P-T phase diagram of a holographic s+p model from Gauss-Bonnet gravity

In this paper, we study the holographic s+p model in 5-dimensional bulk gravity with the Gauss-Bonnet term. We work in the probe limit and give the $\Delta$-T phase diagrams at three different values of the Gauss-Bonnet coefficient to show the effect of the Gauss-Bonnet term. We also construct the P-T phase diagrams for the holographic system using two different definitions of the pressure and compare the results.Comment: 17 pages, 5 figures, we have added new P-T phase diagrams with the pressure defined in boundary stress-energy tenso

Shear Viscosity from the Effective Coupling of Gravitons

We review the progress in the holographic calculation of shear viscosity for strongly coupled field theories. We focus on the calculation of shear viscosity from the effective coupling of transverse gravitons and present some explicit examples.Comment: 10 pages, invited presentation for the 9th Asia-Pacific International Conference On Gravitation And Astrophysics (ICGA 9), June 28-July 2, 2009, Wuhan, China; for the proceedings to be published by World Scientifi

Optimizing Quantum Programs against Decoherence: Delaying Qubits into Quantum Superposition

Quantum computing technology has reached a second renaissance in the last decade. However, in the NISQ era pointed out by John Preskill in 2018, quantum noise and decoherence, which affect the accuracy and execution effect of quantum programs, cannot be ignored and corrected by the near future NISQ computers. In order to let users more easily write quantum programs, the compiler and runtime system should consider underlying quantum hardware features such as decoherence. To address the challenges posed by decoherence, in this paper, we propose and prototype QLifeReducer to minimize the qubit lifetime in the input OpenQASM program by delaying qubits into quantum superposition. QLifeReducer includes three core modules, i.e.,the parser, parallelism analyzer and transformer. It introduces the layered bundle format to express the quantum program, where a set of parallelizable quantum operations is packaged into a bundle. We evaluate quantum programs before and after transformed by QLifeReducer on both real IBM Q 5 Tenerife and the self-developed simulator. The experimental results show that QLifeReducer reduces the error rate of a quantum program when executed on IBMQ 5 Tenerife by 11%; and can reduce the longest qubit lifetime as well as average qubit lifetime by more than 20% on most quantum workloads.Comment: To appear in TASE2019 - the 13th International Symposium on Theoretical Aspects of Software Engineering (submitted on Jan 25, 2019, and this is camera-ready version

Three essays on acquisition and CSR choices and firm value: Role of managerial traits and actions

This thesis consists of three essays that examine the role of managerial traits (specifically managerial conservatism, interest alignment with shareholders and debtholders, beliefs about firm value and hubris) on their firms’ acquisition and CSR choices and their valuation effects. All the essays use hand-collected pension plan data. The first essay finds support for a managerial conservatism explanation for acquirer acquisition choices and M&A price effects. More conservatively managed acquirers are more likely to use cash as the method of payment and to target less risky firms (e.g. being public or having lower leverage or managerial conservatism). We find that acquirers experience poorer price effects for stock versus cash payment even after controlling for the equity price effect and that these price effects monotonically deteriorate with increasing managerial conservatism, consistent with the agency problems associated with managerial conservatism. These results remain robust using propensity score matching, a four- or five-factor model, the BHAR methodology, top five executives instead of CEO when measuring managerial conservatism, and the inclusion of various controls (e.g., multiple or single acquirers, policy uncertainty, business cycle, managerial hubris, firm mispricing and Republican orientation). The second essay finds that managerial interest alignment with shareholders (debtholders) of acquirers is positively related to the likelihood of using stock (cash) as the M&A payment method, positively (negatively) related with M&A acquirer equity price effects, and negatively (positively) related with M&A acquirer bond price effects. While managerial conservatism is positively related with an acquirer’s CSR ranking it is negatively related with an acquirer’s M&A price effects. Information about an acquirer’s misvaluation contained in pre-announcement short selling by investors and the abnormal trading of its executives also affects the acquirer’s choice of payment method and M&A price effects