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Abstract Background Health screening is undertaken to identify individuals who are deemed at higher risk of disease for further diagnostic testing so that they may possibly benefit from interventions to modify the natural course of disease. In Singapore, screening tests are widely available in the form of a package, which bundles multiple tests in one session and commonly includes non-recommended tests. There are various ethical issues associated with such testing as they may not be clinically appropriate and can result in more harm than benefit. This article describes the practice of health screening packages, identifies the ethical issues arising from such packages and discusses the implications of these ethical issues on policy and practice of screening in Singapore. Methods A content analysis of the websites of providers offering general health screening packages to individuals was conducted. A total of 14 health screening package providers were analysed for how packages were conducted and promoted, how clinically appropriate screening tests were, and the price range and composition of screening packages. A normative ethical analysis based on the four principles approach of beneficence, non-maleficence, autonomy and justice in biomedical ethics was used. Results Twelve of the 14 providers included non-recommended tests such as tumour markers, treadmill stress tests and MRI scans in their general health screening packages. Package prices ranged from S$26 to S$10,561, with providers charging higher when more tests were included. Health screening packages were broadly conducted in three stages: (1) the offer and selection of a health screening package; (2) medical assessment and performance of screening tests; (3) a post-screening review. While material provided by all providers was factual, there was no information on the potential risks or harms of screening. Conclusion Several ethical issues were identified that should be addressed with regard to health screening packages in Singapore. A key issue was the information gap between providers and patients, which may result in patients undergoing inappropriate testing that may be more harmful than beneficial. Health screening packages can stimulate unnecessary demand for healthcare and contribute to an inequitable distribution of healthcare resources.

In this article, we report the effect of poly (isoprene-random-3-methacryloxypropyltrimethoxysilane) random copolymer (PIPMSI) on the properties of kaolin-reinforced styrene-butadiene rubber (SBR). First, PIPMSI was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization as a modifier of kaolin. Then, the PIPMSI solution in dichloromethane was sprayed onto the surface of kaolin and dried to obtain kaolin grafted with polyisoprene (MSi-Kaol). Fourier transform infrared spectral studies indicated that the MSi-Kaol surface was covered with a layer of PIPMSI. The storage modulus (G') of SBR/MSi-Kaol compounds at low strains was significantly higher than that of SBR/kaolin blends, and the vulcanization rate of SBR/MSi-Kaol compounds was significantly lower than that of SBR/kaolin. The results of scanning electron microscopy showed that kaolin domains in SBR/MSi-Kaol vulcanizates were much better dispersed and distributed than in SBR/kaolin composites. Compared with SBR/kaolin composites, tensile strength, elongation at break, and tear strength of SBR/MSi-Kaol composites were significantly improved. KEYWORDS curing properties, kaolin, mechanical properties, RAFT polymerization, SBR, 1 | INTRODUCTION Styrene-butadiene rubber (SBR) is an important synthetic rubber that is widely used in tire treads, adhesive tapes, rubber hoses, wires and cables, and medical appliances, and its [...]

Appropriate constitutive models and reliable excavation and support sequences are believed to be the major concern in using finite element (FE) analysis to simulate shield tunnel excavation. This paper presents systematic two-dimensional (2D) and three-dimensional (3D) FE analyses employing a number of constitutive models accounting for initial soil anisotropy and non-coaxial plasticity, as evidenced within site investigations from the Tsinghuayuan Tunnel of the Jing-Zhang high-speed railway in China. The aim is to assess the effects of both the initial soil anisotropy and non-coaxiality on longitudinal and transverse tunneling-induced surface settlements. It is shown that the excavation procedures combined with the degree of cross-anisotropy are key towards the accurate prediction of maximum vertical displacements from tunneling, matching field data. Knowledge of the initial soil strength anisotropy can further improve the shape prediction of the transverse tunneling-induced surface settlement troughs. When considering n = 0.6 and [beta] = 0[degrees] in simulations, the transverse surface settlement trough obtained is almost coincident with monitored field data. Initial stiffness anisotropy used in the prediction of shield tunnel-induced surface settlements in sandy pebble soils does improve realism of results significantly. The maximum longitudinal settlement predicted by considering cross-anisotropy is larger than that predicted by its isotropic counterpart. Key words: tunneling, surface settlements, finite element (FE) modelling, constitutive models, soil anisotropy, non-coaxial plasticity. La question de l'utilisation de l'analyse par elements finis (EF) pour simuler l'excavation de tunnel a bouclier est consideree comme une preoccupation majeure dans l'utilisation de modeles constitutifs appropries et de sequences d'excavation et de soutien fiables. La presente etude presente des analyses systematiques par EF en deux dimensions (2D) et trois dimensions (3D) utilisant un certain nombre de modeles constitutifs tenant compte de l'anisotropie initiale du sol et de la plasticite non coaxiale, comme le montrent les etudes du site du tunnel de Tsinghuayuan de la ligne ferroviaire a grande vitesse Jing-Zhang en Chine. Cette etude vise a evaluer les effets de l'anisotropie initiale du sol et de la non-coaxialite sur les tassements de surface longitudinaux et transversaux induits par le creusement du tunnel. Il est revele que les procedures d'excavation combinees avec le degre d'anisotropie transversale sont la cle d'une prediction precise des deplacements verticaux maximums issus du creusement de tunnels, correspondant aux donnees de terrain. La connaissance du degre d'anisotropie de la resistance initiale du sol peut ameliorer la prediction de la forme des creux de tassement de surface transversal induit par le creusement de tunnel. En prenant en compte n = 0,6 et [beta] = 0[degrees] dans les simulations, le creux de tassement de surface transversal obtenu coincide presque avec les donnees de terrain controlees. Les resultats de l'anisotropie de la rigidite initiale utilisee dans la prediction des tassements de surface induits par le tunnel de bouclier dans les sols de galets sablonneux ameliorent le realisme des resultats de maniere significative. Le tassement longitudinal maximal predit en considerant l'anisotropie croisee est plus important que celui predit par sa contrepartie isotrope. [Traduit par la Redaction] Mots-cles : creusement de tunnels, tassements de surface, modelisation par elements finis (EF), modeles constitutifs, anisotropie du sol, plasticite non coaxiale., Introduction Serviceability design of shield tunnels requires accurate estimation of the surface settlements, especially for city areas, where there is existing sensitive infrastructure above the ground (e.g., Ou et al. [...]