1,904 research outputs found

    Generalized Hybrid Evolutionary Algorithm Framework with a Mutation Operator Requiring no Adaptation

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    This paper presents a generalized hybrid evolutionary optimization structure that not only combines both nondeterministic and deterministic algorithms on their individual merits and distinct advantages, but also offers behaviors of the three originating classes of evolutionary algorithms (EAs). In addition, a robust mutation operator is developed in place of the necessity of mutation adaptation, based on the mutation properties of binary-coded individuals in a genetic algorithm. The behaviour of this mutation operator is examined in full and its performance is compared with adaptive mutations. The results show that the new mutation operator outperforms adaptive mutation operators while reducing complications of extra adaptive parameters in an EA representation

    Searching for X0(2900) X_{0}(2900) and X1(2900) X_{1}(2900) through the kaon induced reactions

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    The productions of the exotic states X0(2900) X_0(2900) and X1(2900) X_1(2900) in K+p→Σc++X0(2900)K^{+}p \to \Sigma_{c}^{++}X_{0}(2900) and K+p→Σc++X1(2900)K^{+}p \to \Sigma_{c}^{++}X_{1}(2900) reactions are studied within an effective Lagrangian approach. The t−t-channel Born term is included to calculate the production cross sections. The numerical results show that the total cross section may reach up to about 0.5 nb and 25 nb for the production of X0(2900) X_0(2900) and X1(2900) X_1(2900) , respectively. The predicted differential cross sections are sensitive to the scattering angles and have strong forward enhancements. The cross sections for the K+n→Λc+X0,1K^{+}n \to \Lambda_{c}^{+}X_{0,1} are also calculated and found to be larger than that in K+pK^{+}p collisions by more than one order of magnitude. The results are helpful to the possible experiments at J-PARC and COMPASS.Comment: 5 pages, 5 figure

    Objective quality prediction of image retargeting algorithms

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    Quality assessment of image retargeting results is useful when comparing different methods. However, performing the necessary user studies is a long, cumbersome process. In this paper, we propose a simple yet efficient objective quality assessment method based on five key factors: i) preservation of salient regions; ii) analysis of the influence of artifacts; iii) preservation of the global structure of the image; iv) compliance with well-established aesthetics rules; and v) preservation of symmetry. Experiments on the RetargetMe benchmark, as well as a comprehensive additional user study, demonstrate that our proposed objective quality assessment method outperforms other existing metrics, while correlating better with human judgements. This makes our metric a good predictor of subjective preference

    Global analyses of endonucleolytic cleavage in mammals reveal expanded repertoires of cleavage-inducing small RNAs and their targets.

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    In mammals, small RNAs are important players in post-transcriptional gene regulation. While their roles in mRNA destabilization and translational repression are well appreciated, their involvement in endonucleolytic cleavage of target RNAs is poorly understood. Very few microRNAs are known to guide RNA cleavage. Endogenous small interfering RNAs are expected to induce target cleavage, but their target genes remain largely unknown. We report a systematic study of small RNA-mediated endonucleolytic cleavage in mouse through integrative analysis of small RNA and degradome sequencing data without imposing any bias toward known small RNAs. Hundreds of small cleavage-inducing RNAs and their cognate target genes were identified, significantly expanding the repertoire of known small RNA-guided cleavage events. Strikingly, both small RNAs and their target sites demonstrated significant overlap with retrotransposons, providing evidence for the long-standing speculation that retrotransposable elements in mRNAs are leveraged as signals for gene targeting. Furthermore, our analysis showed that the RNA cleavage pathway is also present in human cells but affecting a different repertoire of retrotransposons. These results show that small RNA-guided cleavage is more widespread than previously appreciated. Their impact on retrotransposons in non-coding regions shed light on important aspects of mammalian gene regulation

    Source attack of decoy-state quantum key distribution using phase information

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    Quantum key distribution (QKD) utilizes the laws of quantum mechanics to achieve information-theoretically secure key generation. This field is now approaching the stage of commercialization, but many practical QKD systems still suffer from security loopholes due to imperfect devices. In fact, practical attacks have successfully been demonstrated. Fortunately, most of them only exploit detection-side loopholes which are now closed by the recent idea of measurement-device-independent QKD. On the other hand, little attention is paid to the source which may still leave QKD systems insecure. In this work, we propose and demonstrate an attack that exploits a source-side loophole existing in qubit-based QKD systems using a weak coherent state source and decoy states. Specifically, by implementing a linear-optics unambiguous-state-discrimination measurement, we show that the security of a system without phase randomization --- which is a step assumed in conventional security analyses but sometimes neglected in practice --- can be compromised. We conclude that implementing phase randomization is essential to the security of decoy-state QKD systems under current security analyses.Comment: 12 pages, 5 figure

    3-[(R)-3,3-Dichloro-2-hydroxy­prop­yl]-8-hydr­oxy-6-meth­oxy-1H-isochromen-1-one

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    The title compound, C13H12Cl2O5, is an isocoumarin compound which has been isolated from the ethyl acetate extract of the fermentation broth of actinomycete Streptomyces sp. (V4) from the South China Sea. There are intra- and inter­molecular hydrogen bonds and halogen bonds [Cl⋯Cl = 3.434 (2) Å; C—Cl⋯Cl = 121.6°]. The intermolecular O—H⋯O hydrogen bonds link mol­ecules into chains along the b axis

    Discovery potential for the LHCb fully-charm tetraquark X(6900)X(6900) state via pˉp\bar{p}p annihilation reaction

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    Inspired by the observation of the fully-charm tetraquark X(6900)X(6900) state at LHCb, the production of X(6900)X(6900) in pˉp→J/ψJ/ψ\bar{p}p\rightarrow J/\psi J/\psi reaction is studied within an effective Lagrangian approach and Breit-Wigner formula. The numerical results show that the cross section of X(6900)X(6900) at the c.m. energy of 6.9 GeV is much larger than that from the background contribution. Moreover, we estimate dozens of signal events can be detected by D0 experiment, which indicates that searching for the X(6900)X(6900) via antiproton-proton scattering may be a very important and promising way. Therefore, related experiments are suggested to be carried out.Comment: 4 pages, 2 figure
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