SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Infrastructure

272

Since their appearance at the end of the 19th century, traffic lights have been the primary mode of granting access to road intersections. Today, this centuries-old technology is challenged by advances in intelligent transportation, which are opening the way to new solutions built upon slot-based systems similar to those commonly used in aerial traffic: what we call Slot-based Intersections (SIs). Despite simulation-based evidence of the potential benefits of SIs, a comprehensive, analytical framework to compare their relative performance with traffic lights is still lacking. Here, we develop such a framework. We approach the problem in a novel way, by generalizing classical queuing theory. Having defined safety conditions, we characterize capacity and delay of SIs. In the 2-road crossing configuration, we provide a capacity-optimal SI management system. For arbitrary intersection configurations, near-optimal solutions are developed. Results theoretically show that transitioning from a traffic light system to SI has the potential of doubling capacity and significantly reducing delays. This suggests a reduction of non-linear dynamics induced by intersection bottlenecks, with positive impact on the road network. Such findings can provide transportation engineers and planners with crucial insights as they prepare to manage the transition towards a more intelligent transportation infrastructure in cities.

Concepts: Transport, Road, Street, Traffic, Infrastructure, Traffic light, 19th century, Pedestrian crossing

99

Coinciding with major changes to its municipal water system, Flint, MI, endured Legionnaires' disease outbreaks in 2014 and 2015. By sampling premise plumbing in Flint in the fall of 2016, we found that 12% of homes harbored legionellae, a frequency similar to that in residences in neighboring areas. To evaluate the genetic diversity of Legionella pneumophila in Southeast Michigan, we determined the sequence type (ST) and serogroup (SG) of the 18 residential isolates from Flint and Detroit, MI, and the 33 clinical isolates submitted by hospitals in three area counties in 2013 to 2016. Common to one environmental and four clinical samples were strains of L. pneumophila SG1 and ST1, the most prevalent ST worldwide. Among the Flint premise plumbing isolates, 14 of 16 strains were of ST367 and ST461, two closely related SG6 strain types isolated previously from patients and corresponding environmental samples. Each of the representative SG1 clinical strains and SG6 environmental isolates from Southeast Michigan infected and survived within macrophage cultures at least as well as a virulent laboratory strain, as judged by microscopy and by enumerating CFU. Likewise, 72 h after infection, the yield of viable-cell counts increased >100-fold for each of the representative SG1 clinical isolates, Flint premise plumbing SG6 ST367 and -461 isolates, and two Detroit residential isolates. We verified by immunostaining that SG1-specific antibody does not cross-react with the SG6 L. pneumophila environmental strains. Because the widely used urinary antigen diagnostic test does not readily detect non-SG1 L. pneumophila, Legionnaires' disease caused by SG6 L. pneumophila is likely underreported worldwide.IMPORTANCEL. pneumophila is the leading cause of disease outbreaks associated with drinking water in the United States. Compared to what is known of the established risks of colonization within hospitals and hotels, relatively little is known about residential exposure to L. pneumophila One year after two outbreaks of Legionnaires' disease in Genesee County, MI, that coincided with damage to the Flint municipal water system, our multidisciplinary team launched an environmental surveillance and laboratory research campaign aimed at informing risk management strategies to provide safe public water supplies. The most prevalent L. pneumophila strains isolated from residential plumbing were closely related strains of SG6. In laboratory tests of virulence, the SG6 environmental isolates resembled SG1 clinical strains, yet they are not readily detected by the common diagnostic urinary antigen test, which is specific for SG1. Therefore, our study complements the existing epidemiological literature indicating that Legionnaires' disease due to non-SG1 strains is underreported around the globe.

Concepts: Epidemiology, Water, Legionellosis, Legionella, Drinking water, Infrastructure, Michigan, Water supply network

70

Ice accretion has a negative impact on critical infrastructure, as well as a range of commercial and residential activities. Icephobic surfaces are defined by an ice adhesion strength τice < 100 kPa. However, the passive removal of ice requires much lower values of τice, such as on airplane wings or power lines (τice < 20 kPa). Such low τice values are scarcely reported, and robust coatings that maintain these low values have not been reported previously. We show that, irrespective of material chemistry, by tailoring the cross-link density of different elastomeric coatings and by enabling interfacial slippage, it is possible to systematically design coatings with extremely low ice adhesion (τice < 0.2 kPa). These newfound mechanisms allow for the rational design of icephobic coatings with virtually any desired ice adhesion strength. By using these mechanisms, we fabricate extremely durable coatings that maintain τice < 10 kPa after severe mechanical abrasion, acid/base exposure, 100 icing/deicing cycles, thermal cycling, accelerated corrosion, and exposure to Michigan wintery conditions over several months.

Concepts: Materials science, Design, Infrastructure

27

Notwithstanding ambiguities, long-term economic resurgence in Afghanistan amidst water insecurity exacerbated by climate change decisively requires a water protection strategy that will complement a multitude of agroindustrial and socioeconomic activities in an environmentally sustainable and climate resilient manner. In this paper, we begin with a perspective on institutions, legislation, and key issues in the water sector of Afghanistan. We then embark on linking the integrated water resources management (IWRM) and strategic environmental assessment (SEA) approaches as a novel framework for strategic water management and subsequently propose a strategy for post-conflict water protection based on the coalesced IWRM and SEA. Context relevant good practices worldwide are presented to provide empirical evidence for this approach whereas perceived opportunities and vulnerabilities in the Afghan context are discussed. Examination of post-conflict water sector initiatives in Afghanistan reveals the critical role of foreign assistance in both water infrastructure rehabilitation and modernization of the institutional aspect of water management. The introduction of IWRM as the basis for a progressive water sector strategy has been seen as a major milestone which is detrimentally matched by substantial deficiency in national capacity for implementation. Concurrently, the role of extra-national actors in relevant policy interventions has been considered catalytic despite criticisms of proposed regulations as being anachronistic to field realities. Therefore the view is maintained to practicable policies by accelerating policy learning in the country’s water and environment sectors to encourage homegrown water strategy innovations. Demonstratively, mainstreaming IWRM-SEA coalescence will bridge institutional gaps for better feedback between local and national water stakeholders, providing a venue for improved delivery of water services to sustain post-conflict socioeconomic recovery and promote environmental stewardship.

Concepts: Water, Water management, Hydrology, Water resources, Infrastructure, Water supply, Water industry, Integrated Water Resources Management

25

The 2014-2015 Legionnaires' disease (LD) outbreak in Genesee County, MI, and the outbreak resolution in 2016 coincided with changes in the source of drinking water to Flint’s municipal water system. Following the switch in water supply from Detroit to Flint River water, the odds of a Flint resident presenting with LD increased 6.3-fold (95% CI: 2.5, 14.0). This risk subsided following boil water advisories, likely due to residents avoiding water, and returned to historically normal levels with the switch back in water supply. During the crisis, as the concentration of free chlorine in water delivered to Flint residents decreased, their risk of acquiring LD increased. When the average weekly chlorine level in a census tract was <0.5 mg/L or <0.2 mg/L, the odds of an LD case presenting from a Flint neighborhood increased by a factor of 2.9 (95% CI: 1.4, 6.3) or 3.9 (95% CI: 1.8, 8.7), respectively. During the switch, the risk of a Flint neighborhood having a case of LD increased by 80% per 1 mg/L decrease in free chlorine, as calculated from the extensive variation in chlorine observed. In communities adjacent to Flint, the probability of LD occurring increased with the flow of commuters into Flint. Together, the results support the hypothesis that a system-wide proliferation of legionellae was responsible for the LD outbreak in Genesee County, MI.

Concepts: Water, Drinking water, Infrastructure, Water supply network, Flint River, Genesee County, Michigan, Flint, Michigan, Swartz Creek, Michigan

25

The national power grid is the most critical and the most vulnerable life-support infrastructure in modern society. Electricity serves as the essential element in sustaining every other sector of critical infrastructure including water, fuel and communications. Collective experience with responding to and recovering from widespread, long-duration power outages - known as black sky events - is nearly non-existent. Understanding these risks and weaknesses requires a collaborative planning effort with the public and private sectors to identify and protect critical nodes within the interdependent infrastructure to ensure that recovery from a catastrophic event is possible. This also requires a ‘whole community’ approach to planning and execution to facilitate a response on an unprecedented level.

Concepts: Sociology, Chemical element, United Kingdom, Knowledge, Infrastructure, Smart grid, Power outage, Electrical grid

24

Roadways pose serious threats to animal populations. The installation of roadway mitigation measures is becoming increasingly common, yet studies that rigorously evaluate the effectiveness of these conservation tools remain rare. A highway expansion project in Ontario, Canada included exclusion fencing and ecopassages as mitigation measures designed to offset detrimental effects to one of the most imperial groups of vertebrates, reptiles. Taking a multispecies approach, we used a Before-After-Control-Impact study design to compare reptile abundance on the highway before and after mitigation at an Impact site and a Control site from 1 May to 31 August in 2012 and 2013. During this time, radio telemetry, wildlife cameras, and an automated PIT-tag reading system were used to monitor reptile movements and use of ecopassages. Additionally, a willingness to utilize experiment was conducted to quantify turtle behavioral responses to ecopassages. We found no difference in abundance of turtles on the road between the un-mitigated and mitigated highways, and an increase in the percentage of both snakes and turtles detected dead on the road post-mitigation, suggesting that the fencing was not effective. Although ecopassages were used by reptiles, the number of crossings through ecopassages was lower than road-surface crossings. Furthermore, turtle willingness to use ecopassages was lower than that reported in previous arena studies, suggesting that effectiveness of ecopassages may be compromised when alternative crossing options are available (e.g., through holes in exclusion structures). Our rigorous evaluation of reptile roadway mitigation demonstrated that when exclusion structures fail, the effectiveness of population connectivity structures is compromised. Our project emphasizes the need to design mitigation measures with the biology and behavior of the target species in mind, to implement mitigation designs in a rigorous fashion, and quantitatively evaluate road mitigation to ensure allow for adaptive management and optimization of these increasingly important conservation tools.

Concepts: Turtle, Reptile, Road, Freeway, Infrastructure, Motorway, Amniote, The Road

22

The evolution of infrastructure networks such as roads and streets are of utmost importance to understand the evolution of urban systems. However, datasets describing these spatial objects are rare and sparse. The database presented here represents the road network at the french national level described in the historical map of Cassini in the 18th century. The digitization of this historical map is based on a collaborative methodology that we describe in detail. This dataset can be used for a variety of interdisciplinary studies, covering multiple spatial resolutions and ranging from history, geography, urban economics to network science.

Concepts: Geography, Social sciences, Road, Street, 18th century, Infrastructure, The Road, Civil engineering

16

The M74 motorway extension, Glasgow, opened in June 2011. One justification for construction was an expectation that it would reduce road traffic accidents (RTAs) on local non-motorway roads. This study evaluated the impact of the extension on the number of RTAs, stratifying by accident severity.

Concepts: Tram accident, Road, Traffic, Freeway, Infrastructure, Motorway, Accidents, Civil engineering

14

There is a global trend towards the use of ad hoc participation processes that seek to engage grassroots stakeholders in decisions related to municipal infrastructure, land use and services. We present the results of a scholarly literature review examining 14 articles detailing specific cases of these processes to contribute to the discussion regarding their utility in advancing health equity. We explore hallmarks of compromised processes, potential harms to grassroots stakeholders, and potential mitigating factors. We conclude that participation processes often cut off participation following the planning phase at the point of implementation, limiting convener accountability to grassroots stakeholders, and, further, that where participation processes yield gains, these are often due to independent grassroots action. Given the emphasis on participation in health equity discourse, this study seeks to provide a real world exploration of the pitfalls and potential harms of participation processes that is relevant to health equity theory and practice.

Concepts: Ad hoc, Explorer, Infrastructure, Equity theory, The Point, Mitigating factor