Exchange rate regime and exchange rate performance: evidence from East Asia

This thesis is intended to be part of a vigorous debate currently going on in the international community of exchange rate regime, monetary policy and related core issues in East Asian economies. From different angles and aspects, this thesis contributes to the related literature, and provides fresh theoretical arguments and comprehensive study on the exchange rate regime and exchange rate performance in East Asia. This thesis firstly investigates the performance and characteristics of exchange rate regimes in a group of East Asian economies during the 1990s. The determination of local currency, the flexibility of exchange rate regime, as well as the regional coordination of exchange rate management have been thoroughly examined. This thesis then considers the implications of exchange rate regimes on the monetary policy. It examines whether the adoption of new exchange rate regime has affected monetary autonomy, concerning the sensitivity of domestic interest rates to international interest rates under different currency regimes, from the cases of the selected East Asian economies during 1994-2004. One of the aspects of the choices of exchange rate regime is its implications for the magnitude of exchange rate volatility and the transmission of this volatility into other countries in the region. This thesis thus carries out an empirical investigation on the exchange rate volatility and cross-country contagion/spillover effect within foreign exchange markets for a group of East Asian countries in the context of the 1997/98 financial crisis. In addition, this thesis provides an investigation on the measurement of foreign exchange market pressure and currency crisis proneness, as well as examines interrelations between exchange market pressure and monetary policy. The post-crisis interactions among EMP, domestic credit growth, and the interest rate differential between domestic and foreign interest rates, in particular, have been investigated for a representative group of East Asian countries. Finally, this thesis provides further evidence on the relationship between stock prices and exchange rates, from the typical case of Hong Kong, to realise what kind of causality prevailed over the period 1995-2001. Based on the high frequency weekly data, both long-run and short-run dynamics between stock prices and exchange rates in Hong Kong are addressed. Various forms of evidence and empirical techniques are extensively applied and fully evaluated for the specific questions addressed in this research. These practical methodologies include Ordinary Least Square (OLS), Generalised Method of Movements (GMM), Generalised Autoregressive Conditional Heteroskedasticity (GARCH), Exponential GARCH (EGARCH), Vector Autoregressions (VAR) and their Impulse Response Functions (IRF), Unit Root Tests, Cointegration, and Granger Causality Tests. All kinds of data sets and sample periods employed in this research provide an interesting comparison to the existing related studies. The main findings and key ideas drawn from this research have important implications for policy markers on the exchange rate management. The study on specific research topics and the comprehensive and thorough applications of various econometric methodologies provide valuable insight in characteristics and patterns of East Asian foreign exchange markets

High-Order Sliding Mode-Based Synchronous Control of a Novel Stair-Climbing Wheelchair Robot

For the attitude control of a novel stair-climbing wheelchair with inertial uncertainties and external disturbance torques, a new synchronous control method is proposed via combing high-order sliding mode control techniques with cross-coupling techniques. For this purpose, a proper controller is designed, which can improve the performance of the system under conditions of uncertainties and torque perturbations and also can guarantee the synchronization of the system. Firstly, a robust high-order sliding mode control law is designed to track the desired position trajectories effectively. Secondly, considering the coordination of the multiple joints, a high-order sliding mode synchronization controller is designed to reduce the synchronization errors and tracking errors based on the controller designed previously. Stability of the closed-loop system is proved by Lyapunov theory. The simulation is performed by MATLAB to verify the effectiveness of the proposed controller. By comparing the simulation results of two controllers, it is obvious that the proposed scheme has better performance and stronger robustness

The ATP-Dependent Protease ClpP Inhibits Biofilm Formation by Regulating Agr and Cell Wall Hydrolase Sle1 in Staphylococcus aureus

Biofilm causes hospital-associated infections on indwelling medical devices. In Staphylococcus aureus, Biofilm formation is controlled by intricately coordinated network of regulating systems, of which the ATP-dependent protease ClpP shows an inhibitory effect. Here, we demonstrate that the inhibitory effect of ClpP on biofilm formation is through Agr and the cell wall hydrolase Sle1. Biofilm formed by clpP mutant consists of proteins and extracellular DNA (eDNA). The increase of the protein was, at least in part, due to the reduced protease activity of the mutant, which was caused by the decreased activity of agr. On the other hand, the increase of eDNA was due to increased cell lysis caused by the higher level of Sle1. Indeed, as compared with wild type, the clpP mutant excreted an increased level of eDNA, and showed higher sensitivity to Triton-induced autolysis. The deletion of sle1 in the clpP mutant decreased the biofilm formation, the level of eDNA, and the Triton-induced autolysis to wild-type levels. Despite the increased biofilm formation capability, however, the clpP mutant showed significantly reduced virulence in a murine model of subcutaneous foreign body infection, indicating that the increased biofilm formation capability cannot compensate for the intrinsic functions of ClpP during infection

A Novel ESAT-6 Secretion System-Secreted Protein EsxX of Community-Associated Staphylococcus aureus Lineage ST398 Contributes to Immune Evasion and Virulence

The ESAT-6 secretion system (ESS) has been reported to contribute to the virulence and pathogenicity of several Staphylococcus aureus strains such as USA300 and Newman. However, the role of the ESS in community-associated S. aureus (CA-SA) lineage ST398 in China is not well understood. By comparing the ess locus of ST398 with the published S. aureus sequence in the NCBI database, we found one gene in the ess locus encoding a novel WXG superfamily protein that is highly conserved only in ST398. LC-MS/MS and Western blot analysis revealed that this protein is a novel secreted protein controlled by the ST398 ESS, and we named the protein EsxX. Although EsxX was not under the control of the accessory gene regulator like many other virulence factors and had no influence on several phenotypes of ST398, such as growth, hemolysis, and biofilm formation, it showed important impacts on immune evasion and virulence in ST398. An esxX deletion mutant led to significantly reduced resistance to neutrophil killing and decreased virulence in murine skin and blood infection models, indicating its essential contribution to the evasion of innate host defense and virulence to support the pathogenesis of ST398 infections. The function of this novel secreted protein EsxX might help us better understand the role of the ESS in the virulence and epidemic success of the CA-SA lineage ST398

The fruits of Xanthium sibiricum Patr: A review on phytochemistry, pharmacological activities, and toxicity

In recent years, drug development and research have gradually shifted from chemical synthesis to biopharmaceutical and natural drugs. Natural medicines, such as traditional Chinese medicine, have been among the first studied because of their long medicinal history, simplicity, and the relatively low cost of research. Among them, Xanthii Fructus (XF) is famous for the treatment of sinusitis. In this article, the achievements of research on XF from 1953 to 2020 are systematically reviewed, focusing on the aspects of chemical constituents, pharmacological effects, clinical applications, toxicity and side effects, and processing methods. To date, there have been significant advances in both the phytochemistry and pharmacology of XF. Some traditional uses have been validated and clarified in modern pharmacological studies. However, its mechanism of action in the treatment of allergic diseases has not been satisfactorily explained. Further in vitro and in vivo studies are required to rationally develop new drugs and to elucidate the therapeutic potential of XF. A comprehensive evaluation of XF and an understanding of network pharmacology are also needed. © 2020 World Journal of Traditional Chinese Medicine | Published by Wolters Kluwer ‑ Medknow

Dynamics of three cavitation bubbles with pulsation and symmetric deformation

A new system of dynamical equations was obtained by using the perturbation and potential flow theory to couple the pulsation and surface deformation of the second-order Legendre polynomials (P2) of three bubbles in a line. The feasibility and effectiveness of the model were verified by simulating the radial oscillations, surface deformation with P2, and shape evolution of three bubbles. The spherical radial pulsation and surface deformation of the three bubbles exhibit periodic behavior. The maximum secondary Bjerknes forces (SBFs) on the three bubbles are found not to depend on the system’s resonance frequency. Within a stable region, the SBFs of the three bubbles increase with increasing sound pressure amplitude but decrease with increasing distance between the bubbles. The primary Bjerknes force (PBF) on a bubble is significantly higher than the SBF on it

Refined secondary Bjerknes force equation for double bubbles with pulsation, translation, and deformation

The secondary Bjerknes force (SBF) is the time-averaged interaction between two bubbles driven in a sound field. We derived a refined formula for the interaction force, incorporating the radial vibration and translational and deformational motions of the bubble. The coupling of pulsation, translation, and deformation enhances the interaction between bubbles but also weakens their stability, making it easier for bubbles to merge or break during motion. The effects of the coupling mode on the magnitude and direction of SBFs coupled with pulsation, translation, and deformation were numerically analyzed and studied. Under certain sound-field conditions, the SBF increased with increasing pressure amplitude, initial radius, and initial velocity, while decreased as the distance increased. In addition, the SBF irregularly increased with increasing frequency

GMANet: Gradient Mask Attention Network for Finding Clearest Human Fecal Microscopic Image in Autofocus Process

The intelligent recognition of formed elements in microscopic images is a research hotspot. Whether the microscopic image is clear or blurred is the key factor affecting the recognition accuracy. Microscopic images of human feces contain numerous items, such as undigested food, epithelium, bacteria and other formed elements, leading to a complex image composition. Consequently, traditional image quality assessment (IQA) methods cannot accurately assess the quality of fecal microscopic images or even identify the clearest image in the autofocus process. In response to this difficulty, we propose a blind IQA method based on a deep convolutional neural network (CNN), namely GMANet. The gradient information of the microscopic image is introduced into a low-level convolutional layer of the CNN as a mask attention mechanism to force high-level features to pay more attention to sharp regions. Experimental results show that the proposed network has good consistency with human visual properties and can accurately identify the clearest microscopic image in the autofocus process. Our proposed model, trained on fecal microscopic images, can be directly applied to the autofocus process of leucorrhea and blood samples without additional transfer learning. Our study is valuable for the autofocus task of microscopic images with complex compositions

Towards indicating human skin state in vivo using geometry-dependent spectroscopic contrast imaging

Skin plays a significant role in human body function and its collagen states change during the human skin ageing process, which affects skin function. We previously reported on geometry-dependent spectroscopic contrast achieved by spectroscopic micro-optical coherence tomography (SμOCT), which discovered that transversely oriented and regularly arranged nano-cylinders selectively backscatter the long-wavelength lights and generate spectral centroid (SC) shifts towards the long wavelengths within a spectral window of 700 - 950 nm. Here we further proposed a novel method towards indicating the state of human skin in vivo using geometry-dependent spectroscopic contrast imaging. The proposed method can obtain spectroscopic contrast images of different human skin layers, including the papillary dermis and reticular dermis, and provide a quantitative method towards indicating collagen state in human skin in vivo. Experimental results have shown that the proposed method may potentially have the ability to assess the state of human skin.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Ministry of Health (MOH)This research was supported by the Singapore Ministry of Health’s National Medical Research Council under its Open Fund Individual Research Grant (MOH-OFIRG19may-0009), Ministry of Education Singapore under its Academic Research Fund Tier 1 (2018-T1-001-144), Agency for Science, Technology and Research (A*STAR) under its Industrial Alignment Fund (Pre-positioning) (H17/01/a0/008) and the National Natural Science Foundation of China under Grant 61905036

Synchronous Phase-Shifting Interference for High Precision Phase Imaging of Objects Using Common Optics

Quantitative phase imaging and measurement of surface topography and fluid dynamics for objects, especially for moving objects, is critical in various fields. Although effective, existing synchronous phase-shifting methods may introduce additional phase changes in the light field due to differences in optical paths or need specific optics to implement synchronous phase-shifting, such as the beamsplitter with additional anti-reflective coating and a micro-polarizer array. Therefore, we propose a synchronous phase-shifting method based on the Mach–Zehnder interferometer to tackle these issues in existing methods. The proposed method uses common optics to simultaneously acquire four phase-shifted digital holograms with equal optical paths for object and reference waves. Therefore, it can be used to reconstruct the phase distribution of static and dynamic objects with high precision and high resolution. In the experiment, the theoretical resolution of the proposed system was 1.064 µm while the actual resolution could achieve 1.381 µm, which was confirmed by measuring a phase-only resolution chart. Besides, the dynamic phase imaging of a moving standard object was completed to verify the proposed system’s effectiveness. The experimental results show that our proposed method is suitable and promising in dynamic phase imaging and measurement of moving objects using phase-shifting digital holography