Evaluation of mechanical strength and durability characteristics of eco-friendly mortar with cementitious additives

The mechanical strength and durability of eco-friendly mortars used in the repair of marine concrete structures exposed to freshwater and seawater environments were evaluated in this paper. The eco-friendly mortar samples were produced using various ratios of fly ash (FA), ground granulated blast-furnace slag (GGBFS), and silica fume (SF) as cementitious materials. Seven mixtures of eco-friendly mortars, including a control mixture; three mixtures with respective substitutions of GGBFS for Portland cement of 10, 20, and 30% by cement mass; and three mixtures with respective additions of SF of 5, 10, and 15% by total binder mass, were used to produce the samples. Tests, including compressive strength, flexural strength, ultrasonic pulse velocity (UPV), electrical surface resistivity (ESR), rapid chloride ion penetration (RCP), thermal conductivity (TC), and microstructure analysis, were conducted to determine the mechanical strength and durability values of the samples. The experimental results show that replacing Portland cement with GGBFS negatively affected the properties of the mortars by reducing the mechanical strength, UPV, ESR, and TC while increasing the RCP in the samples. Also, adding an appropriate amount of SF could improve the mechanical strength and durability characteristics of the eco-friendly mortars. As a result, the mortar sample containing 30% GGBFS and 10% SF earned compressive and flexural strength values of approximately 49.2 and 13.8 MPa, respectively, at 56 days of curing age. Mortar samples with UPV values >3660 m/s were identified as "high quality". The corrosion resistance of all of the samples was found to be high, particularly in chloride-contaminated environments, due to relatively low (1000 - 2000 Coulombs) RCP values. The best overall performance was recorded for the sample containing 30% GGBFS and 10% SF.Web of Science24455254

ASSESSMENT OF GEOMORPHIC PROCESSES AND ACTIVE TECTONICS IN CON VOI MOUNTAIN RANGE AREA (NORTHERN VIETNAM) USING THE HYPSOMETRIC CURVE ANALYSIS METHOD

the Day Nui Con Voi (DNCV) area of Vietnam. For this purpose, a spatial database was collected and constructed, including DEM (Digital Elevation Model) and a geological map. The hypsometric curve (HC) analysis method and its statistical moments were adopted to use for the assessment. These methods have been widely used for the assessment of geomorphic processes and active tectonics in many areas in the world showing promising results. A total of 44 sub-basins of the Red River and the Chay river were analyzed. The result shows that 3 curve-types such as "straight- shape", "S- shape", and concave were found; with the concave curve being the dominant and widely distributed in the northeast side and in the south of the southwestern side of the study area. The hypsometric integral (HI) values are rather small with the largest value is 0.37 and the smallest one is 0.128. Other statistical moments of the hypsometric curve, i.e. skew (SK), kurtosis (KUR), and the density function (density skew - DSK and density kurtosis-DKUR) show great values, which increased in the south direction of the area study. Accordingly, recent active tectonics (uplift-lower) in the study area is generally weak; however, they are also not completely homogeneous and can be distinguished by different levels. The southwestern side is being lifted higher than the northeastern side. The northern part is being lifted larger than the southern part. In the region, the uplift activities were increased gradually in the Pliocene-Quaternary and could have stopped at certain time in the past. The current geomorphic processes are mainly headward erosion in the upstream.References Allen, C.R., Gillepie, A.R., Han, Y., Sieh, K.E., Zhu, C., 1984. Red River and associated faults, Yunnan province, China: Quaternary geology, slip rates, and seismic hazard, Geological Society of America Bulletin,  686-700, 21 fig.Azor, A., Keller, E.A., Yeats, R.S., 2002. Geomorphic indicators of active fold growth: South Mountain-Oak Ridge anticline, Ventura basin, southern California. Geological Society of America Bulletin 114, 745-753.Chen, Y.C., Sung, Q., Cheng, K.Y., 2003. Along-strike variations of morphotectonic features in the Western Foothills of Taiwan: tectonic implications based on stream gradient and hypsometric analysis. Geomorphology 56, 109-137.Delcaillau, B., Deffontaines, B., Floissac, L., Angelier, J., Deramond, J., Souquet, P., Chu, H.T., Lee, J.F., 1998. Morphotectonic evidence from lateral propagation of an active frontal fold; Pakuashan anticline, foothills of Taiwan. Geomorphology 24, 263-290.Delcaillau, B., Laville, E., Amhrar, M., Namous, M., Dugué, O., Pedoja, K., 2010. Quaternary evolution of the Marrakech High Atlas and morphotectonic evidence of activity along the Tizi N'Test Fault, Morocco. Geomorphology 118, 262-279.El Hamdouni, R., Irigaray, C., Fernández, T., Chacón, J., Keller, E.A., 2008. Assessment of relative active tectonics, southwest border of the Sierra Nevada (southern Spain). Geomorphology 96, 150-173.Font, M., Amorese, D., Lagarde, J.L., 2010. DEM and GIS analysis of the stream gradient index to evaluate effects of tectonics: the Normandy intraplate area (NW France). Geomorphology 119, 172-180.Gardner, T.W., Sasowsky, K.C., Day, R.L., 1990. Automated extraction of geomorphometric properties from digital elevation models. Zeischrift für Geomorphologie Supplemental Band 80, 57-68.Harlin, J.M., 1978. Statistical moments of the hypsometric curve and its density function. Mathematical Geology 10, 59-72.Howard, A.D., 1990. Role of hypsometry and planform in basin hydrologic response. Hydrological Processes 4, 373-385.Huang, X.J., Niemann, J.D., 2006. Modelling the potential impacts of groundwater hydrology on long-term drainage basin evolution. Earth Surface Processes and Landforms 31, 1802-1823.Joshi, P.N,. Maurya, D.M., Chamyal, L.S., 2013. Morphotectonic segmentation and spatial variability of neotectonic activity along the Narmada-Son Fault, Western India: Remote sensing and GIS analysis. Geomorphology 180-181 (2013) 292-306.Keller, E.A., Pinter, N., 2002. Active Tectonics. Earthquakes, Uplift and Landscape. Prentice Hall, New Jersey, 362.Le Duc An, 2003. About the exhumation of metamorphic rocks of Con Voi range. Journal of Sciences of the Earth,No.1, 93-95 (In Vietnamese with English abstract).Le Duc An, Dao Dinh Bac, Uong Dinh Khanh, Vo Thinh, Tran Hang Nga, Ngo Tuan Anh, Nguyen Thi Le Ha, 2004. Geomorphology of Red River Fault Zone and natural hazard.P 459-532. Science and Technics Publishing House, Hanoi (In Vietnamese with English abstract).Le Duc An, Lai, Huy Anh, Vo Thinh, Ngo Tuan Anh, Do Minh Tuan, Tran Hang Nga, 2001. Steps of relief of Convoi Mountain characteristics. Journal of Sciences of the Earth, 23(2), 97-104. (In Vietnamese with English abstract).Leloup, P.H., Arnaud, N., Lacassin, R., Kienast, J.R., Harrison, T.M., Trinh, P.T., Replumaz, A., Tapponnier, P., 2001. New constraints on the structure, thermochronology, and timing of the Ailao Shan-Red River shear zone, SE Asia, Journal of Geophysical Research, B, v. 106, 6683-6732.Leloup, P.H., Chen Wenji, Harrison, T.M., Tapponnier, P., 1994. Timing of shear sense inversion along the Red River fault zone. Int. Workshop on Seismotectonics and Seismic Hazard in South East Asia, Hanoi.Leloup, P.H., Lacasin, Tapponnier, P., Scharer, U., Dalai, Z., Xaohan, L., Zhangshan, Shaocheng, J., Trinh, P.T., 1995. The Ailao Shan -  Red Rive shear zone (Yunnan, China), Tertiary transform boundary of  Indochina. Tectonophysics, v. 251,  pp. 3-84.Leloup, P.H., Lacassin, R., Tapponnier, P., Harrison, T.M., 2001. Comment on “Onset timing of left-lateral movement along the Ailao Shan±Red River Shear Zone: 40Ar/39Ar dating constraint from the Nam Dinh Area, northeastern Vietnam” by Wang et al., 2000. Journal of Asian Earth Sciences 18, 281-292. Journal of Asian Earth Sciences 20, 95-99.Lifton, N. A., Chase, C.G., 1992. Tectonic, climatic and lithologic influences on landscape fractal dimension and hypsometry: implications for landscape evolution in the San Gabriel Mountains, California. Geomorphology 5, 77-114.Luo, W., 1998. Hypsometric analysis with a geographic information system. Computers Geosciences, Vol. 245, No. 8, 815-821.Luo, W., 2000. Quantifying groundwater- sapping landforms with a hypsometric technique. Journal of Geophysical Research, Vol. 105, No. El, Pages 1685-1694, January 25.Mahmood, S. A., and Gloaguen, R.,  2012. Appraisal of active tectonics in Hindu Kush: Insights from DEM derived geomorphic indices and drainage analysis. Geoscience Frontiers 3(4), 407-428.Moglen, G.E., Bras, R.L., 1995. The effect of spatial heterogeneities on geomorphic expression in a model of basin evolution. Water Resources Research 31, 2613-2623.Ngo Van Liem, 2011. Characteristics of landform evolution in relation to recent geodynamics along the Red River Fault Zone, Doctorate thesis, Institute of Geological Sciences, Hanoi (In Vietnamese with English abstract).Ngo Van Liem, Phan Trong Trinh, Hoang Quang Vinh, 2006. The active faults and the maximum earthquakes of the Red River Fault zone in Lao Cai-Yen Bai area, Journal of Sciences of the Earth, Vol. 28, (2), 110-120 (In Vietnamese with English abstract).Ngo Van Liem, Phan Trong Trinh, Nguyen Van Huong, Nguyen Cong Quan, Tran Van Phong, Nguyen Phuc Dat, 2016. Analyze the correlation between the geomorphic indices and recent tectonic active of the Lo River fault zone in southwest of Tam Dao range. Vietnam Journal of Earth Sciences. Vol. 38, No. 1, 1-13 (In Vietnamese with English abstract).Nguyen Quoc Cuong., Zuchiewicz, W., Tokarski. A. K., 1999. Morphotectonic evidence for right-lateral normal slip in the Red River Fault Zone: insights from the study on Tam Dao fault scarp (Viet Nam), J. Geology, Seri B, 13-14, 57-59.Nguyen Xuan Nam, 2015. Quaternary Geology characteristics, present-day tectonic geomorphology of the Da river valley from HoaBinh to Viet Tri and correlation with geological hazards. Doctorate Thesis. Hanoi University of Mining and Geology (In Vietnamese with English abstract).Ohmori, H., 1993. Changes in the hypsometric curve through mountain building resulting from concurrent tectonics and denudation. Geomorphology 8, 263-277.Pedrera, A., Pérez-Peña, J.V., Galindo-Zaldívar, J., Azañón, J.M., Azor, A., 2009. Testing the sensitivity of geomorphic indices in areas of low-rate active folding (eastern Betic Cordillera, Spain). Geomorphology 105, 218-231.Pérez-Peña, J.V., Azañón, J.M., Azor, A., 2009. CalHypso: An ArcGIS extension to calculate hypsometric curves and their statistical moments. Applications to drainage basin analysis in SE Spain. Computers Geosciences 35, 1214-1223.Phan Trong Trinh, Hoang Quang Vinh, Leloup Philippe Hervé, Giuliani, G., Vincent Garnier., Tapponnier, P., 2004. Cenozoic deformation, thermodynamic evolution, slip mechanism of Red River shear zone and ruby formation. Science and Technics Publishing House, Hanoi. P5-72 (In Vietnamese with English abstract).Phan Trong Trinh, Ngo Van Liem, Nguyen Van Huong, Hoang Quang Vinh, Bui Van Thom, Bui Thi Thao, Mai Thanh Tan, Nguyen Hoang, 2012. Late Quaternary tectonics and seismotectonics along the Red River fault zone, North Vietnam. Earth-Science Reviews 114, 224-235.Phan Van Quynh, Vo Nang Lac, and Tran Ngoc Nam, 1995. Some features of late Paleozoic-Cenozoic deformation tectonics on the territory of Vietnam and neighboring areas. In: Geology, Mineral Resources and Petroleum of Vietnam. Geological Survey of Vietnam, Hanoi, 171-183 (in Vietnamese with an English abstract).Phung Thi Thu Hang, 2011. Study and comparison recent active tectonics between the Red River and the Dien Bien - Lai Chau Fault Zones base on geomorphic indices. Master thesis. VNU University of Science, Hanoi.Shahzad, F., and Gloaguen, R., 2011. TecDEM: AMATLAB based tool box for tectonic geomorphology, Part 1: Drainage network preprocessing and stream profile analysis. Computers Geosciences 37, 250-260.Strahler, A.N., 1952. Hypsometric (area-altitude) analysis of erosional topography. Geological Society of America Bulletin 63, 1117-1142.Strahler, A.N., 1957. Quantitative analysis of watershed geomorphology. Transactions of the American Geophysical Union 38, 913-920.Tran Dinh To, 2002. The characterize of  Neotectonics of Red River-Chay River Fault Zone. Doctorate Thesis, Institute of Geological Sciences, Hanoi, (In Vietnamese with English abstract).Tran Dinh To, Duong Chi Cong, Vy Quoc Hai, Matthias Becker, Marina Neuman, 2003. Activity  of Red River fault zone at Tam Dao-Ba Vi derived from GPS data (1994-1996-1998-2000). Journal of Sciences of the Earth, 25(4)PC, 511-515 (In Vietnamese with English abstract).Tran Dinh To, Nguyen Trong Yem, 2001.Amplitude and rate of slip of the Red River Zone in late Cenozoic. Journal of Sciences of the Earth, 23(4), 334-353. (In Vietnamese with English abstract).Tran Ngoc Nam, 1999. Red River Fault zone - focus of the scientific debate. Part II: P-T-t paths and post-metamorphic exhumation, Journal of Sciences of the Earth, No.3, 161-167 (In Vietnamese with English abstract).Tran Ngoc Nam, 2002. Exhumation mechanisms of the Day Nui Con Voi. Journal of Sciences of the Earth, No.3,  286-288 (In Vietnamese with English abstract).Tran Ngoc Nam, Mitsuhiro Toriumi, TetsumaruItaya, 1998. P-T-t paths and post-metamorphic exhumation of the Day Nui Con Voi shear zone in Vietnam. Tectonophysics 290, 299-318.Tran Ngoc Nam., Toriumi, M., Sano, Y., Terada, K., Ta, T.T.,, 2003. 2.9, 2.36, and 1.96 Ga zircons in orthogneiss south of the Red River shear zone in Viet Nam: evidence from SHRIMP U-Pb dating and tectonothermal implications. Journal of Asian Earth Sciences 21, 743-753.Trinh Thi Thuy, 2014. Assessment of modern tectonic activity of the Son La fault zones on the basis of tectonic geomorphology. Master thesis. The University of Science - Vietnam National University, Hanoi (In Vietnamese with English abstract).Wang, P.L., Lo, C.H., Chung, S.L., Lee T.Y., Lan, C.Y., Thang, T.V., 2000. Onset timing of left-lateral movement along the Ailao Shan±Red River Shear Zone: 40Ar/39Ar dating constraint from the Nam Dinh Area, northeastern Vietnam. Journal of Asian Earth Sciences. Volume 18, Issue 3, 1 June 2000, 281-292.Willgoose, G., 1994. A physical explanation for an observed area-slope-elevation relationship for catchments with declining relief. Water Resources Research 30, 151-159.Willgoose, G., Hancock, G., 1998. Revisiting the hypsometric curve as an indicator of form and process in transport-limited catchment. Earth Surface Processes and Landforms 23, 611-623.Zuchiewicz, W., Nguyen Quoc Cuong, Jerzy Zasadni, Nguyen Trong Yem, 2013. Late Cenozoic tectonics of the Red River Fault Zone, Vietnam, in the light of geomorphic studies. Journal of Geodynamics 69, 11-30. 

Some study results of Cam Ranh - Binh Thuan mud eruption strip

Most of the mud eruption locations are distributed in a stretching strip, running in NE-SW direction from Cam Ranh - Ninh Thuan - Binh Thuan NE-SW tectonic fault zone and coinciding with a tectonically crushed zone. The erupted mud consists of sand, mud, clay. The clay contains alkaline montmorillonite, formed following chemical weathering and re-sedimentation processes from rocks containing alkaline minerals in a semi-arid climate area, located in a low terrain or a tectonic subsiding zone with a large fluctuation in groundwater level. The mud eruption  has a close relation to factors (of) climate, topography, geomorphology, hydrogeology, petrography and tectonic activities in the area. Among these, tectonic factors are the most important for they create not only soil and rock crushed zone, paving favorable conditions for strong weathering process at depth, but also to form canals to bring hot groundwater and minerals from certain depths upward, and by the effects of pressurized groundwater and partly due to the expansion in volume of bentonite clay pushing the muddy clay material through the tectonic cracks to the surface of the current terrain. The mud eruption process is not deep; but it may occur from a shallow level, about 4-18 m below, under the impact of the above elements.ReferencesCao Dinh Trieu, 2006. Characteristics of Earthquake Activities of Central Southern and Southern Sea.  Journal of Geology, Range A, 293(3-4), Hanoi.   Cao Dinh Trieu, et al., 2013. Modern geodynamics in Vietnamese territory. Natural Sciences and Technology Publishing House, Hanoi, 242.Ho Vuong Binh, et al., 1990. Research report on evaluation of prospects and possibility of using alkaline bentonite at Thuan Hai. Archived at the Center for Information Archives of Geology, Hanoi.Le Duc An, 1990. Geomorphological and neotectonic features of Thuan Hai area. Geological Science and Technique Information, (1-2), 5-25, Hanoi.Le Duy Bach, et al., 2007. Tectonic features Pliocene - Quaternary at Southeast continental shelf of Vietnam. Journal of Sciences of the Earth, 29(3), 218-227, Hanoi.Mazzini. A, A. Nermoen, M. Krotkiewski, Y. Podladchikov, S. Planke, H. Svensen, 2009. Strike-slip faulting as a trigger mechanism for overpressure release through piercement structures. Implications for the Lusi mud eruption, Indonesia. Marine and Petroleum Geology, doi:10.1016/j.marpetgeo.2009.03.001Medialdea. T, et al., 2003. Tectonics and mud eruption  development in the Gulf of Cadiz.  Marine Geology, 261(1-4), 48-63.Nguyen Duc Thai, et al., 2011. Report on survey results of land crack and mud appearance locations at Suoi Da village, Loi Hai commune, Thuan Bac district, Ninh Thuan province. Archived at Division for Water Resources Planning and Investigation for the Central Region of Vietnam.Nguyen Duc Thang (chief author) et al., 1988. Report on surveying and mapping of Geology and Minerals in Phan Rang-Nha Trang area at 1:200,000 scale. Archived at the Center for Information Archives of Geology, Hanoi.Nguyen Hong Phuong, 2004. Map of earthquake dangerous rate in Vietnam and the East Sea. Journal of Sciences of the Earth,  26(2), 97-111, Hanoi.Pham Van An, et al., 1990. Features of weathering crust at dry hot area Thuan Hai and origin of alkaline bentonite clay. Geological Science and Technique Information, (1-2), 72-79, Hanoi.Pham Van Hung, 2000. Determining kinematic properties of cracks by analyzing tectonic cracks in the South Central region, Journal of Sciences of the Earth, 29(2), 113-119, (in Vietnamese).Pham Van Hung, 2001. Quaternary - modern operational features of tectonic fault at the East edge of Kon Tum massif. Journal of Geology, 267, 43-49, Hanoi.Pham Van Nam, et al., 1988. Report on hydrogeological-engineering geological Mapping at 1:200,000 scale in Phan Rang-Nha Trang region. Archived at Division for Water Resources Planning and Investigation for the Central Region of Vietnam, Nha Trang.Phan Trong Trinh, 2012. Recent tectonics and modern geodynamics in Vietnam’s Sea and adjacent zones. Natural Sciences and Technology Publishing House, Hanoi, 331p.Pham Van Thuc, et al., 2004. Seismic zoning of the East Sea and coastal area in Vietnam. Journal of Geology, Range A, 285(11-12), Hanoi.Phung Van Phach, et al., 1996. Some research results of gases ash eruption phenomenon at Pleiku Highland in 1993. Geological Resources, 1, Science and Technique Publishing House, 396-405.Quo-Cheng Sung, Hung-Cheng Chang, HSing-Chang Liu, Yen-Chieh Chen, 2010. Mud eruption along the chihan fault in Southwestern Taiwan Arelease bend model. Geomorphology, 118, 188-198.Tran Van Thang, et al., 2006. Tectonic development characteristics of Da Lat zone and adjacent zone in late Mezozoi-Kainozoi. Journal of Sciences of the Earth, 28(2), 140-149, (in Vietnamese)..Stepanek P., Ho Trong Ty, 1986. Report on mineral geological mapping at Phan Rang-Cam Ranh at 1:50,000 scale. Archived at the Center for Information Archives of Geology, Hanoi.Vo Cong Nghiep, et al., 1998. List of hot water and minerals resources in Vietnam. Ministry of Industry, General Department of Geology and Minerals of Vietnam, Hanoi. 308p.Uong Dinh Khanh, 2004. Geomorphological characteristics of the hilly areas Ninh Thuan - Binh Thuan. Doctorate thesis, archived at National Library, Hanoi.Yin. P, S. Bern, P. Vagner, B. Loubrieu, Z. Liu, 2003. Mud eruption at the shelf margin of the East China Sea. Marine Geology, 194(3-4), 135-149.http://www.mhc.vn/. Minh Ha Bentonite Minerals JSC. 

M^2UNet: MetaFormer Multi-scale Upsampling Network for Polyp Segmentation

Polyp segmentation has recently garnered significant attention, and multiple methods have been formulated to achieve commendable outcomes. However, these techniques often confront difficulty when working with the complex polyp foreground and their surrounding regions because of the nature of convolution operation. Besides, most existing methods forget to exploit the potential information from multiple decoder stages. To address this challenge, we suggest combining MetaFormer, introduced as a baseline for integrating CNN and Transformer, with UNet framework and incorporating our Multi-scale Upsampling block (MU). This simple module makes it possible to combine multi-level information by exploring multiple receptive field paths of the shallow decoder stage and then adding with the higher stage to aggregate better feature representation, which is essential in medical image segmentation. Taken all together, we propose MetaFormer Multi-scale Upsampling Network (M$^2$UNet) for the polyp segmentation task. Extensive experiments on five benchmark datasets demonstrate that our method achieved competitive performance compared with several previous methods

Isolation and identification of triterpenoid compounds from Couroupita guianensis Aubl.

In this report, the extracts from the fruit and leaves of Couroupita guianensis were isolated using chromatographic methods and investigated for chemical composition. Four triterpenoid compounds were isolated and identified as betulinic acid, oleanolic acid, β-amyrin and friedelin. Their chemical structures were interpreted based on modern spectra such as MS, NMR and compared with previously published spectral data

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

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

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions

Superposition et perturbation du champ des contraintes : determination du tenseur de contrainte et modelisation numerique

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Study on the Hai-Phong Bay coastal evolution over a sixty year period using remote sensing data

In this present paper, we firstly present the results of the SAR images of ERS-1, ERS-2 and RADARSAT satellites analysis to extract the wave pattern. Such information has been proved to be necessary to explain the beacg-h erosion areas. The second step is to confirm and complete the results derived from a diachronic analysis of aerial photos of 1952 and 1993 completed by SPOT-HRV together with LANDSAT-TM satellite images. The results of this comparison allow (i) the cartography of the erosion and sedimentation areas and (ii) to highlight the relation between these coastal geomorphological processes and the wave patterns. A second cartography of the erosion and sedimentation areas has been established from the comparison of the RADARSAT and the SPOT-HRV images. These data have been used afterwards as a back-image. Over this raster layer, we have superposed a vector layer wich presents the coastal boundaries digitized from the topographic map of 1939 and the aerial photos of 1992. The two coastal lines have been crossed thanks to the ARC/INFO software to obtain a precise estimation of the surface values of the eroded or prograded areas. From this map, it can be concluded that sedimentation mostly occurs along channels and estuaries while erosion areas generally located on the sea front. Coastal erosion processes seem to be driven by the wave and tidal currents in case of storms. In this particular case study, remote sensing data allow the reconstitution of the littoral environment on both long (53 years) and short (4 years) periods of time. This is made possible because the yearly coastal erosion rate can be up to ten meters. It appears that, in this case, the SPOT-XS image is the best choice for the detection of sediment concentration in the estuaries and for the cartography of the coastal evolution. Furthermore, the results are getting better with the ERS-1, ERS-2 and RADARSAT and SPOT-XS data fusion because of the combination of high spectral resolution (SPOT-XS) with a high spatial resolution (ERS-1, ERS-2 and RADARSAT, 12.5 meters)