Prof. Chuan-Chou Shen and geological research team at National Taiwan University published in the leading Journal, Proceedings of the National Academy of Sciences of the United States of America
Study Selected as Cover Article for Journal of Material Chemistry A
Developing Machine Learning Algorithms for Tracking Epidemics in Time and Space
Ongoing project / Led by Prof. Chuan-Chou Shen
Our goals are (1) to explore the pace of climate and environmental change in Taiwan and the Western Pacific over the past 3000 years and to study the relationship between the South East Asian monsoon, the Pacific Ocean climate system, and the global climate system; and (2) to study the impact of anthropogenic nitrogen on the marine ecology of the Western Pacific over the past century.
Top geomagnetic breakthroughs by geological research team at National Taiwan University, directed by Dr. Chuan-Chou Shen, a Distinguished Professor at the Department of Geosciences, just published in the leading Journal Proceedings of the National Academy of Sciences of the United States of America on Augustn 20, 2018.
The intensity of Earth’s magnetic field varies continuously and has decreased by 10-15% over the past century, which has led to suggestions of a possible impending reversal. However, no single reversal has been observed by humans in contemporary times. The transition time and detailed process of a reversal event have remained elusive even though that geomagnetic field had been well known over two thousand years and the geomagnetic reversals were discovered in igneous rocks a century ago. It is why Sciencemagazine listed it as one of 125 unsolved scientific questions in 2005.
Understanding the physical processes responsible for reversals has been hindered by the short timescale of modern observations and the intrinsic limitations of geological materials that are studied to learn about these processes. Stalagmites, used in our study, have proven to be highly suitable for paleomagnetic reconstructions because of their continuous formation and simple mechanism by which they record magnetic information. Recent developments in refined radioisotopic dating methods and high-sensitivity superconducting magnetometry add further to the advantage of stalagmites for such studies. However, the most difficult challenge is to find a suitable stalagmite carbonate with sufficient magnetic mineral contents for paleomagnetic analysis.
After searching for over a decade, Dr. Chuan-Chou Shen and his team found ideal stalagmite samples from southern China with trace amounts of magnetic minerals. Even so, the magnetic intensity in the studied stalagmite is one thousand-times less than in most igneous rocks. The team coupled the world-leading high-precision U-Th radioisotopic dating techniques with high-sensitivity paleomagnetic analysis and obtained 180 paleomagnetic data points with 70 age control points to build a robust 16,000-year record of geomagnetic field variations from 107 to 91 thousand years ago . In this multidecadally-resolved record, an abrupt centennial reversal transition, which occurred within a century, is revealed at 98,000 years ago. This change is more than 10 times more rapid than previous estimates for the fastest rate of change, and more than 30 times more rapid than the generally accepted duration for polarity transitions.
The unprecedented chronology precision provides an important step toward understanding processes that control polarity reversals, where the speed of reversal was not previously appreciated. This research is just the beginning. Future work on other stalagmite records shed further light on the nature of geomagnetic field variability and polarity reversals and excursions.
Human beings and our ancestors have lived on Earth for several millions of years. Many polarity reversals have occurred throughout this time, so reversals do not represent a challenge to our survival. However, polarity transitions can cause severe disordering of the ionosphere, atmosphere, and biosphere. Such abrupt events could have serious implications for animal navigation, radio communication, satellites, and electronic power systems. Infrastructure and facilities for communication and transportation are likely to be affected, which could include the global internet system and stock markets.
The full research article “Multidecadally resolved polarity oscillations during a geomagnetic excursion” will be available on http://www.pnas.org/content/early/2018/08/14/1720404115.
Prof. Chuan-Chou Shen of the Department of Geosciences, National Taiwan Univerity, surveyed in cave. (Image courtesy of Chuan-Chou Shen)
Geomagnetic field shields Earth from direct impact of solar wind and cosmic radiation. (Image courtesy of Yu-Min Chou)
(A) Stalagmite-revealed unique oscillations of the geomagnetic pole on centennial-to-millennial scales. One surprisingly rapid reversal event occurred just around 144 years at 98 thousand year ago. (B) The calculated transition path of the geomagnetic pole during the reversal event from 98,360 to 98,216 years before present (yr BP). Star symbol denotes Sanxing Cave where the stalagmite was collected. (Image courtesy of Yu-Min Chou)
Ongoing project / Led by Prof. Yih-Min Wu
We perform integrated observations of Earth surface dynamics under extreme weather conditions on time scales ranging from tens to thousands of years. Our approaches include: (1) seismic noise and imaging technology to measure the mass of landslides, debris flows, and river sediment transport capacity; and (2) geochemical tracers to estimate rates and amounts of carbon dioxide released or absorbed by erosion and weathering.
Ongoing project / Led by Prof. Ya-Hsuan Liou
We integrate expert knowledge across the fields of geology, environmental engineering, biology and environmental management, to understand the physical, chemical and biological roles of heavy metal pollution in sediments. Our goals are to promote new remediation technologies and to propose effective strategies to manage polluted sites.
NTU Prof. of Geosciences Ya-Hsuan Liou (劉雅瑄) and post-doctoral researcher Li-Cheng Gao (高立誠) have found a simple route to synthesize heterogeneous crystal structures in hierarchical architectures with vacancy-driven defects through the oriented attachment growth mechanism. Their study was published in the Royal Society of Chemistry’s renowned Journal of Material Chemistry A (impact factor: 8.8) and selected as the cover article for the June 21, 2018 issue.
With the advancements in electron microscopy and nanotechnology, researchers can now use electron microscopes to observe crystal growth processes that were previously unknown to them. In this study, Prof. Liou and Dr. Gao successfully fabricated anatase/rutile TiO2 nanorod arrays as a large-scale film on substrates using a simple liquid-phase growth method—the oriented attachment growth mechanism. When nanomaterials grow via oriented attachment, the structural differences between the lattice planes of two distinct planes may result in the presence of interface dislocations, or defects, which would then alter the activity of the material.
The team not only overcame the difficulty of growing anatase TiO2 on substrates, but also changed the growth mechanism and crystalline form by modifying the liquid-phase environment. In collaboration with Dr. Jinghua Guo from the Advanced Light Source at Lawrence Berkeley National Laboratory in California, the team adopted synchrotron-based X-ray spectroscopy to characterize both the physical and chemical properties of the nanomaterials and identify the spatial distribution of different crystalline forms. Also, resonant inelastic X-ray scattering was utilized to observe and determine oriented attachment growth-induced defects. The photocatalytic degradation of contaminants indicated that materials with a heterogeneous crystal structure exhibit enhanced photocatalytic activity. In sum, the TiO2 nanomaterials developed in this study have great potential as promising photocatalysts in the energy and environmental fields.
This study was supported by the Ministry of Science and Technology (project no.: 105-2917-I-002-008 & 105-2628-M-002-008-MY3) and Higher Education Sprout Project at NTU. The team’s findings were published under the title, “A Facile Route for the Synthesis of Heterogeneous Crystal Structures in Hierarchical Architectures with Vacancy-Driven Defects via the Oriented Attachment Growth Mechanism,” (DOI: 10.1039/C8TA01027G), and selected as the cover for the Journal of Material Chemistry A (Vol. 6, No. 23, June 21, 2018).
Ongoing project / Led by Prof. Jen-Jia Lin
Within this theme, we explore challenges to nature and humanity across East Asia, including: (1) human adaptations to environmental change and their impact on human development; (2) the impact of human impacts on the environment with an emphasis on biogeochemical cycles; and (3) studies on political ecology, such as environmental governance, indigenous community governance, the tea industry, and border management, to bridge the juxtaposition of nature and humanity.
Epidemic diffusion is a space–time process, which can be considered as the movement of linked cases through space and time. Therefore, space-time locations of cases are key to identify any diffusion process. Dr. Tzai-Hung Wen, Professor at Department of Geography, National Taiwan University, borrowed the concepts of tracking the routes of typhoons for developing machine learning algorithms for profiling diffusion dynamics of disease clustering and epidemic propagation. The novel algorithms that utilize the temporal lag within the diffusion process and the spatial distance between cases to detect the spatial-temporal sub-clusters and to uncover the development of progression chains. The progression of dengue epidemics in south Taiwan from 1998 to 2015 are used for demonstrating the capability of the algorithms. Dr. Wen's work contributes a more detailed and in-depth understanding of the geographic diffusion process of epidemics. These results have been published in the international journals, including Scientific Reports 7:12565 and Annals of the American Association of Geographers 108(4):1168-1186.
Dr. Wen suggests that health authorities can integrate the epidemic reporting system with the algorithms as an automatic early-warning decision tool for uncovering the evolution of disease transmission in time and space, such as dengue, measles and tuberculosis. Currently, the algorithms are adopted in National Mosquito-Borne Diseases Control Research Center at National Health Research Institutes (NHRI) and the local government’s Department of Health for tracking the epidemic progression of dengue fever outbreaks this September.
We propose a new classification of disease cluster evolution (Figure 1) separated into single and multiple disease clusters. The changes in the center and the area of a transmission cluster were used to monitor the single pattern. Each of these changes implies a significant property of diffusion, namely, that distinct strategies for public health are needed. For example, if the epidemic in a transmission cluster becomes more prevalent than before, the area might get larger. The health authority could focus its attention there. If a transmission cluster moves to another place, its center could move. The health authority could track its trajectory and try to stop its progression. By combining the changes in these two characteristics, six distinct types of single cluster evolution patterns could be discovered. Furthermore, characterizing interaction cluster evolution patterns focuses on the changes resulting from the interaction between two or more transmission clusters.
To further prove the effectiveness of our algorithm, Figure 2 shows that our approach is more intuitive than the ST-KDE. Our approach, MST-DBSCAN algorithm, can further demonstrate a dominated diffusion type in each hot spot of ST-KDE. It includes that Hot spot I is the earliest one among these four hot spots, and its location is zone 1. Hot spots II and III are located in zone 4, and hot spot IV is located in zone 5. The emergence of hot spot IV occurs later than that of the previous two hot spots.
Figure 1: Types of cluster evolution
Figure 2: Comparing the results of MST-DBSCAN algorithm with space–time kernel density estimation (ST-KDE).
Published papers (27)
Chang, N. N., Lin, L. H., Tu, T. H., Jeng, M. S., Chikaraishi, Y., & Wang, P. L. (2018). Trophic structure and energy flow in a shallow-water hydrothermal vent: Insights from a stable isotope approach. Public Library of Science ONE, 13(10), 1-23. https://doi.org/10.1371/journal.pone.0204753
Chen, S. K., Wu, Y. M., & Chan, Y. C. (2018). Episodic slow slip events and overlying plate seismicity at the southernmost Ryukyu Trench. Geophysical Research Letters, 45(19), 10369-10377. https://doi.org/10.1029/2018GL079740
Chen, T. H., Chen, Y. J., & Wen, T. H. (2018). Revisiting the role of rainfall variability and its interactive effects with the built environment in urban dengue outbreaks. Applied Geography, 101(12), 14-22. https://doi.org/10.1016/j.apgeog.2018.10.005
Chou, Y. M., Jiang, X., Liu, Q., Hu, H. M., Wu, C. C., Liu, J., Jiang, Z., Lee, T. Q., Wang, C. C., Song, Y. F., Chiang, C. C., Tan, L., Lone, M. A., Pan, Y., Zhu, R., He, Y., Chou, Y. C., Tan, A. H., Roberts, A. P., Zhao, X., & Shen, C. C. (2018). Multidecadally resolved polarity oscillations during a geomagnetic excursion. Proceedings of the National Academy of Sciences, 115(36), 8913-8918. https://doi.org/10.1073/pnas.1720404115
Chuang, C. K., Lo, L., Zeeden, C., Chou, Y. M., Wei, K. Y., Shen, C. C., Mii, H. S., Chang, Y. P., & Tung ,Y. H. (2018). Integrated stratigraphy of ODP Site 1115 (Solomon Sea, southwestern equatorial Pacific) over the past 3.2 Ma. Marine Micropaleontology, 144, 25-37. https://doi.org/10.1016/j.marmicro.2018.09.003
Fan, D., Shang, S., & Burr, G. (2018). Sea level implications from Late Quaternary/Holocene paleosols from the Oujiang Delta, China. Radiocarbon, 1-17. https://doi.org/10.1017/RDC.2018.77
Feng, C., Chen, Y. A., Yu, C. P., & Hou, C. H. (2018). Highly porous activated carbon with multi-channeled structure derived from loofa sponge as a capacitive electrode material for the deionization of brackish water. Chemosphere, 208, 285-293. https://doi.org/10.1016/j.chemosphere.2018.05.174
Gázquez, F., Columbu, A., Waele, J. D., Breitenbach, S. F. M., Huang, C. R., Shen, C. C., Lu, Y., Calaforra, J. M., Mleneck-Vautravers, M. J. & Hodell, D. A. (2018) Quantification of paleo-aquifer changes using clumped isotopes in subaqueous carbonate speleothems. Chemical Geology, 493, 246-257. https://doi.org/10.1016/j.chemgeo.2018.05.046
Huang, C. Y., Archer, S. R., McClaran, M. P., & Marsh, S. E. (2018) Shrub encroachment into grasslands: end of an era? PeerJ, 6, 1-19. 10.7717/peerj.5474
Huang, C. Y., Wei, H. L., Rau, J. Y., & Jhan, J. P. (2018). Use of principal components of UAV-acquired narrow-band multispectral imagery to map the diverse low stature vegetation fAPAR. GIScience & Remote Sensing. https://doi.org/10.1080/15481603.2018.1550873
Hung, P. Y., & Hsiao, H. T. (2018). Apples in action: Territoriality and land use politics of mountain agriculture in Taiwan. Asia Pacific Viewpoint, 59(3), 349-367. https://doi.org/10.1111/apv.12194
Kao, L. C., Ye, Y., Liu, Y. S., Dong, C. L., Guo, J. & Liou, Y. H. (2018) A facile route for the synthesis of heterogeneous crystal structures in hierarchical architectures with vacancy-driven defects via the oriented attachment growth mechanism. Journal of Materials Chemistry A, 6(23), 10663-10673. 10.1039/C8TA01027G
Koralay, T., Baykara, M. O., Deniz, K., Kadioğlu, Y. K., Duman, B., & Shen C. C. (2018). Multi-Isotope investigations for scientific characterisation and provenance implication of banded travertines from Tripolis Antique City (Denizli–Turkey). Environmental Archaeology. https://doi.org/10.1080/14614103.2018.1498164
Ku, C. S., Kuo, Y. T., Chao, W. A., You, S. H., Huang, B. S., Chen, Y. G., Taylor, F. W., & Wu, Y. M. (2018). A first‐layered crustal velocity model for the Western Solomon Islands: Inversion of the measured group velocity of surface waves using ambient noise. Seismological Research Letters, 89(6), 2274-2283. https://doi.org/10.1785/0220180126
Lei, I. L., Ng, D. Q., Sable, S. S., & Lin, Y. P. (2018). Evaluation of lead release potential of new premise plumbing materials. Environmental Science and Pollution Research, 25(28), 27971-27981. https://doi.org/10.1007/s11356-018-2816-2
Lin, J. J. & Wei, Y. H. (2018). Assessing area-wide bikeability: A grey analytical network process. Transportation Research Part A: Policy and Practice, 113, 381-396. https://doi.org/10.1016/j.tra.2018.04.022
Lin, J. J., Zhao, P., Takada, K., Li, S. Yai, T., & Chen, C. H. (2018). Built environment and public bike usage for metro access: A comparison of neighborhoods in Beijing, Taipei, and Tokyo. Transportation Research Part D: Transport and Environment, 63, 209-221. https://doi.org/10.1016/j.trd.2018.05.007
Lin, Y. T., Tu, T. H., Wei, C. L., Rumble, D., Lin, L. H., & Wang, P. L. (2018). Steep redox gradient and biogeochemical cycling driven by deeply sourced fluids and gases in a terrestrial mud volcano. FEMS Microbiology Ecology 94(11). https://doi.org/10.1093/femsec/fiy171
Magnabosco, C., Lin, L.H., Dong, H., Bomberg, M., Ghiorse, W., Stan-Lotter, H., Pedersen, K., Kieft, T. L., van Heerden, E., & Onstott, T. C. (2018). The biomass and biodiversity of the continental subsurface. Nature Geoscience, 11, 707-717. https://doi.org/10.1038/s41561-018-0221-6
Maxwell, K. V., Ramos, N. T., Tsutsumi, H., Chou, Y. C., Duan F., & Shen, C. C. (2018). Late Quaternary uplift across northwest Luzon Island, Philippines constrained from emergent coral reef terraces. Earth Surface Processes and Landforms, 43, 3114-3132 https://doi.org/10.1002/esp.4474
Ng, D. Q., Chen, C. Y., & Lin, Y. P. (2018). A new scenario of lead contamination in potable water distribution systems: Galvanic corrosion between lead and stainless steel. Science of The Total Environment, 637-638, 1423-1431. https://doi.org/10.1016/j.scitotenv.2018.05.114
Owen, R. B., Muiruri, V. M., Lowenstein, T. K., Renaut, Robin W.; Rabideaux, Nathan; Luo, Shangde; Deino, Alan L.; Sier, Mark J.; Dupont-Nivet, G., McNulty, E. P., Leet, K., Cohen, A., Campisano, C., Deocampo, D., Shen, C. C., Billingsley, A., & Mbuthia, A. (2018). Progressive aridification in East Africa over the last half million years and implications for human evolution. Proceedings of the National Academy of Sciences, 115(44), 11174-11179. https://doi.org/10.1073/pnas.1801357115
Shih, Y. T., Chen, P. H., Lee, L. C., Liao, C. S., Jien, S. H., Shiah, F. K., Lee, T. Y., Hein, T., Zehetner, F., Chang, C. T., & Huang, J. C. (2018). Dynamic responses of DOC and DIC transport to different flow regimes in a subtropical small mountainous river. Hydrology and Earth System Sciences, 22(12), 6579-6590. https://doi.org/10.5194/hess-22-6579-2018
Wang, K. S., Chao, W. A., Mittal, H., & Wu, Y. M. (2018). Building effects on the P‐alert‐based real‐time shaking map determination. Seismological Research Letters, 89(6), 2314-2321. https://doi.org/10.1785/0220170252
Wen, T. H., Hsu, C. S., & Hu, M. C. (2018). Evaluating neighborhood structures for modeling intercity diffusion of large-scale dengue epidemics. International Journal of Health Geographics, 17(9), 1-15. https://doi.org/10.1186/s12942-018-0131-2
Wu, C. C., Shen, C. C., Lo, Li; Hsin, Y. C., Yu, K., Chang, C. C., Lam, D. D., Chou, Y. M., Liu, Y., Pallister, J., Song, S. R., Chiang, H. W., & Burr, G. S. (2018). Pinatubo volcanic eruption exacerbated an abrupt coral mortality event in 1991 summer. Geophysical Research Letters, 45, 12396-12402. https://doi.org/10.1029/2018GL079529
Yang, W. K., Chiang, L. F., Tan, S. W., & Chen, P. J. (2018). Environmentally relevant concentrations of di (2-ethylhexyl) phthalate exposure alter larval growth and locomotion in medaka fish via multiple pathways. Science of The Total Environment, 640-641, 512-522. https://doi.org/10.1016/j.scitotenv.2018.05.312
Papers in press (13)
Bloemsma, M., Croudace, I., Daly, J. S., Edwards, R. J., Francus, P., Galloway, J. M., Gregory, B. R. B., Huang, J. J. S., Jones, A. F., Kylander, M., Löwemark, L., Luo, Y., Maclachlan, S., Ohlendorf, C., Patterson, R. T., Pearce, C., Profe, J., Reinhardt, E. G., Stranne, C., Tjallingi, R., & Turner, J. N. (2018). Practical guidelines and recent advances in the Itrax XRF core-scanning procedure. Quaternary International. https://doi.org/10.1016/j.quaint.2018.10.044
Huang, T. C. & Wu, Y. M. (2019). A robust algorithm for automatic P-wave arrival time picking based on the local extrema scalogram. Bulletin of the Seismological Society of America.
Jiang, X., He, Y., Wang, X., Dong, J., Li, Z., Lone, M. A., & Shen, C. C. (2018). Sub-decadally-resolved Asian monsoon dynamics during Chinese interstadial 21 in response to northern high-latitude climate. Journal of Asian Earth Sciences. https://doi.org/10.1016/j.jseaes.2018.09.017
Kuo, Y. T., Wang, Y., Hollingsworth, J., Huang, S. Y., Chuang, R. Y., Lu, C. H., Hsu, Y. C., Tung, H., Yen, J. Y., & Chang, C. P. (2019). Shallow fault rupture of the Milun Fault in the 2018 Mw 6.4 Hualien earthquake: A high resolution approach from optical correlation of Pléiades satellite imagery. Seismological Research Letters. 10.1785/0220180227
Lee, A. S., Huang, J. J., Burr, G., Kao, L. C., Wei, K. Y., & Liou, Y. H. (2018). High resolution record of heavy metals from estuary sediments of Nankan River (Taiwan) assessed by rigorous multivariate statistical analysis. Quaternary International. https://doi.org/10.1016/j.quaint.2018.11.018
Liu, Y., Li, X., Zeng, Z., Yu, H. M., Huang, F., Felis, T., & Shen, C. C. (2018). Annually-resolved coral skeletal δ138/134Ba records: A new proxy for oceanic Ba cycling. Geochimica et Cosmochimica Acta. https://doi.org/10.1016/j.gca.2018.12.022
Ma, K. F. & Wu, Y. M. (2018). Preface to the focus section on 6 February 2018 Mw 6.4 Hualien, Taiwan, earthquake. Seismological Research Letters. https://doi.org/10.1785/0220180356
Ma, X., Chen, Y. A., Zhou, K., Wu, P. C., & Hou, C. H. (2019) Enhanced desalination performance via mixed capacitive-Faradaic ion storage using RuO2-activated carbon composite electrodes. Electrochimica Acta, 295, 769-777. https://doi.org/10.1016/j.electacta.2018.10.180
Wu, Y. M., Mittal, H., Huang, T. C., Yang, B. M.; Jan, J. C., Chen, S. K. (2019). Performance of a low-cost earthquake early warning system (P-alert) and shake map production during the 2018 M w 6.4 Hualien, Taiwan, earthquake. Seismological Research Letters. https://doi.org/10.1785/0220180170
Yang, R. J., Wang, S.L, Burr, G. S., Liu, J. T., & Fan, D. (2018). Holocene variation of radiocarbon reservoir age offshore western Taiwan, derived from paired charcoals and mollusks. Quaternary International. https://doi.org/10.1016/j.quaint.2018.07.001
Yen, J. Y., Lu, C. H., Dorsey, R. J., Hao, K. C., Chang, C. P., Wang, C. C., Chuang, R. Y., Kuo, Y. T., Chiu, C. Y., Chang, Y. H., Bovenga, F., Chang, W. Y. (2018). Insights into seismogenic deformation during the 2018 Hualien, Taiwan, earthquake sequence from InSAR, GPS, and modeling. Seismological Research Letters. 10.1785/0220180228
Yuan, H. Y., Wen, T.H., Kung, Y. H., Tsou, H. H., Chen, C.H., Chen, L.W., & Lin, P. S. (2019). Prediction of annual dengue incidence by hydro-climatic extremes for southern Taiwan. International Journal of Biometeorology.
Zheng, Z. J., Lin, M. Y., Chiueh, P. T., and Lo, S. L. (2019). Framework for determining optimal strategy for sustainable remediation of contaminated sediment: A case study in Northern Taiwan. Science of The Total Environment, 654, 822-831. https://doi.org/10.1016/j.scitotenv.2018.11.152