Xi Chen explores the question of why there has been a dramatic rise in and routinization of social protests in China since the early 1990s. Drawing on case studies, in-depth interviews and a unique ...data set of about 1,000 government records of collective petitions, this book examines how the political structure in Reform China has encouraged Chinese farmers, workers, pensioners, disabled people and demobilized soldiers to pursue their interests and claim their rights by staging collective protests. Chen suggests that routinized contentious bargaining between the government and ordinary people has remedied the weaknesses of the Chinese political system and contributed to the regime's resilience. Social Protest and Contentious Authoritarianism in China challenges the conventional wisdom that authoritarian regimes always repress popular collective protest and that popular collective action tends to destabilize authoritarian regimes.
•Landslide modeling use optimized KLR with different kernel functions.•Optimization of factors using FR analysis and multicollinearity analysis.•Comparison of landslide susceptibility maps to reveal ...difference affected by factors.
Globally, but especially in China, landslides are considered to be one of the most severe and significant natural hazards. In this study, bivariate statistical-based kernel logistic regression (KLR) models with different kernel functions (Polynomial, PUK, and Radial Basis Function), named the PLKLR, PUKLR, and RBFKLR models, were proposed for landslide susceptibility evaluation in Zichang City, China. Meanwhile, the present study aims to build landslide susceptibility maps based on bivariate statistical correlation analysis, optimization of different kernel functions, comparison of three landslide susceptibility maps and systematic analysis of spatial patterns. The steps of this article are organized as follows: Firstly, a landslide inventory containing 263 historical landslide locations was constructed. For the purpose of training and validation of models, 263 landslide locations were randomly divided into two parts with a ratio of 70/30. Secondly, 14 landslide conditioning factors were extracted from the spatial database. Subsequently, correlation analysis between the conditioning factors and the occurrence of landslides was conducted using frequency ratios. Then, the conditioning factors with normalized frequency ratios values were used as inputs to build the landslide susceptibility maps using the three models. A multicollinearity analysis was performed using collinearity statistics. Finally, the area under the receiver operating characteristic curve (AUC) was used for comparison and validation of models for recognizing the prediction capability. By further quantitative comparing mapped susceptibility values on a pixel-by-pixel basis, which can acquire underestimations and overestimations of factors (distance to river and slope) and susceptibility area. The results indicated that the PUKLR model had superior performance in landslide susceptibility assessment, with the highest AUC values of 0.884 and 0.766 for training and validation datasets, respectively. This model was followed by the RBFKLR model and the PLKLR model for the training datasets (AUC values of 0.879 and 0.797, respectively), and the PLKLR model and the RBFKLR model for the validation datasets (AUC values of 0.758 and 0.752, respectively). The landslide susceptibility map could help government agencies and decision-makers make wise decisions for future natural hazards prevention in Zichang region.
Esophageal squamous dysplasia is believed to be the precursor lesion of esophageal squamous cell carcinoma (ESCC); however, the genetic evolution from dysplasia to ESCC remains poorly understood. ...Here, we applied multi-region whole-exome sequencing to samples from two cohorts, 45 ESCC patients with matched dysplasia and carcinoma samples, and 13 tumor-free patients with only dysplasia samples. Our analysis reveals that dysplasia is heavily mutated and harbors most of the driver events reported in ESCC. Moreover, dysplasia is polyclonal, and remarkable heterogeneity is often observed between tumors and their neighboring dysplasia samples. Notably, copy number alterations are prevalent in dysplasia and persist during the ESCC progression, which is distinct from the development of esophageal adenocarcinoma. The sharp contrast in the prevalence of the 'two-hit' event on TP53 between the two cohorts suggests that the complete inactivation of TP53 is essential in promoting the development of ESCC.The pathogenesis of oesophageal squamous cell carcinoma is a multi-step process but the genetic determinants behind this progression are unknown. Here the authors use multi-region exome sequencing to comprehensively investigate the genetic evolution of precursor dysplastic lesions and untransformed oesophagus.
A transformation of fluxional into configurationally stable axially chiral N‐arylpyrroles was achieved with a highly atroposelective electrophilic aromatic substitution catalyzed by a chiral‐at‐metal ...rhodium Lewis acid. Specifically, N‐arylpyrroles were alkylated with N‐acryloyl‐1H‐pyrazole electrophiles in up to 93 % yield and with up to >99.5 % ee, and follow‐up conversions reveal the synthetic utility of this new method. DFT calculations elucidate the origins of the observed excellent atroposelectivity.
Freeze, don't move: A transformation of fluxional into configurationally stable axially chiral N‐arylpyrroles was achieved through a highly atroposelective electrophilic aromatic substitution catalyzed by a chiral‐at‐metal rhodium Lewis acid, with follow‐up transformations leading to structurally diverse axially chiral N‐arylpyrroles.
Metal-support interaction is of great significance for catalysis as it can induce charge transfer between metal and support, tame electronic structure of supported metals, impact adsorption energy of ...reaction intermediates, and eventually change the catalytic performance. Here, we report the metal size-dependent charge transfer reversal, that is, electrons transfer from platinum single atoms to sulfur-doped carbons and the carbon supports conversely donate electrons to Pt when their size is expanded to ~1.5 nm cluster. The electron-enriched Pt nanoclusters are far more active than electron-deficient Pt single atoms for catalyzing hydrogen evolution reaction, exhibiting only 11 mV overpotential at 10 mA cm
and a high mass activity of 26.1 A mg
at 20 mV, which is 38 times greater than that of commercial Pt/C. Our work manifests that the manipulation of metal size-dependent charge transfer between metal and support opens new avenues for developing high-active catalysts.
This study models local and cross-city transmissions of the novel coronavirus in China between January 19 and February 29, 2020. We examine the role of various socioeconomic mediating factors, ...including public health measures that encourage social distancing in local communities. Weather characteristics 2 weeks prior are used as instrumental variables for causal inference. Stringent quarantines, city lockdowns, and local public health measures imposed in late January significantly decreased the virus transmission rate. The virus spread was contained by the middle of February. Population outflow from the outbreak source region posed a higher risk to the destination regions than other factors, including geographic proximity and similarity in economic conditions. We quantify the effects of different public health measures in reducing the number of infections through counterfactual analyses. Over 1.4 million infections and 56,000 deaths may have been avoided as a result of the national and provincial public health measures imposed in late January in China.
Lithium–sulfur batteries with high energy capacity are promising candidates for advanced energy storage. However, their applications are impeded by shuttling of soluble polysulfides and sluggish ...conversion kinetics with inferior rate performance and short cycling life. Here, single-atom materials are designed to accelerate polysulfide conversion for Li–S batteries. Nitrogen sites in the structure not only anchor polysulfides to alleviate the shuttle effect but also enable high loading of single-atom irons. Density functional theory calculations indicate that single-atom sites reduce the energy barrier of electrochemical reactions and thus improve the rate and cycling performances of batteries. The coin battery shows impressive energy storage properties, including a high reversible capacity of 1379 mAh g–1 at 0.1 C and a high rate capacity of 704 mAh g–1 at 5 C. The ratio of electrolyte dosage/energy density is as low as 5.5 g Ah1–. It exhibits excellent cycling performance with a capacity retention of 90% even after 200 cycles at 0.2 C.
This study examines whether the Visible Infrared Imaging Radiometer Suite (VIIRS) nighttime lights can be used to predict population migration in small areas in European Union (EU) countries. The ...analysis uses the most current data measured at the smallest administrative unit in 18 EU countries provided by the European Commission. The ordinary least squares regression model shows that, compared to population size and gross domestic product (GDP), lights data are another useful predictor. The predicting power of lights is similar to population but it is much stronger than GDP per capita. For most countries, regression models with lights can explain 50–90% of variances in small area migrations. The results also show that the annual VIIRS lights (2015–2016) are slightly better predictors for migration population than averaged monthly VIIRS lights (2014–2017), and their differences are more pronounced in high latitude countries. Further, analysis of quadratic models, models with interaction effects and spatial lag, shows the significant effect of lights on migration in the European region. The study concludes that VIIRS nighttime lights hold great potential for studying human migration flow, and further open the door for more widespread application of remote sensing information in studying dynamic demographic processes.
Abstract
Metal single-atom catalysts (M-SACs) have emerged as an attractive concept for promoting heterogeneous reactions, but the synthesis of high-loading M-SACs remains a challenge. Here, we ...report a multilayer stabilization strategy for constructing M-SACs in nitrogen-, sulfur- and fluorine-co-doped graphitized carbons (M = Fe, Co, Ru, Ir and Pt). Metal precursors are embedded into perfluorotetradecanoic acid multilayers and are further coated with polypyrrole prior to pyrolysis. Aggregation of the metals is thus efficiently inhibited to achieve M-SACs with a high metal loading (~16 wt%). Fe-SAC serves as an efficient oxygen reduction catalyst with half-wave potentials of 0.91 and 0.82 V (versus reversible hydrogen electrode) in alkaline and acid solutions, respectively. Moreover, as an air electrode in zinc–air batteries, Fe-SAC demonstrates a large peak power density of 247.7 mW cm
−2
and superior long-term stability
.
Our versatile method paves an effective way to develop high-loading M-SACs for various applications.
N‐Boc‐protected α‐amino acids are synthesized in two steps from linear or branched carboxylic acid feedstocks. In the first step, the carboxylic acid is coupled with tert‐butyl aminocarbonate ...(BocNHOH) to generate azanyl ester (acyloxycarbamate) RCO2NHBoc. In the second step, this azanyl ester undergoes a stereocontrolled iron‐catalyzed 1,3‐nitrogen migration to generate the N‐Boc‐protected non‐racemic α‐amino acid. This straightforward protocol is applicable to the catalytic asymmetric synthesis of α‐monosubstituted α‐amino acids with aryl, alkenyl, and alkyl side chains. Furthermore, α,α‐disubstituted α‐amino acids are accessible in an enantioconvergent fashion from racemic carboxylic acids. The new method is also advantageous for the synthesis of α‐deuterated α‐amino acids. N‐Boc‐protected α‐amino acids synthesized using this two‐step protocol are ready‐to‐use building blocks.
A straightforward two‐step protocol was developed to convert linear or α‐branched carboxylic acids into non‐racemic N‐Boc‐protected α‐monosubstituted (asymmetric catalysis) or α,α‐disubstituted (enantioconvergent catalysis) α‐amino acids.
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