6,705 research outputs found

    Model Selection for High Dimensional Quadratic Regression via Regularization

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    Quadratic regression (QR) models naturally extend linear models by considering interaction effects between the covariates. To conduct model selection in QR, it is important to maintain the hierarchical model structure between main effects and interaction effects. Existing regularization methods generally achieve this goal by solving complex optimization problems, which usually demands high computational cost and hence are not feasible for high dimensional data. This paper focuses on scalable regularization methods for model selection in high dimensional QR. We first consider two-stage regularization methods and establish theoretical properties of the two-stage LASSO. Then, a new regularization method, called Regularization Algorithm under Marginality Principle (RAMP), is proposed to compute a hierarchy-preserving regularization solution path efficiently. Both methods are further extended to solve generalized QR models. Numerical results are also shown to demonstrate performance of the methods.Comment: 37 pages, 1 figure with supplementary materia

    Structural Changes and Regional Disparity in China's Inflation

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    The inflation problem in China has attracted a great deal of international attention in recent years. This paper examines the time series properties of China's CPI series. It is found that the overall inflation series and the inflation of food, tobacco, clothes, urban transport and urban housing are not persistent. Structural breaks in inflation are found in 2003 and 2004. The degree of rural-urban inflation disparity in China is also investigated. We find evidence that rural residents experience higher inflation than their urban counterparts.Structural Break, Unit Root, ADF Test, Rural and Urban Inflation.

    Top quark decays with flavor violation in the B-LSSM

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    The decays of top quark tcγ,  tcg,  tcZ,  tcht\rightarrow c\gamma,\;t\rightarrow cg,\;t\rightarrow cZ,\;t\rightarrow ch are extremely rare processes in the standard model (SM). The predictions on the corresponding branching ratios in the SM are too small to be detected in the future, hence any measurable signal for the processes at the LHC is a smoking gun for new physics. In the extension of minimal supersymmetric standard model with an additional local U(1)BLU(1)_{B-L} gauge symmetry (B-LSSM), new gauge interaction and new flavor changing interaction affect the theoretical evaluations on corresponding branching ratios of those processes. In this work, we analyze those processes in the B-LSSM, under a minimal flavor violating assumption for the soft breaking terms. Considering the constraints from updated experimental data, the numerical results imply Br(tcγ)5×107Br(t\rightarrow c\gamma)\sim5\times10^{-7}, Br(tcg)2×106Br(t\rightarrow cg)\sim2\times10^{-6}, Br(tcZ)4×107Br(t\rightarrow cZ)\sim4\times10^{-7} and Br(tch)3×109Br(t\rightarrow ch)\sim3\times10^{-9} in our chosen parameter space. Simultaneously, new gauge coupling constants gB,  gYBg_{_B},\;g_{_{YB}} in the B-LSSM can also affect the numerical results of Br(tcγ,  cg,  cZ,  ch)Br(t\rightarrow c\gamma,\;cg,\;cZ,\;ch).Comment: 20 pages, 4 figures, published in EPJC. arXiv admin note: substantial text overlap with arXiv:1803.0990

    Experimental demonstration of a non-destructive controlled-NOT quantum gate for two independent photon-qubits

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    Universal logic gates for two quantum bits (qubits) form an essential ingredient of quantum information processing. However, the photons, one of the best candidates for qubits, suffer from the lack of strong nonlinear coupling required for quantum logic operations. Here we show how this drawback can be overcome by reporting a proof-of-principle experimental demonstration of a non-destructive controlled-NOT (CNOT) gate for two independent photons using only linear optical elements in conjunction with single-photon sources and conditional dynamics. Moreover, we have exploited the CNOT gate to discriminate all the four Bell-states in a teleportation experiment.Comment: 4 pages, 4 figures, submitte

    HBX-Mediated Migration of HBV-Replicating HepG2 Cells: Insights on Development of Hepatocellular Carcinoma

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    Hepatitus B virus (HBV) is a major cause of the development of hepatpcellular carcinoma (HCC). One of the significant characteristics of tumor progression is cell migration which is reflective of cytoskeletal dynamics. The Rho GTPases contribute to a multiple cellular processes, including the cellular cytoskeletal reorganization and motility. It has been found that some Rho GTPases have oncogenic activity and can promote cancer cell invasion. Here we discuss one of the Rho GTPases, Rac1 can be activated by HBV replication and such activation results in the high motility of HBV-replicating cells. The enhanced cell motility can be interestingly alleviated by the mutation at the sites of proline rich domain located in HBX. Our findings may provide new insights on the mechanism of HCC development associated with chronic HBV infection
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