The hydrodynamics of galaxy formation on Kiloparsec scales

Two dimensional numerical simulations of Zeldovich pancake fragmentation in a dark matter dominated universe were carried out to study the hydrodynamical and gravitational effects on the formation of structures such as protogalaxies. Preliminary results were given in Yuan, Centrella and, Norman (1991). Here we report a more exhaustive study to determine the sensitivity of protogalaxies to input parameters. The numerical code we used for the simulations combines the hydrodynamical code ZEUS-2D (Stone and Norman, 1992) which was modified to include the expansion of the universe and radiative cooling of the gas with a particle-mesh code which follows the motion of dark matter particles. The resulting hybrid code is able to handle highly nonuniform grids which we utilized to obtain a high resolution (much greater than 1 kpc) in the dense region of the pancake

Vibration induced by subway trains: open-trench mitigation analysis in the time and frequency domains

In this paper, we analyse the mitigation effects of open trenches on the vibrations induced by subway trains. The study is performed by using both physical model tests and numerical simulations. The effectiveness is evaluated by calculating the frequency response function (FRF) and the vibration acceleration peak (VAP) in both time and frequency domains. The experimental and numerical results demonstrate that the open trench has clear effects on the dynamic soil response. Both time and frequency domain results suggest that the dynamic response of the soils beyond the open trenches could be significantly affected, due to the existence of the open trench. According to the frequency domain analysis, the inclusion of open trenches could effectively reduce the soil response in a higher frequency range. Due to reflection effects at the boundaries of the trench, an amplification of the soil response in front of the open trench is observed. Parametric study by means of numerical simulations is also performed. The width of the open trench demonstrates negligible effects on the dynamic soil response, whilst the trench depth exhibits a large influence on the trench isolation performance. With an increase in the trench depth, the isolation performance is significantly improved. It is concluded that the open trenches perform well as an isolation barrier, in mitigating the vibration induced by subway trains

The Margin Abatement Costs of CO2 in Chinese industrial sectors

AbstractUsing the directional distance function estimating by a non-parametric method, this paper measured shadow prices indicating the margin abatement costs (MACs) of CO2 emissions of China's industrial sectors. The results show that the MACs are within 0.2 thousand Yuan per ton to 120.3 thousand Yuan per ton, differentiating among sectors. In average, the MACs of heavy and chemical industries are lower than that of light and high-tech industries

Lugrandoside attenuates spinal cord injury by targeting peli1 and TLR4/NF-κB pathway to exert anti-inflammatory and anti-apoptotic effects

Purpose: To investigate the curative effect and mechanism of lugrandoside (LG) on spinal cord injury (SCI).Methods: We probed the expression of Pellino1 (peli1) in microglia and spinal cord tissues withdifferent treatments of LG. Lipopolysaccharide (LPS) was used to activate the microglia. Furthermore, rats were used to establish SCI model, and LG, at low and high concentrations, was administered to injured animals to ascertain whether LG exerted a therapeutic effect on SCI.Results: LG inhibited the activation and recruitment of glial cells by acting as a negative regulator of glial inflammation, and this reverse the targeting of peli1 and TLR4/NF-κB pathway. Furthermore, the in vivo data showed that LG exerted a neuroprotective effect, following SCI, via anti-inflammatory and antiapoptotic effects. Furthermore, Peli1 and TLR4/NF-κB were suppressed by LG stimuli.Conclusion: These results suggest that LG protects neural tissue against neuroinflammation and apoptosis by suppressing TLR4/NF-κB pathway and negatively targeting peli1. The findings may provide new insights into the treatment of spinal cord injury

Effect of particle size and surface charge on nanoparticles diffusion in the brain white matter

This project has received funding from the European Unions Horizon 2020 research and innovation programme under Grant Agreement No. 688279. Daniele Dini would like to acknowledge the support received from the EPSRC under the Established Career Fellowship Grant No. EP/N025954/1. Tian Yuan would also like to acknowledge financial support from CSC Imperial Scholarship. The authors declare that they have no conflict of interest.Peer reviewedPublisher PD

Mathematical Optimisation of Magnetic Nanoparticle Diffusion in the Brain White Matter

European Unions Horizon 2020 research and innovation programme under Grant Agreement No. 688279. EPSRC Established Career Fellowship Grant No. EP/N025954/1. Children with Cancer UK Grant No. 16-224.Peer reviewedPublisher PD

Target Detection Framework for Lobster Eye X-Ray Telescopes with Machine Learning Algorithms

Lobster eye telescopes are ideal monitors to detect X-ray transients, because they could observe celestial objects over a wide field of view in X-ray band. However, images obtained by lobster eye telescopes are modified by their unique point spread functions, making it hard to design a high efficiency target detection algorithm. In this paper, we integrate several machine learning algorithms to build a target detection framework for data obtained by lobster eye telescopes. Our framework would firstly generate two 2D images with different pixel scales according to positions of photons on the detector. Then an algorithm based on morphological operations and two neural networks would be used to detect candidates of celestial objects with different flux from these 2D images. At last, a random forest algorithm will be used to pick up final detection results from candidates obtained by previous steps. Tested with simulated data of the Wide-field X-ray Telescope onboard the Einstein Probe, our detection framework could achieve over 94% purity and over 90% completeness for targets with flux more than 3 mCrab (9.6 * 10-11 erg/cm2/s) and more than 94% purity and moderate completeness for targets with lower flux at acceptable time cost. The framework proposed in this paper could be used as references for data processing methods developed for other lobster eye X-ray telescopes.Comment: Accepted by the APJS Journal. Full source code could be downloaded from the China VO with DOI of https://doi.org/10.12149/101175. Docker version of the code could be obtained under request to the corresponding autho

Determination of Volatile Compounds of Illicium verum Hook. f. Using Simultaneous Distillation-Extraction and Solid Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry

Purpose: To determine the characteristic aromatic constituents of star anise (Illicium verum Hook. f.) and identify its main aroma compounds for sensory evaluation.Methods: The volatile compounds of star anise were prepared by simultaneous distillation-extraction (SDE) and the compounds were identified by gas chromatography-mass spectroscopy (GC-MS). The flavor compounds were confirmed by gas chromatography-olfactometry (GC-O). Their flavor dilution factor (FD) values were determined using aroma extract dilution analysis (AEDA). Finally, standard samples that meet the requirements for sensory evaluation were extracted by the solid-phase microextraction (SPME) to further validate characteristic aroma molecules.Results: Forty seven compounds were confirmed, with trans-anethole, estragole, and anisaldehyde the main aroma components. The content of trans-anethole was the highest (75.76 %), followed by linalool (1.44 %). Limonene (1.01 %) and 4’- ethoxypropiophenone (0.72 %) were the lowest.Conclusion: Combining SDE coupled with AEDA and SPME coupled with GC-MS is beneficial for identifying characteristic aroma compounds for star anise, such as trans-anethole, linalool and limonene in terms of FD value. The findings may be useful for star anise quality control in the food industry.Keywords: Aroma, Flavor dilution factor (FD value), Gas chromatography-olfactometry, Simultaneous distillation-extraction, Sensory evaluation, Star anise, Illicium verum, Trans-anethole, Linaloo, Limonen

Hydraulic loss analysis in a pump-turbine with special emphasis on local rigid vortex and shear

Since the pump as turbine is increasingly employed in energy storage, improving efficiency in both pump and turbine modes is required for economic benefits. This study aims to analyze vortex flow characteristics and vortex control methods in both modes to reduce hydraulic loss. In this paper, a delayed detached eddy simulation was applied in a low specific speed pump-turbine. Based on the entropy production analysis and vorticity binary decomposition in the local vortices, the results show that the local shear is the leading cause of hydraulic loss instead of the existence of vortices. The average wake loss can be 1.6 times higher than the loss in jet regions in pump mode, but there is little difference in the distribution of shear and vortices in the wake flow in turbine mode. The local loss caused by the rotor-stator interaction with a tongue effect at blade passing frequency is up to threefold over the loss without a tongue effect in both modes. Reducing shear and ratio of shear to rigid vorticity of the local vortices via modification in the volute tongue angle to suppress the tongue effect can be an effective way to decrease hydraulic loss in both modes