymerization of pyrrole in the presence of GQD suspension. The obtained composites with different mass ratios were characterized by X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). GQD enhanced electrochemical performance of PPY and, as supercapacitor electrodes, the PPY/GQD composites with the mass ratio of PPY to GQD at 50:1 showed a competitive specific capacitance of 485 F·g-1 at a scan rate of 0.005 V·s-1. The attenuation of the specific capacitance is about 2% after 2000 cycles. The high specific capacitance and good stability of the PPY/GQD nanocomposites are promising for applications in electrochemical supercapacitors.This work was supported by the National Natural Science Foundation of China (No. 20906055), National “973 Program” (No. 2010CB933900), and the State Key Laboratory of Bioreactor Engineering (No. 2060204).This work was supported by the National Natural Science Foundation of China (No. 20906055), National “973 Program” (No. 2010CB933900), and the State Key Laboratory of Bioreactor Engineering (No. 2060204).作者联系地址：上海交通大学微纳科学技术研究院，上海 200240Author's Address: Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240, China通讯作者E-mail：[email protected]

<i>Bauhinia</i> (Leguminosae) Fossils from the Paleogene of Southwestern China and Its Species Accumulation in Asia

Extant Bauhinia (Leguminosae) is a genus of 300 species of trees, shrubs, and lianas, widely distributed in pantropical areas, but its diversification history in southeastern Asia, one of its centers of highest diversity, remains unclear. We report new fossils of three Bauhinia species with cuticular preservation from the Paleogene of Puyang Basin, southwestern China. Our finding likely extends the emergence of Bauhinia in Asia to the late Eocene. Together with previously reported fossil records, we show that the diversification of Bauhinia in Asia and the phenomenon of a small region harboring multiple Bauhinia species in southwestern China could be traced back to the Paleogene