584 research outputs found
Extended Quark Potential Model from Random Phase Approximation
The quark potential model is extended to include the sea quark excitation
using the random phase approximation (RPA). The effective quark interaction
preserves the important Quantum Chromodynamics (QCD) properties -- chiral
symmetry and confinement simultaneously. A primary qualitive analysis shows
that the meson as a well-known typical Goldstone boson and the other
mesons made up of valence quark pair such as the meson can
also be described in this extended quark potential model
Study of Deformation-Compensated Modeling for Flexible Material Path Processing Based on Fuzzy Neural Network and Fuzzy Clustering
In this paper, the Flexible Material Path Processing (FMPP) deformation compensation modeling method based on T-S fuzzy neural network is proposed. This method combined with T S fuzzy reasoning and fuzzy neural network.Firstly, fuzzy clustering is introduced to extract fuzzy membership functions and the fitness of fuzzy rules of T S fuzzy neural network antecedent from historical processing data; secondly, through back-propagation iteration to calculate connection weights of the network. Processing experiments shows that T S fuzzy neural network modeling in this paper is superior to typical T S model,the angle error and straightness error processing by NTS FNN is decreased than these of STS FNN
Deformation-compensated modeling of flexible material processing based on T-S fuzzy neural network and fuzzy clustering
According to the factors that influence flexible material processing (FMP), the deformation compensation modeling method based on T-S fuzzy neural network is proposed. This method combines T-S fuzzy reasoning with a fuzzy neural network. Firstly, fuzzy clustering is introduced to extract fuzzy membership functions and the fitness of fuzzy rules of T-S fuzzy neural network antecedent from the past processing data. Secondly, with the steepest descent method, back-propagation iteration is used to calculate the connection weights of the network. The processing of experiments shows that T-S fuzzy neural network modeling is superior to typical T-S model. The angle error and the straightness error processed by NTS-FNN is 40.4 %, 28.8 % lower than those of STS-FNN. The minimum processing time processed by NTS-FNN is lower by 46.1 % than that of STS-FNN
FinTech and rural household entrepreneurship.
Entrepreneurship activities play an important role in economic growth and job creation. Based on China Family Panel Studies (CFPS) survey data in 2014, 2016, 2018 and 2020, and combing it with the financial technology (FinTech) Index, this study explores the impact of FinTech on rural household entrepreneurship using the Logit and IV estimations. The empirical findings highlight the significant role of FinTech in promoting rural household entrepreneurship. The mechanism analysis shows that FinTech positively modulates the relationship between formal finance and rural credit constraints, thereby fostering rural entrepreneurship. Notably, the impact of FinTech on entrepreneurship is particularly pronounced in areas with lower urbanization levels, indicating a greater potential for promoting entrepreneurship in less economically developed regions. Therefore, this study recommends expanding the coverage of FinTech to encourage rural household entrepreneurship and accelerate efforts towards rural revitalization
Promoting or inhibiting: The role of socio-economic integration on migrant entrepreneurship
Entrepreneurship plays a key role in promoting the global economic growth. However, the association between socio-economic integration and migrant entrepreneurship goes unnoticed. Based on 2017 China Migrants Dynamic Survey (CMDS), using a baseline regression model, Heckman two-stage model and IV Probit model, our research evidences a positive correlation between migrants’ integration into the society and their entrepreneurship. Specifically, for every standard deviation increase in the socio-economic integration level of migrants, the probability of having entrepreneurial engagement increases by 1.4%. Further findings indicates that migrant’s socio-economic integration is negatively correlated with migrant necessity-based entrepreneurship, while indicating a positive relationship between migrants’ socio-economic integration and opportunity-based entrepreneurship. The underlying mechanism of how socio-economic integration impacts migrant necessity-based entrepreneurship is through changes in the perception of difficulty and migrants’ settlement intention. The internal mechanism of how socio-economic integration influences migrant opportunity-based entrepreneurship is by changing localised social capital and migrants’ risk preference. More extensive investigations evidence that the degree of marketisation and the level of information have significant regulatory effect on the relationship between socio-economic integration and migrant entrepreneurship. Heterogeneity analysis shows that the relationship between socio-economic integration and migrant entrepreneurship varies across different levels of human capital, material capital and experience capital
Direct measurement of the Raman enhancement factor of rhodamine 6G on graphene under resonant excitation
Graphene substrates have recently been found to generate Raman enhancement. Systematic studies using different Raman probes have been implemented, but one of the most commonly used Raman probes, rhodamine 6G (R6G), has yielded controversial results for the enhancement effect on graphene. Indeed, the Raman enhancement factor of R6G induced by graphene has never been measured directly under resonant excitation because of the presence of intense fluorescence backgrounds. In this study, a polarization-difference technique is used to suppress the fluorescence background by subtracting two spectra collected using different excitation laser polarizations. As a result, enhancement factors are obtained ranging between 1.7 and 5.6 for the four Raman modes of R6G at 611, 1,183, 1,361, and 1,647 cm[superscript −1] under resonant excitation by a 514.5 nm laser. By comparing these results with the results obtained under non-resonant excitation (632.8 nm) and pre-resonant excitation (593 nm), the enhancement can be attributed to static chemical enhancement (CHEM) and tuning of the molecular resonance. Density functional theory simulations reveal that the orbital energies and densities for R6G are modified by graphene dots.National Natural Science Foundation (China) (Nos. 21233001, 50972001, and 21129001)China. Ministry of Science and Technology (Nos. 2011YQ0301240201 and 2011CB932601)Beijing Natural Science Foundation (No. 2132056
The SNP rs961253 in 20p12.3 Is Associated with Colorectal Cancer Risk: A Case-Control Study and a Meta-Analysis of the Published Literature
Background: Colorectal cancer (CRC) is the third common cancer and the fourth leading cause of cancer death worldwide. A single nucleotide polymorphism (SNP), rs961253 located in 20p12, was firstly described to be associated with the increased risk of CRC in a genome-wide association study; however, more recent replication studies yielded controversial results. Methodology/Principal Findings: A hospital-based case-control study in a Chinese population was firstly performed, and then a meta-analysis combining the current and previously published studies were conducted to explore the real effect of rs961253 in CRC susceptibility. In the Chinese population including 641 cases and 1037 controls, per-A-allele conferred an OR of 1.60 (95 % CI = 1.26–2.02) under additive model. In the meta-analysis including 29859 cases and 29696 controls, per-Aallele have an OR of 1.13 (95 % CI = 1.09–1.18) under a random-effects model due to heterogeneity (P = 0.019). Nevertheless, the heterogeneity can be totally explained by ethnicity, with the tau 2 reduced to 0 after including ethnicity in metaregression model. In stratified analysis by ethnicity, per-A-allele had ORs of 1.34 (95 % CI = 1.20–1.50) and 1.11 (95% CI = 1.08–1.14) for Asian and European, respectively, without heterogeneity. Modest influence of each study was observed on overall estimate in sensitive analysis, and evident tendency to significant association was seen in cumulative analysis over time, together indicating the robust stability of the current results
Effects of magnesium-modified biochar on soil organic carbon mineralization in citrus orchard
In order to investigate the carbon sequestration potential of biochar on soil, citrus orchard soils with a forest age of 5 years was taken as the research object, citrus peel biochar (OBC) and magnesium-modified citrus peel biochar (OBC-mg) were selected as additive materials, and organic carbon mineralization experiments were carried out in citrus orchard soil. OBC and OBC-Mg were applied to citrus orchard soils at four application rates (0, 1, 2, and 4%), and incubated at a constant temperature for 100 days. Compared with CK, the cumulative mineralization of soil organic carbon decreased by 5.11% with 1% OBC and 2.14% with 1% OBC-Mg. The application of OBC and OBC-Mg significantly increased the content of soil organic carbon fraction, while the content of soil organic carbon fraction was higher in OBC-Mg treated soil than in OBC treated soil. Meanwhile, the cumulative mineralization of soil organic carbon was significantly and positively correlated with the activities of soil catalase, urease and sucrase. The enzyme activities increased with the cumulative mineralization of organic carbon, and the enzyme activities of the OBC-Mg treated soil were significantly higher than those of the OBC treated soil. The results indicated that the OBC-Mg treatment inhibited the organic carbon mineralization in citrus orchard soils and was more favorable to the increase of soil organic carbon fraction. The Mg-modified approach improved the carbon sequestration potential of biochar for citrus orchard soils and provided favorable support for the theory of soil carbon sink in orchards
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