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Recently, the collisionless pitch-angle scattering for relativistic runaway electrons (REs) in toroidal geometries such as tokamaks was discovered through a full orbit simulation approach (Liu et al., Nucl. Fusion, vol. 56, 2016, p. 064002), and it was then theoretically investigated that a new expression for the magnetic moment, including the second-order corrections, could essentially reproduce the so-called collisionless pitch-angle scattering process (Liu et al., Nucl. Fusion, vol. 58, 2018, p. 106018). In this paper, with synchrotron radiation, extensive numerical verification of the validity of the high-order guiding-centre theory is given for simulations involving REs by incorporating such an expression for the magnetic moment into our particle tracing code. A high-order guiding-centre simulation approach with synchrotron radiation (HGSA) is applied. Synchrotron radiation plays an essential role in the life cycle of REs. The energy of REs first increases and then becomes saturated until the electric field acceleration is balanced by the radiation dissipation. Unfortunately, the process cannot be simulated accurately with the standard guiding-centre model, i.e. the first-order guiding-centre model. Remarkably, it is found that the HGSA can effectively produce the fundamental process of REs. Since the time scale of the energy saturation of REs is close to seconds, the computational cost becomes significant. In order to save costs, it is necessary to estimate the time of energy saturation. An analytical estimate is derived for the time it takes for synchrotron drag to balance an accelerating electric field and the provided formula has been numerically verified. Test calculations reveal that HGSA is favourable for exploiting the dynamics of REs in tokamak plasmas.
COVID-19 has long-term impacts on public mental health, while few research studies incorporate multidimensional methods to thoroughly characterise the psychological profile of general population and little detailed guidance exists for mental health management during the pandemic. This research aims to capture long-term psychological profile of general population following COVID-19 by integrating trajectory modelling approaches, latent trajectory pattern identification and network analyses.
Longitudinal data were collected from a nationwide sample of 18 804 adults in 12 months after COVID-19 outbreak in China. Patient Health Questionnaire-9, Generalised Anxiety Disorder-7 and Insomnia Severity Index were used to measure depression, anxiety and insomnia, respectively. The unconditional and conditional latent growth curve models were fitted to investigate trajectories and long-term predictors for psychological symptoms. We employed latent growth mixture model to identify the major psychological symptom trajectory patterns, and ran sparse Gaussian graphical models with graphical lasso to explore the evolution of psychopathological network.
At 12 months after COVID-19 outbreak, psychological symptoms generally alleviated, and five psychological symptom trajectories with different demographics were identified: normal stable (63.4%), mild stable (15.3%), mild-increase to decrease (11.7%), mild-decrease to increase (4.0%) and moderate/severe stable (5.5%). The finding indicated that there were still about 5% individuals showing consistently severe distress and approximately 16% following fluctuating psychological trajectories, who should be continuously monitored. For individuals with persistently severe trajectories and those with fluctuating trajectories, central or bridge symptoms in the network were mainly ‘motor abnormality’ and ‘sad mood’, respectively. Compared with initial peak and late COVID-19 phase, aftermath of initial peak might be a psychologically vulnerable period with highest network connectivity. The central and bridge symptoms for aftermath of initial peak (‘appetite change’ and ‘trouble of relaxing’) were totally different from those at other pandemic phases (‘sad mood’).
This research identified the overall growing trend, long-term predictors, trajectory classes and evolutionary pattern of psychopathological network of psychological symptoms in 12 months after COVID-19 outbreak. It provides a multidimensional long-term psychological profile of the general population after COVID-19 outbreak, and accentuates the essentiality of continuous psychological monitoring, as well as population- and time-specific psychological management after COVID-19. We believe our findings can offer reference for long-term psychological management after pandemics.
This experiment was conducted to evaluate the impact of substituting rice straw with citrus pulp (CRP), sweet potato peels (SPP) and vines (SPV) on fermentation quality and in vitro digestibility when ensiled with or without wet brewers' grains (WBG). Seven treatments were set as follows: (i) rice straw only (control); (ii) 800 g rice straw/kg + 200 g CRP/kg (RC); (iii) 720 g rice straw/kg + 180 g CRP/kg + 100 g WBG/kg (RC+); (iv) 800 g rice straw/kg + 200 g SPP/kg (RP); (v) 720 g rice straw + 180 g SPP/kg + 100 g WBG/kg (RP+); (vi) 800 g rice straw/kg + 200 g SPV/kg (RV); (vii) 720 g rice straw/kg + 180 g SPV/kg + 100 g WBG/kg (RV+). After ensiling for 3, 7, 14, 30 and 60 days, silos were opened for fermentation profile, aerobic stability and in vitro parameter analyses. All substitution types improved fermentation quality, characterized by significantly lower pH and NH3-N content, higher lactic acid content and V-scores. WBG application promoted hetero-fermentation and significantly increased DM losses, acetic acid and ethanol contents. After 60 days of ensiling, the NDF, ADF and cellulose contents in mixed silages significantly decreased compared to control. During aerobic exposure, WBG application significantly prolonged aerobic stability. SPV substitution significantly improved in vitro digestibility of dry matter, NDF and ADF. In conclusion, the SPP substitution combined with WBG application was recommended as a result of the optimal balance of fermentation quality, aerobic stability and in vitro digestibility.
The optimization of laser pulse shapes is of great importance and a major challenge for laser direct-drive implosions. In this paper, we propose an efficient intelligent method to perform laser pulse optimization via hydrodynamic simulations guided by the genetic algorithm and random forest algorithm. Compared to manual optimizations, the machine-learning guided method is able to efficiently improve the areal density by a factor of 63% and reduce the in-flight-aspect ratio by a factor of 30% at the same time. A relationship between the maximum areal density and ion temperature is also achieved by the analysis of the big simulation dataset. This design method has been successfully demonstrated by the 2021 summer double-cone ignition experiments conducted at the SG-II upgrade laser facility and has great prospects for the design of other inertial fusion experiments.
The present study aimed to explore the association between dietary patterns in abdominal obesity obtained by reduced-rank regression (RRR) with visceral fat index (VFI) as a dependent variable and dyslipidemia in rural adults in Henan, China. A total of 29538 people aged 18–79 were selected from the Henan Rural Cohort Study. RRR analysis was used to identify dietary patterns; logistic regression analysis and restricted cubic spline regression models were applied to analyze the association between dietary patterns in abdominal obesity and dyslipidemia. VFI was used as a mediator to estimate the mediation effect. The dietary pattern in abdominal obesity was characterized by high carbohydrate and red meat intake and low consumption of fresh fruits, vegetables, milk, etc. After full adjustment, the highest quartile of dietary pattern scores was significantly associated with an increased risk of dyslipidemia (OR: 1·33, 95 % CI 1·23–1·44, Ptrend < 0·001), there was a non-linear dose–response relationship between them (Poverall-association < 0·001, Pnon-lin-association = 0·022). The result was similar in dose-response between the dietary pattern scores and VFI. The indirect effect partially mediated by VFI was significant (OR: 1·07, 95 % CI 1·06–1·08). VIF explained approximately 53·3 % of odds of dyslipidemia related to the dietary pattern. Abdominal obesity dietary pattern scores positively affected VFI and dyslipidemia; there was a dose-response in both relationships. Dyslipidemia progression increased with higher abdominal obesity dietary pattern scores. In addition, VFI played a partial mediating role in relationship between abdominal obesity dietary pattern and dyslipidemia.
Salicylic acid (SA), a phytohormone, has been considered to be a key regulator mediating plant defence against pathogens. It is still vague how SA activates plant defence against herbivores such as chewing and sucking pests. Here, we used an aphid-susceptible wheat variety to investigate Sitobion avenae response to SA-induced wheat plants, and the effects of exogenous SA on some defence enzymes and phenolics in the plant immune system. In SA-treated wheat seedlings, intrinsic rate of natural increase (rm), fecundity and apterous rate of S. avenae were 0.25, 31.4 nymphs/female and 64.4%, respectively, and significantly lower than that in the controls (P < 0.05). Moreover, the increased activities of phenylalanine-ammonia-lyase, polyphenol oxidase (PPO) and peroxidase in the SA-induced seedlings obviously depended on the sampling time, whereas activities of catalase and 4-coumarate:CoA ligase were suppressed significantly at 24, 48 and 72 h in comparison with the control. Dynamic levels of p-coumaric acid at 96 h, caffeic acid at 24 and 72 h and chlorogenic acid at 24, 48 and 96 h in wheat plants were significantly upregulated by exogenous SA application. Nevertheless, only caffeic acid content was positively correlated with PPO activity in SA-treated wheat seedlings (P = 0.031). These findings indicate that exogenous SA significantly enhanced the defence of aphid-susceptible wheat variety against aphids by regulating the plant immune system, and may prove a potential application of SA in aphid control.
Schools offer an ideal setting for childhood obesity interventions due to their access to children and adolescents. This review aimed to systematically review the impact of school-based intervention for the treatment of childhood obesity.
Eight databases were searched from inception till 30 May 2020. A revised Cochrane risk-of-bias tool and the Grading of Recommendations, Assessment, Development and Evaluations criteria were used to evaluate the risk of bias and overall evidence. Meta-analysis and meta-regression were performed on Stata software using the random effects model. Overall effect was evaluated using Hedges’ g, and heterogeneity was assessed using Cochran’s Q and I2.
Cluster randomised controlled trials (cluster-RCT) delivered in school.
Children and adolescents (6–18 years of age) with overweight and obesity.
Twelve cluster-RCT from seven countries with 1755 participants were included in the meta-analysis. School-based interventions for the treatment of childhood obesity reduced BMI and BMI z-scores with a medium effect (g = 0·52). Subgroup analyses showed greater effectiveness of brief school-based interventions and the interventions conducted in lower-middle to upper-middle economies. Meta-regression assessed the heterogeneity and the final model, with covariates of the type of economies and trial duration, accounted for 41·2 % of the variability. The overall quality of evidence was rated low because of the high risk of bias and inconsistency.
School-based interventions are a possible approach to provide universal healthcare for the treatment of childhood obesity, and further well-designed cluster-RCT with longer follow-up are needed. This study is registered with PROSPERO (CRD42020160735).
Over recent decades, Chinese giant salamanders Andrias spp. have declined dramatically across much of their range. Overexploitation and habitat degradation have been widely cited as the cause of these declines. To investigate the relative contribution of each of these factors in driving the declines, we carried out standardized ecological and questionnaire surveys at 98 sites across the range of giant salamanders in China. We did not find any statistically significant differences between water parameters (temperature, dissolved oxygen, ammonia, nitrite, nitrate, salinity, alkalinity, hardness and flow rate) recorded at sites where giant salamanders were detected by survey teams and/or had been recently seen by local respondents, and sites where they were not detected and/or from which they had recently been extirpated. Additionally, we found direct and indirect evidence that the extraction of giant salamanders from the wild is ongoing, including within protected areas. Our results support the hypothesis that the decline of giant salamanders across China has been primarily driven by overexploitation. Data on water parameters may be informative for the establishment of conservation breeding programmes, an initiative recommended for the conservation of these species.
The coronavirus disease 2019 (COVID-19) pandemic is a major threat to the public. However, the comprehensive profile of suicidal ideation among the general population has not been systematically investigated in a large sample in the age of COVID-19.
A national online cross-sectional survey was conducted between February 28, 2020 and March 11, 2020 in a representative sample of Chinese adults aged 18 years and older. Suicidal ideation was assessed using item 9 of the Patient Health Questionnaire-9. The prevalence of suicidal ideation and its risk factors was evaluated.
A total of 56,679 participants (27,149 males and 29,530 females) were included. The overall prevalence of suicidal ideation was 16.4%, including 10.9% seldom, 4.1% often, and 1.4% always suicidal ideation. The prevalence of suicidal ideation was higher in males (19.1%) and individuals aged 18–24 years (24.7%) than in females (14.0%) and those aged 45 years and older (11.9%). Suicidal ideation was more prevalent in individuals with suspected or confirmed infection (63.0%), frontline workers (19.2%), and people with pre-existing mental disorders (41.6%). Experience of quarantine, unemployed, and increased psychological stress during the pandemic were associated with an increased risk of suicidal ideation and its severity. However, paying more attention to and gaining a better understanding of COVID-19-related knowledge, especially information about psychological interventions, could reduce the risk.
The estimated prevalence of suicidal ideation among the general population in China during COVID-19 was significant. The findings will be important for improving suicide prevention strategies during COVID-19.
The North Qilian orogenic belt in North China has been defined as a subduction–collision zone between the Alxa Block and the Qilian Block. We present petrography, zircon U–Pb geochronology, major- and trace-element geochemistry, and Sr–Nd–Pb–Hf isotope analysis for the Yushigou diabase from the Longshoushan area, which is located SW of the Alxa Block, aiming to understand its petrogenetic link to subduction processes. The Yushigou diabase belongs to the tholeiite series, and shows enrichment in light rare earth and large-ion lithophile elements, and a depletion in heavy rare earth and high-field-strength elements. Laser ablation – inductively coupled plasma – mass spectrometry U–Pb zircon dating yielded an emplacement age of 414 ± 9 Ma, with an ϵHf(t) value in the range of −10.3 to 1.8. The whole-rock initial 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of the diabase range over 16.811–17.157, 15.331–15.422 and 37.768–37.895, respectively. The (87Sr/86Sr)i ratios vary between 0.7086 and 0.7106, and ϵNd(t) values vary between −14.4 and −13.4, which are significantly higher than the ϵHf(t) value (Nd–Hf decoupling). An interpretation of the elemental and isotopic data suggests that the Yushigou diabase was derived from partial melting of an enriched mantle I (EM-I) -type lithospheric mantle in the spinel–garnet transitional zone. Based on the geochemical features and previous regional geological data, we propose that the Silurian magmatism was most likely triggered by slab break-off after the closure of the North Qilian Ocean, and ancient continental materials from the subduction slab metasomatized the overlying lithospheric mantle during exhumation.
The factors associated with suicidal ideation among adolescents have been extensively characterised, but the mechanisms underlying the complexities of the relationship between experiences of childhood trauma and suicidal ideation have been less studied. This study examined the direct effect of childhood trauma on suicidal ideation on the one hand and whether school bullying victimisation and Internet addiction mediate the association between childhood trauma and suicidal ideation on the other hand.
This school-based mental health survey was carried out in Qinghai Province in Northwest China in December 2019. We employed standardised questionnaires to collect sociodemographic and target mental health outcomes. Hierarchical multiple logistic regression and structural equation modelling were performed for the data analyses.
This study included 5864 university students. The prevalence of lifetime suicidal ideation and Internet addiction were 34.7% and 21.4%, respectively. Overall, 16.4% and 11.4% of participants reported experiences of childhood trauma and school bullying victimisation, respectively. There were direct effects of childhood trauma, school bullying victimisation and Internet addiction on suicidal ideation. The total effect of childhood trauma on suicidal ideation was 0.201 (p < 0.001). School bullying victimisation and Internet addiction mediated the relationship between childhood trauma and suicidal ideation. Internet addiction played a mediating role between school bullying and suicidal ideation.
Childhood trauma had both direct and indirect effects on suicidal ideation; these effects were mediated by school bullying victimisation and Internet addiction in Chinese university students. Elucidating these relationships will therefore be useful in developing and implementing more targeted interventions and strategies to improve the mental well-being of Chinese university students.
Octapyrgites elongatus n. gen. n. sp., a relatively rare, tetraradial olivooid (Cnidaria, Medusozoa), is described from Bed 5 of the Yanjiahe Formation (Cambrian Stage 2) near Yichang, China. Although similar to Olivooides and Quadrapyrgites from the Fortunian Stage in consisting of a partially corrugated (longitudinal) periderm with a quadrate (transverse) apical portion and V-shaped apertural lobes, O. elongatus is substantially larger than other olivooids. The elongate apical region of O. elongatus is similar to four-sided Anaconularia anomala (Barrande, 1867), though with a flat tip that may have been an adaption for a sessile mode of life. As in other olivooids, embryonic development in O. elongatus may have been direct. Last, the paucity of olivooids and the absence of pentaradial cnidarians and carinachitids in Cambrian Stage 2 indicate a marked decline in the disparity of cnidarians near the Fortunian–Cambrian Age 2 boundary, when by contrast bilaterians underwent rapid diversification.
We construct a multiply Xiong chaotic set with full Hausdorff dimension everywhere that is contained in some multiply proximal cell for the full shift over finite symbols and the Gauss system, respectively.
Ceramics are strong but brittle. According to the classical theories, ceramics are brittle mainly because dislocations are suppressed by cracks. Here, the authors report the combined elastic and plastic deformation measurements of nanoceramics, in which dislocation-mediated stiff and ductile behaviors were detected at room temperature. In the synchrotron-based deformation experiments, a marked slope change is observed in the stress–strain relationship of MgAl2O4 nanoceramics at high pressures, indicating that a deformation mechanism shift occurs in the compression and that the nanoceramics sample is elastically stiffer than its bulk counterpart. The bulk-sized MgAl2O4 shows no texturing at pressures up to 37 GPa, which is compatible with the brittle behaviors of ceramics. Surprisingly, substantial texturing is seen in nanoceramic MgAl2O4 at pressures above 4 GPa. The observed stiffening and texturing indicate that dislocation-mediated mechanisms, usually suppressed in bulk-sized ceramics at low temperature, become operative in nanoceramics. This makes nanoceramics stiff and ductile.
Nanotechnology has been considered as a promising strategy for diagnosis and treatment of various diseases. However, the stability and circulation times of the conventional nano-carriers, such as liposomes and micelles, are still unsatisfied. Perfluorocarbons (PFCs) are biologic inert synthetic materials, which are highly hydrophobic and have a tendency to self-aggregation. Additionally, PFCs themselves can act as 19F magnetic resonance imaging agents and oxygen carriers. Thus, the construction of the fluorinated carriers will not only improve the stability of the carriers, but also endow them with additional functions. Here we review the recent advances of PFC-based nanosystems for diagnosis and treatment of diseases.
The number of elderly individuals living in China is increasing rapidly. The aim of this study was to examine the potential risk factors of geriatric depression in rural areas.
A repeated cross-sectional study was conducted between January 2015 and October 2016 in rural China. Nine hundred forty-five elderly individuals were included in both investigations. A generalized estimating equation (GEE) was used to examine the relationships between geriatric depression and socio-demographics, the number of chronic diseases, ADL (Activity of Daily Living) disability, cognitive impairment, and anxiety.
Among the participants, the majority was female (61.4%) and illiterate (81.5%) and had a general economic status (63.0%) and more than two kinds of chronic diseases (62.9%). The bivariate analysis indicated that geriatric depression was associated with social support, education level, economic status, ADL disability, anxiety disorders, and cognitive impairment at both survey time points. The GEE results showed that poor economic status (OR = 8.294, p < 0.001), the presence of more than two chronic diseases (OR = 1.681, p = 0.048), ADL disability (OR = 2.184, p < 0.001), cognitive impairment (OR = 1.921, p < 0.001), and anxiety (OR = 5.434, p < 0.001) were risk factors for geriatric depression in rural China; better social support (OR = 0.924, 95% CI = 0.899–0.949, p < 0.001) was found to be a protective factor.
Geriatric depression in rural China was associated with several socio-demographic, physical, and mental factors. Targeted interventions are essential to improve the psychological health of aged individuals in rural China.
A coaxial-output rolled strip pulse-forming line (RSPFL) with a dry structure is researched for the purpose of miniaturization and all-solid state of pulse-forming lines (PFL). The coaxial-output RSPFL consists of a coaxial-output electrode (COE) and a rolled strip line (RSL). The COE is characterized by quasi-coaxial structure, making the output pulse propagate along the axial direction with a small output inductance. The RSL is rolled on the COE, whose transmission characteristics are analyzed theoretically. It shows that the RSL can be regarded as a planar strip line when the rolling radius of the strip line is larger than 60 times of the thickness of the insulation dielectric layer of RSL. CST modeling was carried out to simulate the discharging characteristic of the coaxial-output RSPFL. It shows that the coaxial-output RSPFL can deliver a discharging pulse with a rise time <6 ns when the impedance of the RSL matches that of the COE, which confirms the theoretical analysis. A prototype of the coaxial-output RSPFL was developed. A 49-kV discharging pulse on a matched load was achieved when it was charged to 100 kV. The discharging waveform has a pulse width of 32 ns, with a rise time of 6 ns, which is consistent with the simulation waveform. An energy-storage density of 1.9 J/L was realized in the coaxial-output RSPFL. By the method of multi-stage connection in series, a much higher output voltage is convenient to be obtained.
We establish a dynamical version of the Kuratowski–Mycielski theorem on the existence of ‘large’ invariant dependent sets. We apply this result to the study of invariant chaotic sets in topological dynamical systems, simplify many known results on this topic and also obtain some new results.
A novel scheme for power-combined frequency tripler adopting 2N diodes is proposed in this work. Even mode coupled suspended substrate stripline is used to divide and recombine the input and output power. The circuits of the tripler are printed on both sides of the substrate, with N diodes on the front side and the other N diodes on the back side. The front diodes and back diodes are in anti-parallel connection, and DC biased separately to increase the bandwidth and power capacity. Three Q-band prototypes with two, four, and six diodes are fabricated and tested. The output compression powers at output frequency of 43.5 GHz for two/four/six-diode tripler are 9.2, 11, and 12 dBm, respectively. Power capacity is improved with the proposed tripler. Optimum DC bias is also discussed in this work, and it is found that it first increases with drive power, and then drops when large drive power applied because of the increased series resistance of the diode due to high junction temperature.