123 research outputs found

    Speedup of Interval Type 2 Fuzzy Logic Systems Based on GPU for Robot Navigation

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    As the number of rules and sample rate for type 2 fuzzy logic systems (T2FLSs) increases, the speed of calculations becomes a problem. The T2FLS has a large membership value of inherent algorithmic parallelism that modern CPU architectures do not exploit. In the T2FLS, many rules and algorithms can be speedup on a graphics processing unit (GPU) as long as the majority of computation a various stages and components are not dependent on each other. This paper demonstrates how to install interval type 2 fuzzy logic systems (IT2-FLSs) on the GPU and experiments for obstacle avoidance behavior of robot navigation. GPU-based calculations are high-performance solution and free up the CPU. The experimental results show that the performance of the GPU is many times faster than CPU

    Chemical constituents from the leaves of Styrax argentifolius H.L. Li and their antioxidative activity

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    Searching for bioactive agents from medicinal plants, the phytochemical investigation on the EtOAc extract of the Vietnamese Styrax argentifolius leaves has resulted in the isolation and structural determination of five compounds, including one nor-neolignan egonoic acid (1), one lignan (+)-pinoresinol (2), one sterol (20R)-3β-hydroxysitgmasta-5,22-dien-7-one (3), and two triterpenoids lupeol (4), and 2α,3α,24-trihydroxy-urs-12-en-28-oic acid (5). The chemical structures of these secondary metabolites were elucidated by NMR and MS spectral data. All isolated compounds were first observed in S. argentifolius species. Sterol 3 and triterpenoid 5 were detected in genus Styrax for the first time. With the IC50 value of 19.10 µg/mL, compound 2 possessed the strong activity in DPPH radical scavenging assay

    Determinants of attitudinal and behavioral loyalty among Vietnamese overseas students: the role of disconfirmation, satisfaction and switching cost

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    International students are important for higher education since they bring additional income for universities, enhance their ranking and reputation and might become high-qualified manpower for host countries in future. This research aims to extend the current knowledge through investigating the effects of disconfirmation, satisfaction and switching cost on attitudinal and behavioural loyalties of international students. A total of 410 Vietnamese overseas students answered our questionnaire survey. Using structural equation model, this study revealed that the mechanism resulting on attitudinal loyalty and behavioural loyalty of international students are different. While satisfaction is found as a partial mediator of the relationship disconfirmation – attitudinal loyalty; switching cost is found as a direct antecedent of behavioural loyalty. This article ends with implications in terms of theory and practice

    Speedup of Interval Type 2 Fuzzy Logic Systems Based on GPU for Robot Navigation

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    As the number of rules and sample rate for type 2 fuzzy logic systems (T2FLSs) increases, the speed of calculations becomes a problem. The T2FLS has a large membership value of inherent algorithmic parallelism that modern CPU architectures do not exploit. In the T2FLS, many rules and algorithms can be speedup on a graphics processing unit (GPU) as long as the majority of computation a various stages and components are not dependent on each other. This paper demonstrates how to install interval type 2 fuzzy logic systems (IT2-FLSs) on the GPU and experiments for obstacle avoidance behavior of robot navigation. GPUbased calculations are high-performance solution and free up the CPU. The experimental results show that the performance of the GPU is many times faster than CPU

    Larval development and breeding ecology of Ziegler's crocodile newt, Tylototriton ziegleri Nishikawa, Matsui and Nguyen, 2013 (Caudata: Salamandridae), compared to other Tylototriton representatives

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    We describe for the first time the larval development and stages of the recently described Ziegler's Crocodile Newt (Tylototriton ziegleri), an endemic species to northern Vietnam. Diagnostic morphological characters are provided for Grosse (1997, 2013) stages 27-32, 35-36, and 44-45, as well as comparisons with larval stages of other Tylototriton representatives. In addition, natural history data and an ecological assessment of the breeding niche are presented for T. ziegleri as well as for T. vietnamensis, from whom the former species was only recently taxonomically separated. We provide data extending the known breeding season of these two cryptic species in the North of Vietnam, which in fact lasts from April until July. On average, the clutches of T. ziegleri consisted of 67 +/- 32 eggs, were found on rock and soil substrates with a distance of 50 +/- 28 cm from water, whereas the clutches of T. vietnamensis were significantly smaller (43 +/- 19 eggs), found only on soil and were further distant from water (80 +/- 41 cm). The known maximum altitudinal distribution of T. vietnamensis is herein increased to 980 m above sea level. Based on the examples of T. ziegleri and T. vietnamensis, this study highlights how important it is to uncover cryptic species, define their exact distribution range, and investigate potential differences in ecological adaptations in order to assess the conservation status, develop proper conservation planning and provide suitable conditions for potential ex situ breeding programs

    chemical constituents from methanolic extract of Garcinia mackeaniana leaves and their antioxidant activity

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    A phytochemical investigation of the methanolic extract of Garcinia mackeaniana leaves led to the isolation, and determination of five secondary metabolites, including one benzophenone 4,3',4'-trihydroxy-2,6-dimethoxybenzophenone (1), two flavone C-glucosides vitexin (2) and its 2''-O-acetyl derivative (3), one biflavone amentoflavone (4), and one mono-phenol methyl protocatechuate (5). The chemical structures of these compounds were characterized by the NMR-spectroscopic method. These isolated compounds were isolated from G. mackeaniana species for the first time. Benzophenone derivative 1 has shown to be associated with a significant IC50 value of 14.97±0.8 µg/mL in the DPPH-antioxidant assay

    Hidden in the jungle of Vietnam: a new species of Quasipaa (Amphibia, Anura, Dicroglossidae) from Ngoc Linh Mountain

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    A new species of Quasipaa is described from Ngoc Linh Mountain of the Kon Tum Massif in central Vietnam. The new species is morphologically distinguishable from its congeners on the basis of a combination of the following diagnostic characters: SVL 79.6–84.3 mm in males and 64.6–69.9 mm in females; head broader than long; vomerine teeth present; external vocal sacs absent; tympanum slightly visible; dorsum with lines of thick ridges and small round tubercles; flanks covered by oval and round tubercles; supratympanic fold present; dorsolateral fold absent; ventrolateral sides, ventral surface of arms, and all fingers with spines in males; the absence of spines on chest and belly in males; toes fully webbed to distal portion of terminal phalanx; in life, dorsum dark brown, chest and belly immaculate white. Phylogenetic analyses found that the genetic divergence of the new species and its congeners ranged from 4.2–5.1% (compared with Quasipaa boulengeri) to 7.6–8.1% (compared with Q. shini) in the 16S gene

    Cytotoxic naphthoquinones from Diospyros fleuryana leaves

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    In the search for anti-cancer plants in Vietnam, the leaves of Diospyros fleuryana were selected for chemical investigation. Phytochemical analysis of the ethyl acetate (EtOAc) extract led to the isolation of two naphthoquinones isodiospyrin (1), and 8'-hydroxyisodiospyrin (2), and one isoflavone 7-O-methylbiochanin A (3). The chemical structures of isolated compounds were determined by 1D-NMR (1H, and 13C-NMR), 2D-NMR spectra (HSQC, and HMBC), and MS spectroscopy. Compound 3 was isolated from genus Diospyros for the first time. Regarding the strong IC50 values of 2.27, and 8.0 µM against KB, and Hep cell lines respectively, cytotoxic examination suggested that compound 2 is a promising agent in anti-cancer treatment.Â

    Socio-Cultural Factors Challenging Development Interventions in Cattle Production in the Remote Areas of Vietnam

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    The northwest highlands of Vietnam are characterized by high altitude, low infrastructure, and low population densities composed of a wide diversity of different ethnic groups. Their socio-cultural characteristics strongly influence their lifestyle and production systems, including agricultural activities. The majority of these people have suffered from slow economic development, with the highest poverty rate in the country. This is a real need for plausible interventions where behavioral changes of smallholders throughout local value chains would be a critical foundation. Our project implemented in this context of development in the Northwest highlands of Vietnam aims to understand the role of socio-cultural factors in cattle production systems in order to propose and examine feasible technical and marketing interventions to improve local grazing-based cattle production. Data on farmers and other actors (collectors, slaughterhouses, retailers and consumers) in local cattle value chains of two selected provinces (Son La and Dien Bien) were collected at the beginning of the project via a baseline survey. In addition, different group discussions with farmers were conducted until the end of the project to monitor the project’s progress and changes created through its interventions. We found that such behavioral changes cannot be motivated by development interventions per se without integrating an understanding of socio-cultural factors (i.e. ethnicity, geographical location and grazing-practices)

    Study on spatial distribution of coral reefs in Nam Yet island by using GIS and remote sensing techniques

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    Research and application of GIS and remote sensing techniques combined with field survey in coastal areas of Nam Yet island had been carried out to establish the distribution map of submarine habitats. Depth-invariant index was used to correct water column’s effects on spectral reflectance of each habitat. The results of satellite image classification showed that area with well-developed coral at great depths accounted for 12%, area with well-developed coral at small depths accounted for 9%, area with poorly-developed coral accounted for 13%, dead coral area accounted for 15% and area of sand, grit, pebbles and weathered coral accounted for 51%. The assessment after classification showed that the overall accuracy of the satellite image interpretation process was 94% and the kappa coefficient was 0.93
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