336 research outputs found
Integer colorings with forbidden rainbow sums
For a set of positive integers , an -coloring of is
rainbow sum-free if it contains no rainbow Schur triple. In this paper we
initiate the study of the rainbow Erd\H{o}s-Rothchild problem in the context of
sum-free sets, which asks for the subsets of with the maximum number of
rainbow sum-free -colorings. We show that for , the interval is
optimal, while for , the set is optimal. We
also prove a stability theorem for . The proofs rely on the hypergraph
container method, and some ad-hoc stability analysis.Comment: 20 page
Hypergraphs with a quarter uniform Tur\'an density
The uniform Tur\'an density of a -uniform hypergraph is
the supremum over all for which there is an -free hypergraph with the
property that every linearly sized subhypergraph with density at least .
Determining for given hypergraphs was suggested by Erd\H{o}s
and S\'os in 1980s. In particular, they raised the questions of determining
and . The former question was solved
recently in [Israel J. Math. 211 (2016), 349-366] and [J. Eur. Math. Soc. 20
(2018), 1139-1159], while the latter is still a major open problem. In addition
to , there are very few hypergraphs whose uniform Tur\'an density
has been determined.
In this paper, we give a sufficient condition for -uniform hypergraphs
satisfying . In particular, currently all known -uniform
hypergraphs whose uniform Tur\'an density is , such as and
the -uniform hypergraphs studied in [arXiv:2211.12747],
satisfy this condition. Moreover, we find some intriguing -uniform
hypergraphs whose uniform Tur\'an density is also .Comment: 23 page
Diagnostic value of cardiac troponin I and N-terminal pro-B-Type Natriuretic Peptide in cardiac syncope
Objective
The study aims to evaluate the diagnostic accuracy of Cardiac Troponin I(cTnI) and N-terminal pro-B-Type Natriuretic Peptide (NT-proBNP) for identifying patients with cardiac syncope.
Methods
This is a prospective, single-center cohort study of patients presenting with syncope hospitalized from June 21,2018 to May 30, 2019. The Evaluation of Guidelines in Syncope Study (EGSYS), a syncope-specific diagnostic score, was used for diagnostic comparator.
Results
A total of 118 patients were enrolled (mean age: 69.1 ​± ​12.3 years, 40% female). Compared to patients with reflex, orthostatic, or unexplained syncope, patients adjudicated to have cardiac syncope showed significantly higher cTnI and NT-proBNP plasma concentrations (p ​< ​0.001 for each comparison). The area under the curve (AUC) of cTnI and NT-proBNP were moderate-to-good [0.77–0.78; 95% confidence interval (CI) 0.66–0.86], and was similar to that of EGSYS (0.71, 95%CI 0.60–0.80). Incorporation of cTnI and/or NT-proBNP into the existing EGSYS score significantly improved the diagnostic accuracy (EGSYS ​+ ​cTnI: AUC 0.83; 95%CI 0.74–0.90; EGSYS ​+ ​NT-proBNP: AUC 0.81; 95%CI 0.71–0.89; EGSYS ​+ ​cTnI ​+ ​NT-proBNP: AUC 0.83; 95%CI 0.73–0.90).
Conclusions
The cTnI and NT-proBNP levels were significantly higher in patients adjudicated to have cardiac syncope and the addition of both biomarkers to the EGSYS score significantly improved the diagnostic value for cardiac syncope
Improved Meet-in-the-Middle Distinguisher on Feistel Schemes
Improved meet-in-the-middle cryptanalysis with efficient tabulation technique has been shown to be a very powerful form of cryptanalysis against SPN block ciphers. However, few literatures show the effectiveness of this cryptanalysis against Balanced-Feistel-Networks (BFN) and Generalized-Feistel-Networks (GFN) ciphers due to the stagger of affected trail and special truncated differential trail. In this paper, we describe a versatile and powerful algorithm for searching the best improved meet-in-the-middle distinguisher with efficient tabulation technique on word-oriented BFN and GFN block ciphers, which is based on recursion and greedy algorithm. To demonstrate the usefulness of our approach, we show key recovery attacks on 14/16-round CLEFIA-192/256 which are the best attacks. We also propose key recovery attacks on 13/15-round Camellia-192/256 (without )
Improved Meet-in-the-Middle Attacks on Reduced-Round Kalyna-128/256 and Kalyna-256/512
Kalyna is an SPN-based block cipher that was selected during Ukrainian National Public Cryptographic Competition (2007-2010)
and its slight modification was approved as the new encryption standard of Ukraine. In this paper, we focus on the key-recovery attacks on reduced-round Kalyna-128/256 and Kalyna-256/512 with meet-in-the-middle method. The differential enumeration technique and key-dependent sieve technique which are popular to analyze AES are used to attack them. Using the key-dependent sieve technique to improve the complexity is not an easy task, we should build some tables to achieve this. Since the encryption procedure of Kalyna employs a pre- and post-whitening operations using addition modulo applied on the state columns independently, we carefully study the propagation of this operation and propose an addition plaintext structure to solve this. For Kalyna-128/256, we propose a 6-round distinguisher, and achieve a 9-round (out of total 14-round) attack. For Kalyna-256/512, we propose a 7-round distinguisher, then achieve an 11-round (out of total 18-round) attack. As far as we know, these are currently the best results on Kalyna-128/256 and Kalyna-256/512
Influence of Helicobacter pylori culture supernatant on the ecological balance of a dual-species oral biofilm
Dental caries is a chronic progressive disease occurring in the tooth hard tissue due to multiple factors, in which bacteria are the initial cause. Both Streptococcus mutans and Streptococcus sanguinis are main members of oral biofilm. Helicobacter pylori may also be detected in dental plaque, playing an important role in the development of dental caries. Objective The aim of this study was to investigate the effect of H. pylori culture supernatant on S. mutans and S. sanguinis dual-species biofilm and to evaluate its potential ability on affecting dental health. Material and methods The effect of H. pylori supernatant on single-species and dual-species biofilm was measured by colony forming units counting and fluorescence in situ hybridization (FISH) assay, respectively. The effect of H. pylori supernatant on S. mutans and S. sanguinis extracellular polysaccharides (EPS) production was measured by both confocal laser scanning microscopy observation and anthrone-sulfuric acid method. The effect of H. pylori supernatant on S. mutans gene expression was measured by quantitative real-time PCR (qRT-PCR) assays. Results H. pylori supernatant could inhibit both S. mutans and S. sanguinis biofilm formation and EPS production. S. sanguinis inhibition rate was significantly higher than that of S. mutans. Finally, S. mutans bacteriocin and acidogenicity related genes expression were affected by H. pylori culture supernatant. Conclusion Our results showed that H. pylori could destroy the balance between S. mutans and S. sanguinis in oral biofilm, creating an advantageous environment for S. mutans, which became the dominant bacteria, promoting the formation and development of dental caries
Cloning of a gene encoding glycosyltransferase from Pueraria lobata (Wild.) Ohwi and its expression in Pichia pastoris
The key enzyme of puerarin biosynthesis in Pueraria lobata (Willd.) Ohwi was unclear but may involve glycosylation. To investigate the regulation of puerarin biosynthesis, a putative UDP-dependent glycosyltransferase (UGT) gene, PlUGT1 was isolated from P. lobata root, which contained abundant puerarin. PlUGT1 encoded 480 deduced amino acid residues with a conserved UDP-glucose-binding domain, which has 61 to 84% similarity to homologues from other plant species. SDS polyacrylamide gel electrophoresis and western blotting results showed that, fusion protein migrated as a single protein band with a molecular weight of 55 kDa. A yeast expression vector pPICZA-PlUGT1 was constructed and was transformed into Pichia pastoris strain GS115. Several recombinants containing multi-copy expression cassettes were obtained on the zeocin-YPD plate and confirmed by southern dot blotting. The yield of PlUGT1 attained 0.05 g/l when recombinant cells were cultured at pH 5.5, 30°C and induced with 0.5% methanol for 72 h. The expression of PlUGT1 protein correlates positively with the copy numbers of PlUGT1 in transformed yeast cells. These results suggest that, the PlUGT1 protein can be expressed efficiently in the P. pastoris expression system and may supply a new economic and convenient way for the production of PlUGT1 protein.Keywords: Pueraria lobata (Willd.) Ohwi, glycosyltransferase, cloning, expression, Pichia pastori
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