678 research outputs found

    Unified Gas-kinetic Wave-Particle Methods III: Multiscale Photon Transport

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    In this paper, we extend the unified gas-kinetic wave-particle (UGKWP) method to the multiscale photon transport. In this method, the photon free streaming and scattering processes are treated in an un-splitting way. The duality descriptions, namely the simulation particle and distribution function, are utilized to describe the photon. By accurately recovering the governing equations of the unified gas-kinetic scheme (UGKS), the UGKWP preserves the multiscale dynamics of photon transport from optically thin to optically thick regime. In the optically thin regime, the UGKWP becomes a Monte Carlo type particle tracking method, while in the optically thick regime, the UGKWP becomes a diffusion equation solver. The local photon dynamics of the UGKWP, as well as the proportion of wave-described and particle-described photons are automatically adapted according to the numerical resolution and transport regime. Compared to the SnS_n -type UGKS, the UGKWP requires less memory cost and does not suffer ray effect. Compared to the implicit Monte Carlo (IMC) method, the statistical noise of UGKWP is greatly reduced and computational efficiency is significantly improved in the optically thick regime. Several numerical examples covering all transport regimes from the optically thin to optically thick are computed to validate the accuracy and efficiency of the UGKWP method. In comparison to the SnS_n -type UGKS and IMC method, the UGKWP method may have several-order-of-magnitude reduction in computational cost and memory requirement in solving some multsicale transport problems.Comment: 27 pages, 15 figures. arXiv admin note: text overlap with arXiv:1810.0598

    Livelihood adaptation and life satisfaction among land-lost farmers: Critiquing China’s urbanisation-driven land appropriation

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    Large-scale rural land appropriation and displacement, driven by the unprecedented urban growth currently experienced in China, has created millions of land-lost peasants who live in the city but remain culturally, socially and institutionally rural. The situation has attracted growing attention in the literature because of its negative social impact, but relatively few studies have addressed how land-lost farmers adapt to urban ways of life and what factors influence their life satisfaction. In this paper, we investigate the predictors of livelihood adaptation and life satisfaction of land-lost farmers from a land appropriation case in the city of Changchun, Northeast China. The results show that, five years after the  appropriation, livelihood adaptation remained very difficult and life satisfaction was poor among the resettlers. Furthermore, marginalised groups, such as those  who were older, less educated and from smaller families, and those with lower pre-displacement income were less likely to have a higher income level after resettlement, resulting in a lower level of life satisfaction. Women also had lower life satisfaction than men. The study highlights an urgent need to improve China’s unjust land appropriation policy with a particular focus on attending to the needs of marginalised groups

    A Novel Web Page Filtering System by Combining Texts and Images

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    With the rapid development of the Internet, people benefit much from the sharing of information. Meanwhile, the WWW era is a double-edged sword which spreads harmful and erotic content widely. In this paper, a new statistical approach has been exploited by combining the results of two or more different classification methods using our filtering system. We first briefly introduce the classification of discrete texts, continuous texts and images separately, and then describe the specific way we have been exploring to merge the text and image classification result. Also there is a section illustrating our system framework. Finally we assess our method by demon-strating the experimental results and comparing it to some common-used filtering methods

    Polyketides From the Endophytic Fungus Cladosporium sp. Isolated From the Mangrove Plant Excoecaria agallocha

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    Five new polyketides (2–6) and ten known compounds (1 and 7–15) were obtained from the fermentation products of the endophytic fungus Cladosporium sp. OUCMDZ-302 with the mangrove plant, Excoecaria agallocha (Euphorbiaceae). The new structures of 2–6 were established on the basis of ECD, specific rotation and spectroscopic data as well as the chemical calculation. Compound 7 showed cytotoxicity against H1975 cell line with an IC50 value of 10.0 μM. Compounds 4 and 8–10 showed radical scavenging activity against DPPH with the IC50 values of 2.65, 0.24, 5.66, and 6.67 μM, respectively. In addition, the absolute configuration of compound 1 was solidly determined by X-ray and sugar analysis of the acidic hydrolysates for the first time as well as those of compounds 8–10 in this paper

    Spectrum of malignancies among the population of adults living with HIV infection in China: A nationwide follow-up study, 2008-2011.

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    BackgroundAlthough increasingly studied in high-income countries, there is a paucity of data from the Chinese population on the patterns of cancer among people living with HIV (PLHIV).MethodsWe conducted a nationwide follow-up study using routinely collected data for adult PLHIV diagnosed on or before 31 December 2011 and alive and in care as of 1 January 2008. Participants were observed from 1 January 2008 (study start) to 30 June 2012 (study end). Main outcome measures were gender-stratified age-standardized incidence rates for China (ASIRC) and standardized incidence ratios (SIR) for all malignancy types/sites observed.ResultsAmong 399,451 subjects, a majority was aged 30-44 years (49.3%), male (69.8%), and Han Chinese (67.9%). A total of 3,819 reports of cancer were identified. Overall, ASIRC was 776.4 per 100,000 for males and 486.5 per 100,000 for females. Malignancy sites/types with highest ASIRC among males were lung (226.0 per 100,000), liver (145.7 per 100,000), and lymphoma (63.1 per 100,000), and among females were lung (66.8 per 100,000), lymphoma (48.0 per 100,000), stomach (47.8 per 100,000), and cervix (47.6 per 100,000). Overall SIR for males was 3.4 and for females was 2.6. Highest SIR was observed for Kaposi sarcoma (2,639.8 for males, 1,593.5 for females) and lymphoma (13.9 for males, 16.0 for females).ConclusionsThese results provide evidence of substantial AIDS-defining and non-AIDS-defining cancer burden among adult Chinese PLHIV between 2008 and 2011. Although further study is warranted, China should take action to improve cancer screening, diagnosis, and treatment for this vulnerable population

    Research on customer relational bonds, affective commitment and payment intention for online education platform of traditional culture Based on the moderation of cultural identity

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    This study focuses on the online education platform of traditional culture, a new product of the Internet era. At present, the traditional culture online education platform is facing many difficulties and challenges. Its poor market performance and poor retention of the industry’s overall users are difficult to solve, which has aroused the common concern of the industry and academia. The existing research on online education platform is mainly based on Technology Acceptance Model and motivation theory to explore the influence of platform attribute and platform content on consumer perception. It explores the use behavior of online education users from the perspective of “technology use”, but ignores the “virtual community” attribute of online education platform. Therefore, based on social exchange theory, combined with the “virtual community” attribute of traditional culture online education platform, this paper uses the theoretical framework of relationship bond affective commitment payment willingness to explore the influencing factors of users’ payment intention for traditional culture online education platform. According to the characteristics of traditional culture online education platform user groups, this study also introduces cultural identity as a potential moderator, trying to improve the theoretical framework more systematically. All the above variables were measured by the maturity scale developed by previous scholars. The research model established in this paper can provide a new perspective for the traditional culture online education platform industry to promote users’ payment intention, and also provide a basic framework for future research in the field of traditional cultural online education. In order to verify the hypotheses, this study will use the judgment sampling method to collect 655 questionnaires from the existing individual user groups of relevant online platforms, and use SPSS and Amos statistical software for empirical analysis

    Narrative Cartography with Knowledge Graphs

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    Narrative cartography is a discipline which studies the interwoven nature of stories and maps. However, conventional geovisualization techniques of narratives often encounter several prominent challenges, including the data acquisition & integration challenge and the semantic challenge. To tackle these challenges, in this paper, we propose the idea of narrative cartography with knowledge graphs (KGs). Firstly, to tackle the data acquisition & integration challenge, we develop a set of KG-based GeoEnrichment toolboxes to allow users to search and retrieve relevant data from integrated cross-domain knowledge graphs for narrative mapping from within a GISystem. With the help of this tool, the retrieved data from KGs are directly materialized in a GIS format which is ready for spatial analysis and mapping. Two use cases — Magellan’s expedition and World War II — are presented to show the effectiveness of this approach. In the meantime, several limitations are identified from this approach, such as data incompleteness, semantic incompatibility, and the semantic challenge in geovisualization. For the later two limitations, we propose a modular ontology for narrative cartography, which formalizes both the map content (Map Content Module) and the geovisualization process (Cartography Module). We demonstrate that, by representing both the map content and the geovisualization process in KGs (an ontology), we can realize both data reusability and map reproducibility for narrative cartography
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