The long-time behaviour of solutions to the defocussing modified Korteweg-de Vries (MKdV) equation is established for initial conditions in some weighted Sobolev spaces. Our approach is based on the nonlinear steepest descent method of Deift and Zhou and its reformulation by Dieng and McLaughlin through $\overline {\partial }$ -derivatives. To extend the asymptotics to solutions with initial data in lower-regularity spaces, we apply a global approximation via PDE techniques.

Automatic emotion recognition has become an important trend in the fields of human–computer natural interaction and artificial intelligence. Although gesture is one of the most important components of nonverbal communication, which has a considerable impact on emotion recognition, it is rarely considered in the study of emotion recognition. An important reason is the lack of large open-source emotional databases containing skeletal movement data. In this paper, we extract three-dimensional skeleton information from videos and apply the method to IEMOCAP database to add a new modality. We propose an attention-based convolutional neural network which takes the extracted data as input to predict the speakers’ emotional state. We also propose a graph attention-based fusion method that combines our model with the models using other modalities, to provide complementary information in the emotion classification task and effectively fuse multimodal cues. The combined model utilizes audio signals, text information, and skeletal data. The performance of the model significantly outperforms the bimodal model and other fusion strategies, proving the effectiveness of the method.

Not all plant-based and animal foods exert the same health effects due to their various nutrient compositions. We aimed to assess the quality of plant-based v. animal foods in relation to mortality in a prospective cohort study. Using data collected from a nationally representative sample of 36 825 adults in the National Health and Nutrition Examination Survey 1999–2014, we developed a de novo Comprehensive Diet Quality Index (cDQI) that assesses the quality of seventeen foods based on the healthfulness and separately scored the quality of eleven plant-based foods in a plant-based Diet Quality Index (pDQI) and six animal foods in an animal-based Diet Quality Index (aDQI). Mortality from all causes, heart disease and cancer were obtained from linkage to the National Death Index up to 31 December 2015. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95 % CI after multivariable adjustments. During a median follow-up of 8·3 years, 4669 all-cause deaths occurred, including 798 deaths due to heart disease and 1021 due to cancer. Compared with individuals in the lowest quartile, those in the highest quartile of cDQI had a lower risk of all-cause mortality (HR 0·75, 95 % CI 0·65, 0·86; Ptrend < 0·001), which largely reflected the inverse relationship between quality of plant-based foods (pDQI) and all-cause mortality (HR 0·66, 95 % CI 0·58, 0·74; Ptrend < 0·001). No independent association was found for the quality of animal foods (aDQI) and mortality. Our results suggest that consuming healthy plant-based foods is associated with lower all-cause mortality among US adults.

We fabricated a van der Waals heterostructure of WS2–ReSe2 and studied its charge-transfer properties. Monolayers of WS2 and ReSe2 were obtained by mechanical exfoliation and chemical vapor deposition, respectively. The heterostructure sample was fabricated by transferring the WS2 monolayer on top of ReSe2 by a dry transfer process. Photoluminescence quenching was observed in the heterostructure, indicating efficient interlayer charge transfer. Transient absorption measurements show that holes can efficiently transfer from WS2 to ReSe2 on an ultrafast timescale. Meanwhile, electron transfer from ReSe2 to WS2 was also observed. The charge-transfer properties show that monolayers of ReSe2 and WS2 form a type-II band alignment, instead of type-I as predicted by theory. The type-II alignment is further confirmed by the observation of extended photocarrier lifetimes in the heterostructure. These results provide useful information for developing van der Waals heterostructure involving ReSe2 for novel electronic and optoelectronic applications and introduce ReSe2 to the family of two-dimensional materials to construct van der Waals heterostructures.

Metal oxides are promising candidates as the anodes of next-generation lithium ion batteries. However, the low electronic conductivities hinder their practical applications. Herein, through a facile calcination process using ammonium bicarbonate (NH4HCO3) as the N source, the nitrogen heteroelement was introduced into the ZnO/CoO micro-/nanospheres, which greatly improves the conductivity of the composites. As the lithium-ion battery anode, the N-doped ZnO/CoO micro-/nanosphere demonstrates much enhanced electrochemical performance. It displays a high initial capacity of 911.8 mA h/g at a current density of 0.2 A/g and long-term cycling stability, with a reversible capacity of 977.8 mA h/g remained after 500 cycles at a current density of 1 A/g. Furthermore, the N-doped ZnO/CoO composite presents an outstanding rate performance, with 605 mA h/g remained even at 5 A/g. The excellent electrochemical properties make N-doped ZnO/CoO micro-/nanospheres a promising candidate as high-performance anodes for next-generation rechargeable LIBs.

Energy chirp compensation of the electron bunch (e-bunch) in a laser wakefield accelerator, which is caused by the phase space rotation in the gradient wakefield, has been applied in many schemes for low energy spread e-bunch generation. We report the experimental observation of energy chirp compensation of the e-bunch in a nonlinear laser wakefield accelerator with a negligible beam loading effect. By adjusting the acceleration length using a wedge-roof block, the chirp compensation of the accelerated e-bunch was observed via an electron spectrometer. Apart from this, some significant parameters for the compensation process, such as the longitudinal dispersion and wakefield slope at the bunch position, were also estimated. A detailed comparison between experiment and simulation shows good agreement of the wakefield and bunch parameters. These results give a clear demonstration of the longitudinal characteristics of the wakefield in a plasma and the bunch dynamics, which are important for better control of a compact laser wakefield accelerator.

In this study, we investigate a new simple scheme using a planar undulator (PU) together with a properly dispersed electron beam ($e$ beam) with a large energy spread (${\sim}1\%$) to enhance the free-electron laser (FEL) gain. For a dispersed $e$ beam in a PU, the resonant condition is satisfied for the center electrons, while the frequency detuning increases for the off-center electrons, inhibiting the growth of the radiation. The PU can act as a filter for selecting the electrons near the beam center to achieve the radiation. Although only the center electrons contribute, the radiation can be enhanced significantly owing to the high-peak current of the beam. Theoretical analysis and simulation results indicate that this method can be used for the improvement of the radiation performance, which has great significance for short-wavelength FEL applications.

Some rare microscopic cycloneuralians are present in the Cambrian of South China, represented by Eopriapulites and Eokinorhynchus (both early Cambrian), fossil embryos of Markuelia (middle to late Cambrian), and palaeoscolecids (early to late Cambrian). Among them, palaeoscolecids are relatively diverse and abundant. Here, we describe new material of three-dimensionally phosphatized and microscopic cycloneuralians from the Paibian Stage of Wangcun Lagerstätte, western Hunan, South China. New material includes fossil embryos assignable to Markuelia sp., two other types of fossil embryos, and three species of palaeoscolecids, including Dispinoscolex decorus Duan, Dong, and Donoghue, 2012, Schistoscolex hunanensis Duan, Dong, and Donoghue, 2012, and Austroscolex sinensis new species. The palaeoscolecid fragments differ mainly in size and armor of the trunk annuli. Since Eokinorhynchus and Eopriapulites occurred the earliest among the Cambrian cycloneuralians, it is proposed here that: (1) cycloneuralians originated in the Cambrian Fortunian small shelly faunas rather than in the early Cambrian macrobenthos, (2) ancestral cycloneuralians may have simple trunk armor, and (3) Eopriapulites represents an ancestral cycloneuralian.

The discovery of the ancient city of Loulan in Xinjiang, China, at the beginning of the 20th century was of great significance for understanding the evolution of culture and civilization in Inner Asia. However, due to the lack of systematic chronological studies, the history of this ancient city remains unclear, particularly the date of its construction and abandonment. Here, we present the results of the first systematic radiocarbon (14C) dating carried out on artifacts from ancient Loulan. Our results show that human activity began as early as 350 cal BC, flourished during the interval from the 1st to 4th centuries AD, and completely disappeared around 600 AD. Most of the buildings in the city were constructed during the Eastern Han Dynasty rather than in Wei/Jin Dynasty, as previously indicated by excavated documents and letters (Hedin 1898; Xiao 2006). The development and flourishing of Loulan coincided with the interval of high ice accumulation and meltwater supply from surrounding mountains. The city began to decline and was finally abandoned following an abrupt decrease in ice accumulation and meltwater supply (Yao et al. 1996; Lauterbach et al. 2014), suggesting that natural climate change was the major factor responsible for the abandonment of Loulan.

We present new estimates on evaporation and groundwater recharge in the Badain Jaran Desert, western Inner Mongolia of northwestern China, based on a modified Penman Equation suitable for lakes in China. Geochemical data and water balance calculations suggest that local rainfall makes a significant contribution to groundwater recharge and that past lake-level variations in this desert environment should reflect palaeoclimatic changes. The chronology of lake-level change, established by radiocarbon and U-series disequilibrium dating methods, indicates high lake levels and a wetter climate beginning at ca. 10 ka and lasting until the late mid-Holocene in the Badain Jaran Desert. The greatest extension of lakes in the inter-dune depressions indicates that the water availability was greatest during the mid-Holocene. Relicts of Neolithic tools and pottery of Qijia Culture (2400–1900 BC) suggest relatively intensive human activity in the Badain Jaran Desert during the early and middle Holocene, supporting our interpretation of a less harsh environment. Wetter climates during the Holocene were likely triggered by an intensified East Asian summer monsoon associated with strong insolation.

Past environmental changes based on diatom relative abundances have been inferred from the maar Lake Erlongwan in northeast China. The limnology of Lake Erlongwan is affected by the strongly seasonal regional climate. The composition of diatom assemblages, in turn, responds to changes in the seasonal duration of ice cover in winter, water-column turnover in spring and autumn, and thermal stratification in summer. Statistical analysis of the sedimentary diatom assemblages reveals three significant stratigraphic zones over the past 1000 yr. The highest abundance of the planktonic species Discostella species occurs between AD 1050 and 1400 and suggests an annual ice-free period of long duration and well-developed summer stratification of the water column. This planktonic diatom peak between ca. AD 1150 and 1200 suggests that this period was the warmest over the past 1000 yr. The interval between AD 1400 and 1800 is marked by a decline in planktonic diatoms and suggests shorter duration of the ice-free season, weaker water stratification and possibly generally cold conditions. After AD 1800 relative abundances of planktonic diatoms, including Puncticulata praetermissa and Asterionella formosa, increase again, which indicates lengthening of the duration of the annual ice-free period and a stronger overturn of the water column. All these data imply that the pattern of the seasons is different between the MWP and the 20th century.

Concentrations of IgA and IgM in milk from normal lactating cows were measured to determine whether they were affected by lactation number, lactation stage, daily milk production, milk composition and somatic cell score (SCS). A total of 284 Chinese Holstein cows showing no signs of mastitis were selected from more than 1600 cows from one farm. Concentrations of IgA and IgM in normal milk were determined by ELISA. Results revealed that average milk IgA and IgM concentrations were 235±11 and 32±3 μg/ml, respectively. IgA and IgM concentrations in milk were found to have an association with lactation number, stage of lactation, daily milk production and SCS. Both SCS and daily milk production were found to be strong significant (P<0·01) direct factors correlating to IgA concentration. Stage of lactation and SCS were found to be strong significant (P<0·01) direct factors correlating to IgM concentration.