1,574 research outputs found

    Fuzzy Filter Spectrum of a BCK Algebra

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    The notion of fuzzy s-prime filters of a bounded BCK-algebra is introduced. We discuss the relation between fuzzy s-prime filters and fuzzy prime filters. By the fuzzy s-prime filters of a bounded commutative BCK-algebra X, we establish a fuzzy topological structure on X. We prove that the set of all fuzzy s-prime filters of a bounded commutative BCK-algebra forms a topological space. Moreover, we show that the set of all fuzzy s-prime filters of a bounded implicative BCK-algebra is a Hausdorff space

    A Clustering Framework for Unsupervised and Semi-supervised New Intent Discovery

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    New intent discovery is of great value to natural language processing, allowing for a better understanding of user needs and providing friendly services. However, most existing methods struggle to capture the complicated semantics of discrete text representations when limited or no prior knowledge of labeled data is available. To tackle this problem, we propose a novel clustering framework, USNID, for unsupervised and semi-supervised new intent discovery, which has three key technologies. First, it fully utilizes unsupervised or semi-supervised data to mine shallow semantic similarity relations and provide well-initialized representations for clustering. Second, it designs a centroid-guided clustering mechanism to address the issue of cluster allocation inconsistency and provide high-quality self-supervised targets for representation learning. Third, it captures high-level semantics in unsupervised or semi-supervised data to discover fine-grained intent-wise clusters by optimizing both cluster-level and instance-level objectives. We also propose an effective method for estimating the cluster number in open-world scenarios without knowing the number of new intents beforehand. USNID performs exceptionally well on several benchmark intent datasets, achieving new state-of-the-art results in unsupervised and semi-supervised new intent discovery and demonstrating robust performance with different cluster numbers.Comment: Accepted by IEEE TKD

    A redescription of Zavrelia bragremia Guo & Wang, 2007 (Diptera: Chironomidae)

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    Examination of the holotype of Zavrelia bragremia Guo & Wang, 2007, revealed a few mistakes in the original description. Based on the type material and additional adult males from Oriental China, Z. bragremia is here redescribed and figured. An updated identification key to the males of Zavrelia is given

    6-Benzyl-6,7-dihydro-5H-pyrrolo­[3,4-b]pyridine-5,7-dione

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    In the title compound, C14H10N2O2, the dihedral angle between the heterocyclic ring system and the phenyl ring is 45.8 (5)°. Weak inter­molecular C—H⋯N hydrogen bonding is present in the crystal structure

    Ethyl 8-chloro-1-cyclo­propyl-6,7-difluoro-4-oxo-1,4-dihydro­quinoline-3-carboxyl­ate

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    In the mol­ecule of the title compound, C15H12ClF2NO3, the quinoline ring system is not planar, the dihedral angle between the pyridine and benzene rings being 3.55 (8)°. In the crystal, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into layers parallel to (101)

    Belamcanda chinensis (l.) Dc: Ethnopharmacology, phytochemistryand pharmacology of an important traditional Chinese medicine

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    Background: Belamcanda chinensis (L.) DC (Iridaceae), a widely used traditional Chinese medicine known as She Gan (Chinese: 射干), is a flowering perennial herb native to East Asia. For thousands of years in China, the rhizome of Belamcanda chinensis has been used to treat inflammation, oxyhepatitis, mumps, acute mastitis, and asthma, as well as throat disorders such as cough, tonsillitis and pharyngitis. Belamcanda chinensis is now listed in the Pharmacopoeia of the People’s Republic of China. The present paper reviews the advancements in the investigation of botany, ethnopharmacology, phytochemistry, pharmacology and toxicology of Belamcanda chinensis.Materials and Methods: Information on Belamcanda chinensis was collected from scientific journals, books, theses and reports via library and electronic search (PubMed, CNKI, Elsevier, ACS, Google Scholar, Baidu Scholar,Web of Science and Science Direct).Results: A number of chemical compounds have been isolated from Belamcanda chinensis, and the major isolated compounds have been identified as isoflavonoids, flavonoids and iridal-type triterpenoids. Among these active compounds, the effects of tectoridin and tectorigenin have been widely investigated. The primary active components in Belamcanda chinensis possess a wide range of pharmacological activities, including anti-inflammatory, anti-oxidative, anti-tumour, anti-alcohol injury, cardiovascular and oestrogenic activities.Conclusions: As an important traditional Chinese medicine, Belamcanda chinensis has been demonstrated to have marked bioactivity, especially in the respiratory system and as an oestrogenic and hepatoprotective agent. This activity is related to its traditional use and provides opportunities for the development of novel drugs and therapeutic products for various diseases. However, the toxicity of Belamcanda chinensis will require further study, and more attention should be devoted to its better utilization.Keywords: Belamcanda chinensis; Ethnopharmacology; Phytochemistry; Pharmacology; Toxicolog

    A new surface gliding species of Chironomidae: An independent invasion of marine environments and its evolutionary implications

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    Insects have invaded marine habitats only rarely and secondarily. Recently, we discovered a flightless dipteran species skating rapidly on the surface of seawater ponds at the Pacific coast of eastern China. Morphological analyses initially suggested an isolated position of the non‐biting midge, suggesting the erection of a new genus within Chironomini (Diptera: Chironomidae). However, an analysis of molecular data revealed that the marine species is in fact nested within the species‐rich genus Dicrotendipes. The apparent conflict between molecular and morphological data can be easily explained. It is likely that the new species has evolved a series of autapomorphic adaptations. These traits clearly distinguish the taxon from other species of the genus but do not justify the erection of a new supraspecific taxon, which would render Dicrotendipes paraphyletic. The switch to marine environments was likely a trigger for various morphological modifications resulting from increased selective pressure. Molecular data suggest that the potential speciation event occurred around 19–29 Ma, linked with a migration from freshwater to seawater ponds along the Pacific Ocean. Considering the results of our analysis, we place the flightless marine skater in the genus Dicrotendipes. All life stages of Dicrotendipes sinicus Qi & Lin sp. n. are described and illustrated, associated with larvae obtained by rearing or confirmed through association with DNA barcodes. The biology and ecology of the species are outlined based on collection data and in situ observations. Evolutionary patterns linked with repeated invasions of marine habitats are discussed

    Mitochondrial matR sequences help to resolve deep phylogenetic relationships in rosids

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    <p>Abstract</p> <p>Background</p> <p>Rosids are a major clade in the angiosperms containing 13 orders and about one-third of angiosperm species. Recent molecular analyses recognized two major groups (i.e., fabids with seven orders and malvids with three orders). However, phylogenetic relationships within the two groups and among fabids, malvids, and potentially basal rosids including Geraniales, Myrtales, and Crossosomatales remain to be resolved with more data and a broader taxon sampling. In this study, we obtained DNA sequences of the mitochondrial <it>matR </it>gene from 174 species representing 72 families of putative rosids and examined phylogenetic relationships and phylogenetic utility of <it>matR </it>in rosids. We also inferred phylogenetic relationships within the "rosid clade" based on a combined data set of 91 taxa and four genes including <it>matR</it>, two plastid genes (<it>rbcL</it>, <it>atpB</it>), and one nuclear gene (18S rDNA).</p> <p>Results</p> <p>Comparison of mitochondrial <it>matR </it>and two plastid genes (<it>rbcL </it>and <it>atpB</it>) showed that the synonymous substitution rate in <it>matR </it>was approximately four times slower than those of <it>rbcL </it>and <it>atpB</it>; however, the nonsynonymous substitution rate in <it>matR </it>was relatively high, close to its synonymous substitution rate, indicating that the <it>matR </it>has experienced a relaxed evolutionary history. Analyses of our <it>matR </it>sequences supported the monophyly of malvids and most orders of the rosids. However, fabids did not form a clade; instead, the COM clade of fabids (Celastrales, Oxalidales, Malpighiales, and Huaceae) was sister to malvids. Analyses of the four-gene data set suggested that Geraniales and Myrtales were successively sister to other rosids, and that Crossosomatales were sister to malvids.</p> <p>Conclusion</p> <p>Compared to plastid genes such as <it>rbcL </it>and <it>atpB</it>, slowly evolving <it>matR </it>produced less homoplasious but not less informative substitutions. Thus, <it>matR </it>appears useful in higher-level angiosperm phylogenetics. Analysis of <it>matR </it>alone identified a novel deep relationship within rosids, the grouping of the COM clade of fabids and malvids, which was not resolved by any previous molecular analyses but recently suggested by floral structural features. Our four-gene analysis supported the placements of Geraniales, Myrtales at basal nodes of the rosid clade and placed Crossosomatales as sister to malvids. We also suggest that the core part of rosids should include fabids, malvids and Crossosomatales.</p
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