As a significant factor in urban planning, traffic forecasting and prediction of epidemics, modeling patterns of human mobility draws intensive attention from researchers for decades. Power-law distribution and its variations are observed from quite a few real-world human mobility datasets such as the movements of banking notes, trackings of cell phone users' locations and trajectories of vehicles. In this paper, we build models for 20 million trajectories with fine granularity collected from more than 10 thousand taxis in Beijing. In contrast to most models observed in human mobility data, the taxis' traveling displacements in urban areas tend to follow an exponential distribution instead of a power-law. Similarly, the elapsed time can also be well approximated by an exponential distribution. Worth mentioning, analysis of the interevent time indicates the bursty nature of human mobility, similar to many other human activities.

Sixty-two new Japanese encephalitis virus (JEV) isolates were obtained from mosquitoes, biting midges, human cerebrospinal fluid and human blood samples in China during [2002][2003][2004][2005]. The E and prM genes were sequenced and phylogenetic analyses were performed with 38 JEV other isolates from China and 36 JEV strains from other countries. Phylogenetic trees based on the E and prM gene sequences were similar. The results indicate that: (i) recent JEV isolates from China are divided into two genotypes, genotype 1 and genotype 3; (ii) recent JEV isolates from China are grouped into the same clusters within genotypes 1 and 3; and (iii) genotype 1 JEV strains have been isolated in China since 1979, whilst genotype 3 JEV strains were isolated before the 1970s. The results suggest that genotype 1 JEV was introduced to China around 1979 and that JEV strains belonging to genotypes 1 and 3 circulate in China.

The vast majority of travel takes place within cities. Recently, new data has become available which allows for the discovery of urban mobility patterns which differ from established results about long distance travel. Specifically, the latest evidence increasingly points to exponential trip length distributions, contrary to the scaling laws observed on larger scales. In this paper, in order to explore the origin of the exponential law, we propose a new model which can predict individual flows in urban areas better. Based on the model, we explain the exponential law of intra-urban mobility as a result of the exponential decrease in average population density in urban areas. Indeed, both empirical and analytical results indicate that the trip length and the population density share the same exponential decaying rate.

Aims-To determine the anatomical site and underlying causes of blindness and severe visual impairment in children under 16 years of age in special education in the People's Republic of China with a view to determining potentially preventable and treatable causes. Methods-A national study of children attending schools for the blind in China was conducted between April and June 1998 using the WHO Prevention of Blindness Programme (WHO/PBL) eye examination record for children with blindness and low vision. Eight Chinese ophthalmologists attended a training workshop before conducting the study. 36 blind schools in 18 provinces of China were included. Results-1245 children aged between 5 and 15 years were examined, of whom 1131 (91%) were blind or severely visually impaired (visual acuity less than 6/60 in the better eye). The commonest anatomical sites of visual loss were whole globe (mainly microphthalmos) 25.5% and retina (mainly dystrophies) 24.9%. Lens was the major site in 18.8%, optic nerve in 13.6%, and glaucoma in 9%. Corneal scarring was not a major cause of visual loss. The aetiology was unknown in 52.9%, hereditary factors were responsible in 30.7%, and childhood causes in 14%. 15% of cases were considered potentially preventable and 22.5% potentially treatable. Conclusion-The pattern of childhood blindness seen in this study is likely to reflect the improved health and socioeconomic status of China but may partly reflect bias in admission to, and location of, blind schools, with higher socioeconomic groups overrepresented. Nutritional and infective causes of blindness are uncommon, and hereditary and unknown factors are now the predominant causes. (Br J Ophthalmol 1999;83:929-932) For a child who is born blind or who becomes blind the total number of years of disability are greater than for a person who becomes blind later in life. Currently it is estimated that there are 1.5 million blind children in the world, of whom one million live in Asia. In order to set priorities for control programmes, baseline epidemiological data of the prevalence and major causes of childhood blindness are required. These are known to vary between regions and countries.1 No data are available for China.The WHO Prevention of Blindness Programme with the International Centre for Eye Health has developed a standard methodology and reporting form to record the causes of visual loss in children with the emphasis on the identification of preventable or treatable causes of blindness. This methodology has now been used in many countries. 2China has a population of 1200 million (1996) of which 378 million are under 18 years of age. China's 22 provinces, five autonomous regions, and 5000 islands are governed from Beijing. (Hong Kong has a special status.) The population is mainly Han Chinese (over 90%) but there are also 200 diVerent ethnic minority groups. The country has a literacy rate of 82%. Health indicators have shown a marked improvement in recent years-for example, the infant mortality (under 1 year) has improved f...

Given the unpredictability of Neisseria meningitidis outbreaks and the increased prevalence of serogroup C strains following the introduction of serogroup A-based vaccines, we conducted an analysis of serogroups and sequence types (STs) in disease-associated and carrier N. meningitidis isolates that have emerged in China since 2003. We used multilocus sequence-typing techniques to investigate 371 N. meningitidis strains isolated from patients with meningitis and healthy carriers. Two lineages were identified in serogroup A and C isolates, genotyped as the ST5 complex and ST4821 complex, respectively. Both clonal complexes were found throughout China, although ST4821 was more concentrated in the eastern region of the country. The ST5 complex has been persistent in China since the late 1980s and has since spread across the entire country. Isolates belonging to the ST4821 complex have been a dominant lineage since 2003.

Change detection (CD) is an active research topic in remote sensing applications including urban studies, disaster assessment, and deforestation monitoring. In this paper, we propose an automatic method for CD in high-resolution remote sensing images that uses a novel strategy for the selection of training samples and an ensemble of multiple classifiers. As for the selection of training samples, our proposed method uses two groups of thresholds instead of just one threshold to enhance the quality of the selected training samples by allowing for their selection in an intelligent manner. In order to achieve high CD accuracy, spatial information such as texture and morphological profiles are utilized in conjunction with spectral information. Our multiple classifier system (MCS) exploits the extreme learning machine (ELM), multinomial logistic regression (MLR), and K-nearest neighbor (KNN) classifiers. To validate our newly proposed approach, we conduct experiments using multispectral images collected by ZY-3. The proposed method provides state-of-the-art CD accuracies as compared with other approaches widely used in the literature for CD purposes.

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