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ALMA observations of the circumstellar envelope around EP Aqr

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Research in Astronomy and Astrophysics 2019年第3期19卷 97-110页

作者： pham thi Tuyet Nhung Do thi Hoai pham Tuan-Anh thibaut Le Bertre Pierre Darriulat pham Ngoc Diep Nguyen thi phuong Nguyen thi thao Jan Martin Winters Department of Astrophysics Vietnam National Space CenterVAST LERMA UMR 8112 CNRS and Observatoire de Paris PSL Research University Graduate University of Science and Technology VAST IRAM 300 rue de la Piscine Domaine Universitaire

Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the *** are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.

关键词： stars: AGB and post-AGB (stars:) circumstellar matter stars: individual: EP Aqr stars:mass-loss radio lines: stars

Synthesis and characterization of NaYF4:Yb3+,Er3+@silica-N=folic acid nanocomplex for bioimaginable detecting MCF-7 breast cancer cells

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Journal of Rare Earths 2019年第11期37卷 1183-1187页

作者： Ha thi phuong Tran Thu Huong Le thi Vinh Hoang thi Khuyen Do thi thao Nguyen Thanh Huong pham thi Lien Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology18 Hoang Quoc VietCau GiayHanoiViet Nam Graduate University of Science and Technology-Vietnam Academy of Science and Technology 18 Hoang Quoc VietCau GiayHanoiViet Nam Department of Chemistry Hanoi Medical University1-Ton That TungDong DaHanoiViet Nam Department of Chemistry Hanoi University of Mining and Geology18-Pho LienBac Tu LiemHanoiViet Nam Institute of Biotechnology Vietnam Academy of Science and Technology18-Hoang Quoc VietCau GiayHanoiViet Nam Duy Tan University K7/25 Quang TrungDa NangViet Nam

Upconversion nanophosphors are new promising nanomaterials to be used as biolabels for detection and imaging of cancer *** nanophosphors absorb long-wavelength excitation radiation in the infrared or near infrared region and emit shorter wavelength,higher energy radiation from ultraviolet to *** this paper,we studied the hydrothermal method and optical properties of the functionalized NaYF4:Yb^3+,Er^3+for biomedical *** synthesis,these NaYF4:Yb^3+,Er^3+nanophosphors were functionalized with aminosilanes and folic *** acid binds to the folate receptor on the surface of MCF-7 breast cancer cells and this binding promotes internalization of the nanophosphors via *** sizes of the functionalized NaYF4:Yb^3+,Er^3+@silica-N=FA(folic acid)nanophosphors can be controlled with length of the rod about 300-800 nm and diameter of the rod about 100-200 *** structure of NaYF4:Yb^3+,Er^3+is in hexagonal crystal *** photo luminescence(PL)spectra of the functionalized NaYF4:Yb^3+,Er^3+@silica-N=FA nanophosphors were *** nanophosphors emit in red color with the strongest band at 650 nm under 980 nm *** result can provide NaYF4:Er^3+,Yb^3+@silica-N=FA complex for developing fluorescence label and image tool in cancer biology and medicine.

关键词： Upconversion luminescence NaYF4:Yb^3+,Er^3+ Nanophosphors Bioimaging Cancer cell Rare earths

Evaluation of five gridded rainfall datasets in simulating streamflow in the upper Dong Nai river basin,Vietnam

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International Journal of Digital Earth 2019年第3期12卷 311-327页

作者： pham thi thao Nhi Dao Nguyen Khoi Nguyen Xuan Hoan Institute of Research and Development Duy Tan UniversityDa NangVietnam Institute for Computational Science and Technology Tan Hiep Chanh WardDistrict 12Ho Chi Minh CityVietnam Faculty of Environment University of ScienceVietnam National University Ho Chi Minh City227 Nguyen Van Cu StreetDistrict 5Ho Chi Minh CityVietnam Ho Chi Minh City University of Food Industry 140 Le Trong Tan StreetTan Phu DistrictHo Chi Minh CityVietnam

Rainfall data with an appropriate spatial resolution is a key input to hydrological ***,networks of rain gauges are often sparsely and unevenly distributed in large catchments,especially in developing ***-resolution rainfall datasets,such as the Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation of Water Resources(APHRODITE),the Climate Forecast System Reanalysis(CFSR),the Climatic Research Unit Time Series(CRUTS),the Global Precipitation Climatology Centre(GPCC)and the Tropical Rainfall Measuring Mission(TRMM),have become available to overcome such *** objective of this study was to evaluate the impacts of four land-based rainfall products(APHRODITE,CFSR,CRU-TS,and GPCC)and a satellite-based rainfall product(TRMM)on streamflow of the upper catchment of Tri An reservoir in Vietnam using the Hydrological Modeling System(HEC-HMS).In addition,the available rain gauges data were used for comparison *** indicates that the TRMM and GPCC data show their best match to rain gauges data in simulating the streamflow in the period 1999–***,the results indicate that the TRMM and GPCC data could be alternative solutions.

关键词： APHRODITE CFSR CRU-TS GPCC TRMM rainfall streamflow HEC-HMS model

Localized Exponential Time Differencing Method for Shallow Water Equations: Algorithms and Numerical Study

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Communications in Computational Physics 2021年第1期29卷 80-110页

作者： Xucheng Meng thi-thao-phuong Hoang Zhu Wang Lili Ju Department of Mathematics University of South CarolinaColumbiaSC 29208USA Department of Mathematics and Statistics Auburn UniversityAuburnAL 36849USA SUSTech International Center for Mathematics Southern University of Science and TechnologyShenzhenGuangdong 518055China Center for Mathematical studies Advanced Institute of Natural SciencesBeijing Normal University at ZhuhaiZhuhaiGuangdong 519087China

In this paper,we investigate the performance of the exponential time differencing(ETD)method applied to the rotating shallow water *** with explicit time stepping of the same order accuracy in time,the ETD algorithms could reduce the computational time in many cases by allowing the use of large time step sizes while still maintaining numerical *** accelerate the ETD simulations,we propose a localized approach that synthesizes the ETD method and overlapping domain *** dividing the original problem into many subdomain problems of smaller sizes and solving them locally,the proposed approach could speed up the calculation of matrix exponential vector *** standard test cases for shallow water equations of one or multiple layers are *** results show great potential of the localized ETD method for high-performance computing because each subdomain problem can be naturally solved in parallel at every time step.

关键词： Exponential time differencing domain decomposition rotating shallow water equa-tions finite volume discretization

Operator Splitting and Local Time-Stepping Methods for Transport Problems in Fractured Porous Media

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Communications in Computational Physics 2023年第10期34卷 1215-1246页

作者： Phuoc-Toan Huynh Yanzhao Cao thi-thao-phuong Hoang Department of Mathematics and Statistics Auburn UniversityAuburn 36849AlabamaUSA

this paper is concerned with efficient numerical methods for the advectiondiffusion equation in a heterogeneous porous medium containing fractures.A dimensionally reduced fracture model is considered,in which the fracture is represented as an interface between subdomains and is assumed to have larger permeability than the surrounding *** develop three global-in-time domain decomposition methods coupled with operator splitting for the reduced fracture model,where the advection and the diffusion are treated separately by different numerical schemes and with different time ***,smaller time steps can be used in the fracture-interface than in the *** first two methods are based on the physical transmission conditions,while the third one is based on the optimized Schwarz waveform relaxation approach with Ventcel-Robin transmission conditions.A discrete space-time interface system is formulated for each method and is solved iteratively and globally in *** results for two-dimensional problems with various P′eclet numbers and different types of fracture are presented to illustrate and compare the convergence and accuracy in time of the proposed methods with local time stepping.

关键词： Domain decomposition reduced fracture model operator splitting nonconforming time grids time-dependent Steklov-Poincare operator optimized Schwarz waveform relaxation

Morphology of the ^(13)CO(3–2) millimetre emission across the gas disc surrounding the triple protostar GG Tau A using ALMA observations

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Research in Astronomy and Astrophysics 2018年第3期18卷 63-76页

作者： Nguyen thi phuong pham Ngoc Diep Anne Dutrey Edwige Chapillon Pierre Darriulat Stéphane Guilloteau Do thi Hoai pham Tuyet Nhung Ya-Wen Tang Nguyen thi thao pham Tuan-Anh Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology Graduate University of Science and Technology Vietnam Academy of Science and Technology Laboratoire d’Astrophysique de Bordeaux Université de Bordeaux IRAM F-38406 Saint Martin d’Hères Cedex Academia Sinica Institute of Astronomy and Astrophysics

Observations by the Atacama Large Millimetre/sub-millimetre Array of the dust continuum and ^13 CO（3–2） millimetre emissions of the triple stellar system GG Tau A are analysed,giving evidence for a rotating gas disc and a concentric and coplanar dust ring. The present work complements an earlier analysis（Tang et al.） by exploring detailed properties of the gas disc. A 95% confidence level upper limit of 0.24＂（34 au） is placed on the disc scale height at a distance of 1＂（140 au） from the central stars. Evidence for Keplerian rotation of the gas disc is presented,with the rotation velocity reaching-3.1 km s^-1 at 1＂ from the central stars,and a 99% confidence level upper limit of 9% is placed on relative contribution from a possible in-fall velocity. Variations of the intensity across the disc area are studied in detail and confirm the presence of a hot spot in the south-eastern quadrant. However several other significant intensity variations,in particular a depression in the northern direction,are also revealed. Variations of the intensity are found to be positively correlated to variations of the line width. Possible contributions to the measured line width are reviewed,suggesting an increase of the disc temperature and opacity with decreasing distance from the stars.

关键词： protoplanetary disks - stars low-mass - stars individual (GG Tau A)

Gravitationally lensed extended sources: the case of QSO RXJ0911

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Research in Astronomy and Astrophysics 2013年第7期13卷 803-814页

作者： Do thi Hoai pham Tuyet Nhung pham Tuan Anh Frederic Boone Pierre Darriulat pham Ngoc Diep pham Ngoc Dong Nguyen Van Hiep Nguyen thi thao VATLY INST179Hoang Quoc VietCau GiayHanoiVietnam IRAP 14avenue Edouard BelinF31400 ToulouseFrance

After a brief reminder of the mechanism of gravitational lensing of ex- tended sources, the particular case of the host galaxy of QSO RXJ0911, a high red-shift （z - 2.8） quadruply imaged quasar, is explored. The non linearity of the problem, together with the proximity of the source to a cusp of the lens inner caustic, has impor-tant consequences on the dependence of the image appearance on the size and shape of the source. Their expected main features and their interpretation in terms of source extension and shape are investigated in a spirit of simplicity and in preparation for the analysis of high sensitivity and spatial resolution images that will soon be within reach with the completion of the Atacama Large Millimeter/submillimeter Array （ALMA）. In particular, the information on source size carded by relative image brightness is dis-cussed. Extension of the results to other types of quadruply imaged quasars is briefly considered.

关键词： gravitational lensing - galaxies: high-redshift

Successful containment of a COVID-19 outbreak in Bach Mai Hospital by prompt and decisive responses

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Asian Pacific Journal of Tropical Medicine 2021年第5期14卷 234-235页

作者： Van Minh Hoang thi phuong thao Tran thi Ngoc phuong Nguyen thi Hai Yen Nguyen Quang Tuan Nguyen Hanoi University of Public Health HanoiVietnam Bach Mai Hospital HanoiVietnam

In low-and middle-income countries,tertiary care hospitals frequently face an extremely heavy workload and shoulder an even heavier burden during the COVID-19 *** Mai Hospital(BMH),one of the leading tertiary hospitals in Vietnam,is on the frontline in the fierce battle against *** letter aims to describe how BMH tackles the COVID-19 outbreak in the hospitallevel battle,which could support policymakers in time-management and well-preparation for this unpredictable pandemic.

关键词： prompt income policy

The COVID-19 pandemic in the ASEAN: A preliminary report on the spread, burden and medical capacities

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Asian Pacific Journal of Tropical Medicine 2020年第6期13卷 247-251页

作者： Minh Van Hoang phuong thi Ngoc Nguyen thao thi phuong Tran Long Quynh Khuong An thi Minh Dao Huy Van Nguyen Riyanti Djalante Hanh thi Tuyet Tran Hanoi University of Public Health HanoiVietnam Hanoi Medical University HanoiVietnam Graduate School of Public Health St.Luke's International UniversityTokyoJapan United Nations University-Institute for the Advanced Study of Sustainability(UNU-IAS) TokyoJapan

Objective:To provide preliminary descriptions of the spread,burden and related medical capacity characteristics of the ASEAN ***:We utilized the data from four main official databases,including WHO reports,the Statistics and Research of the Coronavirus Disease,and the Southeast Asia Program of the Center for Strategic and International *** spread of the COVID-19 pandemic,current burden and the COVID-19 medical response capacities were extracted before April 11,***:As of April 13,2020,the ASEAN countries reported19547 COVID-19 positive cases with 817 deaths(case-facility rate of 4.2%).Thailand was the first country in the region that reported having the COVID-19 cases,while Laos was the last to report confirmed COVID-19 *** for the number of deaths to double were between 8-12 *** the testing and treatment capacities,the number of PCR tests provided to the populations was the highest in Vietnam,followed by Singapore,Malaysia,and ***,the percentage of the population being tested was the highest in Brunei(2.31%),followed by Singapore(1.30%).Conclusions:A wide range of interventions were taken into practice in response to the outbreak with an effort of curbing the rise of this ***,special care should not be overlooked as the pandemic is placing a huge impact on the population and becomes increasingly *** tackle the spread of the pandemic in the region,the ASEAN countries should work together as one community to provide better responses to future pandemics and other transboundary public health challenges.

关键词： COVID-19 SARS-CoV-2 ASEAN South-East Asia Epidemiology