Characterizing Human Mobility Patterns in a Large Street Network

Previous studies demonstrated empirically that human mobility exhibits Levy flight behaviour. However, our knowledge of the mechanisms governing this Levy flight behaviour remains limited. Here we analyze over 72 000 people's moving trajectories, obtained from 50 taxicabs during a six-month period in a large street network, and illustrate that the human mobility pattern, or the Levy flight behaviour, is mainly attributed to the underlying street network. In other words, the goal-directed nature of human movement has little effect on the overall traffic distribution. We further simulate the mobility of a large number of random walkers, and find that (1) the simulated random walkers can reproduce the same human mobility pattern, and (2) the simulated mobility rate of the random walkers correlates pretty well (an R square up to 0.87) with the observed human mobility rate.Comment: 13 figures, 17 page

Fractal pore and its impact on gas adsorption capacity of outburst coal: Geological significance to coalbed gas occurrence and outburst

Pore structure and methane adsorption of coal reservoir are closely correlated to the coalbed gas occurrence and outburst. Full-scale pore structure and its fractal heterogeneity of coal samples were quantitatively characterized using low-pressure N2 gas adsorption (LP-N2GA) and high-pressure mercury intrusion porosimetry (HP-MIP). Fractal pore structure and adsorption capacities between outburst and nonoutburst coals were compared, and their geological significance to gas occurrence and outburst was discussed. The results show that pore volume (PV) is mainly contributed by macropores ( \u3e 1000 nm) and mesopores (100-1000 nm), while specific surface area (SSA) is dominated by micropores ( \u3c 10 nm) and transition pores (10 - 100 nm). On average, the PV and SSA of outburst coal samples are 4.56 times and 5.77 times those of nonoutburst coal samples, respectively, which provide sufficient place for gas adsorption and storage. The pore shape is dominated by semiclosed pores in the nonoutburst coal, whereas open pores and inkbottle pores are prevailing in the outburst coal. The pore size is widely distributed in the outburst coal, in which not only micropores are dominant, but also, transition pores and mesopores are developed to a certain extent. Based on the data from HP-MIP and LP-N2GA, pore spatial structure and surface are of fractal characteristics with fractal dimensions Dm1 (2.81 - 2.97) and Dn (2.50 - 2.73) calculated by Menger model and Frenkel-Halsey-Hill (FHH) model, respectively. The pore structure in the outburst coal is more heterogeneous as its Dn and Dm1 are generally larger than those of the nonoutburst coal. The maximum methane adsorption capacities (VL: 15.34 - 20.86 cm 3 / g) of the outburst coal are larger than those of the nonoutburst coal (VL : 9.97-13.51cm 3 / g). The adsorptivity of coal samples is governed by the micropores, transition pores, and Dn because they are positively correlated with the SSA. The outburst coal belongs to tectonically deformed coal (TDC) characterized by weak strength, rich microporosity, complex pore structure, strong adsorption capacity, but poor pore connectivity because of inkbottle pores. Therefore, the area of TDC is at high risk for gas outburst as there is a high-pressure gas sealing zone with abundant gas enrichment but limited gas migration and extraction

Progressive Research in the Molecular Mechanisms of Chronic Fluorosis

Long-term excessive intake of fluoride (F) leads to chronic fluorosis, resulting in dental fluorosis and skeletal fluorosis. Chronic exposure to high doses of fluoride can also cause damage to soft tissues, especially when it passes through the blood-brain, blood-testis, and blood-placenta barrier, causing damage to the corresponding tissues. Fluorosis has become a public health problem in some countries or regions around the world. Understanding the pathogenesis of fluorosis is very important. Although the exact mechanism of fluorosis has not been fully elucidated, various mechanisms of fluoride-induced toxicity have been proposed. In this chapter, we will introduce the research progress of the mechanism of fluorosis, focusing on dental fluorosis, skeletal fluorosis, nervous and reproductive system toxicity, and influential factors related to fluoride toxicity (i.e., genetic background, co-exposure with other element). In addition, the application of proteomics and metabolomics in the study of the pathogenesis of fluorosis is also introduced. Currently, there is still no specific treatment for fluorosis. However, since fluorosis is caused by excessive intake of fluoride, avoiding excessive fluoride intake is the critical measure to prevent the disease. In endemic regions, health education and supplement diet with vitamins C, D and E, and calcium and antioxidant compounds are important

Precision Medicine: Role of Biomarkers in Early Prediction and Diagnosis of Alzheimer’s Disease

Alzheimer’s disease (AD), the most common form of dementia in the aged people, is a chronic and irreversible neurodegenerative disorder. Early prediction, intervention, and objective diagnosis are very critical in AD. In this chapter, we will introduce the current progress in the prediction and diagnosis of AD, including recent development in diagnostic criteria, genetic testing, neuroimaging techniques, and neurochemical assays. Focus will be on some new applied methods with more specific examples, that is, cerebrospinal fluid (CSF) and blood proteins and peptides, which might serve as biomarkers for the diagnosis of AD. We will also discuss biomarker-based diagnostic strategies and their practical application

Whether the CEO Turnover Can Improve the Conversion of Enterprise’s New and Old Driving Force?

After 2014, China focused on supply-side reform and put forward the concept of replacing old driving with new driving force, which can create a new round of economic improvement. From the perspective of the conversion of old and new driving forces of enterprises, this paper takes the listed enterprises in China’s a-share manufacturing industry from 2016 to 2018 as samples. This paper also discusses the “Net Effect” of CEO turnover on the conversion of new and old driving forces of enterprises. The results reflect that CEO turnover has a negative effect on the conversion of old and new driving force. Moving forward, when the CEO and chairman changes at the same time or the ownership of the enterprise turns to state-owned, the change of CEO has a higher degree of prevention on the conversion of old and new force. The number of board’s conferences and the degree of equity balance will increase the negative effect of CEO turnover on the conversion of old and new driving force

Agriculture under Climate Change in China: Mitigate the Risks by Grasping the Emerging Opportunities

There have been increasing concerns on risks and uncertainty posed by climate change to China’s future crop production. The existing assessments using popular process-based and site-specific crop growing models highlight the significant extent of climate-induced yield reduction, and thus suggest a scary downward risk for China’s future food production. Surprisingly, much less attention has been paid to exploring the potential gains that may also be bought by climate change. To address this imbalance, we develop an integrated agro-climatic and ecological assessment tool that is capable of detecting the shifts of multi-cropping opportunities under different climate change scenarios. The application of this tool to the context of China reveals significant extension of multi-cropping opportunities brought in by climate change. We argue for an active adaptation to such emerging opportunities through both market and policy incentives, because the aggregate gain of such adaptation is sufficient to overweigh the loss as revealed by the existing assessments

Boosting the Signal Intensity of Nanoelectrospray Ionization by Using a Polarity-Reversing High-Voltage Strategy

Continuous efforts have been made to further improve the performance of nano-ESI. In this work, we made use of a polarity-reversing high-voltage strategy for the generation of nano-ESI (PR-nESI). Typically, a negative high voltage of −3.0 kV was first applied to the electrode and maintained for 6 s. Then the polarity was reversed, and a positive high voltage of +1.75 kV was applied for the generation of electrospray. Compared with conventional nano-ESI, PR-nESI significantly enhanced the signal intensity of protonated protein ions. The signal-to-noise ratio (S/N) of protonated protein ions was increased by 1–2 orders of magnitude. The increase of S/N was even more remarkable at lower concentrations. Furthermore, PR-nESI also had a desalting effect. Metal ion adducts of proteins were effectively removed. No metal ion adducts were identified from the spectra, even if the concentration of salt was increased to the millimolar level. The performance of PR-nESI was confirmed in the detection of different molecules including proteins, peptides, amino acids, and other small-molecule compounds. The intact folded structure of proteins was preserved during PR-nESI. No unfolding was observed in the spectra. PR-nESI was further applied to the analysis of noncovalent protein–ligand complexes and protein digest. At last, investigations into the mechanism of PR-nESI were carried out. The enhancement of signal intensity and desalting effect were related to the electromigration of the solutes in solution. With all the advantages above, PR-nESI would be a promising method in the future analytical and bioanalytical applications