7,947 research outputs found

    Lifshitz holographic superconductor in Horava-Lifshitz gravity

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    We study the holographic phase transition of superconductor dual to a Lifshitz black brane probed by an anisotropic scalar field in the probe limit in Ho\u{r}ava-Lifshitz gravity. With the use of numerical and analytical method, we investigate how the critical temperature of the condensation is affected by the Lifshitz exponent zz, α\alpha-correction term in the action as well as the dimensions of the gravity. We also numerically explore the condensation of the dual operator and optical conductivity of the holographic system. Various interesting properties of the holographic condensation affected by the parameters of model are discussed

    Geometric bionics: Lotus effect helps polystyrene nanotube films get good blood compatibility

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    Various biomaterials have been widely used for manufacturing biomedical applications including artificial organs, medical devices and disposable clinical apparatus, such as vascular prostheses, blood pumps, artificial kidney, artificial hearts, dialyzers and plasma separators, which could be used in contact with blood^1^. However, the research tasks of improving hemocompatibility of biomaterials have been carrying out with the development of biomedical requirements^2^. Since the interactions that lead to surface-induced thrombosis occurring at the blood-biomaterial interface become a reason of familiar current complications with grafts therapy, improvement of the blood compatibility of artificial polymer surfaces is, therefore a major issue in biomaterials science^3^. After decades of focused research, various approaches of modifying biomaterial surfaces through chemical or biochemical methods to improve their hemocompatibility were obtained^1^. In this article, we report that polystyrene nanotube films with morphology similar to the papilla on lotus leaf can be used as blood-contacted biomaterials by virtue of Lotus effect^4^. Clearly, this idea, resulting from geometric bionics that mimicking the structure design of lotus leaf, is very novel technique for preparation of hemocompatible biomaterials

    Correlated metallic state in honeycomb lattice: Orthogonal Dirac semimetal

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    A novel gapped metallic state coined orthogonal Dirac semimetal is proposed in the honeycomb lattice in terms of Z2Z_{2} slave-spin representation of Hubbard model. This state corresponds to the disordered phase of slave-spin and has the same thermaldynamical and transport properties as usual Dirac semimetal but its singe-particle excitation is gapped and has nontrivial topological order due to the Z2Z_{2} gauge structure. The quantum phase transition from this orthogonal Dirac semimetal to usual Dirac semimetal is described by a mean-field decoupling with complementary fluctuation analysis and its criticality falls into the universality class of 2+1D Ising model while a large anomalous dimension for the physical electron is found at quantum critical point (QCP), which could be considered as a fingerprint of our fractionalized theory when compared to other non-fractionalized approaches. As byproducts, a path integral formalism for the Z2Z_{2} slave-spin representation of Hubbard model is constructed and possible relations to other approaches and the sublattice pairing states, which has been argued to be a promising candidate for gapped spin liquid state found in the numerical simulation, are briefly discussed. Additionally, when spin-orbit coupling is considered, the instability of orthogonal Dirac semimetal to the fractionalized quantum spin Hall insulator (fractionalized topological insulator) is also expected. We hope the present work may be helpful for future studies in Z2Z_{2} slave-spin theory and related non-Fermi liquid phases in honeycomb lattice.Comment: 12 pages,no figures, more discussions added. arXiv admin note: text overlap with arXiv:1203.063

    Designing Enhanced Multi-dimensional Constellations for Code-Domain NOMA

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    This paper presents an enhanced design of multi-dimensional (MD) constellations which play a pivotal role in many communication systems such as code-domain non-orthogonal multiple access (CD-NOMA). MD constellations are attractive as their structural properties, if properly designed, lead to signal space diversity and hence improved error rate performance. Unlike the existing works which mostly focus on MD constellations with large minimum Euclidean distance (MED), we look for new MD constellations with additional feature that the minimum product distance (MPD) is also large. To this end, a non-convex optimization problem is formulated and then solved by the convex-concave procedure (CCCP). Compared with the state-of-the-art literature, our proposed MD constellations lead to significant error performance enhancement over Rayleigh fading channels whilst maintaining almost the same performance over the Gaussian channels. To demonstrate their application, we also show that these MD constellations give rise to good codebooks in sparse code multiple access systems. All the obtained MD constellations can be found in https://github.com/Aureliano1/Multi-dimensional-constellation

    Antioxidant and anti-diabetic effects of caffeic acid in a rat model of diabetes

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    Purpose: To determine the antioxidant and anti-diabetic potential of a natural flavonoid, caffeic acid in a streptozotocin-induced diabetic rat model.Methods: Experimental diabetes was induced in Wistar rats using streptozotocin injection. Caffeic acid was administered orally on daily basis for 5 weeks. A glucometer was used to monitor fasting blood glucose levels. Insulin levels were estimated using enzyme-linked immunosorbent assay (ELISA). The antioxidant potential of caffeic acid was measured by determining the activities of superoxide dismutase (SOD) and catalase (CAT), and levels of reduced glutathione (GSH) in rat liver. Standard assays were performed to determine the lipid profile of the rats. Histopathological analysis was performed to determine differences in microscopic structures of pancreas among the different treatment groups.Results: Caffeic acid administration resulted in significant enhancement of serum insulin level, and decrease in blood glucose level of diabetic rat models (p < 0.05). Caffeic acid exerted antioxidant effects by significantly increasing GSH levels and activities of CAT and SOD (p < 0.05). Histologicalexamination of the pancreas depicted normal islet morphology under caffeic acid administration in diabetic rats.Conclusion: These results reveal the antioxidant potential and anti-diabetic effect of caffeic acid in a diabetic rat model and point towards the potential applicability of caffeic acid in the management of diabetes mellitus. Keywords: Diabetes mellitus, Streptozotocin, Caffeic acid, Phenolics, Anti-diabetic, Antioxidan

    SC-TVP Green Practice Initiative in China’s Logistics Market Based on Case Analysis

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    In the era of circular economy, the concept of sustainable development has attracted more and more attention. With the development of cross-border e-commerce, the demand for logistics services has continued to surge, and the pressure on them to provide sustainable services has risen sharply. In 2020, China officially put forward the “double carbon” strategic goal, and green logistics has become the new direction of industry development, in line with the concept of sustainable development. However, the actual impact of green logistics practice on China’s sustainable logistics services is unknown. This paper aims to study the current situation and results of green logistics practice through data analysis and case analysis, including green design, green transportation, green management and other indicators. Based on the case analysis in this paper, the SC-TVP model is constructed to provide an effective green logistics practice framework, with a view to improving the management level of green logistics, promoting the development of enterprises, and providing some reference for the logistics development in the post-epidemic era

    Prevalence and molecular typing of the antiseptic resistance genes qacA/B among Staphylococcus aureus strains isolated in a teaching hospital

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    The qacA/B genes are found in Staphylococcus aureus and confer resistance to various antiseptics and disinfectants. Herein, the prevalence of the qacA/B genes in methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) was investigated. Molecular typing systems were used to analyse the relatedness of these qacA/B-positive strains. 176 six strains of clinically isolated S. aureus were collected between July, 2008 and June, 2010. The strains carrying the qacA/B genes were characterised by pulse-field gel electrophoresis (PFGE) typing, Staphylococcus protein A (spa) typing, Panton-Valentine leucocidin (pvl) polymerase chain reaction (PCR) detection, staphylococcal chromosomal cassette (SCC) mec typing, and antimicrobial resistance profiles. Strains carrying the qacA/B genes composed 9.1% of the strains isolated, but the incidence of qacA/B genes in MRSA strains was significantly higher than that in MSSA strains (14.6 versus 4.3%, p < 0.05). Additionally, two predominant PFGE (B and A) and spa types (t037 and t042) were identified along with two major antimicrobial resistance profiles. All of these qacA/B-positive strains strains were pvl-negative by PCR. The qacA/B-positive MRSA strains all contained the group III SCCmec element. These strains were obtained mainly from patients in surgical wards; therefore, the neurosurgical ward and ICU may be considered as a source of MRSA strains carrying the qacA/B genes. Finally, the strain identified as spa type t037 is likely to be an epidemiological clone. The presence of the antiseptic resistance genes qacA/B by MRSA could potentially lead to MRSA strain prevalence. Thus, the optimal usage of antiseptics and disinfectants is warranted. A policy of molecular typing needs to be implemented to track the possible dissemination of these resistance genes.Key words: Staphylococcus aureus, mecA, qacA/B and pvl genes, methicillin-resistant,  Staphylococcus aureus (MRSA), methicillin-sensitive Staphylococcus aureus (MSSA)

    Quantitative analysis reveals increased histone modifications and a broad nucleosome-free region bound by histone acetylases in highly expressed genes in human CD4+ T cells

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    AbstractGenome-wide mapping of nucleosomes and histone modifications revealed meaningful patterns. Despite advances in resolving the associations between chromatin and transcription, quantitative chromatin dynamics have not been well defined. We quantitatively determined differences in histone modifications, nucleosome positions, DNA methylation, and transcription factor binding in highly expressed and repressed genes in human CD4+ T cells. We showed that the first (−1) nucleosome upstream of the transcription start site (TSS) is shifted to the 5′ direction, thus forming a broad nucleosome-free region (NFR) near the TSS in highly expressed genes in CD4+ T cells. Moreover, the transcription factor YY1 and histone acetyltransferases bind the NFR with high affinity. Most of histone acetylations drastically increase in transcription activation (>5 folds). We also suggested that single nucleotide polymorphisms (SNPs) occur at a much lower frequency in highly expressed genes than in repressed genes. Our analysis quantitatively revealed details of chromatin dynamics
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