67 research outputs found

    Liouville-type theorem for some nonlinear systems in a half-space

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    Ultra-broadband and tunable infrared absorber based on VO2 hybrid multi-layer nanostructure

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    We propose an ultra-broadband near- to mid-infrared (NMIR) tunable absorber based on VO2 hybrid multi-layer nanostructure by hybrid integration of the upper and the lower parts. The upper part is composed of VO2 nanocylinder arrays prepared on the front illuminated surface of quartz substrate, and VO2 square films and VO2/SiO2/VO2 square nanopillar arrays prepared on the back surface. The lower part is an array of SiO2/Ti/VO2 nanopillars on Ti substrate. The effects of different structural parameters and temperature on the absorption spectra were analyzed by the finite-difference time-domain method. An average absorption rate of up to 94.7% and an ultra-wide bandwidth of 6.5 μm were achieved in NMIR 1.5–8 μm. Neither vertical incident light with different polarization angles nor large inclination incident light has a significant effect on the absorption performance of the absorber. The ultra-broadband high absorption performance of this absorber will be widely used in NMIR photodetectors and other new optoelectronic devices

    Integrating Node Importance and Network Topological Properties for Link Prediction in Complex Network

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    Link prediction is one of the most important and challenging tasks in complex network analysis, which aims to predict the likelihood of the existence of missing links based on the known information in the network. As critical topological properties in the network, node degree and clustering coefficient are well-suited for describing the tightness of connection between nodes. The node importance can affect the possibility of link existence to a certain extent. By analyzing the impact of different centrality on links, which concluded that the degree centrality and proximity centrality have the greatest influence on link prediction. So, a link prediction algorithm combines node importance and attribute, called DCCLP, is proposed in this paper. In the training phase of the DCCLP algorithm, the maximized AUC indicator in the training set as the objective, and the optimal parameters are estimated by utilizing the White Shark Optimization algorithm. Then the prediction accuracy of the DCCLP algorithm is evaluated in the test set. By experimenting on twenty-one networks with different scales, and comparing with existing algorithms, the experimental results show that the effectiveness and feasibility of DCCLP algorithm, and further illustrate the importance of the degree centrality of node pairs and proximity centrality of nodes to improve the prediction accuracy of link prediction

    Microbialproperty improvement of saline-alkali soil for vegetable cultivation in Shanghai coastal area and its evaluation

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    In order to improve the fertility of saline-alkali soil in Shanghai coastal area,and make it suitable for vegetable cultiration,in the study,the saline-alkali soil was mixed with organic fertilizer,and then sprayed with composite microbes,which have the ability of the synergistically degrading organic substrate.The results showed that the saline-alkali soil added with 5∶1 organic fertilizer can rapidly increase the utilization ability soil organic matter.The soil microbial populations and microbial diversity index were significantly improved when applied with the 0.5% composite microbial liquid which containeds 1∶3∶3∶1 of Bacillus licheniformis,Pseudomonas sp., Flavobacterium sp.and Sphingomonas sp..At the same time,the enzymology indicators of soil urease,phosphatase,cellulase and catalase increased significantly.The vegetable cultivation experiments showed that:the biomass of Brassica chinensis nearly doubled in the original saline-alkali soil,while the yield of organic fertilizer increased 30.2% after 50 days.The research result on of the biological improvement for saline-alkali soil will have good application value in vegetable planting in coastal saline-alkali soil

    Beating of a Spherical Liquid Crystal Elastomer Balloon under Periodic Illumination

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    Periodic excitation is a relatively simple and common active control mode. Owing to the advantages of direct access to environmental energy and controllability under periodic illumination, it enjoys broad prospects for application in soft robotics and opto-mechanical energy conversion systems. More new oscillating systems need to be excavated to meet the various application requirements. A spherical liquid crystal elastomer (LCE) balloon model driven by periodic illumination is proposed and its periodic beating is studied theoretically. Based on the existing dynamic LCE model and the ideal gas model, the governing equation of motion for the LCE balloon is established. The numerical calculations show that periodic illumination can cause periodic beating of the LCE balloon, and the beating period of the LCE balloon depends on the illumination period. For the maximum steady-state amplitude of the beating, there exists an optimum illumination period and illumination time rate. The optimal illumination period is proved to be equivalent to the natural period of balloon oscillation. The effect of system parameters on beating amplitude are also studied. The amplitude is mainly affected by light intensity, contraction coefficient, amount of gaseous substance, volume of LCE balloon, mass density, external pressure, and damping coefficient, but not the initial velocity. It is expected that the beating LCE balloon will be suitable for the design of light-powered machines including engines, prosthetic blood pumps, aircraft, and swimmers

    Abnormal event detection in crowded scenes using histogram of oriented contextual gradient descriptor

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    Abstract Detecting abnormal events in crowded scenes is an important but challenging task in computer vision. Contextual information is useful for discovering salient events in scenes; however, it cannot be characterized well by commonly used pixel-based descriptors, such as the HOG descriptor. In this paper, we propose contextual gradients between two local regions and then construct a histogram of oriented contextual gradient (HOCG) descriptor for abnormal event detection based on the contextual gradients. The HOCG descriptor is a distribution of contextual gradients of sub-regions in different directions, which can effectively characterize the compositional context of events. We conduct extensive experiments on several public datasets and compare the experimental results using state-of-the-art approaches. Qualitative and quantitative analysis of experimental results demonstrate the effectiveness of the proposed HOCG descriptor

    Isolation and Characterization of the First Temperate Virus Infecting Psychrobacillus from Marine Sediments

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    Viruses are far more abundant than cellular microorganisms in the marine ecosystem. However, very few viruses have so far been isolated from marine sediments, especially hydrothermal vent sediments, hindering the understanding of the biology and ecological functions of these tiny organisms. Here, we report the isolation and characterization of a temperate bacteriophage, named PVJ1, which infects Psychrobacillus from a hydrothermal vent field in Okinawa Trough. PVJ1 belongs to the Myoviridae family of the order Caudovirales. The tailed phage possesses a 53,187 bp linear dsDNA genome, with 84 ORFs encoding structural proteins, genome replication, host lysis, etc. in a modular pattern. The phage genome is integrated into the host chromosome near the 3′-end of deoD, a gene encoding purine nucleoside phosphorylase (PNP). The phage integration does not appear to disrupt the function of PNP. The phage DNA is packaged by the headful mechanism. Release of PVJ1 from the host cell was drastically enhanced by treatment with mitomycin C. Phages encoding an MCP sharing significant similarity (≥70% identical amino acids) with that of PVJ1 are widespread in diverse environments, including marine and freshwater sediments, soils, artificial ecosystems, and animal intestines, and primarily infect Firmicutes. These results are valuable to the understanding of the lifestyle and host interactions of bacterial viruses at the bottom of the ocean

    Epidemiology and prevalence of pulmonary sequestration in Chinese population, 2010–2019

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    Abstract Background Pulmonary sequestration (PS) is the second common congenital lung malformation and has been known for over 150 years. However, there is a scarcity of epidemiological studies on it. This study aimed to characterize the epidemiology of pulmonary sequestration in Chinese population in the recent decade by using a nationwide database. Methods Using data from the Chinese Birth Defects Monitoring Network during 2010–2019, the prevalence rates for PS were calculated by birth year, maternal age, residence area, geographical region, and infant sex. Variations in prevalence and changes over time were further examined. Other variables of interest for analysis included the pregnancy outcomes of affected infants, the prenatal diagnosis, and the co-occurring anomalies of PS cases. Results During the study period, we identified an average prevalence rate of 0.31, 0.11, and 0.42 per 10,000 live and still births for the isolated, non-isolated, and overall PS, respectively. An upward trend was observed for each category of PS. The prevalence rates varied significantly by maternal age (< 20 years, 0.34/10,000; 20–24 years, 0.33/10,000; 25–29 years, 0.45/10,000; 30–34 years, 0.46/10,000; ≥ 35 years, 0.36/10,000), residence area (urban vs. rural, 0.51/10,000 vs. 0.30/10,000), geographical region (western, 0.33/10,000; eastern, 0.49/10,000; central, 0.43/10,000), and by infant sex (male vs. female, 0.45/10,000 vs. 0.38/10,000). Non-isolated PS cases were more likely born prematurely than isolated cases (15.29% vs. 7.83%). 40.28% and 33.80% of non-isolated cases were accompanied by additional respiratory, and circulatory system malformations, respectively. Conclusions The study presents for the first time the prevalence of pulmonary sequestration in Chinese population. The rising prevalence and relatively poor perinatal outcome of affected fetuses or newborns indicate the necessity to improve perinatal management of PS

    Characterization of the relationship between APOBEC3B deletion and ACE Alu insertion.

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    The insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE), commonly associated with many diseases, is believed to have affected human adaptation to environmental changes during the out-of-Africa expansion. APOBEC3B (A3B), a member of the cytidine deaminase family APOBEC3s, also exhibits a variable gene insertion/deletion polymorphism across world populations. Using data available from published reports, we examined the global geographic distribution of ACE and A3B genotypes. In tracking the modern human dispersal routes of these two genes, we found that the variation trends of the two I/D polymorphisms were directly correlated. We observed that the frequencies of ACE insertion and A3B deletion rose in parallel along the expansion route. To investigate the presence of a correlation between the two polymorphisms and the effect of their interaction on human health, we analyzed 1199 unrelated Chinese adults to determine their genotypes and other important clinical characteristics. We discovered a significant difference between the ACE genotype/allele distribution in the A3B DD and A3B II/ID groups (P = 0.045 and 0.015, respectively), indicating that the ACE Alu I allele frequency in the former group was higher than in the latter group. No specific clinical phenotype could be associated with the interaction between the ACE and A3B I/D polymorphisms. A3B has been identified as a powerful inhibitor of Alu retrotransposition, and primate A3 genes have undergone strong positive selection (and expansion) for restricting the mobility of endogenous retrotransposons during evolution. Based on these findings, we suggest that the ACE Alu insertion was enabled (facilitated) by the A3B deletion and that functional loss of A3B provided an opportunity for enhanced human adaptability and survival in response to the environmental and climate challenges arising during the migration from Africa
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