Impact of hyper-elasticity on cyclic sand modelling: A numerical study based on SANISAND-MS

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Influence of NH 4

The influence of NH4Cl on hydrothermal formation of CaSO4·0.5H2O whiskers from CaSO4·2H2O precursor at 135°C was investigated in this paper. Compared with the blank experiment, the presence of 3 × 10−2 mol·L−1 NH4Cl led to the increase of the lengths of the whiskers from 50 to 160 μm to 150 to 300 μm and the decrease of the diameters from 1.0 to 1.5 μm to 0.2 to 0.5 μm. The dissolution of CaSO4·2H2O was accelerated by the complex interactions with NH4Cl and the soluble cations, which led to the decrease of the induction time for the occurrence of α-CaSO4·0.5H2O from 46 minutes to 34 minutes and the formation of CaSO4·0.5H2O whiskers with high aspect ratios. Furthermore the critical supersaturation for the formation of α-CaSO4·0.5H2O was investigated

Y-Single Nucleotide Polymorphisms Diversity in Chinese Indigenous Horse

In contrast to high genetic diversity of mitochondrial DNA (mtDNA), equine Y chromosome shows extremely low variability, implying limited patrilines in the domesticated horse. In this study, we applied direct sequencing and restriction fragment length polymorphism (RFLP) methods to investigate the polymorphisms of 33 Y chromosome specific loci in 304 Chinese indigenous horses from 13 breeds. Consequently, two Y-single nucleotide polymorphisms (SNPs) (Y-45701/997 and Y-50869) and one Y-indel (Y-45288) were identified. Of those, the Y-50869 (T>A) revealed the highest variation frequency (24.67%), whereas it was only 3.29% and 1.97% in Y-45288 (T/-) and Y-45701/997 (G>T) locus, respectively. These three mutations accounted for 27.96% of the total samples and identified five Y-SNP haplotypes, demonstrating genetic diversity of Y chromosome in Chinese horses. In addition, all the five Y-SNP haplotypes were shared by different breeds. Among 13 horse breeds analyzed, Balikun horse displayed the highest nucleotide diversity (π = 5.6×10−4) and haplotype diversity (h = 0.527), while Ningqiang horse showed the lowest nucleotide diversity (π = 0.00000) and haplotype diversity (h = 0.000). The results also revealed that Chinese horses had a different polymorphic pattern of Y chromosome from European and American horses. In conclusion, Chinese horses revealed genetic diversity of Y chromosome, however more efforts should be made to better understand the domestication and paternal origin of Chinese indigenous horses

Taking the pulse of COVID-19: A spatiotemporal perspective

The sudden outbreak of the Coronavirus disease (COVID-19) swept across the world in early 2020, triggering the lockdowns of several billion people across many countries, including China, Spain, India, the U.K., Italy, France, Germany, and most states of the U.S. The transmission of the virus accelerated rapidly with the most confirmed cases in the U.S., and New York City became an epicenter of the pandemic by the end of March. In response to this national and global emergency, the NSF Spatiotemporal Innovation Center brought together a taskforce of international researchers and assembled implemented strategies to rapidly respond to this crisis, for supporting research, saving lives, and protecting the health of global citizens. This perspective paper presents our collective view on the global health emergency and our effort in collecting, analyzing, and sharing relevant data on global policy and government responses, geospatial indicators of the outbreak and evolving forecasts; in developing research capabilities and mitigation measures with global scientists, promoting collaborative research on outbreak dynamics, and reflecting on the dynamic responses from human societies.Comment: 27 pages, 18 figures. International Journal of Digital Earth (2020

Single nucleotide polymorphisms of Kit gene in Chinese indigenous horses

Kit gene is a genetic determinant of horse white coat color which has been a highly valued trait in horses for at least 2,000 years. Single nucleotide polymorphisms (SNPs) in Kit are of importance due to their strong associations with melanoblast survival during embryonic development. In this study, a mutation analysis of all 21 Kit exons in 14 Chinese domestic horse breeds revealed six SNPs (g.91214T＞G, g.143245T＞G, g.164297C＞T, g.170189C＞T, g.171356C＞G, and g.171471G＞A), which located in 5’-UTR region, intron 6, exon 15, exon 20, intron 20, and exon 21 of the equine Kit gene, respectively. Subsequently, these six SNPs loci were genotyped in 632 Chinese horses by PCR-RFLP or direct sequencing. The six SNPs together defined 18 haplotypes, demonstrating abundant haplotype diversities in Chinese horses. All the mutant alleles and haplotypes were shared among different breeds. But fewer mutations were detected in horses from China than that from abroad, indicating that Chinese horses belong to a more ancient genetic pool. This study will provide fundamental genetic information for evaluating the genetic diversity of Kit gene in Chinese indigenous horse breeds

TCGL: Temporal Contrastive Graph for Self-supervised Video Representation Learning

Video self-supervised learning is a challenging task, which requires significant expressive power from the model to leverage rich spatial-temporal knowledge and generate effective supervisory signals from large amounts of unlabeled videos. However, existing methods fail to increase the temporal diversity of unlabeled videos and ignore elaborately modeling multi-scale temporal dependencies in an explicit way. To overcome these limitations, we take advantage of the multi-scale temporal dependencies within videos and proposes a novel video self-supervised learning framework named Temporal Contrastive Graph Learning (TCGL), which jointly models the inter-snippet and intra-snippet temporal dependencies for temporal representation learning with a hybrid graph contrastive learning strategy. Specifically, a Spatial-Temporal Knowledge Discovering (STKD) module is first introduced to extract motion-enhanced spatial-temporal representations from videos based on the frequency domain analysis of discrete cosine transform. To explicitly model multi-scale temporal dependencies of unlabeled videos, our TCGL integrates the prior knowledge about the frame and snippet orders into graph structures, i.e., the intra-/inter- snippet Temporal Contrastive Graphs (TCG). Then, specific contrastive learning modules are designed to maximize the agreement between nodes in different graph views. To generate supervisory signals for unlabeled videos, we introduce an Adaptive Snippet Order Prediction (ASOP) module which leverages the relational knowledge among video snippets to learn the global context representation and recalibrate the channel-wise features adaptively. Experimental results demonstrate the superiority of our TCGL over the state-of-the-art methods on large-scale action recognition and video retrieval benchmarks.The code is publicly available at https://github.com/YangLiu9208/TCGL.Comment: This work has been published in IEEE Transactions on Image Processing. The code is publicly available at https://github.com/YangLiu9208/TCGL. arXiv admin note: substantial text overlap with arXiv:2101.0082

Preparation of Hierarchical CaSO 4

CaSO4 whiskers (CSW) can be used to reinforce PVC matrix to produce light and strong composites. However, the weak interfacial interaction between the smooth CSW and PVC matrix limited the fabrication of PVC composite with perfect mechanical properties. In this work, CaCO3 nanoparticles were coated on CSW surface by wet modification of CSW in Na2CO3 solution at 80°C, which increased the surface roughness of CSW from 56.8 nm to 115.6 nm. The use of the hierarchical CSW rather than the raw CSW in the fabrication of CSW/PVC composite led to the increase of the flexural strength from 86.3 MPa to 113.2 MPa and the impact strength from 56.7 kJ·m−2 to 82.5 kJ·m−2 owing to the enhanced mechanical interlocking between CSW and PVC matrix