Regulation of the informal transport sector in Rio de Janeiro,Brazil: welfare impacts and policy analysis

In Brazil, the explosion of informal transport activity during the past decade has had profound effects on formal public transport systems and is a source of great controversy in the urban transportation sector. A variety of policies have been proposed to manage the growth of the sector. This study seeks to understand how proposed policies will impact the users of these systems. A corridor in Rio de Janeiro with substantial informal activity was used as a case study. Measures of welfare changes in a discrete choice framework were used to estimate proposed policies’ impacts on users. Eleven candidate policies were evaluated, ranging from the eradication of the informal modes and investment in formal modes, to the legalization of the informal modes. Benefits were compared with costs and the distribution of benefits across income classes was explored. Net benefits from some policies were found to be substantial. Legalizing the informal sector was found to benefit users slightly but further investments in the sector are probably inefficient. Users benefited most from improvements in formal mass transit modes, at roughly 100–200 dollars per commuter per year. Finally, policies to foster a competitive environment for the delivery of both informal and formal services were shown to benefit users about 100 dollars per commuter per year. Together, the regulation of the informal sector and investments in the formal sector serve to reinforce the movement towards competitive concessions for services and help reduce the impacts of cartelization and costly in-road competition.

Assessing the Potential for Surf Break Co-Management: Evidence from New Zealand

The involvement of surfers in surf break co-management initiatives may assist local authorities in providing for surf breaks and develop community stewardship. This research involved a comparative case study of the Auckland and Otago regions in New Zealand to assess the potential, and identify key ingredients, for successful surf break co-management. An online survey of surf break users (n = 181) and qualitative interviews (n = 16) considered the potential voluntary involvement of surfers, the role of local authorities and types of approach to surf break co-management. Findings indicate a level of support from a proportion of surfers to be involved and stress the need for local authorities to provide a supporting policy response. A local-scale co-management approach, similar to National Surfing Reserves in New South Wales, Australia, is considered more likely to produce positive outcomes compared to the involvement of surf break interests in coastal-wide co-management approaches.     

沥青路面JTJ014与AASHTO设计方法比较

现行JTJ014规范与AASHTO指南两种沥青路面结构设计方法是不同的体系,对两者作一定量的比较.分析和讨论表明,虽然两种结构设计方法有重要区别,但结果高度相关,区别主要体现在可靠度上.在标准排水条件下,JTJ014规范定值设计大体与AASHTO指南标准差S0=0.50、可靠度水平R=90%的结果相当;对于高速、一级公路,这个水平偏低,而对于三、四级公路可能不必要.可靠度的要求可以近似地用BZZ-100累计作用次数的倍数表达;如果需要,可以采用放大或缩小设计累计轴次的方式考虑可靠度作为过渡措施.可靠度可以在很大程度上影响路面的设计结果;研究开发反映实际情况的沥青路面可靠度标准,应当可以提到议事日程.     

脑缺血大鼠脑皮层中强啡肽A（1—13）的经时表达及脑含水量的变化

目的 研究局灶性脑缺血大鼠脑皮层中强啡肽A(1-13)的经时表达及脑含水量的变化.方法 用线栓法建立大鼠大脑中动脉梗塞模型,用免疫组织化学方法观察脑缺血组大鼠及假手术对照组大鼠缺血侧及非缺血侧脑皮层强啡肽A(1-13)在脑缺血100 min后再灌注4、8、24 h的表达及脑含水量的变化.结果 假手术对照组大鼠缺血侧及非缺血侧脑皮层表达强啡肽A(1-13)的细胞数分别是每高倍镜视野(60.2±5.1)个及(61.1±3.9)个,在脑缺血后再灌注4、8、24 h大鼠缺血侧及非缺血侧脑皮层的强啡肽A(1-13)表达细胞数分别是每高倍镜视野(39.3±6.2)个及(60.3±3.7)个、(41.5±5.8)个及(60.1±3.9)个、(25.2±5.1)个及(59.6±5.9)个;而脑缺血后再灌注4、8、24 h的缺血侧含水量逐渐增加.结论 大鼠脑缺血后缺血侧脑皮层的强啡肽A(1-13)表达逐渐减少而含水量逐渐增加.     

破产or救助哪个更能拯救美国汽车业？

2008年,由于汽车销量骤跌、燃油价格飞涨,以及经济萧条等因素,底特律汽车“三巨头”被推向了可能申请破产保护的危险境地。虽然,美国政府打算介入。但关于到底选择破产还是救援的辩论仍然十分激烈。这两个论点都有其道理,那么。奥巴马政府会采取什么方案呢？     

Hedonic modeling of commercial property values: distance decay from the links and nodes of rail and highway infrastructure

Transportation - This study investigates the impacts of positive and negative externalities of highways and light rail on commercial property values in Phoenix, Arizona. We hypothesize that the...     

孔隙介质中含砷聚集物的三维成像

为观测砷沉积导致的孔隙介质内部结构的改变,采用X射线差异微断层扫描技术,扫描从Loa流域获得的河床沉积物和实验室配制的含砷样品,对含砷聚集物在孔隙介质中的分布进行了成像分析.经过图像处理去除图像上的噪点和增强图像中砷的信息,获得了孔隙介质中含砷聚集物的三维数据组;采用Avizo 6和Blob3D等工具,对三维数据组进行重建和可视化.成像显示:大量含砷聚集物沉积在介质孔隙和介质表面;不同尺寸聚集物的形态呈现出明显的多样化特征——小颗粒聚集物趋于球形,大颗粒聚集物则趋于扁平状.研究表明,该技术可在不破坏样品的前提下,实现对孔隙介质沉积前后内部结构变化的直接观测.     

Snowplow Steering Guidance with Gain Stabilization

Acquisition and utilization of lateral guidance information is crucial for steering a vehicle. With practice, drivers can successfully perform the steering function using visual perception and hand-eye coordination. However, this seemingly simple task becomes difficult when the visual information loses its clarity. Driving a snowplow during whiteout conditions is one such example. In order to improve the safety and efficiency of snow removal operations, a supplemental guidance display was proposed and successfully implemented in a California Department of Transportation (Caltrans) snowplow. The guidance information was calculated based on the magnetic markers embedded in the roadway. The crucial step to this success is a transformation of the guidance display problem into a robust driver-in-the-loop control problem. This transformation considers the 'display' law as part of the overall driver-steering-control algorithm. Two key 'assumptions' for this design are (1) the 'display' law should be designed in such a way that drivers can use 'proportional' control gain alone to satisfy the performance and stability requirements of the steering tasks, and (2) the driver steering model can be described as a combination of gain and dynamic delay under the display law in (1). This paper describes the validation process for the 'gain' stabilization design concept as well as the associated driver steering model using the initial snowplow test data.     

A justice-theoretic approach to the distribution of transportation benefits: Implications for transportation planning practice in the United States

Transportation improvements inevitably lead to an uneven distribution of user benefits, in space and by network type (private and public transport). This paper makes a moral argument for what would be a fair distribution of these benefits. The argument follows Walzer’s “Spheres of Justice” approach to define the benefits of transportation, access, as a sphere deserving a separate, non-market driven, distribution. That distribution, we propose, is one where the maximum gap between the lowest and highest accessibility, both by mode and in space, should be limited, while attempting to maximize average access. We then review transportation planning practice for a priori distributional goals and find little explicit guidance in conventional and even justice-oriented transportation planning and analyses. We end with a discussion of the implications for practice.