2,679 research outputs found

    Helical and nonhelical (magneto-)Burgers turbulence: I. Compressibility reduction and beyond

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    We compare the helical and nonhelical (magneto-)Burgers turbulence for the \textit{helicity fastening effect}. Theoretical arguments and heuristic mathematical analysis are offered for the latter notion in the new system loosing some ``nice'' properties as previously used in addressing the Navier-Stokes and various plasma fluids. Miscellaneous discussions are also offered, including the inferences of several consequences on the transports of passive scalars for both the density and tracer, particularly, the opposite consequences of the helicity fastening effect for the latter two scalars in appropriate situations (with the caveat of the possibility of the inverse cascade of the tracer energy). Basic numerical results of the fractions of the parallel-mode spectra, with maximally-helical random forcing on some small-wavenumber modes, present a benefit of about 0.20.2 over those with nonhelical forcing, indicating regularization (to some degree) of the solutions. Such helicity ``fastening'' effect of Burgers turbulence is much more marked than that for low-Mach-number Navier-Stokes turbulence. The magnetic helicity in magneto-Burgers dynamics can present an even stronger benefit, of around 0.5+0.5+

    Remote information concentration and multipartite entanglement in multilevel systems

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    Remote information concentration (RIC) in dd-level systems (qudits) is studied. It is shown that the quantum information initially distributed in three spatially separated qudits can be remotely and deterministically concentrated to a single qudit via an entangled channel without performing any global operations. The entangled channel can be different types of genuine multipartite pure entangled states which are inequivalent under local operations and classical communication. The entangled channel can also be a mixed entangled state, even a bound entangled state which has a similar form to the Smolin state, but has different features from the Smolin state. A common feature of all these pure and mixed entangled states is found, i.e., they have d2d^2 common commuting stabilizers. The differences of qudit-RIC and qubit-RIC (d=2d=2) are also analyzed.Comment: 10 pages, 3 figure

    Failure Mechanism Analysis and Failure Number Prediction of Wind Turbine Blades

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    Pertinent to the problems that wind turbine blades operate in complicated conditions, frequent failures and low replacement rate as well as rational inventory need, this paper, we build a fault tree model based on in-depth analysis of the failure causes. As the mechanical vibration of the wind turbine takes place first on the blades, the paper gives a detailed analysis to the Failure mechanism of blade vibration. Therefore the paper puts forward a dynamic prediction model of wind turbine blade failure number based on the grey theory. The relative error between its prediction and the field investigation data is less than 5%, meeting the actual needs of engineering and verifying the effectiveness and applicability of the proposed algorithm. It is of important engineering significance for it to provide a theoretical foundation for the failure analysis, failure research and inventory level of wind turbine blades

    Attenuation of sepsis-induced rat liver injury by epigallocatechin gallate via suppression of oxidative stress-related inflammation

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    Purpose: To evaluate the effect of epigallocatechin gallate (EGCG) on sepsis-induced liver injury in a rat model of sepsis established by cercal ligation and puncture (CLP). Methods: Male Wistar rats were randomly divided into 6 groups (n = 12): normal control, sepsis, dexamethasone (5 mg/kg), low-dose EGCG (12.5 mg/kg), medium-dose EGCG (25 mg/kg), and highdose EGCG (50 mg/kg) groups. Dexamethasone and EGCG were given once daily. Survival rates following CLP were recorded. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured to evaluate liver function. Tumor necrosis factor-α (TNF-α) and interleukin (IL)-10 were determined by ELISA. Superoxide dismutase (SOD) and levels of glutathione (GSH) and malondialdehyde (MDA) were assayed to evaluate oxidative stress. Protein and mRNA expression levels of heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor (Nrf2) were measured by Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR), respectively. Results: Survival rates were significantly (p < 0.05) increased by EGCG (83.3 %) when compared to the untreated sepsis group (33.3 %) or dexamethasone-treated sepsis group (41.7 %). The increase in survival rates was associated with significant decreases in AST, ALT, MDA, and TNF-α, and significant elevations in SOD, GSH, and IL-10. QRT-PCR and Western blotting data indicate that there was increase in hepatic expression of Nrf-2 and HO-1 of EGCG-treated sepsis rats, relative to the untreated sepsis group. Conclusion: These results suggest that EGCG treatment reduces sepsis-induced liver injury and improves the survival rate of rats with polymicrobial sepsis by reducing oxidative stress via regulation of Nrf2/HO-1 signaling. These findings highlight the promising potential of EGCG for the treatment of sepsis. Keywords: Epigallocatechin gallate, Cecal ligation and puncture (CLP), Sepsis, Liver injury, Oxidative stress, Inflammatio

    miR-638 is a new biomarker for outcome prediction of non-small cell lung cancer patients receiving chemotherapy.

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    MicroRNAs (miRNAs), a class of small non-coding RNAs, mediate gene expression by either cleaving target mRNAs or inhibiting their translation. They have key roles in the tumorigenesis of several cancers, including non-small cell lung cancer (NSCLC). The aim of this study was to investigate the clinical significance of miR-638 in the evaluation of NSCLC patient prognosis in response to chemotherapy. First, we detected miR-638 expression levels in vitro in the culture supernatants of the NSCLC cell line SPC-A1 treated with cisplatin, as well as the apoptosis rates of SPC-A1. Second, serum miR-638 expression levels were detected in vivo by using nude mice xenograft models bearing SPC-A1 with and without cisplatin treatment. In the clinic, the serum miR-638 levels of 200 cases of NSCLC patients before and after chemotherapy were determined by quantitative real-time PCR, and the associations of clinicopathological features with miR-638 expression patterns after chemotherapy were analyzed. Our data helped in demonstrating that cisplatin induced apoptosis of the SPC-A1 cells in a dose- and time-dependent manner accompanied by increased miR-638 expression levels in the culture supernatants. In vivo data further revealed that cisplatin induced miR-638 upregulation in the serum derived from mice xenograft models, and in NSCLC patient sera, miR-638 expression patterns after chemotherapy significantly correlated with lymph node metastasis. Moreover, survival analyses revealed that patients who had increased miR-638 levels after chemotherapy showed significantly longer survival time than those who had decreased miR-638 levels. Our findings suggest that serum miR-638 levels are associated with the survival of NSCLC patients and may be considered a potential independent predictor for NSCLC prognosis

    Gauged Q ball in a piecewise parabolic potential

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    Q ball solutions are considered within the theory of a complex scalar field with a gauged U(1) symmetry and a parabolic-type potential. In the thin-walled limit, we show explicitly that there is a maximum size for these objects because of the repulsive Coulomb force. The size of Q ball will increase with the decrease of local minimum of the potential. And when the two minima degenerate, the energy stored within the surface of the Q ball becomes significant. Furthermore, we find an analytic expression for gauged Q ball, which is beyond the conventional thin-walled limit.Comment: 1 figure
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