Nontrivial worldline winding in non-Hermitian quantum systems

Amid the growing interest in non-Hermitian quantum systems, non-interacting models have received the most attention. Here, through the stochastic series expansion quantum Monte Carlo method, we investigate non-Hermitian physics in interacting quantum systems, e.g., various non-Hermitian quantum spin chains. While calculations yield consistent numerical results under open boundary conditions, non-Hermitian quantum systems under periodic boundary conditions observe an unusual concentration of imaginary-time worldlines over nontrivial winding and require enhanced ergodicity between winding-number sectors for proper convergences. Such nontrivial worldline winding is an emergent physical phenomenon that also exists in other non-Hermitian models and analytical approaches. Alongside the non-Hermitian skin effect and the point-gap spectroscopy, it largely extends the identification and analysis of non-Hermitian topological phenomena to quantum systems with interactions, finite temperatures, biorthogonal basis, and periodic boundary conditions in a novel and controlled fashion. Finally, we study the direct physical implications of such nontrivial worldline winding, which bring additional, potentially quasi-long-range contributions to the entanglement entropy

The Beauty of Repetition in Machine Composition Scenarios

Repetition, a basic form of artistic creation, appears in most musical works and delivers enthralling aesthetic experiences.Comment: Published on ACM Multimedia 202

Role of influenza A virus NP acetylation on viral growth and replication

Lysine acetylation is a post-translational modification known to regulate protein functions. Here we identify several acetylation sites of the influenza A virus nucleoprotein (NP), including the lysine residues K77, K113 and K229. Viral growth of mutant virus encoding K229R, mimicking a non-acetylated NP lysine residue, is severely impaired compared to wildtype or the mutant viruses encoding K77R or K113R. This attenuation is not the result of decreased polymerase activity, altered protein expression or disordered vRNP co-segregation but rather caused by impaired particle release. Interestingly, release deficiency is also observed mimicking constant acetylation at this site (K229Q), whereas virus encoding NP-K113Q could not be generated. However, mimicking NP hyper-acetylation at K77 and K229 severely diminishes viral polymerase activity, while mimicking NP hypo-acetylation at these sites has no effect on viral replication. These results suggest that NP acetylation at K77, K113 and K229 impacts multiple steps in viral replication of influenza A viruses

Performance study of efficient cooperative communication systems

The cooperative relaying technique has gained a lot of research interest recently. It can obtain the spatial diversity and improve the system performance as the multiple-input multiple-output (MIMO) technique does, but without the requirement of installing multiple antennas in mobile devices. However, due to the half-duplex constraint that mobile terminals cannot transmit and receive at the same time over the same frequency band, some conventional cooperative protocols have to sacrifice the spectral efficiency to trade the accurate transmission. In the thesis, we concentrate on analyzing the performance of cooperative relaying systems with efficient and effective transmission protocols, which can achieve the full spatial diversity gain as well as improve the spectrum efficiency significantly. Firstly, to achieve the full cooperative diversity gain of a single-relay system with fixed decode-and-forward (DF) relaying protocol, the cooperative maximal-ratio combining (C-MRC) scheme is employed. The bit-error rate (BER) performance of C-MRC and maximal-ratio combining (MRC) schemes is analyzed in the presence of independent and non-identical Nakagami-m fading channels. The BER upper bounds of both schemes are derived and the achievable diversity orders are compared. It is illustrated that by smartly designing weighting factors, the C-MRC scheme can achieve the full spatial diversity gain of the system. Additionally, C-MRC is shown to achieve higher diversity order than MRC in the fixed DF relaying protocol as well as outperform the adaptive DF relaying protocol.DOCTOR OF PHILOSOPHY (EEE

The temperature and load stresses of elastic layer system

Paper presented at the South African Transport Conference 17 - 20 July 2000 "Action in transport for the new millennium", CSIR International Convention Centre, Pretoria, South Africa. ABSTRACT: Strength and deformation behave of layer system is important to road engineering. According to thermo-elastic theory, expressions of stress and displacement of homogeneous layer system under both temperature change and static load are presented in this paper. The static loads enclodes single or poly circular loads and Fourier-Hankel transformation is used in study. The results of this study can be easily used in road engineering.This paper was transferred from the original CD ROM created for this conference. The material on the CD ROM was published using Adobe Acrobat technology. The original CD ROM was produced by Document Transformation Technologies Postal Address: PO Box 560 Irene 0062 South Africa. Tel.: +27 12 667 2074 Fax: +27 12 667 2766 E-mail: [email protected] URL: http://www.doctech.co.z

An efficient successive relaying protocol for multiple-relay cooperative networks

We propose an efficient successive relaying (SR) transmission protocol for multiple-relay cooperative systems under the half-duplex constraint. In this protocol, the process of relay selection is conducted once the instantaneous channel state information changes. During each channel coherent interval, the source keeps transmitting newly generated messages, and two selected relays successively decode and forward the source's information to the destination. In particular, in one time slot, a selected relay jointly decodes both signals transmitted from the source and the other selected relay. In the next time slot, this relay forwards the superposition of these two decoded signals. The destination jointly decodes messages at the end of each interval. The lower bound of outage probability is derived in a closed-form expression and the diversity-multiplexing trade-off (DMT) performance is characterized as well. It is demonstrated by the numerical results that the proposed SR protocol is capable of achieving both full diversity gain and high multiplexing gain

Urban Mixed Traffic Flow Considering the Influence by Origin-destination of Public Transportation

With the increasing of cars, the influences of bus stops on urban transportation have become increasingly prominent. The researches about the origin-destination of public transportation will help to optimize layout of bus stops, reduce the influences of origin-destination of public transportation on the traffic, and improve the traffic efficiency of bus station road. In this paper, basing on the nagel-schreckenberg models of traffic flow and using the two-lane aggressive lane-changing rule, the influence of the origin-destination of the public transportation on the urban bidirectional four-lane mixed traffic flow is simulated with the open boundary conditions. Taking the departure time interval, the inject probability and the location of the origin-destination of the public transportation. We get the reasonable value of the bus departure frequency and the location of public transportation, which can offer a practical reference to the improvement for the urban road traffic and the traffic management