79 research outputs found
Strong convergence of a linearization method for semi-linear elliptic equations with variable scaled production
No full textThis work is devoted to the development and analysis of a linearization algorithm for microscopic elliptic equations, with scaled degenerate production, posed in a perforated medium and constrained by the homogeneous Neumann-Dirichlet boundary conditions. This technique plays two roles: to guarantee the unique weak solvability of the microscopic problem and to provide a fine approximation in the macroscopic setting. The scheme systematically relies on the choice of a stabilization parameter in such a way as to guarantee the strong convergence in H-1 norm for both the microscopic and macroscopic problems. In the standard variational setting, we prove the H-1-type contraction at the micro-scale based on the energy method. Meanwhile, we adopt the classical homogenization result in line with corrector estimate to show the convergence of the scheme at the macro-scale. In the numerical section, we use the standard finite element method to assess the efficiency and convergence of our proposed algorithm.V.A.K. thanks Prof. Adrian Muntean for being his supervisor since March, 2015 and for giving him invaluable advice. V.A.K thanks Prof. Iuliu Sorin Pop (Hasselt, Belgium) for recent supports in his research career and acknowledges the hospitality of the Hasselt University during the time he is hosted as a postdoctoral fellow. N.N.N. acknowledges the support of the project INdAM Doctoral Programme in Mathematics and/or Applications Cofunded by Marie Sklodowska-Curie Actions, acronym: INdAM-DP-COFUND-2015, grant number: 713485.Ngoc, NN (corresponding author), Politecn Milan, Dipartimento Matemat, I-20133 Milan, Italy.
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Existence, blow-up and exponential decay of solutions for a porous-elastic system with damping and source terms
No full textIn this paper we consider a porous-elastic system consisting of nonlinear boundary/interior damping and nonlinear boundary/interior sources. Our interest lies in the theoretical understanding of the existence, finite time blow-up of solutions and their exponential decay using non-trivial adaptations of well-known techniques. First, we apply the conventional Faedo-Galerkin method with standard arguments of density on the regularity of initial conditions to establish two local existence theorems of weak solutions. Moreover, we detail the uniqueness result in some specific cases. In the second theme, we prove that any weak solution possessing negative initial energy has the latent blow-up in finite time. Finally, we obtain the so-called exponential decay estimates for the global solution under the construction of a suitable Lyapunov functional. In order to corroborate our theoretical decay, a numerical example is provided.This research is funded by Vietnam National University Ho Chi Minh City (VNU-HCM) under Grant no. B2017-18-04. The work of the first author was partly supported by a postdoctoral fellowship of the Research Foundation-Flanders (FWO)
Thu Vo Phien (Vo Phien's Letters) [In Vietnamese]
No full textVO PHIEN'S LETTERS In this book (384 pages), I write about Vo Phien's letters. In Western countries, collections of letters written by famous writers are fairly common. This has a long tradition which can be traced back more than two thousand years to ancient Greek literature. In Vietnam the situation is different: This is the first collection of letters written by a Vietnamese author which has been published. Vo Phien's letters are not only beautifully written but also reveal his colorful life and his deep thoughts on literature and art. It is useful for critics and literary historians who want to study modern Vietnamese literature, particularly, literature in exile
Correction to: Strong convergence of a linearization method for semi-linear elliptic equations with variable scaled production
No full textThis article is a correction to our paper Khoa et al. (2020b).Ngoc, NN (corresponding author), Politecn Milan, Dipartimento Matemat, I-20133 Milan, Italy.
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Panisea sondangii Aver. 2023, comb. nov.
No full textPanisea sondangii (Vuong, Aver. & V.H.Bui) Aver., comb. nov. ≡ Coelogyne sondangii Vuong, Aver. & V.H.Bui in, D.T. Vo et al. (2022: 201, fig. 1). Type: — VIETNAM. Lai Chau Province, Sin Ho District, Lang Mo Commune, forest around Tu Cua Phin Village, 23 March 2022, Truong Ba Vuong, Bui Van Huong, BV 1357 (holotype VNM 00069946). Notes:—Following almost all recent orchid assessments and monographs (Seidenfaden 1986, 1992, Lund 1987, Pearce & Cribb 2002, Schuiteman et al. 2008, Chen et al. 2009, Rokaya et al. 2013: 539, Zhou et al. 2016: 34, Ormerod et al. 2021: 74), we accept Panisea (Lindley 1833: 44) Steudel (1841: 265) as a genus separate from Coelogyne Lindley (1821: t. 33) due to clear morphological evidence. Hence, we proposed the new nomenclatural combination made above. Data on ecology, phenology, distribution, and conservation status were reported earlier (Vo et al. 2022).Published as part of Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), pp. 87-110 in Phytotaxa 597 (2) on page 93, DOI: 10.11646/phytotaxa.597.2.1, http://zenodo.org/record/792919
Parnassia procul H. Turner & Veldkamp 2001
No full text2. Parnassia aff. procul H. Turner & Veldkamp (2001: 601) (Fig. 5) Specimen examined: — VIETNAM. Lam Dong Province: Lac Duong District, Langbian Mountain, near summit, grassland area in evergreen forest, around point 12°01.879’N 108°24.759’E, at an elevation of 1847 m a.s.l., 5 September 2018, Pham Van The, Vo Duc Quang PVT1027 (photos LE: LE01093239 http://en.herbariumle.ru/?t=occ&id=99498). Phenology: —Flowering and fruiting in August–September. Habitat and ecology: —The species grows in an open place near the mountain summit. The area is covered with a pine forest; the forest floor is inhabited by various ferns, Poaceae and Melastomataceae. Brief description and notes: —The population recently discovered in mountains of Lam Dong Province is insufficiently known, but quite distinct morphologically. It is characterized by broadly cordate basal leaves, floriferous stem with a single cauline leaf inserted approximately at its middle, almost entirely white petals (only very slightly greenish at base adaxially) divided into claw and blade, obovate-rhomboid petal blade, triangular petal apex, fimbriate petal margin with fimbriations of short to medium length, anther connective without apical projection, and conspicuously three-lobed staminodes with subequal slightly thickened lobes. The plants in question do not correspond to any of the species included in the treatment of Parnassia in «Flora of China » (Gu & Hultgård 2001). The keys provided by Gu & Hultgård (2001) lead to P. epunctulata J.T. Pan (1985: 220) endemic to NW Yunnan, from which the Lam Dong plants differ in several traits including broader basal leaves and uniformly subequal (vs. sometimes unequal) staminode lobes. Within the preliminary account of Parnassia in Thailand (Suksathan 2009), P. mysorensis B.Heyne ex Wight & Arnott (1834: 35) is described to have a broad variation, so that the Lam Dong plant appears to fit within the concept of this species. However, the concept proposed by Suksathan (2009) contradicts the description of P. mysorensis by Gu & Hultgård (2001): in the latter treatment, P. mysorensis is stated to possess entire, erose, or serrate (but not fimbriate) petal margin, which prevents assignment of the Lam Dong plant to this species. The record Pham Van The, Vu Dinh An PVT1027 is remarkably similar to P. procul in the majority of vegetative and floral traits, including leaf shape, shape of petal margin and staminode morphology (Turner & Veldkamp 2001, see also De Wilde & Duyfjes 1994). The Lam Dong plant differs from P. procul in obovate-rhomboid (vs. spathulate) petals with triangular and more or less acute (vs. obtuse to truncate) apex; however, this difference can possibly be a manifestation of an infraspecific variation. A significant variation of petal shape is already known, for example, in P. wightiana (Gu & Hultgård 2001). Taking all these arguments into account, we provisionally assign Pham Van The, Vu Dinh An PVT1027 to P. procul, a species hitherto known only from Mount Leuser in northern Sumatra (Turner & Veldkamp 2001). This finding represents a second species of Parnassia recorded in the flora of Vietnam. We argue that a comprehensive investigation of this population, including molecular phylogenetic studies, is needed for further clarification of its identity. In addition, a broad-scale morphological and phylogenetic revision of Asian tropical and subtropical Parnassia is required in order to better understand species boundaries in this genus, and make the species identification more straightforward.Published as part of Pham, Ngoc Hoai, Ren, Ming-Xun, Nuraliev, Maxim S., Trinh, Ngoc Bon, Nguyen, Tien Dat, Ragupathi, Gopi & Pham, Van The, 2022, The genus Parnassia in Vietnam, and a checklist of Vietnamese Celastraceae, pp. 213-227 in Phytotaxa 536 (3) on pages 220-221, DOI: 10.11646/phytotaxa.536.3.2, http://zenodo.org/record/633184
Research on the Role of Student-Faculty Social Interaction Outside Class in Training Soft Skills
No full textThe research assessed the importance of social interaction outside class between lecturers and university students in training soft skills courses at FPT University in Ho Chi Minh City. The results of a random survey of 363 students studying at the university using questionnaires and in-depth interviews show the significant role of implementing and maintaining social interactions from various angles. The importance is increasing the interestingness of the lessons, thereby enhancing learning outcomes and the practical experience related to the course. So, they help those courses achieve the original purpose for which the school included them in the curriculum framework. Overall, most students have a relatively high level of satisfaction with their instructors in these social interactions. However, some lecturers are still cautious about this trend, thus causing student satisfaction levels to move in the opposite direction. Besides, the research also shows much lack of standards among students when their relationship with lecturers is no longer encapsulated in the classroom. Since then, the author has also come up with several solutions so that social interaction outside class can maximize its role in teaching and learning soft skills courses
Antimicrobial activity of marine fungi isolated from the Son Tra peninsula, Da Nang, Vietnam
No full textMarine fungi have become an important source of bioactive natural products. The present study was concerned with the screening of antimicrobial activity from 73 fungal strains isolated from various marine habitats collected from five different localities at the Son Tra Peninsula, Da Nang, Vietnam. For the first step of screening, ethyl acetate extract of each fungal isolate was prepared and their antimicrobial activity against the human microbial pathogens was investigated using the disc diffusion method. The panel of human microbial pathogens used were Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Listeria monocytogenes ATCC 19111, Streptococcus faecalis ATCC 19433 and Candida albicans ATCC 10231. Among 73 fungal isolates, 29 exhibited antimicrobial activity against at least two tested pathogens. The proportion of the fungal isolates having anti-microbial activity against B. cereus, S. faecalis, L. monocytogenes, S. aureus, E. coli, C. albicans and P. aeruginosa were 42, 33, 31, 22, 7, 5 and 3%, respectively. Further investigations to isolate and characterize the anti-microbial components in the extracts are needed. Citation: Phan Thi Hoai Trinh, Ngo Thi Duy Ngoc, Vo Thi Dieu Trang, Le Quoc Phong, Phi Quyet Tien, Bui Minh Ly, Tran Thi Thanh Van, 2017. Antimicrobial activity of marine fungi isolated from the Son Tra peninsula, Da Nang, Vietnam. Tap chi Sinh hoc, 39(4): 457-462. DOI: 10.15625/0866-7160/v39n4.8889. *Corresponding author: [email protected] Received 20 November 2016, accepted 12 August 2017 </jats:p
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