Regression in random design and Bayesian warped wavelets estimators

In this paper we deal with the regression problem in a random design setting. We investigate asymptotic optimality under minimax point of view of various Bayesian rules based on warped wavelets and show that they nearly attain optimal minimax rates of convergence over the Besov smoothness class considered. Warped wavelets have been introduced recently, they offer very good computable and easy-to-implement properties while being well adapted to the statistical problem at hand. We particularly put emphasis on Bayesian rules leaning on small and large variance Gaussian priors and discuss their simulation performances comparing them with a hard thresholding procedure

The effects of corporate governance mechanisms on the financial leverage–profitability relation

Purpose This paper aims to investigate the moderating effects of corporate governance mechanisms on the financial leverage–profitability relation in emerging market firms. Design/methodology/approach The paper examines the impacts by estimating the empirical model in which a firm’s accounting profitability is a dependent variable, while financial leverage, board size, board independence, CEO duality, CEO ownership, state ownership and the interaction variables are predictors. The paper uses the panel data set of 295 listed firms in Vietnam in the period 2011-2015 and two key econometric methods for panel data, namely, the two-stage least square instrumental variable and general moments method. Findings The paper finds the evidence for the significant and positive effect of board size, board independence and state ownership on the financial leverage–profitability relation. The effect of CEO duality on the financial leverage–profitability relation tends to be negative, and the impact CEO ownership inclines to be positive, although both of them are statistically insignificant. The results are consistent across different estimation methods. Originality/value This paper is the first investigating the moderating effect of various corporate governance mechanisms on the financial leverage–profitability relationship in emerging market firms

Debt financing and firm performance: The moderating role of board independence

This article investigates the moderating role of board independence in the relationship between debt financing and performance of emerging market firms. We have used an empirical model in which the firm’s accounting profitability is a dependent variable and the independent variables are debt financing, board independence, the interaction variable made of debt financing and board independence as well as various control variables. Our analysis is based on a panel data set of 300 listed firms in Vietnam between 2013 and 2017. Our study finds that debt financing has a significantly negative effect and that board independence reduces the adverse impact of debt financing on accounting profitability. Our results are consistent across different estimation models and methods

Changes of benthic macroinvertebrates in Thi Vai River and Cai Mep Estuaries under polluted conditions with industrial wastewater

The pollution on the Thi Vai River has been spreading out rapidly over the two lasted decades caused by the wastewater from the industrial parks in the left bank of Thi Vai River and Cai Mep Estuaries. The evaluation of the benthic macroinvertebrate changes was very necessary to identify the consequences of the industrial wastewater on water quality and aquatic ecosystem of Thi Vai River and Cai Mep Estuaries. In this study, the variables of benthic macroinvertebrates and water quality were investigated in Thi Vai River and Cai Mep Estuaries, Southern Vietnam. The monitoring data of benthic macroinvertebrates and water quality parameters covered the period from 1989 to 2015 at 6 sampling sites in Thi Vai River and Cai Mep Estuaries. The basic water quality parameters were also tested including pH, dissolved oxygen (DO), total nitrogen, and total phosphorus. The biodiversity indices of benthic macroinvertebrates were applied for water quality assessment. The results showed that pH ranged from 6.4 – 7.6 during the monitoring. The DO concentrations were in between 0.20 – 6.70 mg/L. The concentrations of total nitrogen and total phosphorous ranged from 0.03 – 5.70 mg/L 0.024 – 1.380 mg/L respectively. Macroinvertebrate community in the study area consisted of 36 species of polychaeta, gastropoda, bivalvia, and crustacea, of which, species of polychaeta were dominant in species number. The benthic macroinvertebartes density ranged from 0 – 2.746 individuals/m2 with the main dominant species of Neanthes caudata, Prionospio malmgreni, Paraprionospio pinnata, Trichochaeta carica, Maldane sarsi, Capitella capitata, Terebellides stroemi, Euditylia polymorpha, Grandidierella lignorum, Apseudes vietnamensis. The biodiversity index values during the monitoring characterized for aquatic environmental conditions of mesotrophic to polytrophic. Besides, species richness positively correlated with DO, total nitrogen, and total phosphorus. The results confirmed the advantage of using benthic macroinvertebrates and their indices for water quality assessment

Student-centredness: Exploring the Culturally Appropriate Pedagogical Space in Vietnamese Higher Education Classrooms using Activity Theory

Recently leaders in many Asian countries have advocated for student-centred reform agendas. However, bringing about pedagogical change is not simply a technical issue of implementing practices designed elsewhere but is a more substantive issue concerned with local cultural values and context. Researchers have claimed that to sustain the reform, the initiative needs to be modified integrating local values in a hybrid manner. The present study, involving two lecturers and 100 university students in Vietnam, used third generation of activity theory, to document how the lecturers created bridging and hybrid strategies that combined both traditional teaching practices and novel student-centred practices. These hybrid practices helped students improve their learning outcomes, especially enhance their complex knowledge. Implications for University providers were discussed

Efficient Inversion of Multiple-Scattering Model for Optical Diffraction Tomography

Optical diffraction tomography relies on solving an inverse scattering problem governed by the wave equation. Classical reconstruction algorithms are based on linear approximations of the forward model (Born or Rytov), which limits their applicability to thin samples with low refractive-index contrasts. More recent works have shown the benefit of adopting nonlinear models. They account for multiple scattering and reflections, improving the quality of reconstruction. To reduce the complexity and memory requirements of these methods, we derive an explicit formula for the Jacobian matrix of the nonlinear Lippmann-Schwinger model which lends itself to an efficient evaluation of the gradient of the data- fidelity term. This allows us to deploy efficient methods to solve the corresponding inverse problem subject to sparsity constraints