128 research outputs found
Application of monte carlo simulation method to estimate the reliability of design problem of the bored pile according to limited state
This paper applies Monte Carlo simulation method to estimate the reliability of bored pile for designing problem at “Tax Office of Phu Nhuan District”. Surveyed random variables are physico-mechanical properties of soil and loads are assumed that they follow the normal distribution. Limit state functions developed from design requirements of Ultimate limit state (ULS) and Serviceability limit state (SLS). Results show that the probability of failure is 0 and the reliability index of ULS is 9.493 and of SLS is 37.076 when examining coefficient of variation of soil and loads of 10%. The paper also considers the safety level when evaluating different coefficients of variation in the range of 10 ~30%. The authors suggest applying the reliability method to design calculation for other construction to help the engineers have a visual perspective, increase safety and avoid wastage
The lasting effects of innovation on firm profitability: panel evidence from a transitional economy
This study is the first to study the lasting effects of innovation on firm profitability in Vietnam. Using a unique panel dataset for the period 2005–2015, our results show that innovators achieve higher profit in comparison with non-innovating firms. The positive effects of innovation on firm profitability are observed not only in the short term but also in the longer term. The benefits of innovation for firm profitability can be seen in higher export probability, better productivity, better access to formal credit, and the ability to secure government support, but only after innovation
PRELIMINARY STUDY OF THE ANTIOXIDANT PROPERTIES OF OPHIOCORDYCEPS SOBOLIFERA
The aim of study was to determine preliminary phytochemical analysis and the antioxidant potential of Ophiocordyceps sobolifera. The antioxidant activity of Ophiocordyceps sobolifera was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and total antioxidant activity methods. Phytochemical analyses revealed the presence of steroids, triterpenoids, alkaloids, phenolics, flavoinods, protein, carbohydarte and saponins. The antioxidant activity of the ethanol extracts and water extracts showed high antioxidant activity with the lowest half maximal inhibitory concentration (IC50) values to 0.70 from 0.95mg/mL, realtively. Total antioxidant capacity of the O. sobolifera showed contained from 5.52 ± 0.14 to 12,71 ± 0.23 mg GA/g or from 3.55 ± 0.15 to 7.87 ± .05 μmol AS/g. These data suggest that O. sobolifera is a natural source of antioxidants
Evaluating the shoreline and bottom terrain variations in the naval port of zone 5, Phu Quoc, Kien Giang by using multi - temporal remote sensing images
In this study, the authors aim to study two major contents: (1) Evaluating the shoreline variation in the naval port of zone 5 (in the years of 1999, 2006, 2009 and 2016); (2) Evaluating the bottom terrain variation in the naval port of zone 5 (in the years of 2007 and 2010). Three main research methodologies were applied: (i) Band rationing method for the shoreline extraction; (ii) Shoreline change analysis method using GPS data; (iii) Digital elevation model integrated with bottom terrain analysis method. The most obvious change in shoreline is in the An Thoi port from Mui Den to Mui Ong Doi. In the shoreline from Mui Den to Mui Con Duong, a backward shoreline evolution (erosion) mainly occurred with an average width of about 40–50 m, while some other places had a forward shoreline evolution (accumulation), especially in Mui Con Duong with a width of 60 m. These sediment materials are sent to conductor and accumulation, making the bottom terrain raised. As on the sections AA’, BB’, CC’, DD’, we could see that the bottom terrain at the channel of naval port of zone 5 has the depth variation only from 2 m to 4 m. The accumulation rate is up to 1 m/year in this period
Chemical Components of Essential Oils From the Leaves of Seven Species Belonging to Rutaceae Family from Binh Chau-Phuoc Buu Nature Reserve, Vietnam
Several plant species of the Rutaceae family are medicinal plants, oil bearing and food crops. To provide more information for utilization of some species of this family in Binh Chau-Phuoc Buu Nature Reserve, we extracted essential oils from the leaves of seven species of the Rutaceae family: Acronychia pedunculata (L.) Miq., Atalantia citroides Pierre ex Guillaumin, Clausena excavata Burm.f., Glycosmis pentaphylla (Retz.) DC., Luvunga scandens (Roxb.) Buch.-Ham. ex Wight & Arn, Melicope pteleifolia (Champ. ex Benth.) T.G. Hartley, and Micromelum sp., via hydrodistillation, and identified their components using GC/MS analysis. A total of 60 compounds were identified from essential oils of seven species. The main components of the essential oils isolated from five species, including A. pedunculata, C. excavata, M. pteleifolia, G. pentaphylla, and Micromelum sp., were caryophyllene (57.63% and 55.41% in A. pedunculata and C. excavata, respectively), 1,9-decadiyne (32.59%, M. pteleifolia), β-ocimene (23.10%, G. pentaphylla), and 3-carene (58.03%, Micromelum sp.). Additionally, this study revealed the chemical composition of essential oils of L. scandens and A. citroides for the first time. The main constituent of A. citroides was 7-oxabicyclo[4.1.0] heptane, 3-oxiranyl- (53.91%) and that of L. scandens was caryophyllene (34.66%). These findings provide the basis for further application of these species in medicine
Clinical Characteristics and Histopathology of Idiopathic Epiretinal Membrane in Vietnam
BACKGROUND: Idiopathic epiretinal membrane (iERM) is an avascular proliferation of different types of cells between the posterior vitreous cortex and the internal limiting membrane. That causes visual impairment including blurry, distortion, scotoma. Many studies of iERM were done to describe the clinical characteristics and investigate the histopathology of this disease. Nonetheless, there has not been a study of iERM histopathology in Vietnam.
AIMS: To describe clinical characteristics and histopathological results of idiopathic retinal membrane and the association between them.
METHODS: A cross sectional decriptive study of 35 iERMs (33 patients) in Vietnam National Institute of Ophthalmology (VNIO).
RESULTS: High morbidity incidence was in group age >50 years (32/35), female gender (26/35), limited movement works (27/35), and high educational levels (28/35). Distortion was the highest (77.14%), scotoma and floater was less frequent (28.5%, 45.7%). Macular edema in all cases and PVD and exudate were high frequent (65.7%, 62.8%). Symptom duration was 8.2 ± 4.7 months, (1-21 months). Mean of central macular thickness was 468.51 ± 97.24 µm (656-274 µm). Six types of cell were detected, including glial cell (35/35), fibroblast (23/35), myofibroblast (23/35), macrophage (13/35), lymphocyte (5/35) and neutrophil (2/35). The number of cell types in one sample ranged from 1-5 types (2.85 ± 1.28 cell types). Number of cell types were correlated to symptom duration (r = 0.47, p = 0.004, Pearson's test) and central macular thickness (r = 0.72, p < 0.001, Pearson's test).
CONCLUSION: There were 6 types of cells in iERM. Glial cell was the most frequent cell, inflammatory cells (macrophage, lymphocyte, neutrophil) was also detected. The number of cell types was stastitically correlated to symptom duration and CMT
Anatomical Characteristics and Variants of Prostatic Artery in Patients of Benign Hyperplasia Prostate by Digital Subtraction Angiography
AIM: This work is aimed to describe anatomical features and variants of the prostatic artery (PA) using digital subtraction angiography (DSA).
METHODS: This is a descriptive statistic study. We reviewed the DSA of 348 patients, who had a PA embolisation to reduce the benign prostatic hyperplasia (BPH) symptoms at Radiology Department of Bach Mai Hospital from Oct – 2014 to Oct – 2018.
RESULTS: PA was found at 660 pelvic halves, of which 30 pelvic halves (4.5%) had two PAs, 630 pelvic halves had one PA. In terms of the origin of PA, in total 690 PAs, the percentage of type 1, 2, 3, 4 and 5 was successively 33.9%, 13.9%, 18.3%, 23.9% and 10.4%, respectively. Atherosclerosis of PA observed in 20.9%. The ‘corkscrew’ pattern was found in 30.4%. The average diameter of PA was 1.5 ± 0.34mm. The anastomosis of PA with surrounding arteries was common. PA may supply rectum (6.1%), seminal vesical (9.6%), bladder (5.2%), contralateral prostatic parenchyma (13.0%), surrounding soft-tissues (3.5%).
CONCLUSION: The common trunk with SVA superior vesical artery was the most common origin of PA. Anastomoses of PA with surrounding tissues were complex
SIP-MBA: A secure IoT platform with brokerless and micro-service architecture
The Internet of Things is one of the most interesting technology trends today. Devices in the IoT network are often geared towards mobility and compact in size, thus having a rather weak hardware configuration. There are many light weight protocols, tailor-made suitable for limited processing power and low energy consumption, of which MQTT is the typical one. The current MQTT protocol supports three types of quality-of-service (QoS) and the user has to trade-off the security of the packet transmission by transmission rate, bandwidth and energy consumption. The MQTT protocol, however, does not support packet storage mechanisms which means that when the receiver is interrupted, the packet cannot be retrieved. In this paper, we present a broker-less SIP-MBA Platform, designed for micro-service and using gRPC protocol to transmit and receive messages. This design optimizes the transmission rate, power consumption and transmission bandwidth, while still meeting reliability when communicating. Besides, we implement users and things management mechanisms with the aim of improving security issues. Finally, we present the test results by implementing a collect data service via gRPC protocol and comparing it with streaming data by using the MQTT protocol.Web of Science12759358
Vectors and malaria transmission in deforested, rural communities in north-central Vietnam
Background: Malaria is still prevalent in rural communities of central Vietnam even though, due to deforestation, the primary vector Anopheles dirus is uncommon. In these situations little is known about the secondary vectors which are responsible for maintaining transmission. Basic information on the identification of the species in these rural communities is required so that transmission parameters, such as ecology, behaviour and vectorial status can be assigned to the appropriate species
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