1,050 research outputs found

    On quasi modules at infinity for vertex algebras

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    A theory of quasi modules at infinity for (weak) quantum vertex algebras including vertex algebras was previously developed in \cite{li-infinity}. In this current paper, quasi modules at infinity for vertex algebras are revisited. Among the main results, we extend some technical results, to fill in a gap in the proof of a theorem therein, and we obtain a commutator formula for general quasi modules at infinity and establish a version of the converse of the aforementioned theorem.Comment: 18 page

    Anomalous hybridization of spectral winding topology in quantized steady-state responses

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    Quantized response is one distinguishing feature of a topological system. In non-Hermitian systems, the spectral winding topology yields quantized steady-state response. By considering two weakly coupled non-Hermitian chains, we discover that the spectral winding topology of one chain can be probed by a steady-state response defined solely on the other chain, even when other important properties, e.g., {energetics} and entanglement entropy, indicate that eigen-solutions are effectively {not hybridized} between the two chains. This intriguing phenomenon, as carefully investigated in a large parameter space with a varying system size, not only offers a new angle to understand interchain signal propagation in a non-Hermitian setting but also reveals unexpected physics of spectral winding topology vs quantized response.Comment: 10 pages, 9 figures, comments are welcom

    System identification of rubber-bearing isolators based on experimental tests

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    Rubber-bearing isolation systems have been used in buildings and bridges. These base isolation systems will become more popular in the future due to their ability to reduce significantly the structural responses induced by earthquakes and other dynamic loads. To ensure the integrity and safety of these base isolation systems, a structural health monitoring system is needed. One important problem in the structural health monitoring is the identification of the system and the detection of damages. This problem is more challenging for the rubberbearing isolation systems because of their nonlinear behavior. In this paper, experimental studies have been conducted for the system identification of nonlinear hysteretic rubberbearings. Experimental tests of a rubber-bearing isolator under El Centro and Kobe earthquakes have been performed. The Bouc-Wen models with 3, 5 and 6 unknown parameters, respectively, have been investigated to represent the hysteretic behavior of rubber-bearing isolators. The extended Kalman filter (EKF) approach has been used to identify the nonlinear parameters of the Bouc-Wen models for the rubber-bearing isolators. Our experimental studies demonstrate that the Bouc-Wen models are capable of describing the nonlinear behavior of rubber-bearing isolators, and that the EKF approach is effective in identifying nonlinear hysteretic parameters

    Tetra­aqua­bis­[5-(3-pyrid­yl)tetra­zolido-κN 5]zinc(II) tetra­hydrate

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    The title compound, [Zn(C6H4N5)2(H2O)4]·4H2O, was synthesized by the hydro­thermal reaction of Zn(CH3COO)2·2H2O with 3-(2H-tetra­zol-5-yl)pyridine. The ZnII ion is located on an inversion center and is coordinated by two pyridine N atoms from two 5-(3-pyrid­yl)tetra­zolide ligands and four coordinated water mol­ecules in a slightly distorted octa­hedral geometry. The dihedral angle between the pyridine and tetra­zole rings is 9.920 (7)°. In the crystal, mol­ecules are linked into a three-dimensional network by inter­molecular O—H⋯O and O—H⋯N hydrogen bonds involving the tetra­zole group N atoms, the aqua ligands and solvent water mol­ecules

    Biphenyl-3,3′-dicarb­oxy­lic acid

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    The asymmetric unit of the title compound, C14H10O4, contains one half mol­ecule, the complete mol­ecule being generated by a twofold axis. The two benzene rings form a dihedral angle of 43.11 (5)°. Inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into one-dimensional zigzag chains. These chains are further connected into two-dimensional supra­molecular layers by weak π–π stacking inter­actions between neighbouring benzene rings, with centroid–centroid distances of 3.7648 (8) Å

    OnionNet-2: A Convolutional Neural Network Model for Predicting Protein-Ligand Binding Affinity based on Residue-Atom Contacting Shells

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    One key task in virtual screening is to accurately predict the binding affinity (â–³\triangleGG) of protein-ligand complexes. Recently, deep learning (DL) has significantly increased the predicting accuracy of scoring functions due to the extraordinary ability of DL to extract useful features from raw data. Nevertheless, more efforts still need to be paid in many aspects, for the aim of increasing prediction accuracy and decreasing computational cost. In this study, we proposed a simple scoring function (called OnionNet-2) based on convolutional neural network to predict â–³\triangleGG. The protein-ligand interactions are characterized by the number of contacts between protein residues and ligand atoms in multiple distance shells. Compared to published models, the efficacy of OnionNet-2 is demonstrated to be the best for two widely used datasets CASF-2016 and CASF-2013 benchmarks. The OnionNet-2 model was further verified by non-experimental decoy structures from docking program and the CSAR NRC-HiQ data set (a high-quality data set provided by CSAR), which showed great success. Thus, our study provides a simple but efficient scoring function for predicting protein-ligand binding free energy.Comment: 7 pages, 4 figures, 1 tabl

    Rapamycin sensitizes T-ALL cells to dexamethasone-induced apoptosis

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    <p>Abstract</p> <p>Background</p> <p>Glucocorticoid (GC) resistance is frequently seen in acute lymphoblastic leukemia of T-cell lineage (T-ALL). In this study we investigate the potential and mechanism of using rapamycin to restore the sensitivity of GC-resistant T-ALL cells to dexamethasone (Dex) treatment.</p> <p>Methods</p> <p>Cell proliferation was detected by 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay. Fluorescence-activated cell sorting (FACS) analysis was used to analyze apoptosis and cell cycles. Western blot analysis was performed to test the expression of the downstream effector proteins of mammalian target of rapamycin (mTOR), the cell cycle regulatory proteins, and apoptosis associated proteins.</p> <p>Results</p> <p>10 nM rapamycin markedly increased GC sensitivity in GC-resistant T-ALL cells and this effect was mediated, at least in part, by inhibition of mTOR signaling pathway. Cell cycle arrest was associated with modulation of G<sub>1</sub>-S phase regulators. Both rapamycin and Dex can induce up-regulation of cyclin-dependent kinase (CDK) inhibitors of p21 and p27 and co-treatment of rapamycin with Dex resulted in a synergistic induction of their expressions. Rapamycin did not obviously affect the expression of cyclin A, whereas Dex induced cyclin A expression. Rapamycin prevented Dex-induced expression of cyclin A. Rapamycin had a stronger inhibition of cyclin D1 expression than Dex. Rapamycin enhanced GC-induced apoptosis and this was not achieved by modulation of glucocorticoid receptor (GR) expression, but synergistically up-regulation of pro-apoptotic proteins like caspase-3, Bax, and Bim, and down-regulation of anti-apoptotic protein of Mcl-1.</p> <p>Conclusion</p> <p>Our data suggests that rapamycin can effectively reverse GC resistance in T-ALL and this effect is achieved by inducing cell cycles arrested at G<sub>0</sub>/G<sub>1 </sub>phase and activating the intrinsic apoptotic program. Therefore, combination of mTOR inhibitor rapamycin with GC containing protocol might be an attracting new therapeutic approach for GC resistant T-ALL patients.</p
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