Spectral stability of travelling waves in the Fisher-Kolmogorov-Petrovsky-Piskunov and Fisher-Stefan models

The reaction-diffusion equations including the Fisher-Kolmogorov-Petrovsky-Piskunov (Fisher-KPP) and Fisher-Stefan model have been used to study biological invasion. In this thesis, we first consider the standing waves and travelling waves of the Fisher- KPP equation and the behaviour of the dynamical system near the equilibrium points. Next, we examine the existence of solutions to the Fisher-KPP model by constructing a trapping region in the plane for the wave speed ≠ 0. Then, we study stability of standing waves and travelling waves of this model by looking at the point spectrum, the asymptotic operator and the essential spectrum. However, a limitation of the Fisher-KPP equation is that it cannot be used to model the extinction of invasive populations in practical situations. Hence, the Fisher-Stefan equation is introduced to simulate both biological invasion for > 0 and recession for < 0. This model is reformulated from the Fisher-KPP equation and includes a moving boundary, which gives rise to a spreading-vanishing dichotomy. Moreover, we look at the existence and uniqueness of solutions to the Fisher-Stefan equation. By analysing the phase portrait, numerical results and the perturbation solutions, we can construct approximate solutions of the Fisher-Stefan equation. This phase portrait of this model also suggests that the solutions of the Fisher-KPP model exist for < 2 but they are unstable. Therefore, these solutions are disregarded when < 2 and considered as not exist. This unstable solution has value in describing solution of Fisher- Stefan problem. Thus, the stable solutions exist in the Fisher-Stefan problem. Last, we consider the spectral stability of the Fisher-Stefan equation by analysing its asymptotic operator, continuous spectrum and point spectrum. The results indicate that there is no point spectrum of the Fisher-Stefan asymptotic solution for the eigenvalue parameter > 1 at ≥ 0

Large displacements of FGSW beams in thermal environment using a finite element formulation

The large displacements of functionally graded sandwich (FGSW) beams in thermal environment  are studied using a finite element formulation. The beams are composed of three layers, a homogeneous core and two functionally graded face sheets with volume fraction of constituents following a power gradation law. The material properties of the beams are considered to be temperature-dependent.  Based on Antman beam model and the total Lagrange formulation, a two-node nonlinear beam element taking the effect of temperature rise into account  is formulated and employed in the study. The element with explicit expressions for the internal force vector and tangent stiffness matrix is derived using linear interpolations and reduced integration technique to avoid the shear locking. Newton-Raphson based iterative algorithm is employed in combination with the arc-length control method to compute the large displacement response of a cantilever FGSW beam subjected to end forces.  The accuracy of the formulated element is confirmed through a comparison study. The effects of the material inhomogeneity, temperature rise and layer thickness ratio on the large deflection response of the beam are examined and highlighted

Factors Affecting Intention to Transact by Electronic Payment in Supermarkets in Hanoi (Vietnam)

The study is conducted based on 391 observational samples in Hanoi with the context that Vietnam is promoting digital transformation in all aspects of life. Research has shown that: “Performance Expectancy”, “Effort Expectancy”, “Social Influence”, “Facility Conditions” and “Security and Privacy” have a positive impact on the e-payment intention of shoppers in supermarkets in Hanoi, especially Facility Condition is the most influential factor. In addition, the result also found that the age variable also acts as a crucial driver factor in the process of forming human intentions, while the gender variable has no impact on that process. The study of factors that can affect the intention of electronic payment contributes more theoretical basis in this field, as well as provide a more realistic view of the situation of using electronic payment in Vietnam in general, creating a driving force for the promotion of the development of electronic payment regularly in terms of frequency of application and diversity of application forms. In this study, the authors, besides inheriting domestic and foreign studies on electronic payment, also develop innovative points compared to previous studies. The study uses the new approach to study electronic payment through transactions in supermarkets and assess the role of demographic variables on user intention. Keywords: electronic payment, supermarket, solutions DOI: 10.7176/EJBM/13-11-02 Publication date:June 30th 202

CAUSE-EFFECT RELATIONS AND OPTIMIZATION OF TABLET CONTAINING EUCOMMIA ULMOIDES AND GARDENIA JASMINOIDES SPRAY-DRIED EXTRACTS

Objective: The E. ulmoides and G. jasminoides (EG) tablets containing 67 mg E. ulmoides spray-dried extract (ESE) and 173 mg G. jasminoides spray-dried extract (GSE) were prepared by employing the direct compression method. Due to the poor flowability and compressibility of the two spray-dried extracts, various excipients were added at different ratios so that the blends can be compressed into tablets with the required standards. This study aimed at the cause-effect relations and optimization of the EG tablet formulation.Methods: Different diluents including dibasic calcium phosphate anhydrous (DCPA), silicified microcrystalline cellulose (SMCC), spray-dried lactose (SDL) and the active ingredients (blend of ESE and GSE at the ratio of 67:173, w/w) were separately investigated their own physical properties. The binary mixtures of the active ingredients with different ratios of DCPA, SMCC, and SDL were evaluated their flowability. D-optimal design based on three independent variables (% DCPA, % croscarmellose sodium (CCS) and % SMCC) was applied to evaluate the cause-effect relations and optimize the EG tablet formulation. The weight variation, disintegration time, hardness and friability were investigated as four dependent variables.Results: The flowability of the powders was found to be affected by the particle size distribution, particle shape and density. The three diluents could significantly improve the flowability of the active ingredients. All independent variables had significant effects on the dependent variables. An increase in % SMCC reduced the weight variation, hardness and increased the friability of tablets. Disintegration time was found to be in the negative relations with % CCS. The tablet hardness was in positive relations with % DCPA. The optimized EG tablet formulation composed of 9 % DCPA (w/w), 35 % SMCC (w/w), and 14 % CCS (w/w) of the excipient blend. The weight variation, disintegration time, hardness and friability of the optimized EG tablets were found to be 1.8 %, 11.7 min, 61.4 N, and 0.5 %, respectively.Conclusion: The ESE and GSE could be formulated into tablet by using direct compression method. The cause-effect relations and optimization of EG tablet formulation were studied and reported for the first time

K.Marx-Engels and Ho Chi Minh Viewpoints on Journalism - and Two Fake News Publishing Cases of Thanhnien.vn and Tuoitre.vn (Online Magazines) in Vietnam and Lessons from Indonesia, Japan Approaches

In this paper, by using qualitative analytical analysis with 2 case examples of Thanh nien and Tuoi tre newspapers (online) in Vietnam, in which there are history of publishing fakes news online from 2015, 2016, 2018, 2022 (with very bad editors Nguyen Ngoc Toan and Dang Thi Phuong Thao), as well as giaoduc.edu.vn and vietnamnet.vn in 2022 so we will address some points in this study based on answers for question: “What are regulatory lessons from Indonesia and Japan approaches on publishing fake news?”. We would suggest that there are penalties for negative behaviors of posting fake news online (any fake information) in the context of covid 19 epidemic. Tapsell (2019) defined ‘hoax news’ as similar to the more globally recognized term ‘fake news’: material deliberately fabricated and masqueraded as truth. At last, we will draw some lessons from K.Marx and Ho Chi Minh viewpoints on journalism for educating young generation in emerging markets such as Vietnam

Publishing Fake Information Online-Case of Online Vietnam Magazines (Thanhnien Newspaper, Tuoi tre newspaper, Vietnamnet.vn, dantri.com.vn, giaoduc.edu.vn, sctv.com.vn, etc.) From an Approach of German and EU Laws and Cybersecurity Regulations

Publishing fake information have at least three bad effects on the community: creating disinformation, anxiety, and disorder in society. Still using qualitative analytical methods with synthesis and inductive methods, the authors will address 2 cases of Vietnam magazines:&nbsp;thanhnien. vn and tuoitre.vn, vietnamnet. vn, giaoduc.edu.vn, dantri.com.vn, (online newspapers) and recently sctv.com.vn&nbsp;with their issue of publishing fake news online, which increasing as a problem in recent years 2015-2020. In this paper, we also use the European approach and laws on exploring the issue of publishing and delivering false information via the internet and social media. Last but not least, the views and ideologies of V.I Lenin and Ho Chi Minh on journalism and journalists are mentioned for educating the young generation

STUDY ON CAUSE-EFFECT RELATIONS AND OPTIMIZATION OF TABLETS CONTAINING AQUILARIA CRASSNA SPRAY-DRIED EXTRACT

Objective: The aim of this study was to develop and optimize the formulation of tablets containing Aquilaria crassna extract using the direct compression method.Methods: D-optimal design based on three independent variables was applied to evaluate the cause-effect relations and optimize the A. crassna tablet formulation. The weight variation (Y1), disintegration time (Y2), hardness (Y3) and friability (Y4) were investigated with respect to three independent variables including % dicalcium phosphate anhydrous (DCPA) in filler (X1), % filler (X2) and % croscarmellose sodium (CCNa) (X3). The dissolution study of the optimized A. crassna tablets were investigated in simulated gastric fluid (SGF) (pH 1.2) using a validated high-performance liquid chromatography (HPLC) method for mangiferin analysis.Results: All investigation factors were found to have significant effects on the physical properties of A. crassna tablet. The tablet hardness and the disintegration time increased in positive relations with the ratios of DCPA. The results exhibited the negative relations between disintegration time and the percentages of CCNa. The optimized A. crassna tablet formulation which included 35 % (w/w) DCPA in filler, 60 % (w/w) filler and 7% (w/w) CCNa possessed the weight variation of 1.38 % (w/w), the disintegration time of 6.29 min, the hardness of 85.63 N and the friability of 0.41 % (w/w). The optimized A. crassna tablet formulation was experimentally examined which demonstrated a good agreement between the experimental and predicted values. Mangiferin was found to release completely from the optimized A. crassna tablets within 30 min.Conclusion: The cause-effect relations and optimization of A. crassna tablet formulation were investigated and reported for the first time. The A. crassna spray-dried extract could be formulated into tablet by direct compression method with good mechanical properties and acceptable release profile

Foreign bank penetration in Vietnam following Vietnam’s accession to the WTO: matching expectations with reality

Vietnam continuously liberalizes the financial market as a requirement for its accession to the World Trade Organization in 2007. This paper discusses the foreign investors’ expectation and their experience when penetrating into Vietnam’s market. The role of the foreign entrants is also assessed. By synthesizing and analyzing relevant research and reports, several important insights are discovered. Firstly, the presence of foreign investors and banks improves market competition, efficiency, and stability. Wholly and partly foreign-owned banks provide the spillover effects in management quality, in the introduction of world standard banking products and services, and in the application of information technology. Secondly, by looking into the foreign owned banks, it is found that the banks’ foreign investors are not likely to play an influential role in managing the banks they invested in. The motive of the investors to control the invested companies leads to their decision of holdings withdrawing