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101.
In this paper, we derive the frozen Gaussian approximation (FGA) for computing the solution to the Dirac equation in curved space in the semi-classical regime.The latter equation is used in particular for modeling electronic scattering on strainedgraphene surfaces. We present numerical comparisons of the Dirac solutions on curvedand flat spaces, illustrating the focusing effect of graphene surfaces, as well as qualitative comparisons with a tight-binding model. A CPU-time comparison shows thatFGA becomes more efficient than an IMEX pseudospectral method when the semiclassical parameter is small. 相似文献
102.
Wenbin Chen Jianyu Jing Qianqian Liu Cheng Wang & Xiaoming Wang 《Communications In Computational Physics》2024,35(3):633-661
A second order accurate in time, finite difference numerical scheme is proposed and analyzed for the Cahn-Hilliard-Navier-Stokes system, with logarithmicFlory-Huggins energy potential. In the numerical approximation to the chemical potential, a modified Crank-Nicolson approximation is applied to the singular logarithmic nonlinear term, while the expansive term is updated by an explicit second orderAdams-Bashforth extrapolation, and an alternate temporal stencil is used for the surface diffusion term. Moreover, a nonlinear artificial regularization term is included inthe chemical potential approximation, which ensures the positivity-preserving property for the logarithmic arguments, i.e., the numerical value of the phase variable isalways between −1 and 1 at a point-wise level. Meanwhile, the convective term in thephase field evolutionary equation is updated in a semi-implicit way, with second orderaccurate temporal approximation. The fluid momentum equation is also computed bya semi-implicit algorithm. The unique solvability and the positivity-preserving property of the second order scheme is proved, accomplished by an iteration process. Amodified total energy stability of the second order scheme is also derived. Some numerical results are presented to demonstrate the accuracy and the robust performanceof the proposed second order scheme. 相似文献
103.
《Clinical gastroenterology and hepatology》2023,21(7):1819-1830.e5
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104.
《Annals of epidemiology》2014,24(4):291-296
PurposeLow-to-moderate alcohol consumption is associated with decreased mortality. However, many aspects of this association are still debated. Our aim was to complement available information by conducting a dose-response analysis of the association between alcohol consumption and survival time.MethodsIn a Swedish population-based cohort of 67,706 middle-aged and elderly men and women, frequency and amount of drinking were assessed through a self-administrated questionnaire. During 15 years of follow-up, 13,323 participants died. Differences in survival (10th percentile differences, PDs) according to levels of alcohol consumption were estimated using Laplace regression.ResultsWe found evidence of nonlinearity between alcohol consumption and survival. Among women, we observed a rapid increase in survival up to 6 g/d of alcohol consumption (0.5 drinks/d) where survival was 17 months longer (PD = 17 months, 95% confidence interval, 10 to 24). After this peak, higher alcohol consumption was progressively associated with shorter survival. Among men, survival improved up to 15 g/d (1.5 drinks/d) where we observed a PD of 15 months (95% confidence interval, 8 to 22).ConclusionsLow alcohol consumption was associated with improved survival up to 1.5 years for women with an average consumption of 0.5 drinks per day and to 1.3 years for men with an average consumption of 1.5 drinks per day. 相似文献
105.
利用正交小波变换的时频分析及多工尺度特点,基于函数逼近以及函数奇性分析的原理,提出了化工生产过程数据压缩及害变信号检测算法,理论分析和仿真研究证实了所提算法的可行性和有效性。 相似文献
106.
Jing Liu Yushan Chen Haoyuan Cai Xiaoyi Chen Changwei Li Cheng-Fu Yang 《Materials》2015,8(5):2688-2699
In this study, the nanosphere lithography (NSL) method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA) numerical method as a function of refractive indexes of substrates and mediums. Simulation results showed that as the substrates had the refractive indexes of 1.43 (quartz) and 1.68 (SF5 glass), the nanoparticle arrays would have better refractive index sensitivity (RIS) and figure of merit (FOM). Simulation results also showed that the peak wavelength of the extinction spectra had a red shift when the medium’s refractive index n increased. The experimental results also demonstrated that when refractive indexes of substrates were 1.43 and 1.68, the nanoparticle arrays and substrate had better adhesive ability. Meanwhile, we found the nanoparticles formed a large-scale monolayer array with the hexagonally close-packed structure. Finally, the hybrid Au-Ag triangular nanoparticle arrays were fabricated on quartz and SF5 glass substrates and their experiment extinction spectra were compared with the simulated results. 相似文献
107.
Srivastava A Sood A Joy PS Mandal S Panwar R Ravichandran S Sarangi S Woodcock J 《The Indian journal of surgery》2010,72(5):355-361
In this sequel, to an earlier article, we discuss the laws of Mechanics, Thermodynamics and Vectors as they apply to soft
and bony tissues. These include the Laplace’s Law as applied to colonic perforation, compression therapy, parturition, variceal
rupture, disc herniations etc. The Pascal’s Law finds use in hernia repair and the Heimlich maneuver. Trigonometrically derived
components of forces, acting after suturing, show ways to reduce cut-through; the thickness and the bite of suture determines
the extent of tissue reaction. The heating effect of current explains the optimum gap between the prongs of a bipolar cautery
and the use of law of transfer of heat in determining relation between healthy wound healing and ambient temperature. 相似文献
108.
Estimation of Population Pharmacokinetic Parameters of Saquinavir in HIV Patients with the MONOLIX Software 总被引:1,自引:1,他引:0
In nonlinear mixed-effects models, estimation methods based on a linearization of the likelihood are widely used although
they have several methodological drawbacks. Kuhn and Lavielle (Comput. Statist. Data Anal. 49:1020–1038 (2005)) developed
an estimation method which combines the SAEM (Stochastic Approximation EM) algorithm, with a MCMC (Markov Chain Monte Carlo)
procedure for maximum likelihood estimation in nonlinear mixed-effects models without linearization. This method is implemented
in the Matlab software MONOLIX which is available at http://www.math.u-psud.fr/~lavielle/monolix/logiciels. In this paper
we apply MONOLIX to the analysis of the pharmacokinetics of saquinavir, a protease inhibitor, from concentrations measured
after single dose administration in 100 HIV patients, some with advance disease. We also illustrate how to use MONOLIX to
build the covariate model using the Bayesian Information Criterion. Saquinavir oral clearance (CL/F) was estimated to be 1.26 L/h
and to increase with body mass index, the inter-patient variability for CL/F being 120%. Several methodological developments
are ongoing to extend SAEM which is a very promising estimation method for population pharmacockinetic/pharmacodynamic analyses. 相似文献
109.
AIM: To study the relationship between quantitative structure and pharmacokinetics (QSPkR) of fluoroquinolone antibacterials. METHODS: The pharmacokinetic (PK) parameters of oral fluoroquinolones were collected from the litera- ture. These pharmacokinetic data were averaged, 19 compounds were used as the training set, and 3 served as the test set. Genetic function approximation (GFA) module of Cerius2 software was used in QSPkR analysis. RESULTS: A small volume and large polarizability and surface area of substituents at C-7 contribute to a large area under the curve (AUC) for fluoroquinolones. Large polarizability and small volume of substituents at N-1 contribute to a long half life elimination. CONCLUSION: QSPkR models can contribute to some fluoroquinolones antibacterials with excellent pharmacokinetic properties. 相似文献
110.