A pilot study of spatial patterns in referrals to a multicentre cancer genetics service

OBJECTIVES: To analyse spatial and temporal patterns in patients referred to a cancer genetics service in order to monitor service utilization and accessibility. METHODS: Postcodes of patients during a 4-year period were used to examine spatial patterns using a Geographical Information System (GIS). Referral rates were compared visually and statistically to explore yearly variation for administrative areas in Wales. RESULTS: There has been a four-fold increase in actual referrals to the service over the period of study. The variance between unitary authority referral rates has decreased from the inception of the service from an almost ten-fold difference between lowest and highest in year 1 to less than a three-fold difference in year 4. CONCLUSIONS: This study shows the potential of GIS to highlight spatial variations in referral rates across Wales. Although the disparity in referral rates has decreased, trends in referral rates are not consistent. Ongoing research will examine those referral and referrer characteristics affecting uptake.     

爆炸冲击波对人体胸部创伤机理的有限元方法研究

通过建立简化的人体胸部三维有限元模型,模拟爆炸冲击波与人体胸部作用,根据人体胸部各个 器官的不同,选择合理的材料模型和参数,提出LS-DYNA有限元程序局部平面波改进方法,研究爆炸冲击波 与人体胸部作用的力学过程。依据人体胸部各个器官运动的速度差,预测创伤的区域分布;给出肺模型的压、 拉应力及剪切应力的变化规律,分析肺的创伤区域的分布,与解剖实验结果基本一致。对比Bowen创伤曲 线,证明人体胸部三维有限元模型可以有效得到冲击波创伤特征。     

Model study of noise field in the human chest due to turbulent flow in a larger blood vessel

An acoustic generation of noise by a larger human blood vessel and noise transmission in the thorax is modelled and studied. In making this, the random statistical nature of the noise sources, the basic vessel properties and the main features of the human chest structure are taken into account. Also the effects of changes in the basic vessel parameters are considered as a first approach to study acoustic effects of a vascular stenosis. The analysis of the resultant acoustic field reveals its similarity to the acoustic fields recorded in the appropriate experiments. The variations in the basic vessel parameters are found to cause the corresponding changes in the sound level and the production of new frequency components in the acoustic power spectrum. The acoustic power from a slightly thickened vessel is shown to be approximately proportional to the fourth power of the flow Reynolds number in the originally normal vessel and the eighth power of the ratio of the vessel diameters.     

Stresses in a human skull due to pulse loading

Summary Assuming the human skull to be an isotropic homogeneous viscoelastic prolate spheroidal shell and the brain to be a homogeneous viscoelastic fluid, the stresses in the skull due to three various types of pulse loading for different load-durations have been reported in the present paper.

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übersicht Unter der Annahme, da? die menschliche Sch?deldecke als isotrope, homogone, viskoelastische, flache sph?roidische Schale und das Gehirn als homogene, viskoelastische Flüssigkeit aufgefa?t werden k?nnen, werden in der vorliegenden Arbeit die Spannungen im Sch?del infolde dreier veschiedener Arten von Impulsbelastungen mit unterschiedlicher Lastdauer dargestellt.

     

An experimental study of pulsed micro-flows pertinent to continuous subcutaneous insulin infusion therapy

An experimental study was conducted to investigate the unsteady micro-flow driven by an insulin pump commonly used in continuous subcutaneous insulin infusion (CSII) therapy. A microscopic particle image velocimetry (PIV) system was used to characterize the transient behavior of the micro-flow upon the pulsed excitation of the insulin pump in order to elucidate the underlying physics for a better understanding of the microphysical process associated with the insulin delivery in CSII therapy. The effects of air bubbles entrained inside the micro-sized CSII tubing system on the insulin delivery process were also assessed based on the micro-PIV measurements. While most solutions to insulin occlusion-related problems are currently based on clinical trials, the findings derived from the present study can be used to provide a better guidance for the troubleshooting of insulin occlusion in CSII therapy.     

Heat conduction in a semi-infinite solid subject to time-dependent surface heat fluxes: an analytical study

A closed-form model for the computation of the transient temperature and heat flux distribution in the case of a semi-infinite solid of constant properties is investigated. The temperature and heat flux solutions are presented for time-dependent, surface-heat flux of the forms: (i) , (ii) , and (iii) , where is a real number and is a positive real number. The dimensionless (or reduced) temperature and heat flux solutions are presented in terms of the Whittaker function, the generalized representation of an incomplete Gamma functionI (b, x) which can also be expressed by the complementary error functions. It is also demonstrated that the present analysis covers some well known (classical) solutions as well as a family of new solutions for the heat transfer through a semi-infinite solid.

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Wärmeleitung in einem halbunendlichen Festkörper bei zeitveränderlichem Randwärmefluß: Eine analytische Untersuchung

Zusammenfassung Es wird ein geschlossenes Modell zur Berechnung der nichtstationären Temperatur- and Wärmestromverteilung für einen halbunendlichen Festkörper mit konstanten Stoffwerten untersucht. Die Lösungen für das Temperatur- und Wärmeflußfeld basieren auf folgenden Zeitgesetzen für den Randwärmefluß: (i) , (ii) , und (iii) wobei eine reelle Zahl und eine positive reelle Zahl ist. Die dimensionslosen Lösungen für das Temperatur- und Wärmflußfeld lassen sich in Form der Whittaker- Funktionen, der verallgemeinerten Darstellung einer unvollständigen Gamma-FunktionI (b, x) angeben, welche auch durch das komplementäre Fehlerintegral ausgedrückt werden kann. Es wird ferner gezeigt, daß die hier durchgeführte Untersuchung sowohl einige bekannte (klassische) Lösungen für die Wärmeleitung im halbunendlichen Festkörper liefert, wie auch eine Familie von neuen Lösungen.

     

Plaque components affect wall stress in stented human carotid artery: A numerical study

Carotid artery stenting presents challenges of in-stent restenosis and late thrombosis, which are caused primarily by alterations in the mechanical environment of the artery after stent implantation. The present study con-structed patient-specific carotid arterial bifurcation models with lipid pools and calcified components based on magnetic resonance imaging. We numerically analyzed the effects of multicomponent plaques on the distributions of von Mises stresses (VMSs) in the patient-specific models after stenting. The results showed that when a stent was deployed, the large soft lipid pool in atherosclerotic plaques cushioned the host artery and reduced the stress within the arterial wall;how-ever, this resulted in a sharp increase of VMS in the fibrous cap. When compared with the lipid pool, the presence of the calcified components led to slightly increased stresses on the luminal surface. However, when a calcification was located close to the luminal surface of the host artery and the stenosis, the local VMS was elevated. Overall, compared with calcified components, large lipid pools severely dam-aged the host artery after stenting. Furthermore, damage due to the calcified component may depend on location.     

Irreversibility investigation of Casson fluid flow in an inclined channel subject to a Darcy-Forchheimer porous medium:a numerical study

The heat transfer and entropy generation characteristics of the magnetohydrodynamic Casson fluid flow through an inclined microchannel with convective boundary conditions are analyzed.Further,the effects of the viscous forces,Joule heating,heat source/sink,and radiation on the flow are taken into account.The non-dimensional transformations are used to solve the governing equations.Then,the reduced system is resolved by the fourth-fifth order Runge-Kutta-Fehlberg method along with the shooting technique.The effects of different physical parameters on the heat transfer and entropy generation are discussed in detail through graphs.From the perspective of numerical results,it is recognized that the production of entropy can be improved with the Joule heating,viscous dissipation,and convective heating aspects.It is concluded that the production of entropy is the maximum with increases in the Casson parameter,the angle of inclination,and the Hartmann number.Both the Reynolds number and the radiation parameter cause the dual impact on entropy generation.