Thermal environment deterioration has seriously threatened urban habitat quality and urban sustainable development. The evolution of the urban built environment (UBE) is an important cause for urban thermal environment variation. However, the dynamic effect of the UBE on the land surface temperature (LST) is rarely studied by combining the local climate zone (LCZ) theory and spatio-temporal heterogeneity. Based on a case study of Beilin District in Xi’an, China, this paper identified LCZ types of Beilin District in 2010, 2015, and 2020 using the GIS method. It also analyzed the spatial–temporal characteristics of the LST in summer based on the remote sensing retrieval method and explored the effects of the built environment on the LST by Geodetector and geographically weighted regression (GWR). The results showed the following: (1) The area share of dense building zones in Beilin District was greater than that of open building zones and natural surface zones, while the share of mid- and high-rise dense building zones continued to increase and the share of low-rise dense building zones continued to decrease during the study period. (2) The LST of different LCZ types in Beilin District was obviously different, and the LST of dense building zones was generally higher than that of open building zones and natural surface zones. Meanwhile, the LST of mid- and low-rise dense building zones increased gradually, and the LST of high-rise open building zones decreased gradually, but the overall warming area was obviously more than the cooling area. (3) The effects of the UBE factors on the LST varied greatly, with their interaction having an enhancement effect. The direct and interactive influence of the two-dimensional (2D) UBE indicators on the LST were greater than those of the three-dimensional (3D) indicators, but there was a gradual decrease in the force of the 2D indicators and a simultaneous diminution, enhancement, and invariance of the force of the 3D indicators. (4) Vegetation cover (VC) and floor area ratio (FAR) acted negatively, and the building height (BH) was changing from a positive to a negative role, with the average action intensity of VC changing from −0.27 to −0.15, FAR from −0.20 to −0.16, and BH from 0.05 to −0.04. The impervious surface area (ISA), building area (BA), and space congestion (SC) acted positively, with the average action intensity of the ISA changing from 0.12 to 0.20, BA from 0.12 to 0.19, and SC was stable at 0.04. The framework enables a deeper portrayal of LST changes in different LCZs, reflecting the direct and interactive effects of different UBE indicators on LST, as well as local variations in the impact effects and provides a basis for urban managers or planners to improve urban heat resilience.
A microfluidic chip was developed for one-step identification and antimicrobial susceptibility testing (AST) of multiple uropathogens. The polydimethylsiloxane (PDMS) microchip used had features of cell culture chamber arrays connected through a sample introduction channel. At the bottom of each chamber, a paper substrate preloaded with chromogenic media and antimicrobial agents was embedded. By integrating a hydrophobic membrane valve on the microchip, the urine sample can be equally distributed into and confined in individual chambers. The identification and AST assays on multiple uropathogens were performed by combining the spatial resolution of the cell culture arrays and the color resolution from the chromogenic reaction. The composite microbial testing assay was based on dynamic changes in color in a serial of chambers. The bacterial antimicrobial susceptibility was determined by the lowest concentration of an antimicrobial agent that is capable of inhibiting the chromogenic reaction. Using three common uropathogenic bacteria as test models, the developed microfluidic approach was demonstrated to be able to complete the multiple colorimetric assays in 15 h. The accuracy of the microchip method, in comparison with that of the conventional approach, showed a coincidence of 94.1%. Our data suggest this microfluidic approach will be a promising tool for simple and fast uropathogen testing in resource-limited settings.
Abstract—This paper investigates the relationship between trade duration and liquidity of Chinese stock market. By using data of ten stocks in Chinese stock market, we employ a Weibull ACD model to decompose trade duration into two components: the expected and the unexpected duration. Then we analyze whether trade duration affects liquidity with regressions. Finally, we find that there exists a strong dependence between consecutive durations especially for liquid stocks. Both the expected and unexpected duration could explain the variation of bid-ask spread but the evidence is mixed in the depth equation. The unexpected duration contributes more to the change in liquidity than the expected duration.
Xiaoqinglong decoction (XQL) has been used in traditional Chinese medicine as a prescription for asthma treatment. We explored the effects of XQL on mucus hypersecretion and ciliophagy in the airways of mice in which asthma had been induced by ovalbumin (OVA). Thirty-six mice were sensitized by OVA injection (i.p.) on day-0 and day-14 and challenged with 1% OVA on day 18–22. Then, they were divided into three groups: model, carbocysteine and XQL. From day-15 to day-22, the XQL group was administered XQL (10 g/kg, p.o.) 1 hour before each aerosol challenge with OVA. To evaluate the effect of XQL on mucus hypersecretion, AB-PAS staining, measurement of serum levels of interleukin (IL)-13, bronchoalveolar lavage fluid (BALF) analyses, ciliophagy analyses, as well as co-expression of Light Chain 3 (LC3) and acetylated α-tubulin by immunofluorescence staining were undertaken. Treatment with XQL (10 g/kg) attenuated mucus secretion in the airways, and reduced the positive areas of AB-PAS staining in histopathologic lung tissues (P < .05). IL-13 expression in serum (P < .01), OVA-induced inflammatory changes, and the number of white blood cells (P < .01) in BALF samples were also reduced. However, the effect on mucus secretion was less apparent in the carbocysteine group compared with the XQL group. XQL treatment also improved the cilia length and elicited a substantial reduction in ciliophagy and LC3 expression in the tracheal epithelium. XQL can attenuate cilia shortening, aid the clearance function of ciliated epithelial cells, and reduce mucus production in an OVA-induced asthma model in mice. XQL can inhibit mucus hypersecretion and could be a new type of pharmacotherapy.
This paper investigates the relationship between trade duration and liquidity of Chinese stock market. Using data of ten stocks, we employ a Weibull ACD model to decompose trade duration into two components: the expected and the unexpected duration. Then we analyze whether trade duration affects liquidity with regressions. We find that there exists a strong dependence between consecutive durations especially for liquid stocks. Both the expected and unexpected duration could explain the variation of bid-ask spread but the evidence is mixed in the depth equation. The unexpected duration contributes more to the change in liquidity than the expected duration.
In recent years, atmospheric pollution represented by fine particulate matter PM2.5 pollution has seriously threatened human health. Therefore, it is important to identify the risk level of population exposure to PM2.5. Based on PM2.5 remote sensing inversion data and population distribution, this study measured the risk level of population exposure to PM2.5 in the Guanzhong area. Furthermore, the methods of Theil-Sen Median trend analysis, Mann-Kendall test, and geo-spatial analysis were used to reveal the temporal and spatial characteristics of population exposures risk to PM2.5 in the Guanzhong area from 2000 to 2016. The results show that:①The years with heavy pollution and wide range in the Guanzhong area are 2006, 2007, and 2013, and the annual average concentration of PM2.5 exceeded 35 μg·m-3 in more than 40% of the Guanzhong area. From 2000 to 2016, the spatial distribution range of PM2.5 in the Guanzhong area continued to expand, forming a continuous belt-shaped concentrated distribution area from the center to the northeast. ②More than 60% of the population in the Guanzhong area was exposed in the areas with annual average concentration of PM2.5 above 35 μg·m-3 from 2000 to 2016, and the population exposure risk continued to increase, especially after 2011, the range of the high-risk area expanded dramatically. ③The pattern of population exposure risk to PM2.5 in the Guanzhong area was generally similar from 2000 to 2016. The areas with higher risk levels were mainly concentrated in the central Guanzhong area, forming a continuous belt-shaped distribution area from west to east. The areas with the highest value were distributed in the urban areas of several major cities, while the areas with the lowest value were mainly concentrated in the surrounding areas of Guanzhong.
Traffic analysis is an effective mean for gathering intelligence from within a large enterprise’s local network. Adversaries are able to monitor all traffic traversing a switch by exploiting just one vulnerability in it and obtain valuable information (e.g., online hosts and ongoing sessions) for further attacking, while administrators have to patch all switches as soon as possible in hope of eliminating the vulnerability in time. Moving Target Defense (MTD) is a new paradigm for reobtaining the upper hand in network defense by dynamically changing attack surfaces of the network. In this paper, we propose U-TRI (unlinkability through random identifier) as a moving target technique for changing the information-leaking identifiers within PDUs for SDN network. U-TRI is based on VIRO protocol and implemented with the help of OpenFlow protocol. U-TRI employs an independent, binary tree-structured, periodically and randomly updating identifier to replace the first part of the static MAC address in PDU, and assigns unstructured random values to the remaining part of the MAC address. U-TRI also obfuscates identifiers in the network layer and transport layer in an unstructured manner. Such a semistructured random identifier enables U-TRI to significantly weaken the linkage between identifiers and end-hosts as well as communication sessions, thus providing anonymous communication in SDN network. The result of analysis and experiments indicates that U-TRI dramatically increases the difficulty of traffic analysis with acceptable burdens on network performance.
Many cities are experiencing persistent risk in China due to frequent extreme weather events. Some extreme weather events, such as extreme heat hazard, have seriously threatened human health and socio-economic development in cities. There is an urgent need to measure the degree of extreme heat risk and identify cites with the highest levels of extreme heat risk. In this study, we presented a risk assessment framework of extreme heat and considered risk as a combination of hazard, exposure, and vulnerability. Based on these three dimensions, we selected relevant variables from historical meteorological data (1960–2016) and socioeconomic statistics in 2016, establishing an indicator system of extreme heat risk evaluation. Finally, we developed an extreme heat risk index to quantify the levels of extreme heat risk of 296 prefecture-level cities in China and revealed the spatial pattern of extreme heat risk in China in 2016 and their dominant factors. The results show that (1) cities with high levels of extreme heat hazard are mainly located in the south of China, especially in the southeast of China; (2) the spatial distribution of the extreme heat risk index shows obvious agglomeration characteristics; (3) the spatial distribution of the extreme heat risk is still mostly controlled by natural geographical conditions such as climate and topography; (4) among the four types of hazard-dominated, exposure-dominated, vulnerability-dominated, and low risk cities, the number of vulnerability-dominated cities is the largest. The results of this study can provide support for the risk management of extreme heat disasters and the formation of targeted countermeasures in China.
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