Improving Non-Cartesian MRI Reconstruction through Discontinuity Subtraction

Non-Cartesian sampling is widely used for fast magnetic resonance imaging (MRI). Accurate and fast image reconstruction from non-Cartesian k-space data becomes a challenge and gains a lot of attention. Images provided by conventional direct reconstruction methods usually bear ringing, streaking, and other leakage artifacts caused by discontinuous structures. In this paper, we tackle these problems by analyzing the principal point spread function (PSF) of non-Cartesian reconstruction and propose a leakage reduction reconstruction scheme based on discontinuity subtraction. Data fidelity in k-space is enforced during each iteration. Multidimensional nonuniform fast Fourier transform (NUFFT) algorithms are utilized to simulate the k-space samples as well as to reconstruct images. The proposed method is compared to the direct reconstruction method on computer-simulated phantoms and physical scans. Non-Cartesian sampling trajectories including 2D spiral, 2D and 3D radial trajectories are studied. The proposed method is found useful on reducing artifacts due to high image discontinuities. It also improves the quality of images reconstructed from undersampled data

The First Study of Mating Mistakes in Stoneflies (Plecoptera) from China, with Remarks on Their Biological Implications

Currently, information on the biology of Plecoptera from China is scarce, particularly on mating behavior. In this paper, the existence of mating mistakes (erroneous mating attempts) involving 13 Chinese stonefly species (belonging to nine genera and three families) is reported. These erroneous mating behaviors can be included into three different categories: mating attempts between conspecific males (including the formation of erroneous mating balls), mating attempts between different taxa (including displacement attempts during copulation), and mating-related behaviors with non-living objects. From these behaviors, some aspects of stoneflies during mating, such as the physical competition between males, the sensorial mechanisms implied in triggering a mating behavior, the conditions favoring the mating mistakes, and the possible consequences of interspecific mating in the hybrid production, are discussed.National Natural Science Foundation of China (No. 32170459; 31872266; 31071958)China Scholarship Council, the Project of Biological Resources Survey in Wuyishan National Park, Investigation and Evaluation of Insect Resources in Huangshan Scenic Spot (Phase I)Insect fauna of Qilian Mountain National Park (Qinghai)Volume of Lepidoptera and Diptera (procurement contract No. QHTX-2021-006, Administration of Qilian Mountain Nature Reserve, Qinghai Province

Lagrangian Stochastic Simulation of Atmospheric Dispersion from Sources near the Ground

A simple Lagrangian stochastic (LS) dispersion model was used to investigate atmospheric dispersion in the lower atmospheric boundary layer, for near-surface sources. The sensitivity of ground-level concentration to numerical errors was revealed. Numerical treatments of inhomogeneous atmospheric turbulence and surface reflection in Lagrangian trajectory calculations may cause non-negligible overestimates of ground-level concentration for elevated sources, although these errors become trivial for surface sources and for concentrations above the ground-level. Using a numerical error-correction scheme, the LS model was evaluated against an analytical model. Close agreement was found between the two models in predicting ground-level concentrations for dispersions in the surface layer. LS simulations for an elevated source were also conducted. A scaling scheme was proposed to normalize the dispersion results, by including the source height as a scaling length. The relationships between the normalized surface concentration and downwind distance were distinguished by atmospheric stabilities. In the near-field, the distance of peak ground-level concentration was 0.5, 1.0, and 2.0 times z(s) U/u(*), where z(s) is the source height, U is the mean wind speed at height 10 m, and u(*) is the friction velocity, for unstable, neutral and stable atmospheric stability conditions, respectively. In the far-field, the concentration approached approximately the "-3/2 "-1" and "-2/3" law for unstable, neutral and stable atmospheres respectively.Geosciences, MultidisciplinaryMeteorology & Atmospheric SciencesOceanographySCI(E)[email protected]

Research on Traffic Optimization of Urban Four-Phase Intersections Based on VISSIM

In order to effectively solve the congestion problem of mixed intersections, improve traffic efficiency, and improve the current congestion situation of urban road network, this paper takes the mixed traffic flow intersection of Shanghai Road and Guyan Street in Yuanzhou District of Guyuan City as an example to carry out optimization research, collect traffic flow and signal timing data during peak hours through field investigation, and establish a microscopic road model by using VISSIM software. Through simulation, the indexes such as vehicle delay and queue length are obtained. Then the lane function of the model is divided, the signal timing is optimized by Webster algorithm and Fuzzy algorithm, and the comparison analysis is carried out. The simulation results show that the vehicle delay and queue length after Fuzzy optimization are greatly reduced, and the traffic running condition is significantly improved, thus verifying the scientificity and rationality of the optimization scheme

Effects of Wenxiao II Decoction on the expression of MCP-1 and VCAM-1 in atherosclerotic rabbits

AbstractObjectiveTo observe the effects of different doses of Wenxiao II Decoction on the expression of monocyte chemoattractant protein-1 (MCP-1) and vascular cell adhesion molecule-1 (VCAM-1) in an experimental model of atherosclerosis in rabbits and to explore the mechanism by which it alleviates atherosclerosis.MethodsSixty 3–4 month-old New Zealand rabbits of both sexes were randomly divided into six groups: simvastain; model; blank; and high-dose, mid-dose, and low-dose Wenxiao II Decoction groups. Except for those in the blank group, all rabbits were fed a high-cholesterol diet. Carotid atherosclerosis was established by balloon-induced injury to the endothelium of the carotid artery in conjunction with consumption of a high-cholesterol diet. After 8 weeks, all rabbits were killed to evaluate the expression of MCP-1 and VCAM-1 by immunohistochemical staining.ResultsExpressions of MCP-1 and VCAM-1 were significantly decreased in all groups except the blank group compared with the model group (P< 0.05). When compared with the simvastain group only variation of MCP-1 expression in low-dose group was not appreciable, and the differences were indistinct (P<0.05). When comparing among Wenxiao II Decoction groups, MCP-1 expression in the mid- and high-dose groups was significantly lower than that seen in the low-dose group (P< 0.01), but there were no differences among three dosage groups with respect to VCAM-1 expression (P>0.05).ConclusionThese data suggested that high, mid, and low doses of Wenxiao II Decoction can inhibit the expression of MCP-1 and VCAM-1, which may prevent the formation of or stabilize atherosclerotic plaques. There may be a direct relationship between the dosage of Wenxiao II Decoction and its therapeutic efficacy