65 research outputs found

    A Link-Based Day-to-Day Traffic Assignment Model

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    Existing day-to-day traffic assignment models are all built upon path flow variables. This paper demonstrates two essential shortcomings of these path-based models. One is that their application requires a given initial path flow pattern, which is typically unidentifiable, i.e., mathematically nonunique and practically unobservable. In particular, we show that, for the path-based models, different initial path flow patterns constituting the same link flow pattern generally gives different day-to-day link flow evolutions. The other shortcoming of the path-based models is the path-overlapping problem. That is, the path-based models ignore the interdependence among paths and thus can give very unreasonable results for networks with paths overlapping with each other. These two path-based problems exist for most (if not all) deterministic day-to-day dynamics whose fixed points are the classic Wardrop user equilibrium. To avoid the two path-based problems, we propose a day-to-day traffic assignment model that directly deals with link flow variables. Our link-based model captures travelers\u27 cost-minimization behavior in their path finding as well as their inertia. The fixed point of our link-based dynamical system is the classic Wardrop user equilibrium

    PO-210 Analysis on the Hotspot and Content of Exercise Therapy for the cerebral oxygen in Foreign Countries——Based on Visualization Research of Scientific Knowledge Map

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    Objective To analyze the hotspot of exercise therapy for cerebral oxygen .  Methods  This study is based on academic literature between1982-2017,which are retrieved from Web of Science. The author uses the software of CitespaceIII to make visual analysis for1701 literatures. Results There has been a steady growth in the publications, countries with most publications include American, Japan,England ,Germony; research institutions are mainly composed of universities in Europe and America; authors forms a major cooperative team but with no obvious cross regional and institutional cooperation;the research focus on the the influence of cerebral blood flow and metabolic、the pressure of carbon dioxide on cerebral oxygen during exercise which pay close attention to cognition; research hotspot is mainly concentrated on the link among cerebral blood flow 、metabolism、automatic control of the brain 、cognition and cerebral oxygen . Conclusions in the individuals of cardiovascular diseases  research hotspot reveals low to moderate exercise is a better way to  improve cognition in view of cerebral oxygen

    Study of a high-precision complex 3D geological modelling method based on a fine KNN and kriging coupling algorithm: a case study for Jiangsu, China

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    A high-precision, complex, three-dimensional (3D) geological model can directly express the attributes of stratum thickness, geological structure, lithology and spatial form, which can provide a reliable basis for the development and utilization of underground space and planning decisions. However, it is difficult to perform accurate modelling due to the lack of basic data. As such, this paper proposes coupling a machine learning algorithm (K-nearest neighbour (KNN)) with the kriging algorithm to construct the topological relationship between the Delaunay triangle and the Thiessen polygon in order to perform the simulation and prediction of virtual drilling. Based on KNN, support vector machine (SVM) and neural network algorithms as well as the virtual borehole encryption data, data standardization processing and analysis are carried out. Through model verification, algorithm optimization is realized, and the optimal modelling method is explored. The results show that the fine KNN algorithm improved by Bayesian optimization can effectively improve the modelling accuracy through 0.1-m encryption, standardization processing and 5-fold cross-validation. Stratum modelling combined with the fine KNN and kriging algorithms can obtain a more accurate modelling without adding virtual boreholes. The improved levels of upper and lower hybrid modelling with an appropriate number of profile boreholes can also effectively optimize model accuracy. Both modelling accuracy and efficiency can be significantly improved by using Delaunay triangles and Thiessen polygons with virtual boreholes. Stratum modelling can effectively express the geological pinch-out in areas with adequate degrees of stratification, and hybrid modelling performs well in irregular geological bodies such as karsts and lenses

    Expression dynamics of phytochrome genes for the shade-avoidance response in densely direct-seeding rice

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    Because of labor shortages or resource scarcity, direct seeding is the preferred method for rice (Oryza sativa. L) cultivation, and it necessitates direct seeding at the current density. In this study, two density of direct seeding with high and normal density were selected to identify the genes involved in shade-avoidance syndrome. Phenotypic and gene expression analysis showed that densely direct seeding (DDS) causes a set of acclimation responses that either induce shade avoidance or toleration. When compared to normal direct seeding (NDS), plants cultivated by DDS exhibit constitutive shade-avoidance syndrome (SAS), in which the accompanying solar radiation drops rapidly from the middle leaf to the base leaf during flowering. Simulation of shade causes rapid reduction in phytochrome gene expression, changes in the expression of multiple miR156 or miR172 genes and photoperiod-related genes, all of which leads to early flowering and alterations in the plant architecture. Furthermore, DDS causes senescence by downregulating the expression of chloroplast synthesis-related genes throughout almost the entire stage. Our findings revealed that DDS is linked to SAS, which can be employed to breed density-tolerant rice varieties more easily and widely

    Evaluation of six satellite-based terrestrial latent heat flux products in the vegetation dominated Haihe river basin of north China

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    In this study, six satellite-based terrestrial latent heat flux (LE) products were evaluated in the vegetation dominated Haihe River basin of North China. These LE products include Global Land Surface Satellite (GLASS) LE product, FLUXCOM LE product, Penman-Monteith-Leuning V2 (PML_V2) LE product, Global Land Evaporation Amsterdam Model datasets (GLEAM) LE product, Breathing Earth System Simulator (BESS) LE product, and Moderate Resolution Imaging Spectroradiometer (MODIS) (MOD16) LE product. Eddy covariance (EC) data collected from six flux tower sites and water balance method derived evapotranspiration (WBET) were used to evaluate these LE products at site and basin scales. The results indicated that all six LE products were able to capture the seasonal cycle of LE in comparison to EC observations. At site scale, GLASS LE product showed the highest coefficients of determination (R2) (0.58, p 2), followed by FLUXCOM and PML products. At basin scale, the LE estimates from GLASS product provided comparable performance (R2 = 0.79, RMSE = 18.8 mm) against WBET, compared with other LE products. Additionally, there was similar spatiotemporal variability of estimated LE from the six LE products. This study provides a vital basis for choosing LE datasets to assess regional water budget

    中国における非在来型ガスを含む天然ガス開発に関する考察

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    Relationship between elevated circulating thrombospondin‐1 levels and vascular complications in diabetes mellitus

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    Abstract Aims/Introduction Thrombospondin‐1 (TSP‐1) participates in a series of physiological and pathological processes by binding to various receptors regulating cell proliferation, adhesion and apoptosis. Elevated circulating TSP‐1 is linked with diabetic vascular complications (DVC). This study aimed to determine the relationship between circulating TSP‐1 levels and DVC. Materials and Methods A comprehensive search of PubMed, Embase, Web of Science and CNKI databases was carried out. A meta‐analysis was carried out to compare circulating TSP‐1 levels between diabetes patients without vascular complications (DNVC), diabetes patients with DVC and non‐diabetes patients. The correlation between TSP‐1 and metabolic parameters was also analyzed. Subgroup analysis was carried out according to complication type, defined as diabetic retinopathy, diabetic nephropathy and diabetic cardiovascular disease (DCVD). Results A total of eight studies were included. Compared with non‐diabetes patients, diabetic patients, including DNVC and DVC, had significantly higher circulating TSP‐1 levels (standardized mean difference [SMD] 2.660, 95% CI 1.17–4.145, P = 0.000). DNVC had significantly higher circulating TSP‐1 levels than non‐diabetes patients (SMD 3.613, 95% CI 1.607–5.619, P = 0.000). DVC had significantly higher TSP‐1 levels than DNVC (SMD 0.568, 95% CI 0.100–1.036, P = 0.017). TSP‐1 was significantly positively correlated with fasting plasma glucose (overall Fisher's z = 0.696, 95% CI 0.559–0.833) and HbA1c (overall Fisher's z = 0.849, 95% CI 0.776–0.923). Conclusions Elevated circulating TSP‐1 levels are closely related to DVC, especially in diabetic nephropathy and diabetic cardiovascular disease. Circulating TSP‐1 detection might be helpful in the timely diagnosis and treatment of DVC

    Disrupted Regional Spontaneous Neural Activity in Mild Cognitive Impairment Patients with Depressive Symptoms: A Resting-State fMRI Study

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    Depressive symptoms are common in individuals with mild cognitive impairment (MCI) who have an increased risk of dementia. It is currently unclear whether the pattern of spontaneous brain activity in patients with MCI differs between subjects with and without depressive symptoms. The current study sought to investigate the features of spontaneous brain activity in MCI patients with depressive symptoms (D-MCI) using coherence regional homogeneity (CReHo) analysis with resting-state functional magnetic resonance imaging (rsfMRI). We obtained rsfMRI data in 16 MCI patients with depressive symptoms and 18 nondepressed MCI patients (nD-MCI) using a 3 T scanner. Statistical analyses were performed to determine the regions in which ReHo differed between the two groups in specific frequency bands, slow-4 (0.027–0.073 Hz) and slow-5 (0.010–0.027 Hz), and typical bands (0.01–0.08 Hz). Correlation analyses were performed between the CReHo index of these regions and clinical variables to evaluate the relationship between CReHo and pathophysiological measures in the two groups. Our results showed that D-MCI patients exhibited significantly higher CReHo in the left Heschl’s gyrus and left thalamus and lower CReHo in the left postcentral gyrus in the typical frequency band. In the slow-4 frequency band, D-MCI patients showed significantly higher CReHo in the left Heschl’s gyrus and left thalamus. In the slow-5 frequency band, D-MCI patients exhibited significantly lower CReHo in the superior medial prefrontal gyrus. In addition, the results revealed that CReHo values in the left thalamus were positively correlated with Hamilton Depression Rating Scale (HAMD) scores in D-MCI patients. These results suggest that the sensorimotor network may be one of the main pathophysiological factors in D-MCI
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