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Continents with cratonic cores can resist deformation, and thus survive billions of years in the geological record. Tectonic reworking is a significant process that weakens and destructs cratons, but our understanding of the process remains incomplete. In the South China Block, Mesozoic cyclical tectonics destructed a large portion of its cratonic lithosphere. Here, we synthesized the structural evolution of extensional domes and illustrated the process of lithospheric thinning. Unlike the previous rapid, one-cycle delamination model, we propose a newmodel that multicycle compression and extension progressively destructed the lithosphere, which reconciles both surface geology and deep process. [ABSTRACT FROM AUTHOR]

An alarming number of students drop out of junior high school in developing countries. In this study, we examine the impacts of providing a social-emotional learning (SEL) program on the dropout behavior and learning anxiety of students in the first two years of junior high. We do so by analyzing data from a randomized controlled trial involving 70 junior high schools and 7,495 students in rural China. After eight months, the SEL program reduces dropout by 1.6 percentage points and decreases learning anxiety by 2.3 percentage points. Effects are no longer statistically different from zero after 15 months, perhaps due to decreasing student interest in the program. However, we do find that the program reduces dropout among students at high risk of dropping out (older students and students with friends who have already dropped out), both after eight and 15 months of exposure to the SEL program.

An alarming number of students drop out of junior high school in developing countries. In this study, we examine the impacts of providing a social-emotional learning (SEL) program on the dropout behavior and learning anxiety of students in the first two years of junior high. We do so by analyzing data from a randomized controlled trial involving 70 junior high schools and 7,495 students in rural China. After eight months, the SEL program reduces dropout by 1.6 percentage points and decreases learning anxiety by 2.3 percentage points. Effects are no longer statistically different from zero after 15 months, perhaps due to decreasing student interest in the program. However, we do find that the program reduces dropout among students at high risk of dropping out (older students and students with friends who have already dropped out), both after eight and 15 months of exposure to the SEL program. [ABSTRACT FROM AUTHOR]

Background Junior high dropout rates are up to 25% in poor, rural areas of China. Although existing studies have examined how factors such as high tuition and opportunity costs contribute to dropout, fewer studies have explored the relationship between dropout rates and mental health in rural China. The overall goal of this study is to examine the relationship between dropout and mental health problems in rural Chinese junior high schools. Methods Correlational analysis was conducted among 4840 students across 38 junior high schools in rural China. Ordinary least squares (OLS) regressions were used to determine the types of students most at risk for mental health problems and whether mental health problems are correlated with dropout behavior. Our measure for mental health is based on the Children's Manifest Anxiety Scale. Results Mental health problems are widespread in the sample of rural children, with 74% of students at risk for mental health problems. The student and family characteristics that correlate with dropout (poverty and low achievement) also correlate with mental health problems. More importantly, even after controlling for these background characteristics, mental health problems remain correlated with dropout rates. Conclusions Mental health problems, especially among low-achieving poor students, may be contributing to the high dropout rates in rural China today. This finding suggests that interventions focusing on mental health in rural areas may also help reduce dropout. [ABSTRACT FROM AUTHOR]

The Bikou Terrane, located at the conjunction of the Longmenshan fold-thrust belt and the west Qinling orogenic belt in centeral China, was involved in the Late Triassic collision between the South China and North China blocks. The Bikou Terrane has preserved crucial information on structural geometry and kinematics of Triassic tectonics, and is therefore of great importance for reconstructing the Paleo-Tethyan evolutionary history. However, multi-phase tectonic events of the Bikou Terrane are unsettled. This work presents detailed structural analysis based on both the field and laboratory works, which reveals three phases of deformation events in Bikou and its adjacent areas, including top-to-the-SW shearing related to SW-ward thrusting (DI) mainly to the north of the Bikou Terrane, top-to-the-NNW shearing related to NNW-ward thrusting (DII) in the Bikou Terrane, and strike-slip faulting (DIII) locally developed in the northern Bikou Terrane. Anisotropy of magnetic susceptibility (AMS) study and related structural analysis not only support the multiphase deformation but also reveal a gradual transition from the DII-related magnetic fabrics to the DIII-related magnetic fabrics in the Bikou Terrane. Integrating published geochronological data, it is constrained that DI occurred at ca. 237-225 Ma, DII occurred at ca. 224-219 Ma, and DIII possibly occurred during the Early Cretaceous. Based on regional tectonics, the DI event corresponds to the collision between the South Qinling block and the Bikou Terrane, and the DII event reflects the intracontinental amalgamation between the Bikou Terrane and the Yangtze block, which indicates a Late Triassic successive amalgamation from the North China block to the South China block. Intracontinental adjustment represented by the strike-slip (DIII event) occurred after the final amalgamation between the North China and South China blocks. By applying AMS on deciphering structural geometry and multiphase deformation, our study suggests that AMS is a useful tool for structural analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Genome-wide data of Polygonatum and its close relatives were obtained by Hyb-Seq. • The genome-wide nuclear and chloroplast data support monophyly of Polygonatum with three major clades. • Hybridization and introgression played a minor role in the evolutionary diversification of Polygonatum. Polygonatum is the largest genus of tribe Polygonateae (Asparagaceae) and is widely distributed in the temperate Northern Hemisphere, especially well diversified in southwestern China to northeastern Asia. Phylogenetic relationships of many species are still controversial. Hence it is necessary to clarify their phylogenetic relationships and infer possible reticulate relationships for the genus. In this study, genome-wide data of 43 species from Polygonatum and its closely related taxa were obtained by Hyb-Seq sequencing. The phylogenetic trees constructed from genome-wide nuclear and chloroplast sequences strongly supported the monophyly of Polygonatum with division into three major clades. A high level of incongruence was detected between nuclear and chloroplast trees as well as among gene trees within the genus, but all occurred within each major clade. However, introgression tests and reticulate evolution analyses revealed low level of gene flow and weak introgression events in the genus, suggesting hybridization and introgression were not dominant during the evolutionary diversification of Polygonatum in the Northern Hemisphere. This study provides important insights into reconstructing evolutionary relationships and speciation pattern of taxa from the north temperate flora. [ABSTRACT FROM AUTHOR]

Pyrrosia petiolosa, Pyrrosia lingua and Pyrrosia sheareri are recorded as original plants of Pyrrosiae Folium (PF) and commonly used as Chinese herbal medicines. Due to the similar morphological features of PF and its adulterants, common DNA barcodes cannot accurately distinguish PF species. Knowledge of the chloroplast (cp) genome is widely used in species identification, molecular marker and phylogenetic analyses. Herein, we determined the complete cp genomes of three original species of PF via high-throughput sequencing technologies. The three cp genomes exhibited a typical quadripartite structure with sizes ranging from 158 165 to 163 026 bp. The cp genomes of P. petiolosa and P. lingua encoded 130 genes, whilst that of P. sheareri encoded 131 genes. The complete cp genomes were compared, and five highly divergent regions of petA-psbJ, matK-rps16, ndhC-trnM, psbM-petN and psaC-ndhE were screened as potential DNA barcodes for identification of Pyrrosia genus species. The phylogenetic tree we obtained indicated that P. petiolosa and P. lingua are clustered in a single clade and, thus, share a close relationship. This study provides invaluable information for further studies on the species identification, taxonomy and phylogeny of Pyrrosia genus species., (Copyright © 2020 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.)