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A terahertz absorber is designed by integrating the graphene dielectric stack (GDS) above and the metal grating below. The GDS is formed through arranging the graphene monolayer and dielectric film periodically. In the case of impedance matching, two near-unity absorption modes arise as the coupling result of Fabry-Pérot (FP) resonance and surface plasmon polaritons (SPP) resonance. Tuning the chemical potential or the period of GDS, both modes can be shifted. Changing the period or the duty cycle of metal grating, all of the locations and amplitudes of modes along with the peak-peak distance between modes are controllable. Altering the thickness of dielectric slab, these modes move towards the same direction linearly almost. Deviating the normal incidence, the number of absorption modes can be increased. The designed graphene absorber should be useful to multiple targets sensing, photoelectric detection and frequency conversion of nonlinear system. [ABSTRACT FROM AUTHOR]

Global warming-related climate changes have significantly impacted the growth of terrestrial vegetation. Quantifying the spatiotemporal characteristic of the vegetation’s response to climate is crucial for assessing the potential impacts of climate change on vegetation. This study analyzed the spatiotemporal responses of different vegetation types across China between the normalized difference vegetation index (NDVI) that reflects vegetation activity and the standardized precipitation evapotranspiration index (SPEI) that indicates drought conditions by reflecting water conditions at different timescales. The NDVI was separated into 12 time series (one per month), and the SPEI of 12 droughts timescales was used to make the correlation. The results suggest that the response of vegetation growth to changes in the SPEI varies according to vegetation type. Specifically, positive correlations are found in arid and sub-arid environments where soil water is a primary constraining factor for plant growth, while negative correlations exist in humid environments, corresponding to regions where soil water is commonly sufficient. The results also show that negative correlations occur primarily at short timescales (1–5 months) in spring and winter and positive correlations correspond to long timescales (9–12 months) in summer. Further spatial analysis indicates that positive correlations are primarily found in northern China which is a region that has a primarily negative water balance (i.e., water deficits) while negative correlations are primarily found in southern China. The disclosed patterns of spatiotemporal responses in vegetation growth to droughts are important for impact assessments of climate change on vegetation growth. [ABSTRACT FROM AUTHOR]

The present study is aimed at exploring the characteristics of Chinese relapsed drug users associated with their treatment experience in police mandatory treatment centers. The exploration is based on a comparison of Chinese drug users who received the police mandatory treatment for multiple times (the 'relapse' group) with those who had the treatment for the first time (the 'first-time' group). The comparative analysis is conducted using data collected from a 2009 survey of 177 drug users in several police mandatory treatment centers in a large city of China. The data indicate that both the 'relapse' and the 'first-time' groups have similar demographic characteristics except age. However, respondents in the 'relapse' group were more likely to be heroin users, have a high level of drug dependence, have prior treatment, experience a high level of mental disorder, and have drug-use friends than those in the 'first-time' group. The findings imply that relapse among Chinese drug users are likely to have multiple factors which is comparable to that discovered in Western research. [ABSTRACT FROM AUTHOR]

Hyperspectral imaging technology is playing an increasingly important role in the fields of food analysis, medicine and biotechnology. To improve the speed of operation and increase the light throughput in a compact equipment structure, a Fourier transform hyperspectral imaging system based on a single-pixel technique is proposed in this study. Compared with current imaging spectrometry approaches, the proposed system has a wider spectral range (400-1100 nm), a better spectral resolution (1 nm) and requires fewer measurement data (a sample rate of 6.25%). The performance of this system was verified by its application to the non-destructive testing of potatoes. [ABSTRACT FROM AUTHOR]