159 research outputs found

    Housing equity and household consumption in retirement: Evidence from the Singapore Life Panel©

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    Ministry of Education, Singapore under its Academic Research Funding Tier

    The Effects of Aqueous Extract from Nardostachys chinensis

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    Aims. The aim of this study was to investigate the effects of the aqueous extract of Nardostachys chinensis Batalin (NCBAE) on blood pressure and cardiac hypertrophy using two-kidney one-clip (2K1C) hypertensive rats. Methods. 2K1C rat models were set up by clipping the left renal artery. Sham-operated rats underwent the same surgical procedure except for renal arterial clipping. 2K1C hypertensive rats were orally given NCBAE at doses of 210, 420, and 630 mg·kg−1·d−1 for 6 weeks. Twelve weeks after surgery, rat SBP and echocardiographic parameters were measured, cardiac histopathology was assessed, serum NO and LDH were detected, and the expression of Bcl-2 and caspase-3 of left ventricular tissue was assessed by western blot. Results. Treatment with NCBAE resulted in a decrease of SBP, LVPWd, LVPWs, IVSd, IVSs, LVW/BW ratio, and cardiomyocyte CSA, an increase of LVEF, and inhibition of 2K1C-induced reduction in serum NO and elevation of LDH compared with 2K1C group. NCBAE intervention also showed a significant increase of Bcl-2 expression and reduction of cleaved caspase-3 level dose-dependently in left ventricular tissue. Conclusion. Our data demonstrate that NCBAE has an antihypertensive property and protective effect on 2K1C-induced cardiac hypertrophy especially at the dose of 630 mg·kg−1·d−1

    Empirical Assessment and Comparison of Educational Efficiency between Major Countries across the World

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    Education is a fundamental factor to enhance a country’s comprehensive national strength and international competitiveness. Recently, several governments have been attracting investments in educational sectors in contemplation of meliorating a country’s overall strength. This study empirically assesses and compares the educational efficiency of 29 major countries across the world using panel data for 2010–2016 by employing data envelopment analysis (DEA) and the super-slacks-based measure (super-SBM) model at the static level combined with the Malmquist index (MI) to investigate educational efficiency at the dynamic level. The results indicate, inter alia, huge average education efficiency differences existed among the studied countries, the highest being Japan (3.2845) and lowest Norway (0.4137), there are differences in the bias of technological progress among the studied countries during the sample period and technological progress directly affects the sustainability of educational efficiency, the growth rate of total factor productivity (TFP) index has been reduced in 2010–2013 but increased in 2014–2016 and techno-logical progress has been the dominant factor influencing the rise of the education TFP index. Based on the results, this study identifies the merits and drawbacks of education efficiency across the sample countries and presents relevant recommendations to promote investment in the education sector and human capital

    An Information Perception-Based Emotion Contagion Model for Fire Evacuation

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    In fires, people are easier to lose their mind. Panic will lead to irrational behavior and irreparable tragedy. It has great practical significance to make contingency plans for crowd evacuation in fires. However, existing studies about crowd simulation always paid much attention on the crowd density, but little attention on emotional contagion that may cause a panic. Based on settings about information space and information sharing, this paper proposes an emotional contagion model for crowd in panic situations. With the proposed model, a behavior mechanism is constructed for agents in the crowd and a prototype of system is developed for crowd simulation. Experiments are carried out to verify the proposed model. The results showed that the spread of panic not only related to the crowd density and the individual comfort level, but also related to people’s prior knowledge of fire evacuation. The model provides a new way for safety education and evacuation management. It is possible to avoid and reduce unsafe factors in the crowd with the lowest cost

    Housing equity and household consumption in retirement: Evidence from the Singapore Life Panel

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    Ministry of Education, Singapore under its Academic Research Funding Tier

    Wave velocity evolution and fracture distribution of soft coal under uniaxial compression

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    In order to study the ultrasonic propagation law and damage characteristics of the soft coal body, coal briquette is selected to replace raw coal, three wave propagation paths were set, and MTS rock mechanics experiment machine and PCI-II acoustic emission instrument were used to carry out the multi-path wave synchronization monitoring test of the coal body under the condition of uniaxial compression, and the anisotropy index was introduced to analyze the wave velocity evolution law. Three transverse and longitudinal sections were selected, and CT scanning equipment was used to carry out damage characterization experiments, reconstruct the micro-structure of the coal body after failure, and compare and study the differences in the distribution of the transverse and longitudinal fissures of two-dimensional slices, and to explore the relationship between the wave velocity and the three-dimensional volume of the fissures. Results show that: â‘  The parallel and vertical loading directions and the average wave velocity of the coal body show the basic law of smoothness followed by decrease and then smoothness with the increase of axial strain.The wave velocity anisotropy index has a smooth, then increasing and then smooth trend with the increase of axial strain, and the wave velocity in the vertical loading direction is the first to decrease, and the decrement is the largest. â‘¡ Compared with the vertical plane, the fracture spectral peak ratio and fractal dimension of the transverse plane of the damaged coal body are larger, the fracture density is higher, and the fracture morphology is also more complicated. â‘¢ With the increase of fissure volume, the average wave velocity of the damaged coal body decreases roughly linearly, and the expansion of internal fissures in the coal body under uniaxial loading is dominated by the parallel loading direction, and the vertical linear expansion of the fissures is the main cause of the variability of the wave velocity in all directions and the damage characteristics of the transverse and longitudinal sections. â‘£ Compared with the parallel loading direction, the damage variables obtained by using the wave velocity in the vertical loading direction are larger and the evaluation of the damage state of the coal body is more reliable. When sound waves are used in the field to evaluate the damage state of coal , it is beneficial to improve the reasonableness of the prediction of instability accidents by making the sound wave propagation path perpendicular to the direction of the coal body loaded (maximum principal stress)

    Experimental Investigation on Compressive Strength, Ultrasonic Characteristic and Cracks Distribution of Granite Rock Irradiated by a Moving Laser Beam

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    Efficient fracturing is the key issue for the exploitation of geothermal energy in a Hot Dry Rock reservoir. By using the laser irradiation cracking method, this study investigates the changes in uniaxial compressive strength, ultrasonic characteristics and crack distributions of granite specimens by applying a laser beam under various irradiation conditions, including different powers, diameters and moving speeds of the laser beam. The results indicate that the uniaxial compressive strength is considerably dependent on the power, diameter and moving speed of the laser beam. The ultrasonic-wave velocity and amplitude of the first wave both increase with a decreased laser power, increased diameter or moving speed of the laser beam. The wave form of irradiated graphite is flattened by laser irradiation comparing with that of the original specimen without laser irradiation. The crack angle and the ratio of the cracked area at both ends are also related to the irradiation parameters. The interior cracks are observed to be well-developed around the bottom of the grooving kerf generated by the laser beam. The results indicate that laser irradiation is a new economical and practical method that can efficiently fracture graphite

    Meso-statistical damage constitutive model and validation of coal under CO2 - load coupling

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    CO2 adsorption causes damage degradation to the coal body and thus reduces its stability, challenging the long-term safety of CO2 sequestration, and it is important to clarify the role of CO2 degradation and establish an ontological model. The damage mechanics theory and statistical theory were used to derive the calculation formula that can comprehensively reflect the total damage variables of the coal body under CO2 adsorption and load coupling, and focusing on the influence of the pressure-tight section, the fine statistical damage ontological equation of the coal body under the action of CO2 was established by segmentation, and the method of determining each parameter of the model was clarified. Finally, the parameters of the constitutive model were determined by CT scanning experiment system and MTS 816 experiment system, and the uniaxial compression experiments of coal body under different CO2 pressures were carried out by the self-developed gas-solid coupling experiment system to verify the rationality of the model. The results show that: ① The damage variables under adsorption and loading were defined based on the fracture rate obtained from CT scanning and by applying the Weibull distribution theory, respectively, and the total damage variable under the coupling of the two was further obtained by combining the damage theory, and a fine-scale statistical damage constitutive model was established; ② Three-dimensional reconstruction of the fracture based on CT scanning technology realistically reflects the fracture extension characteristics before and after CO2 interaction, the higher the CO2 pressure, the fuller the fracture expansion, the greater the three-dimensional fracture parameters and damage variables of the coal samples, and the more complex the spatial fracture network formed; ③ CO2 had a significant deterioration effect on the physical properties of the coal body, and the compressive strength and modulus of elasticity of the coal body were both reduced by 49.78% and 22.63%, respectively, with the increase of CO2 pressure, and the combined effect of dissolution, plasticization and air wedge effect of CO2 on the coal body led to the reduction of the mechanical parameters; ④ The theoretical curves of the fine statistical damage model of the coal body under the action of CO2 have a high degree of agreement with the uniaxial experimental curves, which indicates that the present structural model can better reflect the damage degradation effect of CO2 on the physical properties of the coal body, and embodies the reasonableness and applicability of the constitutive model and the method for determining the model parameters
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