In this paper, the spaceborne wide-area surveillance ground moving target indication (WAS-GMTI) mode is proposed. In the proposed mode, the requirement of detecting targets from different aspect angles with a high revisit rate can be achieved by modifying the TOPS mode which steers antenna in the azimuth direction. And a three-channel system is chosen to achieve fine GMTI performance. With the three-channel system, the detection of moving targets is realized by displaced phase center antenna (DPCA) technique and the motion parameter is estimated using the interferometric phase. The feasibility of the proposed mode as well as the performance of GMTI is validated by theoretical analysis and simulation experiments.
Ambiguity phenomenon appears in all spaceborne SAR, and degrades their image qualities. Ambiguity to signal ratio(ASR) is an important parameter for evaluating the performance of spaceborne SAR system. Accurate ASR estimate is essential for system design. In conventional ambiguity analysis methods, the antenna gain of ambiguity signal just is considered in two main section planes of the pattern. It results in computation error. This paper proposes a precise ambiguity analysis method. It starts off by analyzing ambiguity principium, and considers accurate ambiguity position in three dimensions antenna pattern and pattern change with time and scanning angle. Besides, the method adequately considers the ambiguity position change with PRF. So, it adapts to the new SAR mode with varying PRF, such as staggered SAR.
Abstract The objective of the study is to evaluate the protective effects of human mesenchymal stem cells (hMSCs) modified with miR‐138‐5p inhibitor against the allergic rhinitis and asthma syndrome (ARAS). MiR‐138‐5p or negative control was transfected into hMSCs, and fluorescence‐activated cell sorting was used to evaluate hMSC surface markers. Quantitative real‐time PCR (qRT‐PCR) was used to evaluate miR‐138‐5p, SIRT1 , caspase‐3, IL‐6, IL‐1β and TNF‐α levels after TNF‐α and IL‐6 stimulations. hMSCs with or without miR‐138‐5p inhibition was intranasally administered into ARAS mice (n = 10 each group), followed by monitoring sneezing and nasal rubbing events to evaluate the allergic symptoms. Histamine, ovalbumin‐specific IgE, IgG2a, IgG1 and LTC4 release were monitored in the serum and nasal lavage fluid using enzyme‐linked immunosorbent assay. Expression of SIRT1 and HMGB1/TLR4 pathway in nasal mucosa was assessed. After miR‐138‐5p inhibitor transfection, the hMSC lineage was preserved. Binding between SIRT1 and miR‐138‐4p was observed, and miR‐138‐5p inhibition led to upregulation of SIRT1 . Inhibition of miR‐138‐5p led to attenuated inflammatory responses of hMSCs upon TNF‐α and IL‐6 stimulation, and allergic symptoms in mice, as well as histamine and ovalbumin‐specific IgG release. hMSCs with miR‐138‐5p inhibition showed characteristics of activated SIRT1 and inhibited HMGB1/TLR4 pathway. Inhibition of miR‐138‐5p in hMSCs enhanced its effects in attenuating inflammatory responses and allergic reaction in the ARAS model, which is presumably regulated by SIRT1 and the HMGB1/TLR4 pathway.
Nitro-oleic acid (OA-NO2), acting as anti-inflammatory signaling mediators, are involved in multiple signaling pathways. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is well known as a cardiovascular risk biomarker. Our results showed that OA-NO2 downregulated the expression of Lp-PLA2 in a time- and dose-dependent manner, whereas native OA had no such effect. Furthermore, OA-NO2 could repress Lp-PLA2 expression in the peripheral blood mononuclear cells of apo CIII-transgenic (apo CIII TG) pigs, which exhibited higher Lp-PLA2 expression and activity than did wild-type (WT) pigs. OA-NO2 inhibited Lp-PLA2 expression in macrophages, independent of nitric oxide formation and PPARγ-activation. However, OA-NO2 downregulates Lp-PLA2 by inhibiting the p42/p44 mitogen-activated protein kinase (MAPK) and the nuclear factor κB (NFκB) pathways. When used to mediate anti-inflammatory signaling, the regulation of inflammatory cytokines and SOD by OA-NO2 might be associated with the reduction of Lp-PLA2. These results suggested that OA-NO2 might exert a vascular-protective effect partially via Lp-PLA2 inhibition.
Optical imaging satellite constellation (OISC) can provide imagery products with optimized coverage performance and high temporal resolution than single satellite, and is widely used in target detecting and analysis. People highly concerns with the performance in target identification of OISC during observation missions, so it is necessary to evaluate the target characteristics (TC) detecting capability of satellite constellation. Based on Analytic Hierarchy Process (AHP), a detection capability evaluation method for OISC is presented in terms of TC in this paper. A hierarchical structure is established to demonstrate the affiliation of indexes concerned with TC and capability of OISC. After that, weight coefficient of each index is computed using AHP. Moreover, we put forward quantitative method to normalize performance indexes of OISC, and calculate the evaluation result by linear-weighted summation method. At last, Jilin-1 Constellation, Zhuhai-1 Constellation, etc., are evaluated with the method to test its feasibility.
The M-learning has brought significant opportunities and challenges for higher education.By analyzing on the relationship between M-learning and traditional teaching as well as adopting the Elements of Information Theory course as a study case, this paper investigated the methods to retrieve the fragmented knowledge units from the fundamental theoretical knowledge architecture which can be displayed by the microlectures.Furthermore, a classroom-game is designed to explore the influence of gamificaiton on traditional teaching.The results show that the M-learning and gamification greatly improve the education effects.
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