Rifting characteristics of eastern subbasin of South China Sea and its spreading pattern

With processing and interpretation of 25 000 km full-coverage multibeam swath data fromthe eastern South China Sea, it is found that NE-trending and NW-trending linear morphological features such as scarps, horsts and grabens, govern the central part (14°-17° N) of eastern subbasin. Compared with reflection seismic profiles, these NE-trending linear morpho-structures are considered to be the representation of basement structures on seabed and can be divided into three linear structural zones. The trend of the central zone is NE45°-50° occurring around extinct spreading center, the trend of the second zone is NE70° - 78° on both sides of the central one and the trend of the third zone is about NE60° just on the north of the second one. These three NE-trending linear zones are formed in late-stage NW - SE-trending seafloor spreading of the eastern subbasin along NW-trending linear faults, and respectively correspond to three spreading episodes: 17.0- 19.0 Ma (5d-5e), 19.0 - 21.0 Ma (5e-6a) and 21.0 - 24.2 Ma (6a-6c) based on the contrast of morpho-structures to magnetic lineation anomalies.

Stochastic modelling of infectious diseases for heterogeneous populations

Background:Infectious diseases such as SARS and H1N1 can significantly impact people’s lives and cause severe social and economic damages.Recent outbreaks have stressed the urgency of effective research on the dynamics of infectious disease spread.However,it is difficult to predict when and where outbreaks may emerge and how infectious diseases spread because many factors affect their transmission,and some of them may be unknown.Methods:One feasible means to promptly detect an outbreak and track the progress of disease spread is to implement surveillance systems in regional or national health and medical centres.The accumulated surveillance data,including temporal,spatial,clinical,and demographic information can provide valuable information that can be exploited to better understand and model the dynamics of infectious disease spread.The aim of this work is to develop and empirically evaluate a stochastic model that allows the investigation of transmission patterns of infectious diseases in heterogeneous populations.Results:We test the proposed model on simulation data and apply it to the surveillance data from the 2009 H1N1 pandemic in Hong Kong.In the simulation experiment,our model achieves high accuracy in parameter estimation(less than 10.0%mean absolute percentage error).In terms of the forward prediction of case incidence,the mean absolute percentage errors are 17.3%for the simulation experiment and 20.0%for the experiment on the real surveillance data.Conclusion:We propose a stochastic model to study the dynamics of infectious disease spread in heterogeneous populations from temporal-spatial surveillance data.The proposed model is evaluated using both simulated data and the real data from the 2009 H1N1 epidemic in Hong Kong and achieves acceptable prediction accuracy.We believe that our model can provide valuable insights for public health authorities to predict the effect of disease spread and analyse its underlying factors and to guide new control efforts.