658 research outputs found

    Temporal Trends and Variability of Daily Maximum and Minimum, Extreme Temperature Events, and Growing Season Length Over the Eastern and Central Tibetan Plateau During 1961–2003

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    Daily and monthly maximum and minimum surface air temperatures at 66 weather stations over the eastern and central Tibetan Plateau with elevations above 2000 m were analyzed for temporal trends and spatial variation patterns during the period 1961–2003. Statistically significant warming trends were identified in various measures of the temperature regime, such as temperatures of extreme events and diurnal temperature range. The warming trends in winter nighttime temperatures were among the highest when compared with other regions. We also confirmed the asymmetric pattern of greater warming trends in minimum or nighttime temperatures as compared to the daytime temperatures. The warming in regional climate caused the number of frost days to decrease significantly and the number of warm days to increase. The length of the growing season increased by approximately 17 days during the 43-year study period. Most of the record-setting months for cold events were found in the earlier part of the study period, while that of the warm events occurred mostly in the later half, especially since the 1990s. The changes in the temperature regime in this region may have brought regional-specific impacts on the ecosystems. It was found that grain production in Qinghai Province, located in the area of prominent warming trends, exhibited strong correlations with the temperatures, although such relationships were obscured by the influence of precipitation in this arid/semiarid environment in juniper tree ring records. In western Sichuan Province under a more humid environment, the tree growth (spruces) was more closely related to the changing temperatures

    FFA-Net: Feature Fusion Attention Network for Single Image Dehazing

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    In this paper, we propose an end-to-end feature fusion at-tention network (FFA-Net) to directly restore the haze-free image. The FFA-Net architecture consists of three key components: 1) A novel Feature Attention (FA) module combines Channel Attention with Pixel Attention mechanism, considering that different channel-wise features contain totally different weighted information and haze distribution is uneven on the different image pixels. FA treats different features and pixels unequally, which provides additional flexibility in dealing with different types of information, expanding the representational ability of CNNs. 2) A basic block structure consists of Local Residual Learning and Feature Attention, Local Residual Learning allowing the less important information such as thin haze region or low-frequency to be bypassed through multiple local residual connections, let main network architecture focus on more effective information. 3) An Attention-based different levels Feature Fusion (FFA) structure, the feature weights are adaptively learned from the Feature Attention (FA) module, giving more weight to important features. This structure can also retain the information of shallow layers and pass it into deep layers. The experimental results demonstrate that our proposed FFA-Net surpasses previous state-of-the-art single image dehazing methods by a very large margin both quantitatively and qualitatively, boosting the best published PSNR metric from 30.23db to 36.39db on the SOTS indoor test dataset. Code has been made available at GitHub.Comment: Accepted by AAAI202

    Performance Analysis of MDMA-Based Cooperative MRC Networks with Relays in Dissimilar Rayleigh Fading Channels

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    Multiple access technology is a key technology in various generations of wireless communication systems. As a potential multiple access technology for the next generation wireless communication systems, model division multiple access (MDMA) technology improves spectrum efficiency and feasibility regions. This implies that the MDMA scheme can achieve greater performance gains compared to traditional schemes. Relayassisted cooperative networks, as a infrastructure of wireless communication, can effectively utilize resources and improve performance when MDMA is applied. In this paper, a communication relay cooperative network based on MDMA in dissimilar rayleigh fading channels is proposed, which consists of two source nodes, any number of decode-and-forward (DF) relay nodes, and one destination node, as well as using the maximal ratio combining (MRC) at the destination to combine the signals received from the source and relays. By applying the state transition matrix (STM) and moment generating function (MGF), closed-form analytical solutions for outage probability and resource utilization efficiency are derived. Theoretical and simulation results are conducted to verify the validity of the theoretical analysis.Comment: 6 pages, 4 figures, conferenc

    Transcriptome analysis to identify genes involved in lignan, sesquiterpenoid and triterpenoid biosynthesis in medicinal plant Kadsura heteroclita

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    Stems and roots of Kadsura plant species were the significant ingredients of traditional Chinese medicine. Kadsura heteroclita is one of the popular medicinal plants used in Tujia and Yao nationalities of China. Antioxidant compounds like lignan, sesquiterpenoid and triterpenoid are the major active components of K. hetroclita. Mass cultivation and bio-manufacturing strategies were being proposed to meet the increasing demand of Kadsura species plant parts. Therefore, it is important to reveal the molecular networks involved in biosynthesis of these highly efficient medicinal compounds. Here, transcriptomes of roots, stems and leaves in K. heteroclite seedling were sequenced by Hiseq2000 and unigenes involved in biosynthesis of lignan, sesquiterpenoid and triterpenoid biosynthesis were mined. As a result, 472 million clean reads were obtained which after aligning resulted in 160,248 transcripts and 98,005 genes. 191 and 279 unigenes were expected to be involved in biosynthesis of lignan, sesquiterpenoid and triterpenoid biosynthetic pathways respectively. Lignan, sesquiterpenoid and triterpenoid biosynthesis pathway genes were highly significant and differentially upregulated in roots and stems and downregulated in leaves. Also, genes encoding for MYB and bHLH transcription factors possibly involved in regulation of lignan, sesquiterpenoid and triterpenoid biosynthesis were discovered. These results provide the fundamental genomic resources for dissecting of biosynthetic pathways of the active components in K. hetroclita
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