STEM Teaching Skills of Primary School Teachers: The Current Situation in Ho Chi Minh City, Vietnam

STEM education is an educational solution that prepares pupils for the future by connecting scientific knowledge with practical applications. This modern method of education is being widely applied in developing countries in order to maintain their scientific and technical standing and strengthen their competition in the global economy. In Vietnam, special attention has been paid to STEM education, as is demonstrated by the policies and guidelines of the Party and State. However, are the skills of the universal teaching staff, particularly in primary schools, sufficient to satisfy the demand for STEM education? A survey was carried out to analyze the current situation with regards the STEM teaching skills of primary school teachers in the district of Thu Duc, Ho Chi Minh City. By analyzing the survey results using SPSS, this article presents the current status of the STEM teaching skills of the primary school teachers in Thu Duc, Ho Chi Minh City, and suggests some solutions to improve and develop teachers’ STEM education skills, suitable for the teaching conditions in Ho Chi Minh City, Vietnam

Precoding Designs for Full-Duplex Multi-User MIMO Cognitive Networks with Imperfect CSI

This paper studies a cognitive radio (CR) network which consists of a full-duplex (FD) multi-user (MU) multipleinput multiple-output (MIMO) secondary user (SU) networks operating within the coverage of multiple primary users (PUs). It is assumed that the channel state information (CSI) matrices associated with SU systems are perfectly known whereas the CSI ones from SUs to PUs are imperfectly estimated. The problem of interest is to design robust precoding matrices at the SUs to maximize the CR sum rate subject to the SU transmit power constraints and harmful interference restrictions at PUs. Due to non-concavity of the objective function and intractability of robust PU interference constraints, the design problem is non-convex and challenging to directly solve. We exploit the difference of two concave functions to recast the sum rate objective function as a lower bounded concave one. In addition, a linear matrix inequality (LMI) transformation is used to handle the semi-infinite robust interference constraints. Then, the sequential convex programming method is carried out to iteratively solve a convex optimization problem in each iteration. The simulation results are provided to investigate the CR sum-rate (spectral efficiency) performance and the robustness against the CSI uncertainty

ẢNH HƯỞNG CỦA ĐỘ MẶN ĐẾN TỐC ĐỘ SINH TRƯỞNG, TỶ LỆ SỐNG VÀ HỆ SỐ CHUYỂN HÓA THỨC ĂN CỦA CÁ BỐNG BỚP (Bostrychus sinensis) GIAI ĐOẠN GIỐNG

Tóm tắt: Đối tượng của nghiên cứu này là con giống từ 1 đến 3 tháng tuổi. Thí nghiệm được tiến hành với 4 độ mặn khác nhau gồm 5, 10, 15 và 20‰, được bố trí theo kiểu ngẫu nhiên hoàn toàn, mỗi nghiệm thức lặp lại 3 lần. Cá thí nghiệm được cho ăn cá nục gai xay nhuyễn, cho cá ăn 2 lần/ngày với lượng cho ăn bằng 5% khối lượng thân. Độ mặn khác nhau có ảnh hưởng đến tốc độ sinh trưởng và hệ số chuyển hóa thức ăn của cá (p < 0,05), nhưng không ảnh hưởng đến tỷ lệ sống của cá (p > 0,05) sau 50 ngày thí nghiệm. Tốc độ sinh trưởng và hệ số chuyển hóa thức ăn của cá tốt nhất khi ương trong môi trường có độ mặn 15‰, có sự khác biệt so với nghiệm thức 5‰ hoặc 20‰ nhưng không khác biệt giữa độ mặn 5, 10 và 20‰ và giữa độ mặn 10‰ và 15‰. Kết quả của thí nghiệm cho thấy có thể tiến hành ương cá bống bớp giai đoạn giống từ 1 đến 3 tháng tuổi ở độ mặn từ 10‰ đến 20‰ để đạt hiệu quả tốt nhất.Từ khóa: cá bống bớp, chuyển hóa thức ăn, độ mặn, sinh trưởng, tỷ lệ sốn

A SURVEY OF STUDENTS’ ABILITY OF IDENTIFYING ERRORS IN WRONG SOLUTIONS FOR THE MATHEMATICAL PROBLEMS RELATED TO THE MONOTONICITY OF FUNCTIONS

The monotonicity of a function plays an important role in the general mathematics curriculum in Vietnam, because it is considered as an effective tool for solving mathematical problems involved with the monotonic intervals of functions, their extreme, absolute maximum value and absolute minimum value. Normally, students commit errors in solving these problems because of their complexity and difficulty. In addition, specific characteristics of knowledge also make children make mistakes. The sample consisted of 362 students, and they had the task of identifying errors in false assumptions. From the results of the survey, it was found that when dealing with the monotonicity of the functions, students were still misled.  Article visualizations

Green Tea Epigallocatechin Gallate Exhibits Anticancer Effect in Human Pancreatic Carcinoma Cells via the Inhibition of Both Focal Adhesion Kinase and Insulin-Like Growth Factor-I Receptor

The exact molecular mechanism by which epigallocatechin gallate (EGCG) suppresses human pancreatic cancer cell proliferation is unclear. We show here that EGCG-treated pancreatic cancer cells AsPC-1 and BxPC-3 decrease cell adhesion ability on micro-pattern dots, accompanied by dephosphorylations of both focal adhesion kinase (FAK) and insulin-like growth factor-1 receptor (IGF-1R) whereas retained the activations of mitogen-activated protein kinase and mammalian target of rapamycin. The growth of AsPC-1 and BxPC-3 cells can be significantly suppressed by EGCG treatment alone in a dose-dependent manner. At a dose of 100 μM which completely abolishes activations of FAK and IGF-1R, EGCG suppresses more than 50% of cell proliferation without evidence of apoptosis analyzed by PARP cleavage. Finally, the MEK1/2 inhibitor U0126 enhances growth-suppressive effect of EGCG. Our data suggests that blocking FAK and IGF-1R by EGCG could prove valuable for targeted therapy, which can be used in combination with other therapies, for pancreatic cancer

Phenomenology of the Reduced Minimal 3-3-1 Model

The detailed analysis of the gauge model based on $\mathrm{SU}(3)_C\otimes \mathrm{SU}(3)_L \otimes \mathrm{U}(1)_X$ group with minimal content of lepton and Higgs is presented. It is shown that with just two Higgs triplets, all fermions and gauge bosons can get correct   masses. The advantage of the model under consideration is that a huge number of free parameters is reduced, and the model's predictiveness is much improved

Isolation and characterization of Rhizobium spp. and Bradyrhizobium spp. from legume nodules

Rhizobia topic has been re-focused in recent years because of new findings on their traits not only as nitrogen-fixing bacteria but also as plant growth-promoting rhizobacteria. When combing rhizobial strains with novel biological carriers (e.g., biochar) for inoculant production, it brings great potential for improving soil health in long-term. Appreciating this trend, this study is designed to isolate and characterize local rhizobial strains from legume fields using the conventional method with some modifications to increase efficiency in rhizobial identification. As a result, 17 rhizobial strains were isolated and classified biochemically that genetic identification outcome confirmed 10 strains belong to 07 different Rhizobium species as R. mayense, R. paknamense, R. pusense, R. miluonense, R. tropici, R. phaseoli, and R. multihospitium while the rest belong to 06 various Bradyrhizobium species as B. elkanii, B. centrosematis, B. guangxiense, B. liaoningense, B. yuanmingense, and B. arachidis. Thermal and saline tolerant tests together with seed germination tests also performed on these rhizobial strains to gain data on their responses to abiotic stresses. By comparing rice and mung bean GI values, we can assess the effectiveness of each rhizobial strains to help seeds at their early germination

Luminescence spectra and kinetics of disordered solid solutions

We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the wells of random potential induced by disorder. Classification of optically active tail states of the main exciton band into two groups is proposed. The majority of the states responsible for the optical absorption corresponds to the group of extended states belonging to the percolation cluster, whereas only a relatively small group of “radiative” states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the “radiative” localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found that the analysis of the exciton-phonon interaction gives the information about the character of the localization of excitons. We have shown that the model used describes quite well the experimental cw spectra of CdS(1−c)Sec and ZnSe(1−c)Tec solid solutions. Further, the experimental results are presented for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated “radiative” states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long delay times are presented. It is shown that the observed temporal behavior can be described in terms of relaxation of separated pairs followed by subsequent exciton formation and radiative recombination. Electron tunneling processes are supposed to be responsible for the luminescence in the long-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence

The Role of Insulin-Like Growth Factor- Binding Protein 5 in Systemic Sclerosis- Associated Pulmonary Fibrosis

Pulmonary fibrosis is a hallmark of diseases such as systemic sclerosis (SSc, scleroderma) and idiopathic pulmonary fibrosis (IPF). SSc is a complex autoimmune disease that is characterized by progressive fibrosis of the skin and multiple visceral organs. Despites multiple studies, the etiology of this connective tissue disease is still unknown, causing high morbidity and mortality in the patients. To date, therapeutic options are limited, and organ transplantation remains the only viable option for SSc­associated lung disease. Therefore, identifying novel therapeutic targets is critical for advancing the treatment of SSc. Insulin-like growth factor-binding protein-5 (IGFBP-5) is the most conserved member of the IGFBP family of proteins that is overexpressed in SSc and IPF. Some of the mechanisms mediating the effects of IGFBP-5 and downstream signaling pathways have been identified, the question to whether the promotion of fibrosis was directly mediated by IGFBP-5 or via other pro-fibrotic factors that may be downstream of IGFBP-5 had remained unanswered. Therefore, we investigated the role of IGFBP-5 in the pathophysiology of SSc using in vitro, ex vivo and in vivo models. Our data showed that both exogenous and adenovirally expressed IGFBP-5 promote fibrosis by increasing the production of extracellular matrix (ECM) genes and the expression of pro-fibrotic genes in primary human lung fibroblasts and tissues. IGFBP-5 also increased expression of the pro-fibrotic growth factor CTGF and levels of the matrix crosslinking enzyme lysyl oxidase (LOX). IGFBP-5 promotes its own expression, generating a positive feedback loop. This suggests that IGFBP-5 likely acts in concert with other growth factors to drive fibrosis and tissue remodeling. Further, our findings demonstrated that LOX expression and activity correlated with fibrosis in vitro, ex vivo, and in vivo. LOX induced ECM production via upregulation of IL-6 and nuclear localization of c-Fos. Thus, LOX has a direct pathogenic role in SSc-associated fibrosis that is independent of its crosslinking function. The pro-fibrotic effects of IGFBP-5 was further examined in transgenic mice overexpressing human IGFBP-5. Our data show that the heterozygous and homozygous mice are viable and express human IGFBP-5 (hIGFBP-5). Transgenic mice had increased expression of extracellular matrix (ECM) genes, especially Col3a1, Fn and Lox in lung and skin tissues of mice expressing higher transgene levels. Histologic analysis of the skin tissues showed increased dermal thickness, and the lung histology showed subtle changes in the heterozygous and homozygous mice compared to the wild-type mice. These changes were more pronounced in animals expressing higher levels of hIGFBP-5. Bleomycin increased ECM gene expression in wild-type and accentuated the increase in ECM gene expression in transgenic mice, suggesting that transgene expression exacerbates bleomycin-induced pulmonary fibrosis. Primary lung fibroblasts cultured from lung tissues of homozygous transgenic mice showed significant increases in ECM gene expression and protein levels, further supporting the observation that IGFBP-5 results in a fibrotic phenotype in fibroblasts. Primary lung fibroblasts cultured from lung tissues of transgenic mice showed increased ECM production, suggesting that the effects of IGFBP-5 are cell-type and tissue-specific. In conclusion, these studies capitalize on knowledge gained about the impact of IGFBP-5 and LOX playing a direct pathogenic role in SSc. Our findings from the study provide a new platform for developing therapies targeting IGFBP-5 and/or LOX function to treat SSc and other fibrotic disorders