Direct resolution of the pitch of DNA on positively charged lipid bilayers by frequency-modulation AFM

High resolution structural studies of DNA and DNA binding proteins by atomic force microscopy (AFM) require well-bound samples on suitably flat substrates. Adsorbing the DNA onto a positively charged supported lipid bilayer has previously been shown to be a potentially effective strategy for structural studies with AFM. Here, using our home-built frequency-modulation AFM (FM-AFM), we show that these bilayer substrates are only maximally effective for high resolution AFM when the samples are short, linear DNA, compared with circular plasmid DNA. We find that, with the former sample, the measured width of the DNA is about 2 nm, the known DNA diameter, and there is a clear height modulation along the length of the DNA with a periodicity of about 3.4 nm, in excellent agreement with the known pitch of the double helix. This sample preparation strategy is expected to enable higher resolution studies of DNA and DNA binding proteins with FM-AFM than that can presently be achieved.     

Energy facility siting in the urban coastal zone: Compatible or not?

Abstract

Most federal and state coastal laws were framed with a distinct emphasis on preservation of rural/recreational areas. Yet in recent years a rural/urban coastal dichotomy has emerged. This has been especially prominent in the siting of energy facilities since these operations are often water dependent; power plants, for example, need huge amounts of cooling water, and offshore oil and gas extraction requires onshore support facilities. Recently, this issue has gained special prominence on the East Coast with the commencement of offshore oil and gas exploration. A case study was conducted in Hudson County, New Jersey, in New York harbor. In this area five oil‐related facility proposals were rejected from 1972 to 1976, primarily due to citizen opposition. Citizen activists now see the urban waterfront as a special place to which they want access and amenity uses rather than a continuation of past, almost exclusive industrial development. Hudson County citizens share the aspirations of those in several urban coastal areas which have experienced waterfront revitalization, including Baltimore, Boston, Chicago, Detroit, New Haven, Philadelphia, San Francisco, Seattle, and Toronto. Innovative siting which utilizes inland, rather than coastal, locations is suggested as one way to lessen urban/rural siting tensions.     

Decision support for risk assessment of mid-air collisions via population-based measures

Specifying proximity warning functions for aircraft in managed airspace has received considerable attention. However, similar functions for aircraft operating in unmanaged airspace have received comparatively little analysis despite the fact that these functions are stressed to a greater physical degree, and perhaps more frequently, than in managed airspace. The mid-air collision hazard and its associated risk are re-examined from both an historical and a systematic engineering modelling viewpoint. Historic measures of this transport risk in managed airspace have been based on fatalities normalized by flight hours or flight movements. However some of these data may not be available in unmanaged airspace. Another approach to measurement directs attention to populations at risk where several measures are now well known: collective risk, individual risk and the frequency of occurrence of the hazards that give rise to such risk. A decision support methodology is presented that relates both transport and population-based approaches. A cohesive and consistent set of aspired goals for various stakeholder groups can be set taking into account the different stakeholder needs. A case study is drawn from historic mid-air collision data to illustrate the process. A consistent basis for national-level policy decisions harmonised with proactive engineering design requirements is achieved. The strengths, limitations and implications of this approach for engineering design purposes are discussed.     

Strategies to achieve deep reductions in metropolitan transportation GHG emissions: the case of Philadelphia

ABSTRACT

This paper investigates strategies that could achieve an 80% reduction in transportation emissions from current levels by 2050 in the City of Philadelphia. The baseline daily lifecycle emissions generated by road transportation in the Greater Philadelphia Region in 2012 were quantified using trip information from the 2012 Household Travel Survey (HTS). Emissions were projected to the year 2050 accounting for population growth and trends in vehicle technology for both the Greater Philadelphia Region and the City of Philadelphia. The impacts of vehicle technology and shifts in travel modes on greenhouse gas (GHG) emissions in 2050 were quantified using a scenario approach. The analysis of 12 different scenarios suggests that 80% reduction in emissions is technically feasible through a combination of active transportation, cleaner fuels for public transit vehicles, and a significant market penetration of battery-electric vehicles. The additional electricity demand associated with greater use of electric vehicles could amount to 10.8 TWh/year. The use of plug-in hybrid electric vehicles (PHEV) shows promising results due to high reductions in GHG emissions at a potentially manageable cost.     

Traffic noise studies in a tropical environment

This paper reports upon a survey of traffic noise annoyance in three residential districts of Trinidad, West Indies. Householder perceptions were solicited by means of a questionnaire survey and direct measurements of traffic noise levels were taken. The results were compared with surveys elsewhere. It was concluded that household status had little effect on annoyance perception, that at L₁₀ levels greater than 70 dB(A) at a dwelling facade the noise level is unacceptable. L₁₀ levels less than 65 dB(A) at the building facade are not perceived as annoying in the environment considered.     

Plan implementation in the Florida keys through land acquisition

Abstract

The Florida Keys are an example of a fragile resource threatened by development. The early division of the area into small lots made conventional planning and regulation difficult. This paper describes the creation of a conservancy for the Keys—the history of development, the conditions necessitating a conservancy, and the political wrangling it took to implement the conservancy.     

就地冷再生技术在高速公路养护工程中的应用研究

就地冷再生技术具有施工便捷、污染小、旧料回收利用率高、节约成本等优势,在公路养护中得到了利用.以S49新扬高速为例,从适用条件、混合料设计、路用性能验证以及社会经济效益等方面,对就地冷再生技术进行系统研究,结果表明就地冷再生技术在高速公路养护工程中应用效果理想,可进行推广运用.     

Les systèmes de vélos en libre-service expliquent-ils le retour du vélo en ville ?

Many French and European cities have developed a bike sharing system since 2005. This policy may be explained in a great part by the success of the Velo??v in Lyon, which contributed to improve the image of cycling in the city. If bicycles, however, appear to find a new place in the city, one can wonder whether this is really due to bike sharing systems? What are the real uses of bicycles in contemporary cities, with or without such a system? To answer these questions, the paper starts with a literature review on bicycle in the city, to draw lessons from recent experiences of bike sharing systems. It then discusses the two cases of Lyon and Lille, which never had a bike sharing system on its own. The evolution of bicycle use is measured with a comparison of household transportation surveys in Lyon (1995 and 1998) and Lille (1998 and 2006). In both cities, the analysis reveals a rise in the proportion of healthiest citizens among urban bikers, as well as a return of bikes in dense areas. Bike sharing systems are part of such tendencies. They support them, but should not become a panacea for policies supporting bike use in the city.