Determining the coupling development mode and evolution process of the tourism industry–urbanization–ecological environment system is of great significance in promoting high-quality and sustainable development of tourism and the urban economy. In this study, an evaluation index system of the tourism–urbanization–ecological environment system was established, and the spatiotemporal differentiation of the coupling and coordination relationship of the tourism–urbanization–ecological environment system was analyzed for 35 major tourist cities in China from 2009 to 2018. The results show that the comprehensive development indices of the tourism industry subsystem and urbanization subsystem of China’s major tourist cities have steadily increased. The comprehensive development indices of large-sized and medium-sized cities in the east are relatively high. From 2009 to 2018, the coordination degree and coupling degree of the tourism–urbanization–ecological environment’’ system of 35 tourist cities showed an upward trend. The growth rate of the coupling coordination degree lags behind the growth rate of the coupling degree, and the overall system coordination level is still low. There are significant differences in the coupling degree and coupling coordination degree among the eastern, central, and western cities. This study offers both theoretical and practical implications for further equalizing the development level between the cities, as well as improving the overall coordination between the tourism industry, urbanization, and the ecological environment in China.
Influenza A viruses possess a high antigenic shift, and the approved anti-influenza drugs are extremely limited, which makes the development of novel anti-influenza drugs for the clinical treatment and prevention of influenza outbreaks imperative. Herein, we report a series of novel aryl benzoyl hydrazide analogs as potent anti-influenza agents. Particularly, analogs 10b, 10c, 10g, 11p, and 11q exhibited potent inhibitory activity against the avian H5N1 flu strain with EC50 values ranging from 0.009 to 0.034 μM. Moreover, compound 11q exhibited nanomolar antiviral effects against both the H1N1 virus and Flu B virus and possessed good oral bioavailability and inhibitory activity against influenza A virus in a mouse model. Preliminary mechanistic studies suggested that these compounds exert anti-influenza virus effects mainly by interacting with the PB1 subunit of RNA-dependent RNA polymerase (RdRp). These results revealed that 11q has the potential to become a potent clinical candidate to combat seasonal influenza and influenza pandemics.
Tourism is crucial for promoting industrial development and is an important driver of China’s new type of urbanization. A tourism urbanization index system was constructed in three dimensions: the tourism industry, urbanization, and the ecological environment. The spatial–temporal differentiation characteristics and influencing factors of tourism urbanization in 35 major tourist cities in China from 2009 to 2018 were analyzed using the state space method, standard deviation ellipse, and spatial autocorrelation analysis. The results show the following. (1) Over time, the tourism industry index displays an upward trend, the urbanization index exhibits a more obvious upward trend, and the ecological environment index fluctuates strongly. Under the influence of all three factors, the tourism urbanization index shows a fluctuating rising trend. (2) Regarding the spatial distribution pattern, the development center of tourism urbanization shifts to the southeast, and the distribution direction is northeast-southwest. There is a significant agglomeration in global spatial autocorrelation. The local spatial correlation pattern is dominated by correlation characteristics and supplemented by different characteristics. (3) In terms of influencing factors, policy and regional development strategy, tourism resource endowment, economic development level, and traffic conditions are listed in descending order of influencing degree. Finally, we put forward some suggestions.
Indoor positioning is one of the core technologies of Internet of Things (IoT) and artificial intelligence (AI), and is expected to play a significant role in the upcoming era of AI. However, affected by the complexity of indoor environments, it is still highly challenging to achieve continuous and reliable indoor positioning. Currently, 5G cellular networks are being deployed worldwide, the new technologies of which have brought the approaches for improving the performance of wireless indoor positioning. In this paper, we investigate the indoor positioning under the 5G new radio (NR), which has been standardized and being commercially operated in massive markets. Specifically, a solution is proposed and a software defined receiver (SDR) is developed for indoor positioning. With our SDR indoor positioning system, the 5G NR signals are firstly sampled by universal software radio peripheral (USRP), and then, coarse synchronization is achieved via detecting the start of the synchronization signal block (SSB). Then, with the assistance of the pilots transmitted on the physical broadcasting channel (PBCH), multipath acquisition and delay tracking are sequentially carried out to estimate the time of arrival (ToA) of received signals. Furthermore, to improve the ToA ranging accuracy, the carrier phase of the first arrived path is estimated. Finally, to quantify the accuracy of our ToA estimation method, indoor field tests are carried out in an office environment, where a 5G NR base station (known as gNB) is installed for commercial use. Our test results show that, in the static test scenarios, the ToA accuracy measured by the 1-σ error interval is about 0.5 m, while in the pedestrian mobile environment, the probability of range accuracy within 0.8 m is 95%.Index Terms-5G new radio (NR), indoor positioning, Internet of Things (IoT), software defined radio (SDR), time of arrival (ToA), delay locked loop (DLL), carrier phase, ranging estimation.
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