The genome of hibiscus hamabo reveals its adaptation to saline and waterlogged habitat

Hibiscus hamabo is a semi-mangrove species with strong tolerance to salt and waterlogging stress. However, the molecular basis and mechanisms that underlie this strong adaptability to harsh environments remain poorly understood. Here, we assembled a high-quality, chromosome-level genome of this semi-mangrove plant and analyzed its transcriptome under different stress treatments to reveal regulatory responses and mechanisms. Our analyses suggested that H. hamabo has undergone two recent successive polyploidy events, a whole-genome duplication followed by a whole-genome triplication, resulting in an unusually large gene number (107 309 genes). Comparison of the H. hamabo genome with that of its close relative Hibiscus cannabinus, which has not experienced a recent WGT, indicated that genes associated with high stress resistance have been preferentially preserved in the H. hamabo genome, suggesting an underlying association between polyploidy and stronger stress resistance. Transcriptomic data indicated that genes in the roots and leaves responded differently to stress. In roots, genes that regulate ion channels involved in biosynthetic and metabolic processes responded quickly to adjust the ion concentration and provide metabolic products to protect root cells, whereas no such rapid response was observed from genes in leaves. Using co-expression networks, potential stress resistance genes were identified for use in future functional investigations. The genome sequence, along with several transcriptome datasets, provide insights into genome evolution and the mechanism of salt and waterlogging tolerance in H. hamabo, suggesting the importance of polyploidization for environmental adaptation.DATA AVAILABILITY: The data supporting the findings of this work are available within the paper and its Supporting Information files. The data sets generated and analyzed during this study are available from the corresponding author upon request. All the whole-genome raw data generated during this study have been deposited in the SRA database under BioProject number PRJNA759075. Transcriptome clean data have been deposited in the SRA database under BioProject number PRJNA759717. The final chromosome-scale genome assembly and annotation data have been deposited in the Figshare database (https://doi.org/10.6084/m9.figshare.19142558.v1).Six Talent Peaks Project of Jiangsu Province (NY-042); Open Fund of the Jiangsu Key Laboratory for the Research and Utilization of Plant Resources (JSPKLB201928); Talent Training Funds of the Institute of Botany, Jiangsu Province and Chinese Academy of Sciences.https://academic.oup.com/hrBiochemistryGeneticsMicrobiology and Plant Patholog

Dynamic portfolio optimization with credit risk

Credit risk, which considers the risk of loss resulting from a counterparty's failure to meet contractual obligations, was not properly studied in the literature of dynamic portfolio optimization problem until the 2008-2009 financial crisis. This thesis is devoted to the dynamic portfolio optimization with credit risk. Two main topics are studied in this thesis. In the first topic, we consider a utility maximization problem with defaultable stocks and looping contagion risk. We assume that the default intensity of one company depends on the stock prices of itself and other companies, and the default of the company induces immediate drops in the stock prices of the surviving companies. Under such looping contagion risk framework, we prove that the value function is the unique viscosity solution of the HJB equation. We also perform some numerical tests to compare and analyse the statistical distributions of the terminal wealth of log utility and power utility based on two strategies, one using the full information of intensity process and the other a proxy constant intensity process. The numerical tests confirm that modeling looping contagion risk properly is important, especially in financial distressed period. The second topic is on dynamic portfolio optimization with contingent convertible (CoCo) bond. As a new type of hybrid product, CoCo bond has the interesting feature that converting from debt to equity is contingent. We model the conversion of CoCo bond by reduced-form approach and assume that the conversion intensity is a deterministic function of the coupon rate and the issuing bank's stock price. Theoretically, we construct the viscosity solution representation between the value function and the corresponding HJB equation. Practically, we compare the performance between investing into CoCo bond and the issuing bank's stock. We analyse the statistical distributions of terminal wealth of log utility and power utility based on these two investment choices. Our simulation results show that, the CoCo bond holders bear more loss than equity holders if conversion occurs. However, investing into CoCo bond gets more profit (mean) while bearing less market risk (volatility) as long as conversion does not occur.Open Acces

Why should we invest in CoCos than stocks? An optimal growth portfolio approach

We investigate an optimal growth portfolio problem with contingent convertible bonds (CoCos). As the conversion risk in CoCos is closely associated with the issuer's capital structure and the stock price at conversion, we model both equity and credit risk to frame this optimisation problem. This study aims to answer two questions that (i) how investors should optimally allocate their financial wealth between a CoCo and a risk-free bond; and (ii) which approach ??? investing in a CoCo or in a stock issued by the same bank ??? could result in higher expected returns. First, we derive the dynamic of a coupon-paying CoCo price under a reduced-form approach. We then decompose the problem into pre- and post-conversion regimes to obtain closed-form optimal strategies. A comparative simulation leads us to conclude that, under various market conditions, investing in a CoCo with a risk-free bond provides a higher expected growth than investing in stock

Correction: Luo et al. The Effects of Different Anode Positions on the Electrical Properties of Square-Silicon Drift Detector. <i>Micromachines</i> 2022, <i>13</i>, 1496

In the original publication [...

The Effects of Different Anode Positions on the Electrical Properties of Square-Silicon Drift Detector

The Silicon Drift Detector (SDD) with square structure is often used in pixel-type SDD arrays to reduce the dead region considerably and to improve the detector performance significantly. Usually, the anode is located in the center of the active region of the SDD with square structure (square-SDD), but the different anode positions in the square-SDD active area are also allowed. In order to explore the effect on device performance when the anode is located at different positions in the square-SDD active region, we designed two different types of square-SDD in this work, where the anode is located either in the center (SDD-1) or at the edge (SDD-2) of its active region. The simulation results of current density and potential distribution show that SDD-1 and SDD-2 have both formed a good electron drift path to make the anode collect electrons. The experimental results of device performance at the temperature range from &minus;60 &deg;C to 60 &deg;C show that the anode current of the two fabricated SDDs both decreased with the decrease of temperature, but their voltage divider characteristics exhibited high stability resistance value and low temperature coefficient, thereby indicating that they could both provide corresponding continuous and uniform electric field at different temperatures. Finally, SDD-1 and SDD-2 have energy resolutions of 248 and 257 eV corresponding to the 5.9 keV photon peak of the Fe-55 radioactive source, respectively. Our experimental results demonstrate that there is no significant impact on the device performance irrespective of the anode positions in the square-SDD devices

Simulation of Silicon Surface Barrier Detector with PN Junction Guard Rings to Improve the Breakdown Voltage

Silicon surface barrier detectors (SSBDs) are normally used to detect high-energy particles due to their excellent properties. For better charge collection efficiency (CCE), the SSBD device should be operated at higher reverse voltages, but this can lead to device breakdown. Therefore, we used a PN junction as a guard ring to increase the breakdown voltage of the SSBD. The structures of two SSBD devices are drawn and simulated in this work. Compared with a conventional SSBD (c-SSBD), the use of a PN junction as a guard ring for an SSBD (Hybrid-SSBD) achieves higher breakdown voltages, of over 1500 V under reverse bias. This means that Hybrid-SSBD devices can operate at higher reverse voltages for better charge collection efficiency (CCE) to detect high-energy particles. Then, we simulated the different structure parameters of the Hybrid-SSBD guard rings. Among them, the doping depth and gap width of the guard ring (between the innermost guard ring and the active area) have a greater impact on the breakdown voltage. Finally, for Hybrid-SSBD devices, the optimal characteristics of the guard ring were 1 &times; 1019 cm&minus;3 doping concentration, 1 &mu;m doping depth, and innermost guard ring width and gap width of 5 &mu;m and 3 &mu;m, respectively

The genome of Hibiscus hamabo reveals its adaptation to saline and waterlogged habitat

Hibiscus hamabo is a semi-mangrove species with strong tolerance to salt and waterlogging stress. However, the molecular basis and mechanisms that underlie this strong adaptability to harsh environments remain poorly understood. Here, we assembled a high-quality, chromosome-level genome of this semi-mangrove plant and analyzed its transcriptome under different stress treatments to reveal regulatory responses and mechanisms. Our analyses suggested that H. hamabo has undergone two recent successive polyploidy events, a whole-genome duplication followed by a whole-genome triplication, resulting in an unusually large gene number (107 309 genes). Comparison of the H. hamabo genome with that of its close relative Hibiscus cannabinus, which has not experienced a recent WGT, indicated that genes associated with high stress resistance have been preferentially preserved in the H. hamabo genome, suggesting an underlying association between polyploidy and stronger stress resistance. Transcriptomic data indicated that genes in the roots and leaves responded differently to stress. In roots, genes that regulate ion channels involved in biosynthetic and metabolic processes responded quickly to adjust the ion concentration and provide metabolic products to protect root cells, whereas no such rapid response was observed from genes in leaves. Using co-expression networks, potential stress resistance genes were identified for use in future functional investigations. The genome sequence, along with several transcriptome datasets, provide insights into genome evolution and the mechanism of salt and waterlogging tolerance in H. hamabo, suggesting the importance of polyploidization for environmental adaptation