Entropy Bound for the Classical Capacity of a Quantum Channel Assisted by Classical Feedback

We prove that the classical capacity of an arbitrary quantum channel assisted by a free classical feedback channel is bounded from above by the maximum average output entropy of the quantum channel. As a consequence of this bound, we conclude that a classical feedback channel does not improve the classical capacity of a quantum erasure channel, and by taking into account energy constraints, we conclude the same for a pure-loss bosonic channel. The method for establishing the aforementioned entropy bound involves identifying an information measure having two key properties: 1) it does not increase under a one-way local operations and classical communication channel from the receiver to the sender and 2) a quantum channel from sender to receiver cannot increase the information measure by more than the maximum output entropy of the channel. This information measure can be understood as the sum of two terms, with one corresponding to classical correlation and the other to entanglement.Comment: v2: 6 pages, 1 figure, final version published in conference proceeding

Kronecker Product Correlation Model and Limited Feedback Codebook Design in a 3D Channel Model

A 2D antenna array introduces a new level of control and additional degrees of freedom in multiple-input-multiple-output (MIMO) systems particularly for the so-called "massive MIMO" systems. To accurately assess the performance gains of these large arrays, existing azimuth-only channel models have been extended to handle 3D channels by modeling both the elevation and azimuth dimensions. In this paper, we study the channel correlation matrix of a generic ray-based 3D channel model, and our analysis and simulation results demonstrate that the 3D correlation matrix can be well approximated by a Kronecker production of azimuth and elevation correlations. This finding lays the theoretical support for the usage of a product codebook for reduced complexity feedback from the receiver to the transmitter. We also present the design of a product codebook based on Grassmannian line packing.Comment: 6 pages, 5 figures, to appear at IEEE ICC 201

Effect of Multi- Steel Bolt Anchorages on Composite Beams

Using fiber-reinforced polymer (FRP) to retrofit or strengthen the concrete structures is an attractive option in construction areas nowadays. However, premature debonding failures limit the efficacy of fiber utilization. It is presently accepted that anchorage system is an attractive option to solve this problem. Much efforts has been made through experimental testing and numerical modeling to investigate the anchorage systems, meanwhile various systems were created and developed. However, researches on the mechanism of the anchorage systems are still too rare to build a countable and union design guideline with respect to different premature debonding failure modes. The present paper focused on two commonly documented anchorage methods: steel bolt anchorage and CFRP end wrapping anchorage and conducted a specially design experiment to further analyze the mechanism of effect of both systems on premature debonding failures (concrete cover separation and IC debonding). Results show that CFRP wrapping and Steel bolts can both effectively stop or suppress the propagation of IC debonding. And the ultimate load is effected by the finally failure mode, which could be changed with different height of steel bolt

Analytical Model for Concrete Jacketed RC Columns with Precorrosion and Postcorrosion Damages Under Uniaxial Loading

The main objective of this study is to investigate the effect of precorrosion and postcorrosion damage on concrete jacketed RC columns under uniaxial loading and to develop a rational methodology for predicting the corresponding compressive strength. The predamage and postdamage involved an electrochemical process to accelerate the migration of chlorides from an external electrolyte into the tested columns and a wetting–drying cycle process with a controlled current to speed up the corrosion of the reinforcing steel bars in the tested columns. An uniaxial loading test was to determine the structural performance of the concrete jacketed columns with or without corrosion damage. The failure mode, load–displacement, and load–strain responses of test columns were recorded, and the related mechanisms were discussed. Then a model that is capable of evaluating peak load of unjacketed or jacketed RC columns with or without corrosion damage was developed. The analytical approach considered the effect of reinforcement corrosion on the effective load-bearing area of concrete and the confinement effect from the web reinforcement. The analytical results agreed well with the experimental results, indicating the reliability and effectiveness of developed models

Expression and evolutionary divergence of the non-conventional olfactory receptor in four species of fig wasp associated with one species of fig

<p>Abstract</p> <p>Background</p> <p>The interactions of fig wasps and their host figs provide a model for investigating co-evolution. Fig wasps have specialized morphological characters and lifestyles thought to be adaptations to living in the fig's syconium. Although these aspects of natural history are well documented, the genetic mechanism(s) underlying these changes remain(s) unknown. Fig wasp olfaction is the key to host-specificity. The <it>Or83b</it> gene class, an unusual member of olfactory receptor family, plays a critical role in enabling the function of conventional olfactory receptors. Four <it>Or83b</it> orthologous genes from one pollinator (PFW) (<it>Ceratosolen solmsi</it>) and three non-pollinator fig wasps (NPFWs) (<it>Apocrypta bakeri, Philotrypesis pilosa </it>and <it>Philotrypesis </it>sp.) associated with one species of fig (<it>Ficus hispida</it>) can be used to better understand the molecular mechanism underlying the fig wasp's adaptation to its host. We made a comparison of spatial tissue-specific expression patterns and substitution rates of one orthologous gene in these fig wasps and sought evidence for selection pressures.</p> <p>Results</p> <p>A newly identified <it>Or83b </it>orthologous gene was named <it>Or2</it>. Expressions of <it>Or2 </it>were restricted to the heads of all wingless male fig wasps, which usually live in the dark cavity of a fig throughout their life cycle. However, expressions were widely detected in the antennae, legs and abdomens of all female fig wasps that fly from one fig to another for oviposition, and secondarily pollination. Weak expression was also observed in the thorax of PFWs. Compared with NPFWs, the <it>Or2 </it>gene in <it>C. solmsi </it>had an elevated rate of substitutions and lower codon usage. Analyses using Tajima's <it>D</it>, Fu and Li's <it>D* </it>and <it>F* </it>tests indicated a non-neutral pattern of nucleotide variation in all fig wasps. Unlike in NPFWs, this non-neutral pattern was also observed for synonymous sites of <it>Or2 </it>within PFWs.</p> <p>Conclusion</p> <p>The sex- and species-specific expression patterns of <it>Or2 </it>genes detected beyond the known primary olfactory tissues indicates the location of cryptic olfactory inputs. The specialized ecological niche of these wasps explains the unique habits and adaptive evolution of <it>Or2 </it>genes. The <it>Or2 </it>gene in <it>C. solmsi </it>is evolving very rapidly. Negative deviation from the neutral model of evolution reflects possible selection pressures acting on <it>Or2 </it>sequences of fig wasp, particularly on PFWs who are more host-specific to figs.</p