Outage Constrained Robust Secure Transmission for MISO Wiretap Channels

In this paper we consider the robust secure beamformer design for MISO wiretap channels. Assume that the eavesdroppers' channels are only partially available at the transmitter, we seek to maximize the secrecy rate under the transmit power and secrecy rate outage probability constraint. The outage probability constraint requires that the secrecy rate exceeds certain threshold with high probability. Therefore including such constraint in the design naturally ensures the desired robustness. Unfortunately, the presence of the probabilistic constraints makes the problem non-convex and hence difficult to solve. In this paper, we investigate the outage probability constrained secrecy rate maximization problem using a novel two-step approach. Under a wide range of uncertainty models, our developed algorithms can obtain high-quality solutions, sometimes even exact global solutions, for the robust secure beamformer design problem. Simulation results are presented to verify the effectiveness and robustness of the proposed algorithms

Molecular evolution of the duplicated TFIIAγ genes in Oryzeae and its relatives

<p>Abstract</p> <p>Background</p> <p>Gene duplication provides raw genetic materials for evolutionary novelty and adaptation. The evolutionary fate of duplicated transcription factor genes is less studied although transcription factor gene plays important roles in many biological processes. TFIIAγ is a small subunit of TFIIA that is one of general transcription factors required by RNA polymerase II. Previous studies identified two <it>TFIIAγ</it>-like genes in rice genome and found that these genes either conferred resistance to rice bacterial blight or could be induced by pathogen invasion, raising the question as to their functional divergence and evolutionary fates after gene duplication.</p> <p>Results</p> <p>We reconstructed the evolutionary history of the <it>TFIIAγ </it>genes from main lineages of angiosperms and demonstrated that two <it>TFIIAγ </it>genes (<it>TFIIAγ1 </it>and <it>TFIIAγ5</it>) arose from a whole genome duplication that happened in the common ancestor of grasses. Likelihood-based analyses with branch, codon, and branch-site models showed no evidence of positive selection but a signature of relaxed selective constraint after the <it>TFIIAγ </it>duplication. In particular, we found that the nonsynonymous/synonymous rate ratio (ω = <it>d</it>_N/<it>d</it>_S) of the <it>TFIIAγ1 </it>sequences was two times higher than that of <it>TFIIAγ5 </it>sequences, indicating highly asymmetric rates of protein evolution in rice tribe and its relatives, with an accelerated rate of <it>TFIIAγ1 </it>gene. Our expression data and EST database search further indicated that after whole genome duplication, the expression of <it>TFIIAγ1 </it>gene was significantly reduced while <it>TFIIAγ5 </it>remained constitutively expressed and maintained the ancestral role as a subunit of the TFIIA complex.</p> <p>Conclusion</p> <p>The evolutionary fate of TFIIA<it>γ </it>duplicates is not consistent with the neofunctionalization model that predicts that one of the duplicated genes acquires a new function because of positive Darwinian selection. Instead, we suggest that subfunctionalization might be involved in <it>TFIIAγ </it>evolution in grasses. The fact that both <it>TFIIAγ1 </it>and <it>TFIIAγ5 </it>genes were effectively involved in response to biotic or abiotic factors might be explained by either Dykhuizen-Hartl effect or buffering hypothesis.</p

Deforming black holes with even multipolar differential rotation boundary

Motivated by the novel asymptotically global AdS$_4$ solutions with deforming horizon in [JHEP {\bf 1802}, 060 (2018)], we analyze the boundary metric with even multipolar differential rotation and numerically construct a family of deforming solutions with quadrupolar differential rotation boundary, including two classes of solutions: solitons and black holes. In contrast to solutions with dipolar differential rotation boundary, we find that even though the norm of Killing vector $\partial_t$ becomes spacelike for certain regions of polar angle $\theta$ when $\varepsilon>2$, solitons and black holes with quadrupolar differential rotation still exist and do not develop hair due to superradiance. Moreover, at the same temperature, the horizonal deformation of quadrupolar rotation is smaller than that of dipolar rotation. Furthermore, we also study the entropy and quasinormal modes of the solutions, which have the analogous properties to that of dipolar rotation.Comment: 18 pages, 21 figure

Observation of valley Landau-Zener-Bloch oscillations and pseudospin imbalance in photonic graphene

We demonstrate inter-valley Bloch oscillation (BO) and Landau-Zener tunneling (LZT) in an optically-induced honeycomb lattice with a refractive index gradient. Unlike previously observed BO in a gapped square lattice, we show non-adiabatic beam dynamics that are highly sensitive to the direction of the index gradient and the choice of the Dirac cones. In particular, a symmetry-preserving potential leads to nearly perfect LZT and coherent BO between the inequivalent valleys, whereas a symmetry-breaking potential generates asymmetric scattering, imperfect LZT, and valley-sensitive generation of vortices mediated by a pseudospin imbalance. This clearly indicates that, near the Dirac points, the transverse gradient does not always act as a simple scalar force as commonly assumed, and the LZT probability is strongly affected by the sublattice symmetry as analyzed from an effective Landau-Zener Hamiltonian. Our results illustrate the anisotropic response of an otherwise isotropic Dirac platform to real-space potentials acting as strong driving fields, which may be useful for manipulation of pseudospin and valley degrees of freedom in graphene-like systems

The Tensor Current Divergence Equation in U(1) Gauge Theories is Free of Anomalies

The possible anomaly of the tensor current divergence equation in U(1) gauge theories is calculated by means of perturbative method. It is found that the tensor current divergence equation is free of anomalies.Comment: Revtex4, 7 pages, 2 figure

Improvement of two-way continuous-variable quantum key distribution using optical amplifiers

The imperfections of a receiver's detector affect the performance of two-way continuous-variable quantum key distribution protocols and are difficult to adjust in practical situations. We propose a method to improve the performance of two-way continuous-variable quantum key distribution by adding a parameter-adjustable optical amplifier at the receiver. A security analysis is derived against a two-mode collective entangling cloner attack. Our simulations show that the proposed method can improve the performance of protocols as long as the inherent noise of the amplifier is lower than a critical value, defined as the tolerable amplifier noise. Furthermore, the optimal performance can approach the scenario where a perfect detector is used.Comment: 14 pages, 7 figure