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Based on a questionnaire survey of senior secondary school students, this study examines the determinants of perceived crowding of juveniles in Hong Kong, a city that has accommodated generations of migrants from mainland China and elsewhere in the world and is renowned for its extreme densities. The analysis is threefold. First, it identifies factors directly affecting perceived crowding such as home density, housing tenure type, and environmental referent. The next stage, then, examines what factors determine home density. It is found that juveniles in both public- and private-sector-owned housing tend to have significantly more housing space than those residing in rented housing. Newcomers to the city enjoy less housing space compared to more established Hong Kong residents. The third stage analyzes the sorting of households into housing tenure types. New migrants are most likely to be private renters. Over time, the difference in home density and housing tenure types between students with locally born parents and those with mainland-born parents becomes smaller. However, no such trend is observed for students of overseas backgrounds. [ABSTRACT FROM AUTHOR]

With the development of society, people are going out more and more, which leads to more and more crowded scenes. The detection of crowd density is particularly important. Aiming at the multi-scale problem of different human scales caused by camera angles in the crowd, a crowd density detection method based on deep semantic segmentation is proposed. The front-end of the network uses an improved VGG network to extract the crowd characteristics, so that the output feature map is 1/8 of the original image to improve the accuracy of the predicted density map. The back-end designs two atrous convolution modules with different array dilation rates to capture the multi-scale features of the crowd. The multi-scale features of the network enable the network to capture more scale details and edge information. The network finally uses 1×1 convolution to cascade the output to obtain a high-quality prediction density map. At the same time, in order to solve the grid effect caused by atrous convolution, a zigzag network structure is designed, so that every pixel in the convolution operation after zero filling is calculated to ensure the continuity of the information, thereby improving the accuracy of the network. The network performance is tested on the ShanghaiTech and UCF_CC_50 datasets. The test results are better than the current mainstream crowd density detection methods. The MAE value obtained from the test is 42.4% and 38.1% higher than that of the MCNN network. Compared with SANet, network performance is increased by 5.3% and 9.6%.

Image semantic segmentation is a necessary part of modern autonomous driving systems, because real-time and accurate capture of road condition information is the key to navigation and action planning. Traffic signs are important road condition information. The traffic sign semantic algorithm with stable performance, high real-time performance and accuracy that can meet the application needs is the basis for the realization of active safe driving systems and automatic driving systems. First, based on the analysis of actual application needs, the GTSDB database is selected as the original data, and a traffic sign data set that can comprehensively evaluate the perfor-mance of the semantic segmentation algorithm is designed. Then, based on the classical semantic segmentation network with stable performance U-Net, the D-Unet (D means dilated convolution), a deep neural network structure is proposed with better segmentation performance and higher real-time performance for small targets such as traffic signs. This method uses fewer pooling layers to retain more image information, and uses dilated convolution instead of conventional convolution to expand the receptive field of convolution, better overall planning global information. Finally, tested on the data set designed in this paper, compared with FCN-8s, SegNet, U-Net and other image segmentation network models, the mean intersection over union (MIoU) of the model is increased by about 11.9 percentage points, 6.09 percentage points and 3.71 percentage points, and the parameter amount is only 4.94%, 22.5% and 85.5% of the other three network models.

Yb3+/Er3+-doped Bi2(MoO4)3−z(WO4)z phosphors were synthesized via a hydrothermal method combined with subsequent calcination. Under the excitation of a light source of 980 nm, Bi2(MoO4)3:Yb3+/Er3+ phosphors exhibited strong upconversion green light and weak red light emissions. By doping WO42− in Bi2(MoO4)3:Yb3+/Er3+ phosphors, the upconversion luminescence intensity of the phosphors significantly enhanced, which is 42 times higher than that of the undoped WO42− phosphor. With an increase in WO42− doping content, the final color coordinates of Bi2(MoO4)3−z(WO4)z:Yb3+/Er3+ phosphors were (0.2352, 0.7274), which is closer to the standard green CIE coordinates. The maximum CP of WO42−-doped phosphors is as high as 116.68%, which is 74.44% higher than that of the undoped WO42− phosphor. Based on the thermally coupled energy levels (TCLs) of Er3+ (2H11/2/4S3/2 → 4I15/2) in Bi2(MoO4)2.7(WO4)0.3:14%Yb3+,3%Er3+ phosphor, the SR value reached a maximum of 0.0081 K−1 at 323 K and the SA value reached a maximum of 0.0099 K−1 at 398 K. The obtained Bi2(MoO4)3−z(WO4)z:Yb3+/Er3+ phosphors are suitable for upconversion luminescent materials for green displays and have potential advantages in optical temperature measurement. [ABSTRACT FROM AUTHOR]

Chromium is a common heavy metal element that is harmful to the ecosystem as well as human health, so sensitive detection of chromium ions in solution is important for life and health. In this paper, a series of Eu3+-doped KBi3F10 fluorescent powders were successfully synthesized by a one-step solvothermal method for the selective detection of Cr3+, CrO42− and Cr2O72− ions in an aqueous solution. When adjusting the pH value to 3 and adding PVP as an additive, the obtained KBi3F10:12%Eu3+ phosphor showed excellent red luminescence. Due to the competitive absorption and the inner filter effect of Cr3+, CrO42− and Cr2O72− ions, the red emission from Eu3+ ions produces fluorescence quenching, which can be used to detect them with good selectivity. And the detection limits are as low as 0.19 μM, 0.38 μM and 0.094 μM for Cr3+, CrO42− and Cr2O72− ions, respectively. Other metal ions and common anions showed little interference with chromium ion detection. The obtained fluorescent probe has good recyclability, accurate and reliable detection results, simple operation and low cost and is easy to promote, which make it an excellent three-in-one probe for chromium detection. [ABSTRACT FROM AUTHOR]

PoRVA and PEDV coinfections are extremely common in clinical practice. Although coinfections of PoRVA and PEDV are known to result in increased mortality, the underlying mechanism remains unknown. Here, we found that PoRVA infection promoted PEDV infection in vivo and in vitro and that PoRVA G9P[23] (RVA-HNNY strain) enhanced PEDV replication more significantly than did PoRVA G5P[7] (RVA-SXXA strain). Metabolomic analysis revealed that RVA-HNNY more efficiently induced an increase in the intracellular glutamine content in porcine small intestinal epithelial cells than did RVA-SXXA, which more markedly promoted ATP production to facilitate PEDV replication, whereas glutamine deprivation abrogated the effect of PoRVA infection on promoting PEDV replication. Further studies showed that PoRVA infection promoted glutamine uptake by upregulating the expression of the glutamine transporter protein SLC1A5. In SLC1A5 knockout cells, PoRVA infection neither elevated intracellular glutamine nor promoted PEDV replication. During PoRVA infection, the activity and protein expression levels of glutamine catabolism-related enzymes (GLS1 and GLUD1) were also significantly increased promoting ATP production through glutamine anaplerosis into the TCA cycle. Consistent with that, siRNAs or inhibitors of GLS1 and GLUD1 significantly inhibited the promotion of PEDV replication by PoRVA. Notably, RVA-HNNY infection more markedly promoted SLC1A5, GLS1 and GLUD1 expression to more significantly increase the uptake and catabolism of glutamine than RVA-SXXA infection. Collectively, our findings illuminate a novel mechanism by which PoRVA infection promotes PEDV infection and reveal that the modulation of glutamine uptake is key for the different efficiencies of PoRVA G9P[23] and PoRVA G5P[7] in promoting PEDV replication. Author summary: All phases of the viral life cycle are heavily dependent on host metabolism, thus virtually all viruses actively reprogram host metabolic networks to support their replication and spread. However, in the case of PoRVA and PEDV coinfection, the impact of host cell metabolic reprogramming induced by PoRVA infection on PEDV replication has not been reported. Herein, we demonstrated that PoRVA infection promotes PEDV replication by targeting glutamine metabolism in porcine intestinal epithelial cells. PoRVA infection induces increased expression levels of SLC1A5, GLS1, and GLUD1, which enhance glutamine uptake, TCA cycle flux, and ATP production. Notably, we found that PoRVA G9P[23] infection more effectively promoted PEDV replication than PoRVA G5P[7] infection by significantly increasing glutamine uptake and anaplerosis into the TCA cycle. [ABSTRACT FROM AUTHOR]

Monoclinic AgTbW2O8:Eu3+ crystals were prepared by a simple one-step hydrothermal method. The phase, morphology and luminescence properties of the obtained phosphors were systematically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and photoluminescence (PL). The effects of solution pH, W/Tb molar ratios and reaction temperatures as well as reaction times on the size and morphology of the final products were discussed, and the possible formation mechanism of the almond-like structure was proposed. The down-conversion luminescence properties and energy transfer behavior of the AgTbW2O8:Eu3+ phosphors were studied under ultraviolet light excitation. The emission lights were obtained from green to yellow-green to yellow to red by setting different ratios of Tb3+/Eu3+. The temperature-dependent fluorescence test data showed that AgTbW2O8:Eu3+ phosphors have good temperature stability. In addition, by doping alkali metal ions Li+, Na+, and K+ in AgTbW2O8:Eu3+ phosphors, it is found that the luminescence intensity of phosphors doped with alkali metal ions is enhanced compared with that of phosphors without alkali metal ions, and the phosphor doped with K+ has the largest luminescence intensity, which is due to the introduction of K+ making the crystal field produce the greatest asymmetry. [ABSTRACT FROM AUTHOR]