2,371 research outputs found

    Constraints on Axion-like Particles from Observations of Mrk 421 using the CLs{\rm CL_s} Method

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    Axion-like particles (ALPs) could mix with photons in the presence of astrophysical magnetic fields, and result in oscillations in the high energy Ξ³\gamma-ray spectra observed by experiments. In this work, we investigate the ALP-photon oscillation effect through the blazar Mrk 421 spectra of 15 periods observed by Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) and Fermi Large Area Telescope (Fermi-LAT). Compared with previous studies, we generate the mock data under the ALP hypothesis and apply the CLs{\rm CL_s} method to set constraints on the ALP parameters. This method is widely employed in high energy experiments and could avoid the possibility of excluding some parameter regions due to the fluctuation. We find that the ALP-photon coupling gaΞ³g_{a\gamma} is constrained to be smaller than ∼2Γ—10βˆ’11\sim 2\times10^{-11} GeVβˆ’1^{-1} for ALP mass ranging from 10βˆ’910^{-9} eV to 10βˆ’710^{-7} eV at a 95\% confidence level. The constraints obtained with the method based on the TS distribution under the null hypothesis, which is adopted in many previous astrophysical ALP studies, are also shown. Our results demonstrate that the joint constraints of all the periods from both methods are consistent. However, the latter method fails to provide constraints for some observation periods, whereas the CLs{\rm CL_s} method remains effective in such cases.Comment: 10 pages, 26 figure

    A maximal clique based multiobjective evolutionary algorithm for overlapping community detection

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    Detecting community structure has become one im-portant technique for studying complex networks. Although many community detection algorithms have been proposed, most of them focus on separated communities, where each node can be-long to only one community. However, in many real-world net-works, communities are often overlapped with each other. De-veloping overlapping community detection algorithms thus be-comes necessary. Along this avenue, this paper proposes a maxi-mal clique based multiobjective evolutionary algorithm for over-lapping community detection. In this algorithm, a new represen-tation scheme based on the introduced maximal-clique graph is presented. Since the maximal-clique graph is defined by using a set of maximal cliques of original graph as nodes and two maximal cliques are allowed to share the same nodes of the original graph, overlap is an intrinsic property of the maximal-clique graph. Attributing to this property, the new representation scheme al-lows multiobjective evolutionary algorithms to handle the over-lapping community detection problem in a way similar to that of the separated community detection, such that the optimization problems are simplified. As a result, the proposed algorithm could detect overlapping community structure with higher partition accuracy and lower computational cost when compared with the existing ones. The experiments on both synthetic and real-world networks validate the effectiveness and efficiency of the proposed algorithm

    Prognostic Value of Survivin in Patients with Non-Small Cell Lung Carcinoma: A Systematic Review with Meta-Analysis

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    The potential prognostic value of survivin in resected non-small cell lung carcinoma (NSCLC) is variably reported. The objective of this study was to conduct a systematic review of literatures evaluating survivin expression in resected NSCLC as a prognostic indicator.Relevant literatures were identified using PubMed, EMBASE and Chinese Biomedicine Databases. We present the results of a meta-analysis of the association between survivin expression and overall survival (OS) in NSCLC patients. Studies were pooled and summary hazard ratios (HR) were calculated. Subgroup analyses and publication bias were also conducted.β€Š=β€Š26.9%). Its effect also appeared significant when stratified according to the studies categorized by histological type, HR estimate, patient race, cutoff point (5%, 10%), detection methods and literature written language except for disease stage. Survivin was identified as a prognostic marker of advanced-stage NSCLC (HRβ€Š=β€Š1.93, 95%CI: 1.49-2.51), but not early-stage NSCLC (HRβ€Š=β€Š1.97, 95%CI: 0.76-5.14), in spite of the combined data being relatively small.This study shows that survivin expression appears to be a pejorative prognostic factor in terms of overall survival in surgically treated NSCLC. Large prospective studies are now needed to confirm the clinical utility of survivin as an independent prognostic marker
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