A Lattice Boltzmann Method for the Advection-Diffusion Equation with Neumann Boundary Conditions

In this paper, we study a lattice Boltzmann method for the advection-diffusion equation with Neumann boundary conditions on general boundaries. A novel mass conservative scheme is introduced for implementing such boundary conditions, and is analyzed both theoretically and numerically.Second order convergence is predicted by the theoretical analysis, and numerical investigations show that the convergence is at or close to the predicted rate. The numerical investigations include time-dependent problems and a steady-state diffusion problem for computation of effective diffusion coefficients.     

Exact Boundary Conditions for Periodic Waveguides Containing a Local Perturbation

We consider the solution of the Helmholtz equation −∆u(x)−n(x)²ω²u(x) = f(x), x = (x,y), in a domain Ω which is infinite in x and bounded in y. We assume that f(x) is supported in Ω⁰ := {x ∈ Ω |a⁻ < x < a⁺} and that n(x) is x-periodic in Ω\Ω⁰. We show how to obtain exact boundary conditions on the vertical segments, Γ⁻ := {x ∈ Ω |x = a⁻} and Γ⁺ := {x ∈ Ω |x = a⁺}, that will enable us to find the solution on Ω⁰ ∪Γ⁺ ∪Γ⁻. Then the solution can be extended in Ω in a straightforward manner from the values on Γ⁻ and Γ⁺. The exact boundary conditions as well as the extension operators are computed by solving local problems on a single periodicity cell.     

Mg

补加Mg2+对三孢布拉霉合成β-胡萝卜素及其生长的影响研究表明,在一定范围内,质量浓度低的Mg2+促进菌体生长,质量浓度高的Mg2+抑制菌体生长,但β-胡萝卜素比产量增加.发酵48 h补加0.3 g/dL Mg2+,β-胡萝卜素产量增加40%.同时,补加Mg2+和β-紫罗酮比仅添加β-紫罗酮、β-胡萝卜素产量提高约11%.     

The TEG® vs the ROTEM® thromboelastography/thromboelastometry systems

We have evaluated the TEG^® thromboelastograph and the ROTEM^® thromboelastometer, two point-of-care devices that measure blood coagulation. During a one-week period, seven consultant anaesthetists, one consultant haematologist, one associate specialist anaesthetist and two senior trainee anaesthetists were trained by the manufacturers and set up, calibrated and used both systems, after which their views were obtained and specific technical/support information was sought from the manufacturers using a questionnaire. Although the devices shared common features, they differed in complexity and aspects of ease of use, and in their purchase and running costs.     

Pseudostress-Based Mixed Finite Element Methods for the Stokes Problem in Rn with Dirichlet Boundary Conditions I: A Priori Error Analysis

We consider a non-standard mixed method for the Stokes problem in Rⁿ, n∈{2,3}, with Dirichlet boundary conditions, in which, after using the incompressibility condition to eliminate the pressure, the pseudostress tensor σ and the velocity vectorubecome the only unknowns. Then, we apply the Babuška-Brezzi theory to prove the well-posedness of the corresponding continuous and discrete formulations. In particular, we show that Raviart-Thomas elements of order k≥0 for σ and piecewise polynomials of degree k foruensure unique solvability and stability of the associated Galerkin scheme. In addition, we introduce and analyze an augmented approach for our pseudostress-velocity formulation. The methodology employed is based on the introduction of the Galerkin least-squares type terms arising from the constitutive and equilibrium equations, and the Dirichlet boundary condition for the velocity, all of them multiplied by suitable stabilization parameters. We show that these parameters can be chosen so that the resulting augmented variational formulation is defined by a strongly coercive bilinear form, whence the associated Galerkin scheme becomes well posed for any choice of finite element subspaces. For instance, Raviart-Thomas elements of order k≥0 for σ and continuous piecewise polynomials of degree k+1 forubecome a feasible choice in this case. Finally, become a feasible choice in this case. Finally, extensive numerical experiments illustrating the good performance of the methods and comparing them with other procedures available in the literature, are provided.     

以Mn2+为探针的磁共振分子影像技术

以二价锰离子(Mn^2 )为探针的磁共振分子影像是近年来发展起来的可在体、动态地观测大脑神经活动的一种脑成像技术。本文利用这项技术对大鼠急性脑缺血模型中的钙离子(Ca^2 超载过程、视觉刺激时猫初级视皮层的活动以及Mn^2 在大鼠脑组织中的选择性沉积进行研究，发现以Mn^2 为探针的磁共振分子影像可用于研究功能或病理状态下Ca^2 作为一种神经传递介质在大脑中的输运过程。随着高信噪比及高时、空分辨率磁共振成像技术的发展，以Mn^2 探针的磁共振分子影像技术必将在神经生物学的研究中取得更为广泛的应用。     

Evaluation of the HemoCue® for measuring intra-operative haemoglobin concentrations: a comparison with the Coulter Max-M®

We compared haemoglobin concentration values obtained using a portable haemoglobinometer, the HemoCue, in the operating theatre with the results obtained by the Coulter Max-M in the laboratory. Haemoglobin concentrations were measured on 52 arterial blood samples obtained from 13 patients during aortic surgery, in theatre with the HemoCue and again by the Coulter Max-M. Twenty routine samples from the laboratory were also analysed by both methods. There was no significant difference between results, with a mean of 10.94 gdl⁻¹ and 10.90 gdl⁻¹ for the HemoCue and Coulter, respectively (p = 0.12, t  = −1.99, df  = 70). The limits of agreement of the two methods (mean difference ± 2 SD) were −0.37 and +0.45 gdl⁻¹. The coefficients of repeatability of the 20 samples analysed in duplicate on each device were 0.26 gdl⁻¹ and 0.33 gdl⁻¹, respectively. The coefficients of variance were 0.74% (HemoCue) and 0.93% (Coulter). With adequate training and monitoring, the HemoCue provides comparable haemoglobin results for near-patient testing in theatre.     

Numerical Investigation on the Boundary Conditions for the Multiscale Base Functions

We study the multiscale finite element method for solving multiscale elliptic problems with highly oscillating coefficients, which is designed to accurately capture the large scale behaviors of the solution without resolving the small scale characters. The key idea is to construct the multiscale base functions in the local partial differential equation with proper boundary conditions. The boundary conditions are chosen to extract more accurate boundary information in the local problem. We consider periodic and non-periodic coefficients with linear and oscillatory boundary conditions for the base functions. Numerical examples will be provided to demonstrate the effectiveness of the proposed multiscale finite element method.     

Evaluation of a novel nanocrystalline hydroxyapatite paste Ostim? in comparison to Alpha-BSM? - more bone ingrowth inside the implanted material with Ostim? compared to Alpha BSM?

Background  

The purpose of this study was to evaluate the performance a newly developed nanocrystalline hydroxyapatite, OSTIM^? following functional implantation in femoral sites in thirty-eight sheep for 1, 2 or 3 months. Ostim^? 35 was compared to an established calcium phosphate, Alpha BSM^?.     

Local Discontinuous Galerkin Methods for the Degasperis-Procesi Equation

In this paper, we develop, analyze and test local discontinuous Galerkin (LDG) methods for solving the Degasperis-Procesi equation which contains nonlinear high order derivatives, and possibly discontinuous or sharp transition solutions. The LDG method has the flexibility for arbitrary hand p adaptivity. We prove the L²stability for general solutions. The proof of the total variation stability of the schemes for the piecewise constant P⁰case is also given. The numerical simulation results for different types of solutions of the nonlinear Degasperis-Procesi equation are provided to illustrate the accuracy and capability of the LDG method.     

Comparison of the Glidescope® and Airtraq® optical laryngoscopes in patients undergoing direct microlaryngoscopy

Optical laryngoscopes have been developed to facilitate difficult airway management. The Airtraq^® is a single-use device and the GlideScope^® is reusable. In this study, the Airtraq and the Glidescope were compared in 60 ASA I-III patients with tumours of the upper airway undergoing direct endoscopic microlaryngoscopy. Patients were randomly assigned to the Airtraq or the Glidescope group and the Cormack and Lehane grade was assessed by Macintosh laryngoscopy prior to tracheal intubation. There were no differences in tracheal intubation success rates or duration of intubation attempts between both devices. The Cormack and Lehane grade was improved in 77% and 82% of cases in the Airtraq and Glidescope group, respectively. Blood traces on the device and traumatic pharyngeal lesions were found more frequently in the Airtraq group. The Airtraq and Glidescope laryngoscopes are valuable tools for the management of patients with potentially difficult airways with the Glidescope appearing to be less traumatic.     

Optimal L2 Error Estimates for the Interior Penalty DG Method for Maxwell's Equations in Cold Plasma

In this paper, we consider an interior penalty discontinuous Galerkin (DG) method for the time-dependent Maxwell's equations in cold plasma. In Huang and Li (J. Sci. Comput., 42 (2009), 321–340), for both semi- and fully-discrete DG schemes, we proved error estimates which are optimal in the energy norm, but sub-optimal in the L²-norm. Here by filling this gap, we show that these schemes are optimally convergent in the L²-norm on quasi-uniform tetrahedral meshes if the solution is sufficiently smooth.