Dalat University Journal of Science / Tạp chí khoa học Đại học Đà Lạt
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SOME GEOMETRIC PROPERTIES OF WHITNEY STRATIFICATIONS
Get PDFWe describe some old and new results about Whitney stratifications and state some open problems
POPULATION GENETIC DIVERSITY OF CAMELLIA DILINHENSIS ON THE DI LINH PLATEAU OF VIETNAM REVEALED BY ISSR AND SCOT MARKERS
Get PDFGenetic diversity of naturally distributed Camellia dilinhensis populations on the Di Linh plateau of Vietnam was assessed by the inter-simple sequence repeat (ISSR) and start codon targeted (SCoT) techniques separately and then by combining data from both techniques for satisfactory results. The genetic diversity parameters and genetic distances among individuals found with the ISSR technique (HeI = 0.1420, II = 0.2092, PPBI = 35.22%, GSCsI = 0.765–0.988, and AGSCI = 0.915) are lower than those found with the SCoT technique (HeS = 0.2100, IS = 0.381, PPBS = 52.27%, GSCsS = 0.644–0.985, and AGSCS = 0.866). Based on the combined data from both techniques, the level of genetic diversity of the investigated population is PPB = 43.77%, He = 0.1720, I = 0.2582, and the genetic similarities among individuals are GSCs = 0.764–0.973 with an average of AGSC = 0.894. The SCoT technique differentiated between individuals better and reflected a higher level of genetic diversity in the population than the ISSR technique, but the ISSR technique revealed more loci in Camellia dilinhensis plants than did the SCoT technique
EULER CHARACTERISTIC OF TANGO BUNDLES
Get PDFWe are interested in a vector bundle constructed by Tango (1976). The Tango bundle is an indecomposable vector bundle of rank on the complex projective space . In particular, we show that the Euler characteristic of the Tango bundle on is equal to
CONCEPTUAL MAPPING MODEL ACROSS LANGUAGES: A TEST IN VIETNAMESE LANGUAGE
Get PDFThe conceptual metaphor, LOVE IS A JOURNEY, has been identified as a process of mapping based on the Conceptual Metaphor Theory (CMT) proposed by Lakoff and Johnson (1980). However, Ahrens (2002) pointed out several problems that the CMT may encounter, especially in setting parameters to be experimentally tested. Ahrens (2002) proposed the Conceptual Mapping Model (CMM) to investigate metaphor expressions by identifying three mappings between the source domain and the target domain: entities, qualities, and functions. After an analysis, the reason for these mappings, called a mapping principle, is indicated. In particular, the CMM can predict the processing of conceptual metaphors in terms of conventional and novel metaphors. This study is intended to test whether the CMM can perform well across languages through the experimental rates of acceptability and interpretability for different types of metaphors. Fifty Vietnamese native speakers were recruited. Each participant judged (on a Likert scale of 1-7) the levels of acceptability and interpretability of three conceptual metaphors in Vietnamese: LIFE IS A BOOK, HAPPINESS IS LIGHT, and LOVE IS FIRE. Each conceptual metaphor consists of six types of sentences, including (a) Literal pair to B, (b) Conventional metaphor, (c) Literal pair to D, (d) Novel metaphor that follows the mapping principle, (e) Literal pair to F, and (f) Novel metaphor that does not follow the mapping principle. The results of t-tests show that in terms of both acceptability and interpretability, conventional metaphors are ranked higher than novel metaphors. The results also indicate that novel metaphors that follow the mapping principle are rated higher than those that do not. Therefore, the mapping principle can constrain the image schemas so that any image that does not belong to the schemas can affect the processing of metaphors
ARCHAEOLOGICAL HERITAGE OF PREHISTORIC CAVES IN BA THUOC DISTRICT, THANH HOA PROVINCE: PRESERVATION AND PROMOTION
Get PDFBa Thuoc is a mountainous district in western Thanh Hoa Province, where more than 20 archaeological sites have been discovered. One of the outstanding features here is the presence of Middle Pleistocene fauna in Lang Trang cave, including fossils of Gigantopithecus blacki, a giant ape. The appearance of early modern human fossils in the Late Pleistocene proves that Vietnam was the site of the earliest modern human evolution in Southeast Asia. In Ba Thuoc district, human communities were in continuous residence from 30,000 to 7,000 years BP and developed the Dieu stone craft industry. This industry merged with the Hoabinhian industry in the development process, creating a cultural nuance for the land of Ba Thuoc. By 7,000 years BP, the boundary between the two industries was virtually nonexistent. The prehistoric inhabitants here contributed to the formation of Middle Neolithic cultures in North Central Vietnam. In addition, the caves in Ba Thuoc were also places for the mountain-dwelling inhabitants of the Dong Son culture to visit and bury their dead in the centuries before and after the beginning of the common era. In this study, we systematized the documents on monuments and artifacts, and evaluated the outstanding cultural heritage of the prehistoric caves in Ba Thuoc district, which need to be preserved and promoted in the present day
DESIGN OF A HIGH-SENSITIVITY DEVICE FOR DETECTING WEAK MAGNETIC FIELDS
Get PDFAn anti-serial fluxgate sensor configuration is proposed in this report. The design comprises two identical bilayer-rod fluxgate sensors connected anti-serially in a straight line. Each bilayer-rod sensor is constructed of an excitation coil and a pick-up coil wrapped around a core. The core material consists of Metglas ribbon, an amorphous alloy with high permeability, negligible hysteresis, and a high saturated magnetic field. The core is cut into a bar shape and uses double layers to enhance modulated flux density. A high sensitivity of 10 mV/Oe (with excitation of 45 kHz and 250 mA) is obtained experimentally with low noise of 1´10-5 Oe/Ö Hz at 1 Hz. In measurements of weak magnetic fields, the azimuth response indicates its vector feature. The proposed design is suitable for electronic compass and displacement applications
CAMELLIA THUANANA (CAMELLIA SECT. CHRYSANTHA) – A NEW SPECIES FROM THE CENTRAL HIGHLANDS, VIETNAM
Get PDFCamellia thuanana, a new species of the genus Camellia L. (Theaceae) is described and illustrated from the Central Highlands, Vietnam. Morphological features of this species are small flowers and pedicellate; leaves stalked, anastomosing venation, blades oblong-elliptic to elliptic, sparsely hirsute along the midrib below; pedicel very short; bracteoles 2–3, triangular; sepals 4–(5) in opposite pairs; corolla light greenish-yellow color; petals 7–8, glabrous; androecium 190–200 stamens, light yellow, in 3–4 circles; gynoecium 3, ovary ovoid and pubescent; styles 3, free to the base, and glabrous. C. thuanana resembles C. thuongiana in some morphological characteristics. C. thuanana is classified into sect. Chrysantha by styles completely free, flowers yellow, ovaries 3–5 locular, and partially connate. The IUCN Redlist Category of C. thuanana was assessed as Critically Endangered (CR)
VIETNAMESE-RUSSIAN COOPERATION IN EXPLORATION AND PRODUCTION OF OIL AND GAS FROM 1980 TO THE PRESENT
Get PDFCooperation in oil and gas exploration and production between Vietnam and Russia has a long history from the 1980s to the present. The cooperation was confirmed and promoted in the first two decades of the 21st century after the two countries established a strategic partnership in 2001 and developed it into a comprehensive strategic partnership in 2012. In this study, we evaluate and analyze the current situation and development trend of the comprehensive strategic partnership between Vietnam and Russia in oil and gas exploration and production. The research shows that the former Soviet Union and the current Russian Federation have supported Vietnam in developing its oil and gas energy industry. Today, both Vietnam and the Russian Federation are very interested in cultivating a cooperative relationship in the oil and gas sector for mutual economic and political interests. The article highlights the economic benefits that Vietnam and the Russian Federation have achieved from this long-term partnership
BOUNDS FOR VOLUMES OF SUB-LEVEL SETS OF POLYNOMIALS AND APPLICATIONS
Get PDFIn this paper, we present some explicit exponents in the estimates for the volumes of sub-level sets of polynomials on bounded sets and applications to the decay of oscillatory integrals and the convergence of singular integrals
YELLOW CAMELLIAS: A REVIEW OF CHEMICAL CONSTITUENTS AND BIOLOGICAL ACTIVITIES
Get PDFTo date, 69 species of yellow Camellia have been found in South China and Vietnam, and they have attracted substantial attention from scientists. Chemical and biological studies have only been carried out on a few species, with the main focus on the Chinese species Camellia nitidissima, but have shown that the main active ingredients of these yellow camellia species include flavonoids, phenolic compounds, saponins, triterpenoids, phytosterols, essential oils, amino acids, and polysaccharides. Many pharmacological studies have proved that the total extracts, fractions, and isolated substances from yellow camellia species possess antioxidant, anticancer, hypolipidemic, hypoglycemic, antiallergic, hepatoprotective, neuroprotective, anxiolytic, and antidepressant activities. This review systematically summarizes recent research results in order to provide a comprehensive and up-to-date understanding of the chemical composition and biological activities of yellow camellia species, creating a basis for research of the yellow camellia species in Vietnam and development of new products from this source.Cho đến nay, đã có 69 loài trà hoa vàng (Yellow Camellias) được tìm thấy ở Nam Trung Quốc và Việt Nam và thu hút được sự chú ý rất lớn của các nhà khoa học. Các nghiên cứu hóa học và tác dụng sinh học mới chỉ được thực hiện trên một số loài, trong đó tập trung chủ yếu vào loài Camellia nitidissima ở Trung Quốc nhưng đã cho thấy thành phần hoạt chất chính của các loài trà hoa vàng này bao gồm flavonoid, các hợp chất phenol, saponin, triterpenoid, phytosterol, tinh dầu, acid amin và polysaccharid. Nhiều nghiên cứu dược lý đã chứng minh các dịch chiết toàn phần, dịch chiết phân đoạn và các chất phân lập được từ các loài trà hoa vàng có tác dụng chống oxy hóa, chống ung thư, hạ lipid máu, hạ đường huyết, bảo vệ gan, bảo vệ thần kinh, chống lo ấu và chống trầm cảm. Bài tổng quan này hệ thống hóa các kết quả nghiên cứu gần đây để có một cái nhìn toàn cảnh về thành phần hóa học và tác dụng sinh học của các loài trà hoa vàng, tạo cơ sở cho việc định hướng nghiên cứu phát triển các loài trà hoa vàng ở Việt Nam tạo các sản phẩm có giá trị phục vụ cộng đồng