A Coupled FEM-BEM Approach for the Solution of the Free-Boundary Axi-Symmetric Plasma Equilibrium Problem

In this paper we present a coupled Finite Element Method – Boundary Element Method (FEM-BEM) approach for the solution of the free-boundary axi-symmetric plasma equilibrium problem. The proposed method, obtained from an improvement of the Hagenow-Lackner coupling method, allows to efficiently model the equilibrium problem in unbounded domains by discretizing only the plasma region; the external conductors can be modelled either as 2D or 3D models, according to the problem of interest. The paper explores different iterative methods for the solution of the nonlinear Grad-Shafranov equation, such as Picard, Newton-Raphson and Newton-Krylov, in order to provide a robust and reliable tool, able to handle large-scale problems (e.g. high resolution equilibria). This method has been implemented in the FRIDA code (FRee-boundary Integro-Differential Axisimmetric – https://github. om/matteobonotto/ FRIDA), together with a suitable Adaptive Integration Technique (AIT) for the computation of the source term. FRIDA has been successfully tested and validated against experimental data from RFX-mod device, and numerical equilibria of an ITER-like device.     

Numerical Integrators for Dispersion-Managed KdV Equation

In this paper, we consider the numerics of the dispersion-managed Korteweg-de Vries (DM-KdV) equation for describing wave propagations in inhomogeneous media. The DM-KdV equation contains a variable dispersion map with discontinuity, which makes the solution non-smooth in time. We formally analyze the convergence order reduction problems of some popular numerical methods including finite difference and time-splitting for solving the DM-KdV equation, where a necessary constraint on the time step has been identified. Then, two exponential-type dispersion-map integrators up to second order accuracy are derived, which are efficiently incorporated with the Fourier pseudospectral discretization in space, and they can converge regardless of the discontinuity and the step size. Numerical comparisons show the advantage of the proposed methods with the application to solitary wave dynamics and extension to the fast & strong dispersion-management regime.     

护士心理安全感在组织支持感与敬业度的中介作用

目的探讨护士组织支持感、心理安全感与敬业度的关系,为提升护士敬业度及改善护理管理提供依据。方法采用一般资料调查表、组织支持感量表、心理安全感量表及盖洛普Q12调查表对天津市3所三级甲等医院的414名护士进行问卷调查。结果护士敬业度总均分为(2.09±0.38)分,处于中等水平,组织支持感总均分为(3.19±0.31)分,心理安全感总均分为(3.42±0.45)分。护士敬业度、组织支持感、心理安全感三者呈正相关(P0.05,P0.01),心理安全感在组织支持感与敬业度的关系中发挥部分中介作用,中介效应为0.34,心理安全感与组织支持感共同解释敬业度总变异的21%。结论护士敬业度处于中等水平,护理管理者应创造良好的组织支持环境,给予护士更多情感支持以提高护士的心理安全感,从而提高其敬业度。     

Impact of supports and partnership on family quality of life

BackgroundIn recent decades, Family Quality of Life (FQOL) has emerged as a decisive construct, both to improve the living conditions of the families of people with disabilities and to assess the results on the services and supports that they receive.The aim of this research is to determine the perception of the families regarding their support needs, the quality of their partnerships with professionals, and their FQOL and then identify to what extent the supports of early childhood intervention centers have a positive impact on the families’ FQOL while exploring whether the family–professional partnership has become a fundamental intervening factor of FQOL.MethodThe participants were 202 families with children aged 0–6 with intellectual and developmental disabilities. We used the structural equation model to analyze the influence that the adequacy of the supports and the partnerships exerted on FQOL.ResultsThe results indicate that the families have language and speech support needs for their children and information needs for themselves, and that they are mostly satisfied with their partnerships with the professionals and their FQOL. Our results also indicate that their degree of satisfaction with the support was a good predictor of FQOL and their ratings of partnership quality was a key factor interceding on this effect.ConclusionsThis study provides professionals and public institutions with guidance when designing plans to improve early childhood intervention centers so the quality of life of these families and the progress of children with disabilities living in Spain become progressively stronger.     

Temperature-controlled power modulation compensates for heterogeneous nanoparticle distributions: a computational optimization analysis for magnetic hyperthermia

Purpose: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia.

Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.

Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.

Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.     

Constrained empirical-likelihood confidence regions in nonignorable covariate-missing data problems

Missing covariates in regression analysis are a pervasive problem in medical, social, and economic researches. We study empirical-likelihood confidence regions for unconstrained and constrained regression parameters in a nonignorable covariate-missing data problem. For an assumed conditional mean regression model, we assume that some covariates are fully observed but other covariates are missing for some subjects. By exploitation of a probability model of missingness and a working conditional score model from a semiparametric perspective, we build a system of unbiased estimating equations, where the number of equations exceeds the number of unknown parameters. Based on the proposed estimating equations, we introduce unconstrained and constrained empirical-likelihood ratio statistics to construct empirical-likelihood confidence regions for the underlying regression parameters without and with constraints. We establish the asymptotic distributions of the proposed empirical-likelihood ratio statistics. Simulation results show that the proposed empirical-likelihood methods have a better finite-sample performance than other competitors in terms of coverage probability and interval length. Finally, we apply the proposed empirical-likelihood methods to the analysis of a data set from the US National Health and Nutrition Examination Survey.     

Response shift effects of quality of life assessments in breast cancer survivors

Measurements of quality of life (QoL) can be distorted by respondents adapting to new situations between measurement points and consequently having a changed frame of reference. To investigate this bias in breast cancer survivors, we compare their QoL with that of the general population and use two complementary methods for detecting this bias. Breast cancer survivors (n = 308, response rate: 91%) were tested with the QoL questionnaire European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30. Response shift was examined with the thentest (retrospective judgements) and with the structural equation modelling (SEM) approach. Compared with the general population, breast cancer survivors showed impaired QoL in all functioning scales (Hedges’ g: ?0.56 to ?0.93) and symptom scales (Hedges’ g: 0.28–0.74).The thentest method indicated recalibration effects in several dimensions including social functioning. The SEM method detected a non‐uniform recalibration effect for social functioning from pretest to posttest and from pretest to thentest, but no effect between thentest and posttest. Breast cancer survivors’ QoL is clearly diminished. Comparing the two approaches for detecting response shift showed that it is also useful to apply SEM to retrospective judgements and that this can reveal response shift effects that would otherwise be overlooked.     

构建自我信心、动机和权威建议影响儿童安全座椅使用的分析模型

目的 建立自我信心、动机和权威建议影响儿童安全座椅使用的模型，并通过结构方程模型进行验证，为推动儿童安全座椅使用宣传倡导工作提供科学依据。方法 采用多阶段整群随机抽样方法，在上海市和深圳市调查9 112位拥有≥ 1辆私家轿车且有0~6岁儿童家庭的儿童监护人关于儿童安全座椅使用的情况，构建自我信心、动机和权威建议影响儿童安全座椅使用的模型，通过结构方程模型对理论模型进行验证和量化分析。结果 整体模型符合预期理论模型，且拟合情况较好，指标均达到标准。RMSEA=0.03，CFI=0.97。各路径标准化系数均有统计学意义（P<0.05）。权威建议和动机对自我信心的影响标准化系数分别为0.45和0.30，自我信心对儿童安全座椅使用的影响标准化系数为0.40。权威建议对动机的影响标准化系数为0.61。结论 在儿童安全座椅宣传倡导工作中应重视使用来源于专业权威、具备较好公信力和公益性的专家及机构组织的建议，应将儿童道路交通安全现况和安全座椅作用机制作为宣传重点之一。