Geant4不同物理模型对放疗质子束模拟的影响

Monte Carlo方法常用于质子束剂量模拟以优化质子束临床治疗,合适的物理模型选择关系到Monte Carlo模拟结果的可靠性及模拟效率。本工作选取9个可用于质子模拟的Geant4物理模型,计算比较了质子束在多种介质中的剂量及次级粒子产额。结果表明:标准电磁物理模型、低能电磁Penelope模型和Livermore模型虽在模拟质子整体剂量分布上可接受,但在微观上缺失重粒子生成。参数化驱动模型LHEP的模拟时间最短,但与QGSP相同,均不能产生复杂重离子。QGSP_BIC_EMY模型较其他模型明显低估Bragg峰-入口剂量比和绝对剂量。QGSP_BERT模型、QGSP_BIC模型和FTFP_BERT模型较适合放疗质子束模拟。     

玄武湖景观区总体规划--以文化游憩为导向的景观区总体规划

面对我国历史文化景观的旅游开发现状，提出以文化游憩为导向的历史文化景观研究方法，提出从文化、游憩及其时空布局来进行历史文化景观发展策划与规划的理论方法，着重论述了文化、景观、游憩的三元关系以及传统文化在景观中的物化。以玄武湖景观区总体规划为例，论述了其文化游憩定性、定位、文化景观的发掘及其传统文化的景观物化。     

天津蓟县、辽宁义县等地古建筑遗存考察纪略(2)

义县八塔山八塔山位于义县城南杨乡八塔子村.距县城约十余公里.南临沟壑.北向俯视宽阔谷地,有八座塔依次建于八个峰顶.据传乃辽圣宗为纪念佛     

赤峰地区辽代建筑遗存考察纪略(一)

近期,建筑文化考察组逐步开展了对辽代木构建筑较为详尽的考察研究,现已将已故建筑历史学家陈明达先生的遗作《独乐寺观音阁、山门的大木制度》增编为图文并茂的专著《蓟县独乐寺》正式出版[1],又与天津大学建筑学院合作,先后对义县奉国寺、涞源阁院寺、大同善化寺、华严寺等重要的建筑实例做了多次考察和详细测绘[2].……     

ZD203型温控不锈钢煮茧机的设计与实效

文章介绍了ZD203型不锈钢温控煮茧机的设计依据及工艺性能,机械结构及自控系统等装置特点,通过多家缫丝厂长期生产结果表明,该机工艺性能优良,煮熟茧质量好,原料适应性强,自立缫可兼用,机械结构紧凑合理,能耗显著减少,总蒸气压力控制及主要区段温度控制系统具有实用性强,可靠性高,维修方便等特点,是目前国内先进设备。     

宁波应成为长江三角洲地区的能源基地

随着长江三角洲地区经济的快速发展,能源供需矛盾越来越突出。虽然西气东输、东海油气田开发和西电东送工程将在一定程度上缓解长江三角洲地区的能源供需矛盾,但仍需要通过港口输入大量能源,发电装机容量也需要大大增加,这样,很有必要在长江三角洲地区选择一个条件最好的港口城市,建立能源输入和转运基地,宁波应是首选。根据宁波的自然地理和经济条件,借鉴国外的经验,我们认为宁波应建设成为石油化工基地、石油中转和储备基地、东海油气田开发的处理、加工、输配和后勤服务基地、LPG接收和转运基地、LNG接收和转运基地、煤炭接收和转运基地及电力生产和供应基地,并配合上海建立石油交易市场。     

城市地下空间开发建设及权属管理研究

随着城市的发展,土地资源变得日益稀缺,土地开发利用的重点已由向四周平面扩展转移到向地下寻求空间的方向上来。发达国家的发展历史经验表明,人均GDP进入1000美元后,基本具备了大规模开发利用地下空间的条件和实力;人均GDP在     

Distribution of transport injury and related risk behaviours in a large national cohort of Thai adults

Background

A major barrier to addressing the problem of transport injury in low to middle-income countries is the lack of information regarding the incidence of traffic crashes and the demographic, behavioural and socio-economic determinants of crash-related injury. This study aimed to determine the baseline frequency and distribution of transport injury and the prevalence of various road safety behaviours in a newly recruited cohort of Thai adults.

Methods

The Thai Health-Risk Transition Study includes an ongoing population-based cohort study of 87,134 adult students residing across Thailand. Baseline survey data from 2005 includes data on self-reported transport injury within the previous 12 months and demographic, behavioural and transportation factors that could be linked to Thailand's transport risks.

Results

Overall, 7279 (8.4% or 8354 per 100,000) of respondents reported that their most serious injury in the 12 months prior to recruitment in the cohort was transport-related, with risk being higher for males and those aged 15–19 years. Most transport injuries occurred while using motorcycles. A much higher proportion of males reported driving after three or more glasses of alcohol at least once in the previous year compared to females. The prevalence of motorcycle helmet and seat belt wearing in this sample were higher than previously reported for Thailand.

Conclusions

The reported data provide the basis for monitoring changes in traffic crash risks and risk behaviours in a cohort of adults in the context of ongoing implementation of policy and programs that are currently being introduced to address the problem of transport-related injury in Thailand.