Corporate Governance and Corporate Performance: Some Evidence from Newly Listed Firms on Chinese Stock Markets

This paper is concerned with some corporate governance issues related to newly listed firms in China based on a sample of 329 firms commencing listing on Shanghai Stock Exchange (SHSE) and Shenzhen Stock exchange (SZSE) during the period from 1998 to 2000. We first investigate the impact of ownership change due to stock market listing on corporate performance. We consider four aspects of corporate performance: profitability, sales, leverage and employee productivity. Our research results indicate that, on average, profitability, sales and employee productivity have improved from pre-listing to post-listing. We further investigate the impacts of state majority control, foreign ownership and regulation effects on corporate performance. Overall, this paper provides some new evidence on the listing effect, ownership structure and regulation effect on Chinese firms which will be valuable to the future reform of state owned enterprises in China.State owned enterprise, corporate governance, and corporate performance

Li, Li, and Dai's Contribution to the Discussion of "Estimating Means of Bounded Random Variables by Betting" by Waudby-Smith and Aaditya Ramdas

We congratulate Waudby-Smith and Ramdas for their interesting paper \cite{waudbysmith2022estimating} in generating confidence intervals and time-uniform confidence sequences for mean estimation with bounded observations. Their methodology utilizes composite nonnegative martingales and establishes a connection to game-theoretic probability. Our comments will focus on numerical comparisons with alternative methods.Comment: 3 pages; 2 figure

Numerical simulation of the optimal two-mode attacks for two-way continuous-variable quantum cryptography in reverse reconciliation

We analyze the security of the two-way continuous-variable quantum key distribution protocol in reverse reconciliation against general two-mode attacks, which represent all accessible attacks at fixed channel parameters. Rather than against one specific attack model, the expression of secret key rates of the two-way protocol are derived against all accessible attack models. It is found that there is an optimal two-mode attack to minimize the performance of the protocol in terms of both secret key rates and maximal transmission distances. We identify the optimal two-mode attack, give the specific attack model of the optimal two-mode attack and show the performance of the two-way protocol against the optimal two-mode attack. Even under the optimal two-mode attack, the performances of two-way protocol are still better than the corresponding one-way protocol, which shows the advantage of making a double use of the quantum channel and the potential of long-distance secure communication using two-way protocol.Comment: 14 pages, 8 figure

Improvement of two-way continuous-variable quantum key distribution with virtual photon subtraction

We propose a method to improve the performance of two-way continuous-variable quantum key distribution protocol by virtual photon subtraction. The Virtual photon subtraction implemented via non-Gaussian post-selection not only enhances the entanglement of two-mode squeezed vacuum state but also has advantages in simplifying physical operation and promoting efficiency. In two-way protocol, virtual photon subtraction could be applied on two sources independently. Numerical simulations show that the optimal performance of renovated two-way protocol is obtained with photon subtraction only used by Alice. The transmission distance and tolerable excess noise are improved by using the virtual photon subtraction with appropriate parameters. Moreover, the tolerable excess noise maintains a high value with the increase of distance so that the robustness of two-way continuous-variable quantum key distribution system is significantly improved, especially at long transmission distance.Comment: 15 pages, 6 figure

Determining relaxation times for porous media: Theory, measurement, and the inverse problem

This thesis provides an introduction to and analysis of the problem of determining nuclear magnetic resonance (NMR) relaxation times of porous media by using the so-called Carr-Purcell-Meiboom-Gill (CPMG) technique. We introduce the principles of NMR, the CPMG technique and the signals produced, porous effects on the NMR relaxation times and discuss various numerical methods for the inverse problem of extracting the relaxation times from CPMG signals. The numerical methods for solving Fredholm integral equations of the first kind are sketched from a series expansion perspective. A method of using arbitrary constituent functions for improving the performance of non-negative least squares (NNLS) is developed and applied to several synthesized data sets and real experimental data sets of saturated porous glass gels. The data sets were obtained by the author of this thesis and the experimental procedure will be presented. We discuss the imperfections in the assumptions on the physical and numerical models, the numerical schemes, and the experimental results, which may lead to new research possibilities

Manipulating Atom-Cavity Interactions with Configurable Atomic Chains

We investigate a ring cavity comprising two degenerate counter-propagating modes coupled to a one-dimensional atomic chain, leading to bidirectional light scattering. The spatial configuration of the atomic chain, described by a structure factor, plays a crucial role in manipulation of the atom-cavity interactions and formation of the collective excitation modes. Remarkably, we observe that a cavity dark mode is induced when the atomic spacing is an integer multiple of half-wavelength. The nodes of this standing-wave dark mode align precisely with the atomic positions, enabling intracavity field conversion without free space scattering. By adjusting the configuration of the atomic chain, we realize optical mode conversion with almost no photon loss and a broad tuning range, making it suitable for various practical applications in quantum technologies

Quench dynamics of Rydberg-dressed bosons on two-dimensional square lattices

We study dynamics of bosonic atoms on a two dimensional square lattice, where atomic interactions are long ranged with either a box or soft-core shape. The latter can be realized through laser dressing ground state atoms to electronically excited Rydberg states. When the range of interactions is equal or larger than the lattice constant, the system is governed by an extended Bose-Hubbard model. We propose a quench process by varying the atomic hopping linearly across phase boundaries of the Mott insulator-supersolid and supersolid-superfluid phases. Starting from a Mott insulator state, dynamical evolution exhibits a universal behaviour at the early stage. We numerically find that the universality is largely independent of interactions during this stage. However, dynamical evolution could be significantly altered by long-range interactions at later times. We demonstrate that density wave excitations are important below a critical quench rate, where non-universal dynamics is found. We also show that the quench dynamics can be analysed through time-of-flight images, i.e. measuring the momentum distribution and noise correlations

An Improved Repetitive Control for Circulating Current Restraining in MMC-MTDC

The modular multilevel converter (MMC) is widely used in many important application fields such as high voltage DC transmission system. And the multi-terminal architecture of it attracts many attentions. However, the circulating current of MMC is an inherent problem which is mainly caused by the voltage mismatch between arms and DC bus. In this paper, an advanced repetitive control method is proposed. This method is based on the even-harmonic characteristic of the circulating current and the potential feature of repetitive control that it has an internal integration part. The pole diagram of the closed loop transform function of the proposed control system proves the stability of the proposed method. And according to the simulation results of a three-terminal MMC-MTDC model in PSCAD/EMTDC, the improved repetitive control presents better circulation repression ability and superior anti-interference capability by comparing with traditional PI control method. Additionally, the simulation results also indicate that the proposed repetitive controller can restrain the fluctuation of SM voltage more effectively than PI control