Showing papers by "Lei Dong published in 2016"

Population-weighted efficiency in transportation networks

Abstract: Transportation efficiency is critical for the operation of cities and is attracting great attention worldwide. Improving the transportation efficiency can not only decrease energy consumption, reduce carbon emissions, but also accelerate people’s interactions, which will become more and more important for sustainable urban living. Generally, traffic conditions in less-developed countries are not so good due to the undeveloped economy and road networks, while this issue is rarely studied before, because traditional survey data in these areas are scarce. Nowadays, with the development of ubiquitous mobile phone data, we can explore the transportation efficiency in a new way. In this paper, based on users’ call detailed records (CDRs), we propose an indicator named population-weighted efficiency (PWE) to quantitatively measure the efficiency of the transportation networks. PWE can provide insights into transportation infrastructure development, according to which we identify dozens of inefficient routes at both the intra- and inter-city levels, which are verified by several ongoing construction projects in Senegal. In addition, we compare PWE with excess commuting indices and the fitting result of PWE is better than excess commuting index, which also proves the validity of our method.

DNA Methylation mediated down-regulating of MicroRNA-33b and its role in gastric cancer.

Abstract: The discovery of microRNAs (miRNAs) provides a new and powerful tool for studying the mechanism, diagnosis and treatment of human cancers. Currently, down-regulation of tumor suppressive miRNAs by CpG island hypermethylation is emerging as a common hallmark of cancer. Here, we reported that the down-regulation of miR-33b was associated with pM stage of gastric cancer (GC) patients. Ectopic expression of miR-33b in HGC-27 and MGC-803 cells inhibited cell proliferation, migration and invasion, which might be due to miR-33b targeting oncogene c-Myc. Moreover, enhanced methylation level of the CpG island upstream of miR-33b in GC patients with down-regulated miR-33b was confirmed by methylation-specific PCR (MSP) amplification. Furthermore, re-introduction of miR-33b significantly suppressed tumorigenesis of GC cells in the nude mice. In conclusion, miR-33b acts as a tumor suppressor and hypermethylation of the CpG island upstream of miR-33b is responsible for its down-regulation in gastric cancer.

microRNA-23a, -27a and -24 synergistically regulate JAK1/Stat3 cascade and serve as novel therapeutic targets in human acute erythroid leukemia

Abstract: Acute erythroid leukemia (AEL) is characterized by lower incidence, poorer prognosis and worse survival than other types of leukemia and results from collaboration of malignant proliferation and erythroid differentiation blockage. The expression, function and therapeutic significance of noncoding RNAs in AEL have not been well studied. Here, we show that one miRNA cluster, including miR-23a, -27a and -24, is dramatically downregulated in AEL patients. Restoration of miR-23a, -27a and -24 expression induces apoptosis and erythropoiesis, inhibits adverse growth and partly relieves the leukemic symptoms of AEL patients. At the whole-genome scale, we identify that miR-23a, -27a and -24 synergistically target multiple members of the oncogenic gp130-JAK1-Stat3 pathway, and thus reinforce their inhibition on the cascade to regulate cell proliferation and apoptosis. Importantly, Ruxolitinib, a JAK1 inhibitor, could rescue the phenotypic changes induced by miR-23a, -27a and -24 inhibitors. Furthermore, miR-23a cluster-mediated-inactivation of the JAK1-Stat3 pathway promotes the expression and activity of GATA1 via inhibiting PU.1, thereby improving erythroid differentiation. Collectively, we reveal an important regulatory circuit comprising GATA1, the miR-23a cluster and gp130-JAK1-Stat3 pathway, that synergistically facilitates apoptosis and erythropoiesis and restrains adverse proliferation, indicating the therapeutic significance of miR-23a, -27a and -24 for AEL treatment.

The Geometric Origins of Complex Cities

Abstract: Due to the rapid urbanization, cities have become a hot topic. Extensive complex phenomena, such as scaling laws with respect to population, morphology, spatial distribution within cities have been revealed and validated by the empirical studies. Yet there’s still no clear answer to the question that what’s the underlying mechanism responsible for these observed complex phenomena. Most of previous studies only focus on one aspect of the city. However, focusing on only one aspect may lose the whole picture of it. Based on a very simple “matching growth” rule and two more simple assumptions, which are all performed locally, we propose a simple model which can derive most of observed macro scaling relations and spatial distribution. All these theoretical deductions can be well supported by empirical data. And the consistency between the exponents of different cumulative spatial distribution may indicates that the city really follows the rules we assumed.

Measuring Economic Activities of China with Mobile Big Data

Abstract: Emerging trends in smartphones, online maps, social media, and the resulting geo-located data, provide opportunities to collect traces of people's socio-economical activities in a much more granular and direct fashion, triggering a revolution in empirical research. These vast mobile data offer new perspectives and approaches for measurements of economic dynamics and are broadening the research fields of social science and economics. In this paper, we explore the potential of using mobile big data for measuring economic activities of China. Firstly, We build indices for gauging employment and consumer trends based on billions of geo-positioning data. Secondly, we advance the estimation of store offline foot traffic via location search data derived from Baidu Maps, which is then applied to predict revenues of Apple in China and detect box-office fraud accurately. Thirdly, we construct consumption indicators to track the trends of various industries in service sector, which are verified by several existing indicators. To the best of our knowledge, we are the first to measure the second largest economy by mining such unprecedentedly large scale and fine granular spatial-temporal data. Our research provides new approaches and insights on measuring economic activities.