1,281 research outputs found

    The Detection of Subsynchronous Oscillation in HVDC Based on the Stochastic Subspace Identification Method 1

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    Abstract: Subsynchronous oscillation (SSO) usually caused by series compensation, power system stabilizer (PSS), high voltage direct current transmission (HVDC) and other power electronic equipment, which will affect the safe operation of generator shafting even the system. It is very important to identify the modal parameters of SSO to take effective control strategies as well. Since the identification accuracy of traditional methods are not high enough, the stochastic subspace identification (SSI) method is proposed to improve the identification accuracy of subsynchronous oscillation modal. The stochastic subspace identification method was compared with the other two methods on subsynchronous oscillation IEEE benchmark model and Xiang-Shang HVDC system model, the simulation results show that the stochastic subspace identification method has the advantages of high identification precision, high operation efficiency and strong ability of anti- noise. Copyright © 2014 IFSA Publishing, S. L

    Early severe coronary heart disease and ischemic heart failure in homozygous familial hypercholesterolemia: A case report

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    RATIONALE: Familial hypercholesterolemia (FH) is a common inherited cause of coronary heart disease (CHD) and premature death in an early age. Nevertheless, an ischemic heart failure (IHF) associated with FH seems to be rare, and an early diagnosis and therapy could influence the prognosis. PATIENT CONCERNS: In this 13-year-old girl, multiple xanthomas began to develop from the first day of birth. Until June, 2017, she was admitted to our center due to edema, oliguria, and dyspnea during exertion, which was attributed to a recent respiratory infection. DIAGNOSIS: Homozygous FH (HoFH), CHD, and IHF. INTERVENTIONS: The patient has been treated with statin, ezetimibe, aspirin, and traditional heart failure (HF) medications. In addition, the beta-blocker was simultaneously administered. OUTCOMES: Genotypes of this proband indicated homozygous mutations of low-density lipoprotein receptor (LDLR) and some co-segregated mutations, such as von Willebrand factor (VWF) and fibroblast growth factor receptors. At 6-month follow-up, we found a decreased level of plasma lipid profile, in addition to a significant improvement in 6-minute walk distance and functional class. Echocardiography indicated nonsignificant improvements in the structure and function of the heart. LESSONS: This case report indicates that HoFH can lead to dramatically progressive endothelial damages and ventricular remodeling, severe atherosclerosis, even IHF. Genetic outcomes indicate IHF with HoFH could possibly result from LDLR mutations and some co-segregated mutations influencing endothelial function and cardiovascular remodeling. In a short-term follow-up, a combination of statins, ezetimibe, aspirin, and traditional HF agents is safe and effective for IHF with HoFH, and there is a need for further identification of drugs to ameliorate endothelial function and cardiovascular remodeling which may play an important role in long-term treatment

    Modeling and Algorithm for Multiple Spanning Tree Provisioning in Resilient and Load Balanced Ethernet Networks

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    We propose a multitree based fast failover scheme for Ethernet networks. In our system, only few spanning trees are used to carry working traffic in the normal state. As a failure happens, the nodes adjacent to the failure redirect traffic to the preplanned backup VLAN trees to realize fast failure recovery. In the proposed scheme, a new leaf constraint is enforced on the backup trees. It enables the network being able to provide 100% survivability against any single link and any single node failure. Besides fast failover, we also take load balancing into consideration. We model an Ethernet network as a twolayered graph and propose an Integer Linear Programming (ILP) formulation for the problem. We further propose a heuristic algorithm to provide solutions to large networks. The simulation results show that the proposed scheme can achieve high survivability while maintaining load balancing at the same time. In addition, we have implemented the proposed scheme in an FPGA system. The experimental results show that it takes only few μsec to recover a network failure. This is far beyond the 50 msec requirement used in telecommunication networks for network protection

    Testing Technicolor Models via Top Quark Pair Production in High Energy Photon Collisions

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    Pseudo-Goldstone boson contributions to ttˉt\bar{t} production rates in technicolor models with and without topcolor at the s=0.5and1.5\sqrt{s}=0.5 and 1.5 TeV photon colliders and hadron colliders are reviewed. For reasonable ranges of the parameters, the contributions are large enough to be experimentally observable. Models with topcolor, without topcolor and the MSSM with tanβ1\tan\beta\geq 1 can be experimentally distinguished.Comment: Talk given by H.Y. Zhou at the III International Conference on Hyperons,Charm and Beauty Hadrons,Genova,Italy,June 30-July 3 199

    Network pharmacology and UPLC-Q-TOF/MS studies on the anti-arthritic mechanism of Pterocephalus hookeri

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    Purpose: To investigate the mechanism underlying the anti-arthritic properties of Pterocephalus hookeri used for treatment of rheumatoid arthritis (RA).Methods: Aqueous methanol extract of P. hookeri was analyzed using UPLC-Q-TOF/MS, a Waters Acquity UPLCR BEH C18 column (2.1 × 100 mm, 1.7 μm) and gradient elution with acetonitrile-formic acid-water. Targets and related pathways were predicted by PharmMapper database and Molecule Annotation System, respectively. The network was built with Cytoscape software.Results: Forty compounds were identified, comprising 17 iridoid glycosides, 7 phenolic acids, 13 triterpenes, and 3 other compounds. A total of 38 targets and 44 pathways associated with RA were obtained. These involved mainly MAPK signaling pathway, adherens junction, and colorectal cancer.Conclusion: These results from network pharmacology suggest that P. hookeri exerts therapeutic effect on RA via multiple components, multiple targets and multiple pathways.Keywords: Pterocephalus hookeri, Rheumatoid arthritis, UPLC-Q-TOF/MS, Chemical composition, Network pharmacolog

    Sorafenib for hepatocellular carcinoma patients beyond Milan criteria after orthotopic liver transplantation: a case control study

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    <p>Abstract</p> <p>Background</p> <p>Orthotopic liver transplantation (OLT) is one of the most effective treatments for patients with hepatocellular carcinoma (HCC) within the Milan criteria. However, for patients beyond these criteria, the recurrence rate is higher and the prognosis is worse. Sorafenib is the only drug showing survival benefits in advanced HCC patients; however, its role in patients beyond the Milan criteria after OLT remains unclear and requires further investigation.</p> <p>Methods</p> <p>As a case-control study, we retrospectively analyzed 17 Chinese patients beyond Milan criteria undergoing OLT for HCC. These patients were stratified into adjuvant (n = 5), palliative (n = 6), and control groups (n = 6).</p> <p>Results</p> <p>Nine of 11 patients who received sorafenib after OLT needed dose reduction due to more than grade 2 side effects. The disease-free survival rates for patients with or without adjuvant sorafenib were 100% versus 37.5% (p = 0.034) at 6 months, 66.7% versus 9.4% (p = 0.026) at 12 months, and 66.7% versus 0.0% (p = 0.011) at 18 months, respectively. The overall survival rates for patients in palliative and control groups were 66.7% versus 40.0% (p = 0.248) at 6 months, 66.7% versus 40.0% (p = 0.248) at 12 months, and 50.0% versus 20.0% (p = 0.17) at 18 months, respectively. Patients in the adjuvant group had better overall survival rates than those in the palliative and control groups (p = 0.031) at 24-month follow-up.</p> <p>Conclusions</p> <p>Adjuvant sorafenib could possibly extend both disease-free and overall survival for HCC patients beyond Milan criteria after OLT.</p
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