Drivers of cropland abandonment in mountainous areas: A household decision model on farming scale and a case study of Southwest China

Cropland abandonment has emerged as a prevalent phenomenon in the mountainous areas of China.While there is a general understanding that this new trend is driven by the rising opportunity cost of rural labor, rigorous theoretical and empirical analyses are largely absent. This paper first develops a theoretical model to investigate household decisions on farming scale when off-farm labor market is accessible and there is heterogeneity of farmland productivity and distribution. The model is capable of explaining the hidden reasons of cropland abandonment in sloping and agriculturally less-favored locations. The model also unveils the impacts of heterogeneity of household labor on fallow decisions and the efficiency loss due to an imperfect labor market. The model is empirically tested by applying the Probit and Logit estimators to a unique household and land-plot survey dataset which contains 5258 plots of599 rural households in Chongqing, a provincial level municipality, in Southwest China. The survey shows that more than 30% of the sample plots have been abandoned, mainly since 1992. The econometric results are consistent with our theoretical expectations. This work would help policy-makers and stakeholders to identify areas with a high probability of land abandonment and farming practice which is less sustainable in the mountainous areas

A New Method of D-TDOA Time Measurement Based on RTT

In this paper, a novel difference-time difference of arrival (D-TDOA) time measurement method based on round-trip transmission (RTT) is proposed. The accuracy of time measurement is critical for high accuracy positioning, yet the traditional time difference of arrival (TDOA) time measurement method cannot deal well with the problem of time synchronization error, such as the initial time offset and transmission cumulate time error caused by clock frequency offset and drift. We formulate a D-TDOA time measurement mechanism to overcome the shortcoming of the traditional TDOA method in eliminating the influence of clock error. It is proved that the D-TDOA method can effectively eliminate the influence of initial time offset by analyzing the simulation data, which can also reduce the cumulate time error remarkably. The simulation results demonstrate that the D-TDOA method can significantly enhance the accuracy of time measurement in the circumstance that the AP clock synchronization is not required seriously

PCB: A pseudotemporal causality-based Bayesian approach to identify EMT-associated regulatory relationships of AS events and RBPs during breast cancer progression.

During breast cancer metastasis, the developmental process epithelial-mesenchymal (EM) transition is abnormally activated. Transcriptional regulatory networks controlling EM transition are well-studied; however, alternative RNA splicing also plays a critical regulatory role during this process. Alternative splicing was proved to control the EM transition process, and RNA-binding proteins were determined to regulate alternative splicing. A comprehensive understanding of alternative splicing and the RNA-binding proteins that regulate it during EM transition and their dynamic impact on breast cancer remains largely unknown. To accurately study the dynamic regulatory relationships, time-series data of the EM transition process are essential. However, only cross-sectional data of epithelial and mesenchymal specimens are available. Therefore, we developed a pseudotemporal causality-based Bayesian (PCB) approach to infer the dynamic regulatory relationships between alternative splicing events and RNA-binding proteins. Our study sheds light on facilitating the regulatory network-based approach to identify key RNA-binding proteins or target alternative splicing events for the diagnosis or treatment of cancers. The data and code for PCB are available at: http://hkumath.hku.hk/~wkc/PCB(data+code).zip

Characterization of the complete mitochondrial genome sequence of Tanichthys albiventris and phylogenetic analysis

In this study, we sequenced, annotated, and characterized the mitogenome of Tanichthys albiventris for the first time. The complete mitogenome is 16,544 bp in length, consisting of 13 protein-coding genes (PCGs), 22 transfer RNA genes, and two ribosomal RNA genes. We found nine genetic overlaps and 17 intergenic spacer regions throughout the mitogenome of T. albiventris. The A + T content of the mitogenome is 60.93%. All PCGs have the same start codon of the standard ATG, excepting for that of cytochrome c oxidase 1 (cox1) which is the GTG. A phylogenetic analysis with another 15 species of the Cyprinidae was performed using MrBayes and IQtree, based on the amino acid sequences of 13 mitochondrial PCGs. The results indicated that T. albiventris shares a close ancestry with Tanichthys albonubes

Characterization of the complete mitochondrial genome sequence of Coilia brachygnathus (Clupeiformes, Engraulidae) from Huai River and its phylogenetic position

The complete mitogenome sequence of Coilia brachygnathus (Kreyenberg & Pappenheim, 1908) from Wabu Lake in Huai River Basin was annotated and characterized in this study. This mitochondrial genome is a circular DNA molecule of 16.896 bp in size with 57.52% AT content, including 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and an AT-rich region (control region) as other bony fishes. There are a total of 10 overlap locations and 15 intergenic spacer regions throughout the mitogenome of C. brachygnathus. All PCGs employed a standard ATG as a start codon, except cytochrome c oxidase 1 (cox1) with GTG. In addition, TAA or TAG was identified as the typical stop codon. A phylogenetic tree reconstructed with the maximum likelihood method depicted a clone relationship with eight species of genus Coilia and our previous study based on the amino acid sequences of 13 mitochondrial PCGs. The complete mitochondrial genome is a valuable resource in classifying and conserving C. brachygnathus

Reliability analysis and optimization of core fuel salt emergency drain system for the molten salt reactor experiment

BackgroundCore fuel salt emergency drain system designed for fuel salt drain and afterheat removal, provides a safe shutdown mode for a molten salt reactor (MSR). It has important significance to evaluate reliability of the system for the safety of MSRs.PurposeThis study aims to quantitatively analyze the failure probabilty of the system and identify the pivotal factors that affecting the system failures, and provide suggestions for optimization of the system in engineering application.MethodsFirst of all, the fault tree analysis was employed to model the reliability of the core fuel salt drain system of MSRE through RiskSpectrum software. Then, the minimum cut sets and importance analysis was adopted to identify the most important basic event in fault tree of the system. Finally, two optimization methods, i.e., reduce the use of welds in bayonet cooling thimbles, and use different types of valves to isolate cooling gas flow of freeze valve, were proposed.ResultsThe results show that failure probability of the system is 5.62×10-4, and the identified pivotal factors affecting the system failures are welds leakage failures of thimbles and common cause failure of two groups valves of freeze valve. The optimization methods based on results of fault tree analysis can significantly reduce the system failure probability.ConclusionsThis study provides reference value for design and engineering application of the core fuel salt emergency drain system for MSRs