The Re-nonnegative definite solutions to the matrix equation AXB=CAXB=C

summary:An $n\times n$ complex matrix $A$ is called Re-nonnegative definite (Re-nnd) if the real part of $x^{\ast } Ax$ is nonnegative for every complex $n$-vector $x$. In this paper criteria for a partitioned matrix to be Re-nnd are given. A necessary and sufficient condition for the existence of and an expression for the Re-nnd solutions of the matrix equation $AXB=C$ are presented

Development Process, Quantitative Models, and Future Directions in Driving Analysis of Urban Expansion

Driving analysis of urban expansion (DAUE) is usually implemented to identify the driving factors and their corresponding driving effects/mechanisms for the expansion processes of urban land, aiming to provide scientific guidance for urban planning and management. Based on a thorough analysis and summarization of the development process and quantitative models, four major limitations in existing DAUE studies have been uncovered: (1) the interactions in hierarchical urban systems have not been fully explored; (2) the employed data cannot fully depict urban dynamic through finer social perspectives; (3) the employed models cannot deal with high-level feature correlations; and (4) the simulation and analysis models are still not intrinsically integrated. Four future directions are thus proposed: (1) to pay attention to the hierarchical characteristics of urban systems and conduct multi-scale research on the complex interactions within them to capture dynamic features; (2) to leverage remote sensing data so as to obtain diverse urban expansion data and assimilate multi-source spatiotemporal big data to supplement novel socio-economic driving factors; (3) to integrate with interpretable data-driven machine learning techniques to bolster the performance and reliability of DAUE models; and (4) to construct mechanism-coupled urban simulation to achieve a complementary enhancement and facilitate theory development and testing for urban land systems

Detection of QTLs for panicle-related traits using an indica × japonica recombinant inbred line population in rice

Background The panicle is the most important organ in rice, and all the panicle-related traits are correlated with rice grain yield. Understanding the underlying genetic mechanisms controlling panicle development is very important for improving rice production. Methods Nine panicle-related traits including heading date, panicle length, number of primary branches, number of secondary branches, number of grains per panicle, number of panicles per plant, number of filled grains per plant, seed-setting rate, and grain yield per plant were investigated. To map the quantitative trait loci (QTLs) for the nine panicle-related traits, a PCR-based genetic map with 208 markers (including 121 simple sequence repeats and 87 InDels) and a high-density linkage map with 18,194 single nucleotide polymorphism (SNP) markers were both used. Results Using a recombinant inbred line population derived from an indica variety Huanghuazhan and a japonica line Jizi 1560, a total of 110 and 112 QTLs were detected for panicle-related traits by PCR-based genetic map and by high-density linkage map, respectively. Most of the QTLs were clustered on chromosomes 1, 2, 3, 6, and 7 while no QTLs were detected on chromosome 10. Almost all the QTLs with LOD values of more than 5.0 were repeatedly detected, indicating the accuracy of the two methods and the stability of the QTL effects. No genes for panicle-related traits have been previously reported in most of these regions. QTLs found in JD1006–JD1007 and RM1148–RM5556 with high LOD and additive values deserved further research. The results of this study are beneficial for marker-assisted breeding and provide research foundation for further fine-mapping and cloning of these QTLs for panicle-related traits

Retrieval of 500 m Aerosol Optical Depths from MODIS Measurements over Urban Surfaces under Heavy Aerosol Loading Conditions in Winter

International audienceModerate Resolution Imaging Spectroradiometer (MODIS) aerosol products are used worldwide for their reliable accuracy. However, the aerosol optical depth (AOD) usually retrieved by the operational dark target (DT) algorithm of MODIS has been missing for most of the urban regions in Central China. This was due to a high surface reflectance and heavy aerosol loading, especially in winter, when a high cloud cover fraction and the frequent occurrence of haze events reduce the number of effective satellite observations. The retrieval of the AOD from limited satellite data is much needed and important for further aerosol investigations. In this paper, we propose an improved AOD retrieval method for 500 m MODIS data, which is based on an extended surface reflectance estimation scheme and dynamic aerosol models derived from ground-based sun-photometric observations. This improved method was applied to retrieve AOD during heavy aerosol loading and effectively complements the scarcity of AOD in correspondence with urban surface of a higher spatial resolution. The validation results showed that the retrieved AOD was consistent with MODIS DT AOD (R =~0.87; RMSE =~0.11) and ground measurements (R =~0.89; RMSE =~0.15) from both the Terra and the Aqua satellite. The method can be easily applied to different urban environments affected by air pollution and contributes to the research on aerosol

Pharmacokinetics and Biodistribution of Aurantiamide and Aurantiamide Acetate in Rats after Oral Administration of Portulaca oleracea L. Extracts

Aurantiamide and aurantiamide acetate are the main active constituents of purslane (Portulaca oleracea L.), an edible plant with various biological activities. In this study, we developed a validated UHPLC-MS/MS method to quantitate the concentrations of aurantiamide and aurantiamide acetate in the plasma and various organ tissues of rat as the basis to study their pharmacological profile and distribution in vivo. Aurantiamide and aurantiamide acetate were rapidly absorbed following oral administration, both achieving a <i>C</i>_max at around 0.2 h. The extent of their metabolisms also varied among different organ tissues, resulting in about 90% reduction in concentrations 4 h after their administration, thus leaving no long-term accumulation in the tissues. This is the first study to examine the pharmacokinetic and biodistribution of aurantiamide and aurantiamide acetate in rat, and our work may serve as the first step toward the investigation of the underlying mechanisms associated with the biological activity of purslane

Pharmacokinetics and Biodistribution of Aurantiamide and Aurantiamide Acetate in Rats after Oral Administration of Portulaca oleracea L. Extracts

Aurantiamide and aurantiamide acetate are the main active constituents of purslane (Portulaca oleracea L.), an edible plant with various biological activities. In this study, we developed a validated UHPLC-MS/MS method to quantitate the concentrations of aurantiamide and aurantiamide acetate in the plasma and various organ tissues of rat as the basis to study their pharmacological profile and distribution in vivo. Aurantiamide and aurantiamide acetate were rapidly absorbed following oral administration, both achieving a <i>C</i>_max at around 0.2 h. The extent of their metabolisms also varied among different organ tissues, resulting in about 90% reduction in concentrations 4 h after their administration, thus leaving no long-term accumulation in the tissues. This is the first study to examine the pharmacokinetic and biodistribution of aurantiamide and aurantiamide acetate in rat, and our work may serve as the first step toward the investigation of the underlying mechanisms associated with the biological activity of purslane

Human malignant melanoma-derived progestagen-associated endometrial protein immunosuppresses T lymphocytes in vitro.

Progestagen-associated endometrial protein (PAEP) is a glycoprotein of the lipocalin family that acts as a negative regulator of T cell receptor-mediated activation. However, the function of tumor-derived PAEP on the human immune system in the tumor microenvironment is unknown. PAEP is highly expressed in intermediate and thick primary melanomas (Breslow's 2.5mm or greater) and metastatic melanomas, correlating with its expression in daughter cell lines established in vitro. The current study investigates the role of melanoma cell-secreted PAEP protein in regulating T cell function. Upon the enrichment of CD3+, CD4+ and CD8+ T cells from human peripheral blood mononuclear cells, each subset was then mixed with either melanoma-derived PAEP protein or PAEP-poor supernatant of gene-silenced tumor cells. IL-2 and IFN-γ secretion of CD4+ T cells significantly decreased with the addition of PAEP-rich supernatant. And the addition of PAEP-positive cell supernatant to activated lymphocytes significantly inhibited lymphocyte proliferation and cytotoxic T cell activity, while increasing lymphocyte apoptosis. Our result suggests that melanoma cell-secreted PAEP protein immunosuppresses the activation, proliferation and cytotoxicity of T lymphocytes, which might partially explain the mechanism of immune tolerance induced by melanoma cells within the tumor microenvironment

Using RNA-seq to Profile Gene Expression of Spikelet Development in Response to Temperature and Nitrogen during Meiosis in Rice (Oryza sativa L.).

Rice reproductive development is sensitive to high temperature and soil nitrogen supply, both of which are predicted to be increased threats to rice crop yield. Rice spikelet development is a critical process that determines yield, yet little is known about the transcriptional regulation of rice spikelet development in response to the combination of heat stress and low nitrogen availability. Here, we profiled gene expression of rice spikelet development during meiosis under heat stress and different nitrogen levels using RNA-seq. We subjected plants to four treatments: 1) NN: normal nitrogen level (165 kg ha-1) with normal temperature (30°C); 2) HH: high nitrogen level (264 kg ha-1) with high temperature (37°C); 3) NH: normal nitrogen level and high temperature; and 4) HN: high nitrogen level and normal temperature. The de novo transcriptome assembly resulted in 52,250,482 clean reads aligned with 76,103 unigenes, which were then used to compare differentially expressed genes (DEGs) in the different treatments. Comparing gene expression in samples with the same nitrogen levels but different temperatures, we identified 70 temperature-responsive DEGs in normal nitrogen levels (NN vs NH) and 135 DEGs in high nitrogen levels (HN vs HH), with 27 overlapping DEGs. We identified 17 and seven nitrogen-responsive DEGs by comparing changes in nitrogen levels in lower temperature (NN vs HN) and higher temperature (NH vs HH), with one common DEG. The temperature-responsive genes were principally associated with cytochrome, heat shock protein, peroxidase, and ubiquitin, while the nitrogen-responsive genes were mainly involved in glutamine synthetase, amino acid transporter, pollen development, and plant hormone. Rice spikelet fertility was significantly reduced under high temperature, but less reduced under high-nitrogen treatment. In the high temperature treatments, we observed downregulation of genes involved in spikelet development, such as pollen tube growth, pollen maturation, especially sporopollenin biosynthetic process, and pollen exine formation. Moreover, we observed higher expression levels of the co-expressed DEGs in HN vs HH compared to NN vs NH. These included the six downregulated genes (one pollen maturation and five pollen exine formation genes), as well as the four upregulated DEGs in response to heat. This suggests that high-nitrogen treatment may enhance the gene expression levels to mitigate aspects of heat-stress. The spikelet genes identified in this study may play important roles in response to the combined effects of high temperature and high nitrogen, and may serve as candidates for crop improvement