289 research outputs found

    Drivers of Urban Sprawl in Urbanizing China – A Political Ecology Analysis

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    Chinese cities have undergone a process of urbanization that has resulted in significant urban sprawl in the past 20 years. This paper uses the \u27ecology of actors\u27 framework to analyze the interactions between various state, market and civil society players that result in excessive land conversion from agricultural to urban use. The paper shows that under the existing institutional setting, the interests of most actors involved in the process are aligned towards greater land development and growth. The more land is developed, the more land lease revenue for the local government, the more profit for developers, and the more opportunities for compensation for farmers. Planning actors have been powerless to apply long term planning principles. There is a need to change the underlying rules of the game so that environmental impacts of land conversion are fully taken into account in the future economic calculations of actors involved in the process

    Protection des Infrastructures Essentielles par Advanced Modélisation, simulation et optimisation pour l’atténuation et résilience de défaillance en cascade

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    Continuously increasing complexity and interconnectedness of modern critical infrastructures, together with increasingly complex risk environments, pose unique challenges for their secure, reliable, and efficient operation. The focus of the present dissertation is on the modelling, simulation and optimization of critical infrastructures (CIs) (e.g., power transmission networks) with respect to their vulnerability and resilience to cascading failures. This study approaches the problem by firstly modelling CIs at a fundamental level, by focusing on network topology and physical flow patterns within the CIs. A hierarchical network modelling technique is introduced for the management of system complexity. Within these modelling frameworks, advanced optimization techniques (e.g., non-dominated sorting binary differential evolution (NSBDE) algorithm) are utilized to maximize both the robustness and resilience (recovery capacity) of CIs against cascading failures. Specifically, the first problem is taken from a holistic system design perspective, i.e. some system properties, such as its topology and link capacities, are redesigned in an optimal way in order to enhance system’s capacity of resisting to systemic failures. Both topological and physical cascading failure models are applied and their corresponding results are compared. With respect to the second problem, a novel framework is proposed for optimally selecting proper recovery actions in order to maximize the capacity of the CI network of recovery from a disruptive event. A heuristic, computationally cheap optimization algorithm is proposed for the solution of the problem, by integrating foundemental concepts from network flows and project scheduling. Examples of analysis are carried out by referring to several realistic CI systems.Sans cesse croissante complexité et l'interdépendance des infrastructures critiques modernes, avec des environs de risque plus en plus complexes, posent des défis uniques pour leur exploitation sûre, fiable et efficace. L'objectif de la présente thèse est sur la modélisation, la simulation et l'optimisation des infrastructures critiques (par exemple, les réseaux de transmission de puissance) à l'égard de leur vulnérabilité et la résilience aux défaillances en cascade. Cette étude aborde le problème en modélisant infrastructures critiques à un niveau fondamental, en se concentrant sur la topologie du réseau et des modèles de flux physiques dans les infrastructures critiques. Un cadre de modélisation hiérarchique est introduit pour la gestion de la complexité du système. Au sein de ces cadres de modélisation, les techniques d'optimisation avancées (par exemple, non-dominée de tri binaire évolution différentielle (NSBDE) algorithme) sont utilisés pour maximiser à la fois la robustesse et la résilience (capacité de récupération) des infrastructures critiques contre les défaillances en cascade. Plus précisément, le premier problème est pris à partir d'un point de vue de la conception du système holistique, c'est-à-dire certaines propriétés du système, tels que ses capacités de topologie et de liaison, sont redessiné de manière optimale afin d'améliorer la capacité de résister à des défaillances systémiques de système. Les deux modèles de défaillance en cascade topologiques et physiques sont appliquées et leurs résultats correspondants sont comparés. En ce qui concerne le deuxième problème, un nouveau cadre est proposé pour la sélection optimale des mesures appropriées de récupération afin de maximiser la capacité du réseau d’infrastructure critique de récupération à partir d'un événement perturbateur. Un algorithme d'optimisation de calcul pas cher heuristique est proposé pour la solution du problème, en intégrant des concepts fondamentaux de flux de réseau et le calendrier du projet. Exemples d'analyse sont effectués en se référant à plusieurs systèmes de CI réalistes

    CPMR: Context-Aware Incremental Sequential Recommendation with Pseudo-Multi-Task Learning

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    The motivations of users to make interactions can be divided into static preference and dynamic interest. To accurately model user representations over time, recent studies in sequential recommendation utilize information propagation and evolution to mine from batches of arriving interactions. However, they ignore the fact that people are easily influenced by the recent actions of other users in the contextual scenario, and applying evolution across all historical interactions dilutes the importance of recent ones, thus failing to model the evolution of dynamic interest accurately. To address this issue, we propose a Context-Aware Pseudo-Multi-Task Recommender System (CPMR) to model the evolution in both historical and contextual scenarios by creating three representations for each user and item under different dynamics: static embedding, historical temporal states, and contextual temporal states. To dually improve the performance of temporal states evolution and incremental recommendation, we design a Pseudo-Multi-Task Learning (PMTL) paradigm by stacking the incremental single-target recommendations into one multi-target task for joint optimization. Within the PMTL paradigm, CPMR employs a shared-bottom network to conduct the evolution of temporal states across historical and contextual scenarios, as well as the fusion of them at the user-item level. In addition, CPMR incorporates one real tower for incremental predictions, and two pseudo towers dedicated to updating the respective temporal states based on new batches of interactions. Experimental results on four benchmark recommendation datasets show that CPMR consistently outperforms state-of-the-art baselines and achieves significant gains on three of them. The code is available at: https://github.com/DiMarzioBian/CPMR.Comment: Accepted by CIKM 2023. Alias: "Modeling Context-Aware Temporal Dynamics via Pseudo-Multi-Task Learning

    Preparation of magnetic chitosan corn straw biochar and its application in adsorption of amaranth dye in aqueous solution

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    In this study, the magnetic chitosan biochar (MCB) was magnetized by chemical coprecipitation after loading chitosan with Schiff base reaction. The prepared MCB was used to remove amaranth dye in solution. The synthesized MCB was characterized to define its surface morphology and specific elements. The amaranth dye adsorption system was optimized by varying the contact time, pH, and initial concentration. The adsorption of MCB on amaranth dye was measured in a wide pH range. According to Zeta potential, the surface of MCB was positively charged in the acidic pH region, which was more conducive to the adsorption of anionic amaranth dye. In addition, the adsorption data was fitted with the pseudo-first-order model and Langmuir adsorption model and the maximum adsorption capacity reached 404.18 mg/g. The adsorption efficiency of MCB was still above 95% after three cycles of adsorption and desorption. The removal percentage in the real sample of amaranth dye by MCB was within 94.5–98.6% and the RSD was within 0.14–1.08%. The MCB adsorbent with advantages of being easy to prepare, easy to separate from solution after adsorption, has good adsorption performance for amaranth dye and is effective potential adsorbent to remove organic anionic dye in wastewater

    Exploration of the use of antibiotics in a hospital based on point prevalence survey

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    Objective·To analyze the changes in the use of antibiotics in a tertiary hospital in Jiangsu Province, so as to provide reference for the improvement of antimicrobial drug management in the hospital.Methods·The point prevalence survey was conducted to investigate the usage of antibiotics and nosocomial infection of Affiliated Hospital of Xuzhou Medical University on October 16, 2019, and September 15, 2022, respectively. The related data were summarized by Excel 16.0 and analyzed by SPSS 26.0 software. The related data were described by utilization rate and constituent ratio, and χ2 test was used for comparative analysis.Results·In 2019, a total of 474 patients were enrolled and their antimicrobial utilization rate was 48.1% on the day of the survey; in 2022, a total of 484 patients were enrolled and their antimicrobial utilization rate was 33.5% on the day of the survey. Compared with 2019, the rate of antibiotic usage in hospitalized patients showed an overall downward trend in 2022. The usage rate of only one antimicrobial agent increased from 38.6% to 82.7% (χ2=75.182, P=0.000), the usage rate of double therapy decreased from 40.8% to 14.2% (χ2=32.048, P=0.000), and the usage rate of quadruple therapy decreased from 14.0% to 0 (χ2=24.769, P=0.000). In 2019 and 2022, the usage rate of surgical prophylactic antibiotics was 61.5% and 88.1%, and the usage rate of two or more surgical prophylactic antibiotics was 38.5% and 11.9%, respectively. The usage rate of surgical prophylactic antibiotics in 2022 was higher than that in 2019 (χ2=27.297, P=0.000). The rate of antibiotic usage with medication records increased from 4.0% to 97.8% (χ2=695.523, P=0.000), and the rate of antibiotic withdrawal records increased from 22.4% to 91.0% (χ2=468.698, P=0.000). The rate of empirical usage of antibiotics by clinicians decreased from 47.3% to 35.8% (χ2=260.038, P=0.000), and the rate of antibiotic usage based on inflammatory indicators increased from 18.9% to 27.0% (χ2=505.637, P=0.000). The rate of antibiotics compliance increased from 88.6% to 92.1% (χ2=464.573, P=0.000). The most common type of nosocomial infection in 2019 and 2022 was pneumonia, accounting for 64.7% and 81.0%.Conclusion·The level of antibacterial drug management in the hospital has been stable and improved, and the standardization of the usage of antibacterial drugs by medical staff has been improved. Hospital managers should improve the construction of information technology for rational use of antimicrobial drugs, emphasize departmental collaboration, and work together to formulate work plans to improve the rate of rational usage of antimicrobial drugs and enhance patient satisfaction

    The two authentic methionine aminopeptidase genes are differentially expressed in Bacillus subtilis

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    BACKGROUND: Two putative methionine aminopeptidase genes, map (essential) and yflG (non-essential), were identified in the genome sequence of Bacillus subtilis. We investigated whether they can function as methionine aminopeptidases and further explored possible reasons for their essentiality or dispensability in B. subtilis. RESULTS: In silico analysis of MAP evolution uncovered a coordinated pattern of MAP and deformylase that did not correlate with the pattern of 16S RNA evolution. Biochemical assays showed that both MAP (MAP_Bs) and YflG (YflG_Bs) from B. subtilis overproduced in Escherichia coli and obtained as pure proteins exhibited a methionine aminopeptidase activity in vitro. Compared with MAP_Bs, YflG_Bs was approximately two orders of magnitude more efficient when assayed on synthetic peptide substrates. Both map and yflG genes expressed in multi-copy plasmids could complement the function of a defective map gene in the chromosomes of both E. coli and B. subtilis. In contrast, lacZ gene transcriptional fusions showed that the promoter activity of map was 50 to 100-fold higher than that of yflG. Primer extension analysis detected the transcription start site of the yflG promoter. Further work identified that YvoA acted as a possible weak repressor of yflG expression in B. subtilis in vivo. CONCLUSION: Both MAP_Bs and YflG_Bs are functional methionine aminopeptidases in vitro and in vivo. The high expression level of map and low expression level of yflG may account for their essentiality and dispensality in B. subtilis, respectively, when cells are grown under laboratory conditions. Their difference in activity on synthetic substrates suggests that they have different protein targets in vivo
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