GRADIENT KIẾN TẠO HIỆN ĐẠI KHU VỰC NINH THUẬN VÀ LÂN CẬN

The estimation of the present day tectonic movement and tectonic gradient (strain rate) has an important practical signification in the assessment of active fault and seismic hazards for the selection of Ninh Thuan nuclear power plant. Based on the three campaigns of GPS measurement between 2012 - 2013, we used BERNESE 5.0 software to determine present day slip rates of 13 stations in ITRF08 frame. The GPS stations move eastwards at the slip rates of 22 - 25 mm/yr, southwards at the velocities of 5 - 10 mm/yr. The standard errors in latitudinal and longitudinal directions are 1.2 mm/yr and 0.9 mm/yr, respectively. Combined with GPS data from the project of the study on actual geodynamics in Tay Nguyen TN3/06, we determined the strain rate ranging from 50 to 100 nanostrains with the standard error of 50 nanostrains. The direction of  maximum compressive strain rate is from northwest - southeast to east - west.Đánh giá vận tốc chuyển động kiến tạo hiện đại và gradient kiến tạo hiện đại có ý nghĩa thực tiễn quan trọng trong việc đánh giá đứt gãy hoạt động nguy hiểm động đất phục vụ xây dụng nhà máy điện hạt nhân Ninh Thuận. Trên cơ sở đo 3 chu kỳ GPS vào các năm 2012 - 2013, sử dụng phần mềm BERNESE 5.0, chúng tôi đã xác lập được vận tốc chuyển động kiến tạo hiện đại tại 13 điểm đo GPS trong khu vực lân cận bao gồm kéo dài từ Nha Trang tới đảo Phú Quý. Vận tốc chuyển dịch kiến tạo hiện đại về phía đông thay đổi từ 22 - 25 mm/năm và chuyển dịch về phía nam với vận tốc giao động từ 5 - 10 mm/năm trên hệ tọa độ toàn cầu ITRF08. Sai số vận tốc chuyển dịch kiến tạo về phía đông giao động trong khoảng 1,2 - 1,5 mm/năm và về phía nam giao động trong khoảng 0,9 - 1,2 mm/năm. Liên kết với giá trị đo GPS từ đề tài nghiên cứu địa động lực hiện đại khu vực Tây Nguyên mã số TN3/T06, chúng tôi đã xác định được giá trị vận tốc biến dạng giao động từ 50 nano tới 100 nano biến dạng với sai số giao động trong khoảng 50 nano biến dạng. Trục biến dạng nén cực đại giao động theo phương thay đổi từ bắc nam sang đông bắc - tây nam. Trục biến dạng căng cực đại có phương thay đổi từ tây bắc - đông nam sang phương đông - tây

PRESENT DAY DEFORMATION IN THE EAST VIETNAM SEA AND SURROUNDING REGIONS

This paper presents velocities of present-day tectonic movement and strain rate in the East Vietnam Sea (South China Sea) and surroundings determined from GPS campaigns between 2007 and 2010. We determine absolute velocities of GPS stations in the ITRF05 frame. The result indicates that GPS stations in the North of East Vietnam Sea move eastwards with the slip rate of 30 - 39 mm/yr, southwards at the velocities of 8 - 11 mm/yr. Song Tu Tay offshore moves eastwards at the rate of ~24 mm/yr and southwards at ~9 mm/yr. GPS stations in the South of East Vietnam Sea move to the east at the rate of ~22 mm/yr and to the south at the velocities of 7 - 11 mm/yr. The effect of relative movement shows that the Western Margin Fault Zone activates as left lateral fault zone at the slip rate less than 4 mm/year.In Western plateau, the first result from 2012 - 2013 GPS measurement shows that the velocities to the east vary from 21.5 mm/yr to 24.7 mm/year. The velocities to the south vary from 10.5 mm/yr to 14.6 mm/year. GPS solutions determined from our campaigns are combined with data from various authors and international projects to determine the strain rate in the East Vietnam Sea. Principal strain rate changes from 15 nanostrain/yr to 9 nanostrain/yr in the East Vietnam Sea. Principal strain rate and maximum shear strain rate along the Red River Fault Zone are in order of 10 nanostrain/year. East Vietnam Sea is considered to belong to the Sunda block

Convolutional Neural Networks Improve Radiologists’ Performance in Breast Cancer Screening for Vietnamese patients

Nowadays, breast cancer is one of the leading cancers in Vietnam, and it causes approximately 6000 deaths every year. The rate of breast cancer patients was calculated as 26.4/100000 persons in 2018. There are 21,555 new cases reported in 2020. However, these figures can be reduced with early detection and diagnosis of breast cancer disease in women through mammographic imaging. In many hospitals in Vietnam, there is a lack of experienced breast cancer radiologists. Therefore, it is helpful to develop an intelligent system to improve radiologists’ performance in breast cancer screening for Vietnamese patients. Our research aims to develop a convolutional neural network-based system for classifying breast cancer X-Ray images into three classes of BI-RADS categories as BI-RADS 1 (“normal”), BI-RADS 23 (“benign”) and BI-RADS 045 (“incomplete and malignance”). This classification system is developed based on the convolutional neural network with ResNet 50. The system is trained and tested on a breast cancer image dataset of Vietnamese patients containing 7912 images provided by Hanoi Medical University Hospital radiologists. The system accuracy uses the testing set achieved a macAUC (a macro average of the three AUCs) of 0.754. To validate our model, we performed a reader study with the breast cancer radiologists of the Hanoi Medical University Hospital, reading about 500 random images of the test set. We confirmed the efficacy of our model, which achieved performance comparable to a committee of two radiologists when presented with the same data. Additionally, the system takes only 6 seconds to interpret a breast cancer X-Ray image instead of 450 seconds interpreted by a Vietnamese radiologist. Therefore, our system can be considered as a “second radiologist,” which can improve radiologists’ performance in breast cancer screening for Vietnamese patients

Economic burden of venous thromboembolism in surgical patients: A propensity score analysis from the national claims database in Vietnam.

BACKGROUND:Venous thromboembolism (VTE) associated with surgery can cause serious comorbidities or death and imposes a substantial economic burden to society. The study examined VTE cases after surgery to determined how this condition imposed an economic burden on patients based on the national health insurance reimbursement database. Methods: This retrospective analysis adopted the public payer's perspective. The direct medical cost was estimated using data from the national claims database of Vietnam from Jan 1, 2017 to Sep 31, 2018. Adult patients who underwent surgeries were recruited for the study. Patients with a diagnostic code of up to 90 days after surgery were considered VTE cases with the outcome measure being the surgery-related costs within 90 days. RESULTS:The 90-day cost of VTE patients was found to be US$2,939. The rate of readmission increased by 5.4 times, the rate of outpatient visits increased by 1.8 times and total costs over 90 days in patients with VTE undergoing surgery increased by 2.2 times. Estimation using propensity score matching method showed that an increase of US$1,019 in the 90-day cost of VTE patients. CONCLUSION:The VTE-related costs can be used to assess the potential economic benefit and cost-savings from prevention efforts

Analysis of PCDD/Fs in environmental samples by using gas chromatography in combination with high resolution mass spectrometry: optimization of sample preparation

This study developed a simple, economical and time-saving clean-up procedure based on an in-house packed column system for the determination of the most toxic-relevant 17 PCDD (polychlorinated dibenzo-p-dioxin) and PCDF (polychlorinated dibenzofuran) congeners in environmental samples following accelerated solvent extraction. The extract solution was cleaned up using a manually packed column system consisting of a multi-layer silica gel column and an activated carbon column. After clean-up, dioxins and furans were analysed by using gas chromatography in combination with high-resolution mass spectrometry. Isotopic labelled spiking experiments investigated the recovery of all dioxin and furan congeners. Then, the clean-up procedure for environmental samples was validated by applying the analysis of both clean soil reference material (CRM EDF-5183) and heavily contaminated sediment reference material (CRM EDF-5184) samples, as well as participating in the proficiency test (PT) for sediment samples. The recovery efficiency of isotope-labelled standard compounds in certified reference material (CRM) samples and PT samples ranged from 35% to 101% and between 46.1% and 105%, respectively. The mass concentrations of 17 PCDD/Fs in CRM samples were in the acceptable range. The absolute z-score value for each PCDD/F congener in the PT samples was below 1, confirming the analytical procedure’s high accuracy. The applied clean-up procedure in this study has demonstrated accuracy, repeatability and a significant increase in sample extraction/preparation productivity by reducing the time for sample preparation.</p

Effects of two types of smartphone-based stress management programmes on depressive and anxiety symptoms among hospital nurses in Vietnam : a protocol for three-arm randomised controlled trial

Introduction : Due to an increasing demand for healthcare in low-income and middle-income countries in Asia, it is important to develop a strategy to manage work-related stress in healthcare settings, particularly among nurses in these countries. The purpose of this three-arm randomised controlled trial (RCT) is to examine the effects of a newly developed smartphone-based multimodule stress management programme on reducing severity of depressive and anxiety symptoms as primary outcomes at 3-month and 7-month follow-ups among hospital nurses in Vietnam. Methods and analysis : The target study population will be registered nurses working in a large general hospital (which employs approximately about 2000 nurses) in Vietnam. They will be invited to participate in this study. Participants who fulfil the eligibility criteria will be randomly allocated to the free-choice, multimodule stress management (intervention group A, n=360), the internet cognitive behavioural therapy (iCBT), that is, fixed-order stress management (intervention group B, n=360), or a treatment as usual control group (n=360). Two types (free-choice and fixed sequential order) of smartphone-based six-module stress management programmes will be developed. Participants in the intervention groups will be required to complete one of the programmes within 10 weeks after the baseline survey. The primary outcomes are depressive and anxiety symptoms, measured by using the Depression Anxiety and Stress Scales (DASS) at 3-month and 7 month follow-ups. Ethics and dissemination : The study procedures have been approved by the Research Ethics Review Board of Graduate School of Medicine/Faculty of Medicine, the University of Tokyo (no 11991) and the Ethical Review Board for Biomedical Research of Hanoi University of Public Health (no 346/2018/YTCC-HD3). If a significant effect of the intervention programmes will be found in the RCT, the programmes will be made available to all nurses in the hospital including the control group. If the positive effects are found in this RCT, the e-stress management programmes will be disseminated to all nurses in Vietnam.Published versio

Multiresidue Pesticides Analysis of Vegetables in Vietnam by Ultrahigh-Performance Liquid Chromatography in Combination with High-Resolution Mass Spectrometry (UPLC-Orbitrap MS)

An ultrahigh-performance liquid chromatography in combination with high-resolution mass spectrometry Thermo Q-Extractive Focus Orbitrap MS has been introduced for analysis of multiclass pesticides in vegetable samples collected in Hanoi, Vietnam. Multiclass pesticides were separated on the Thermo Hypersil Gold PFP column utilizing a gradient of the mobile phase consisting of 5 mM ammonium formate, 0.1% formic acid in deionized water, and methanol. The target analytes were detected in the full-scan mode on Thermo Scientific Q-Exactive Focus Orbitrap MS for quantitation at the optimum operating conditions. These conditions included, but not limit to, the resolution of 70000 at the full width at half maximum in both positive and negative mode, mass range from 80 to 1000 m/z, and optimized parameters for the heated electrospray ionization source. The identification of the analytes in real samples was based on retention times, mass to charge ratios, mass accuracies, and MS/MS spectra at the confirmation mode with the inclusion list of target analytes. The mass accuracies of target analytes were from −4.14 ppm (dinotefuran) to 1.42 ppm (cinosulfuron) in the neat solvent and from −3.91 ppm (spinosad D) to 1.29 ppm (cinosulfuron) in the matrix-matched solution. Target analytes in the vegetable-based matrix were extracted by the QuEChERS method. Some critical parameters of the analytical method such as linearity, repeatability, limit of detection, and limit of quantitation have been evaluated and implemented. Excellent LOD and LOQ of the developed method were achieved at the range of 0.04–0.85 and 0.13–2.9 μg·kg−1, respectively. Intraday and interday repeatability of the analytical signal (peak area, n=6) of the developed method were below 3% and 10%, correspondingly. The matrix effect, extraction recovery, and overall recovery were fully investigated by spiking experiments. Experimental results demonstrated that the ionization suppression or enhancement was the main contribution on the overall recoveries of target analytes. Finally, the in-house validated method was applied to pesticides screening in vegetables samples in local villages in Hanoi, Vietnam. The concentrations of all target analytes were below limit of quantitation and lower than US-FDA or EU maximum residue levels