Validating quantum-supremacy experiments with exact and fast tensor network contraction

The quantum circuits that declare quantum supremacy, such as Google Sycamore [Nature \textbf{574}, 505 (2019)], raises a paradox in building reliable result references. While simulation on traditional computers seems the sole way to provide reliable verification, the required run time is doomed with an exponentially-increasing compute complexity. To find a way to validate current ``quantum-supremacy" circuits with more than $50$ qubits, we propose a simulation method that exploits the ``classical advantage" (the inherent ``store-and-compute" operation mode of von Neumann machines) of current supercomputers, and computes uncorrelated amplitudes of a random quantum circuit with an optimal reuse of the intermediate results and a minimal memory overhead throughout the process. Such a reuse strategy reduces the original linear scaling of the total compute cost against the number of amplitudes to a sublinear pattern, with greater reduction for more amplitudes. Based on a well-optimized implementation of this method on a new-generation Sunway supercomputer, we directly verify Sycamore by computing three million exact amplitudes for the experimentally generated bitstrings, obtaining an XEB fidelity of $0.191\%$ which closely matches the estimated value of $0.224\%$. Our computation scales up to $41,932,800$ cores with a sustained single-precision performance of $84.8$ Pflops, which is accomplished within $8.5$ days. Our method has a far-reaching impact in solving quantum many-body problems, statistical problems as well as combinatorial optimization problems where one often needs to contract many tensor networks which share a significant portion of tensors in common.Comment: 7 pages, 4 figures, comments are welcome

Ecological restoration approaches for degraded muddy coasts: Recommendations and practice

Scientific selection of an ecological restoration approach from among the three common approaches: natural restoration, assisted restoration, and ecological reconstruction is the first step to successful ecological restoration. This study chose the appropriate ecological restoration approach for the study area from the following two perspectives. The threshold effect considers the degree of damage to the muddy coast and makes an estimate of its resilience. The development needs of the coastal zone consider the needs of muddy coasts for ecological protection, safety, and culture and aesthetics; development planning aims to determine the priority of these three needs. This study also assessed common technical measures for ecological restoration of muddy coasts and analyzed the applicability and advantages and disadvantages of each perspective to assist in the selection of specific ecological restoration measures suited to local conditions. The target area for ecological restoration was the muddy coastal area around Yundanmen Island, Sansha Bay, Ningde City, China, which had been degraded by reclamation and aquaculture. Based on conceptual models for selection, ecological restoration approaches for the study area were determined, technical measures were selected, and the plan was developed and implemented. We analyzed the initial effects of ecological restoration on birds, vegetation, and benthic organisms to verify the effectiveness of the chosen ecological restoration approach. This study provides scientific support for rationally planning the ecological restoration of muddy coasts and a reference for the selection of other coastal ecological restoration approaches and technical measures

Diversities Within Genotypes, Bioactivity and Biosynthetic Genes of Endophytic Actinomycetes Isolated from Three Pharmaceutical Plants

One hundred and fifty endophytic actinomycetes were isolated from three pharmaceutical plants, Annonaceae squamosal, Camptotheca acuminate and Taxus chinensis. Bioactivity test showed that 72.4% of the endophytic actinomycetes displayed inhibition against more than one indicator microorganism. In total, 9.3 and 10.7% showed the cytotoxicity and antioxidant activity, respectively. 3-Amino-5-hydroxybenzoic acid synthase (AHBA), ketosynthase (KS), cytochrome P450 hydroxylases (CYPs) and epoxidase (ES) encoding genes were found in 8.8, 23.8, 2.8 and 11.7% isolates, respectively, by genes screening. The identification based on traditional and molecular methods indicated that diverse genotypes of Streptomyces were distributed in the three pharmaceutical plants, and a few strains of Amycolatopsis were also found in the root of T. chinensis. These results indicated that endophytic actinomycetes associated with pharmaceutical plants could be a promising source of drug leads.National Natural Sciences Foundation of China [30500632

Expression Patterns and Regulation of Non-Coding RNAs during Synthesis of Cellulose in Eucalyptus grandis Hill

Cellulose, an essential structural component in the plant cell wall and a renewable biomass resource, plays a significant role in nature. Eucalyptus’s excellent timber tree species (including Eucalyptus grandis Hill) provide many raw materials for the paper and wood industries. The synthesis of cellulose is a very complex process involving multiple genes and regulated by various biological networks. However, research on regulating associated genes and non-coding RNAs during cellulose synthesis in E. grandis remains lacking. In this study, the wood anatomical characteristics and chemical indexes of E. grandis were analyzed by taking three different parts (diameter at breast height (DBH), middle and upper part of the trunk) from the main stem of E. grandis as raw materials. The role of non-coding RNAs (Long non-coding RNA, lncRNA; Micro RNA, miRNA; Circle RNA, circRNA) on regulating candidate genes was presented, and the network map of ceRNA (Competing endogenous RNA) regulation during wood cellulose biosynthesis of E. grandis was constructed. The transcriptome sequencing of nine samples obtained from the trunk of the immature xylem in E. grandis at DBH, middle and upper parts had a 95.81 G clean reading, 57,480 transcripts, 7365 lncRNAs, and 5180 circRNAs. Each sample had 172–306 known miRNAs and 1644–3508 new miRNAs. A total of 190 DE-lncRNAs (Differentially expressed long non-coding RNAs), 174 DE-miRNAs (Differentially expressed micro RNAs), and 270 DE-circRNAs (Differentially expressed circle RNAs) were obtained by comparing transcript expression levels. Four lncRNAs and nine miRNAs were screened out, and the ceRNA regulatory network was constructed. LncRNA1 and lncRNA4 regulated the genes responsible for cellulose synthesis in E. grandis, which were overexpressed in 84K (Populus Alba × Populus glandulosa) poplar. The cellulose and lignin content in lncRNA4-oe were significantly higher than wild type 84K poplar and lncRNA1-oe. The average plant height, middle and basal part of the stem diameter in lncRNA4-oe were significantly higher than the wild type. However, there was no significant difference between the growth of lncRNA1-oe and the wild type. Further studies are warranted to explore the molecular regulatory mechanism of cellulose biosynthesis in Eucalyptus species

Comparative transcriptomics and bioinformatics analysis of genes related to photosynthesis in Eucalyptus camaldulensis

The timber species Eucalyptus camaldulensis is one of the most important in southern China. Therefore, it is essential to understand the photosynthetic pattern in eucalyptus leaves. In the present study, eighteen photosynthesis-related genes were analyzed using bioinformatics methods. The results indicated that there were ten differentially expressed ribose-5-phosphate isomerase genes (RPI), and six of them were up-regulated in the mature leaves compared to the young leaves, while others were down-regulated. The differential expression of four rubisco methyltransferase genes (RBCMT) were observed. Two of them were up-regulated, while two were down-regulated in mature leaves compared to young leaves. Furthermore, two ribulose-phosphate-3-epimerase genes (RPE) were up-regulated in the mature leaves compared to the young leaves. In contrast, two genes involved in triosephosphate isomerase (TIM) were down-regulated in mature leaves compared with young leaves. The current study provides basic information about the transcriptome of E. camaldulensis and lays a foundation for further research in developing and utilizing important photosynthetic genes

A Molecular-Sieving Interphase Towards Low-Concentrated Aqueous Sodium-Ion Batteries

Highlights A molecular-sieving electrode coating towards low-concentrated aqueous sodium-ion batteries is constructed by applying a composite of NaX zeolite and NaOH-neutralized Nafion. Resulting from a molecular sieving effect of zeolite channels and size-shrunken ionic domains in Nafion, the as-prepared coating layer reject hydrated Na+ ions and allow fast dehydrated Na+ permeance. 200 cycles of Na2MnFe(CN)6//NaTi2(PO4)3 full cells can be achieved in a practically feasible 2 m aqueous electrolyte

Mycoepoxydiene, a fungal polyketide, induces cell cycle arrest at the G2/M phase and apoptosis in HeLa cells

NSFC [90913024]; 863 Program [2007AA091503, 2006AA09Z410]; 973 Program [2010CB83 3802]; National Science Fund for Distinguished Young Scholars [30325044]; United States Department of Agriculture [2008-34526-19199]Mycoepoxydiene (MED) is a polyketide isolated from a marine fungus associated with mangrove forests. It contains an oxygen-bridged cyclooctadiene core and an alpha,beta-unsaturated delta-lactone moiety. MED induced the reorganization of cytoskeleton in actively growing HeLa cells by promoting formation of actin stress fiber and inhibiting polymerization of tubulin. MED could induce cell cycle arrest at G2/M in HeLa cells. MED-associated apoptosis was characterized by the formation of fragmented nuclei, PARP cleavage, cytochrome c release, activation of caspase-3, and an increased proportion of sub-G1 cells. Additionally, MED activated MAPK pathways. Interestingly, the time of JNK, p38, and Bcl-2 activation did not correlate with the release of cytochrome c. This study is the first report demonstrating the action mechanism of MED against tumor cell growth. These results provide the potential of MED as a novel low toxic antitumor agent. (C) 2010 Elsevier Ltd. All rights reserved