82,841 research outputs found

    Doppler Amplification of Motion of a Trapped Three-Level Ion

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    The system of a trapped ion translationally excited by a blue-detuned near-resonant laser, sometimes described as an instance of a phonon laser, has recently received attention as interesting in its own right and for its application to non-destructive readout of internal states of non-fluorescing ions. Previous theoretical work has been limited to cases of two-level ions. Here, we perform simulations to study the dynamics of a phonon laser involving the Λ\Lambda-type ^{138}\mbox{Ba}^{+} ion, in which coherent population trapping effects lead to different behavior than in the previously studied cases. We also explore optimization of the laser parameters to maximize amplification gain and signal-to-noise ratio for internal state readout

    Arithmetic Properties of Overpartition Pairs

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    Bringmann and Lovejoy introduced a rank for overpartition pairs and investigated its role in congruence properties of ppˉ(n)\bar{pp}(n), the number of overpartition pairs of n. In particular, they applied the theory of Klein forms to show that there exist many Ramanujan-type congruences for the number ppˉ(n)\bar{pp}(n). In this paper, we shall derive two Ramanujan-type identities and some explicit congruences for ppˉ(n)\bar{pp}(n). Moreover, we find three ranks as combinatorial interpretations of the fact that ppˉ(n)\bar{pp}(n) is divisible by three for any n. We also construct infinite families of congruences for ppˉ(n)\bar{pp}(n) modulo 3, 5, and 9.Comment: 19 page

    Using LIP to Gloss Over Faces in Single-Stage Face Detection Networks

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    This work shows that it is possible to fool/attack recent state-of-the-art face detectors which are based on the single-stage networks. Successfully attacking face detectors could be a serious malware vulnerability when deploying a smart surveillance system utilizing face detectors. We show that existing adversarial perturbation methods are not effective to perform such an attack, especially when there are multiple faces in the input image. This is because the adversarial perturbation specifically generated for one face may disrupt the adversarial perturbation for another face. In this paper, we call this problem the Instance Perturbation Interference (IPI) problem. This IPI problem is addressed by studying the relationship between the deep neural network receptive field and the adversarial perturbation. As such, we propose the Localized Instance Perturbation (LIP) that uses adversarial perturbation constrained to the Effective Receptive Field (ERF) of a target to perform the attack. Experiment results show the LIP method massively outperforms existing adversarial perturbation generation methods -- often by a factor of 2 to 10.Comment: to appear ECCV 2018 (accepted version

    DLC2 modulates angiogenic responses in vascular endothelial cells by regulating cell attachment and migration.

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    Deleted in liver cancer 1 (DLC1) is a RhoGTPase activation protein-containing tumor suppressor that associates with various types of cancer. Although DLC2 shares a similar domain structure with that of DLC1, the function of DLC2 is not well characterized. Here, we describe the expression and ablation of DLC2 in mice using a reporter-knockout approach. DLC2 is expressed in several tissues and in endothelial cells (ECs) of blood vessels. Although ECs and blood vessels show no histological abnormalities and mice appear overall healthy, DLC2-mutant mice display enhanced angiogenic responses induced by matrigel and by tumor cells. Silencing of DLC2 in human ECs has reduced cell attachment, increased migration, and tube formation. These changes are rescued by silencing of RhoA, suggesting that the process is RhoA pathway dependent. These results indicate that DLC2 is not required for mouse development and normal vessel formation, but may protect mouse from unwanted angiogenesis induced by, for example, tumor cells

    Irreducible MultiQutrit Correlations in Greenberger-Horne-Zeilinger Type States

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    Following the idea of the continuity approach in [D. L. Zhou, Phys. Rev. Lett. 101, 180505 (2008)], we obtain the degrees of irreducible multi-party correlations in two families of nn-qutrit Greenberger-Horne-Zeilinger type states. For the pure states in one of the families, the irreducible 2-party, nn-party and (nm)(n-m)-party (0<m<n20< m < n-2) correlations are nonzero, which is different from the nn-qubit case. We also derive the correlation distributions in the nn-qutrit maximal slice state, which can be uniquely determined by its (n1)(n-1)-qutrit reduced density matrices among pure states. It is proved that there is no irreducible nn-qutrit correlation in the maximal slice state. This enlightens us to give a discussion about how to characterize the pure states with irreducible nn-party correlation in arbitrarily high-dimensional systems by the way of the continuity approach.Comment: 5p, no fi
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