Objectives, stimulus and feedback in signal control of road traffic

This article identifies the prospective role of a range of intelligent transport systems technologies for the signal control of road traffic. We discuss signal control within the context of traffic management and control in urban road networks and then present a control-theoretic formulation for it that distinguishes the various roles of detector data, objectives of optimization, and control feedback. By reference to this, we discuss the importance of different kinds of variability in traffic flows and review the state of knowledge in respect of control in the presence of different combinations of them. In light of this formulation and review, we identify a range of important possibilities for contributions to traffic management and control through traffic measurement and detection technology, and contemporary flexible optimization techniques that use various kinds of automated learning

Pedestrian route choice: an empirical study

There has been relatively little work done on route choice for pedestrians. The present paper addresses this issue by using a sample survey of daily walks in a UK urban area. The walks undertaken are reconstructed using a geographical information system and compared with the shortest available route. It was found that about 75 per cent of walkers in the sample chose the shortest available route. Two strategies were used to synthesise sets from which pedestrians could have chosen their routes. These choice sets can then be used in discrete choice modelling to study route choice and to determine which factors are important to pedestrians in this. At the time of writing, it is proposed to proceed with this modelling. The structure of the paper is as follows. Section 2 describes the various sources of data used in this work, section 3 discusses the choice set generation strategies that were developed, section 4 briefly compares the walks with the corresponding shortest routes, while section 5 presents the conclusions that were drawn from this

Islands contribute disproportionately high amounts of evolutionary diversity in passerine birds

Island systems generally have fewer species than continental areas due to their small size and geographical isolation. Low island diversity reduces the possibility of exportation of island lineages and island systems are not thought to have a major influence on the build-up of continental diversity. However, the view that islands represent the end of the colonization road has recently been challenged and islands do represent the origin of some specific continental lineages. Here we assess the net contribution of island systems to global diversity patterns of passerine birds, using a complete phylogeny (5,949 species), biogeographical regionalization and null-model comparisons. We show that, in contrast to major continental regions, island regions export relatively more evolutionary lineages than would be expected based on current distributional patterns. This result challenges a central paradigm in island biogeography and changes our perception of the relative importance of islands for the build-up of global diversity

Conformational and thermodynamic hallmarks of DNA operator site specificity in the copper sensitive operon repressor from Streptomyces lividans

Metal ion homeostasis in bacteria relies on metalloregulatory proteins to upregulate metal resistance genes and enable the organism to preclude metal toxicity. The copper sensitive operon repressor (CsoR) family is widely distributed in bacteria and controls the expression of copper efflux systems. CsoR operator sites consist of G-tract containing pseudopalindromes of which the mechanism of operator binding is poorly understood. Here, we use a structurally characterized CsoR from Streptomyces lividans (CsoRSl) together with three specific operator targets to reveal the salient features pertaining to the mechanism of DNA binding. We reveal that CsoRSl binds to its operator site through a 2-fold axis of symmetry centred on a conserved 5′-TAC/GTA-3′ inverted repeat. Operator recognition is stringently dependent not only on electropositive residues but also on a conserved polar glutamine residue. Thermodynamic and circular dichroic signatures of the CsoRSl-DNA interaction suggest selectivity towards the A-DNA-like topology of the G-tracts at the operator site. Such properties are enhanced on protein binding thus enabling the symmetrical binding of two CsoRSl tetramers. Finally, differential binding modes may exist in operator sites having more than one 5′-TAC/GTA-3′ inverted repeat with implications in vivo for a mechanism of modular control. © 2013 The Author(s)

Role of rodents in transmission of Salmonella and Campylobacter

Salmonella and Campylobacter are generally regarded as the most important food-borne pathogens in the world. Reduction or elimination of these pathogens in the first part of the food chain (on the farm) is important to prevent disease among consumers of animal products. In organic farming, elimination becomes more difficult, as food animals are allowed outdoors and have easy access to potential sources of hazardous pathogens. Whilst rodents are often associated by organic farmers with infrastructural damage and eating or spoiling of stored feed and products, their zoonotic risks are frequently underestimated. They can amplify the number of pathogens in the environment and transfer them to food animals. Thus organic farmers should be aware of the need for rodent control from a food safety perspective. Preferably, rodent control should form an integral part of a total package of hygiene measures to prevent transfer of food-borne pathogens. These should also include e.g. control of wild birds and flies and obligatory disinfection of boots/clothes and equipment for farm workers and visitors

Determination of thickness and density of a wet multilayer polymer system with sub-nanometer resolution by means of a dual polarization silicon-on-insulator microring

Determination of both thickness and refractive index of a thin biomolecular or polymer layer in wet conditions is a task not easily performed. Available tools such as XPS, AFM, ellipsometry and integrated photonic sensors often have difficulties with the native wet condition of said agents-under-test, perform poorly in the sub-5 nm regime or do not determine both characteristics in an absolute simultaneous way. The thickness of a multilayer system is often determined by averaging over a large amount of layers, obscuring details of the individual layers. Even more, the interesting behavior of the first bound layers can be covered in noise or assumptions might be made on either thickness or refractive index in order to determine the other. To demonstrate a solution to these problems, a silicon-on-insulator (SOI) microring is used to study the adsorption of a bilayer polymer system on the silicon surface of the ring. To achieve this, the microring is simultaneously excited with TE and TM polarized light and by tracking the shifts of both resonant wavelengths, the refractive index and the thickness of the adsorbed layer can be determined with a resolution on thickness smaller than 0.1 nm and a resolution on refractive index smaller than 0.01 RIU. An adhesive polyethyleneimine (PEI) layer is adsorbed to the surface, followed by the adsorption of poly(sodium-4-styrene sulfonate) (PSS) and poly(allylamine) hydrochloride (PAH). This high-resolution performance in wet conditions with the added benefits of the SOI microring platform such as low cost and multiplexibility make for a powerful tool to analyze thin layer systems, which is promising to research binding conformation of proteins as well

A market-based transmission planning for HVDC grid—case study of the North Sea

There is significant interest in building HVDC transmission to carry out transnational power exchange and deliver cheaper electricity from renewable energy sources which are located far from the load centers. This paper presents a market-based approach to solve a long-term TEP for meshed VSC-HVDC grids that connect regional markets. This is in general a nonlinear, non-convex large-scale optimization problem with high computational burden, partly due to the many combinations of wind and load that become possible. We developed a two-step iterative algorithm that first selects a subset of operating hours using a clustering technique, and then seeks to maximize the social welfare of all regions and minimize the investment capital of transmission infrastructure subject to technical and economic constraints. The outcome of the optimization is an optimal grid design with a topology and transmission capacities that results in congestion revenue paying off investment by the end the project's economic lifetime. Approximations are made to allow an analytical solution to the problem and demonstrate that an HVDC pricing mechanism can be consistent with an AC counterpart. The model is used to investigate development of the offshore grid in the North Sea. Simulation results are interpreted in economic terms and show the effectiveness of our proposed two-step approach

Convective injection and photochemical decay of peroxides in the tropical upper troposphere: Methyl iodide as a tracer of marine convection

The convective injection and subsequent fate of the peroxides H2O2 and CH3OOH in the upper troposphere is investigated using aircraft observations from the NASA Pacific Exploratory Mission-Tropics A (PEM-Tropics A) over the South Pacific up to 12 km altitude. Fresh convective outflow is identified by high CH3I concentrations; CH3I is an excellent tracer of marine convection because of its relatively uniform marine boundary layer concentration, relatively well-defined atmospheric lifetime against photolysis, and high sensitivity of measurement. We find that mixing ratios of CH3OOH in convective outflow at 8-12 km altitude are enhanced on average by a factor of 6 relative to background, while mixing ratios of H2O2 are enhanced by less than a factor of 2. The scavenging efficiency of H2O2 in the precipitation associated with deep convection is estimated to be 55-70%. Scavenging of CH3OOH is negligible. Photolysis of convected peroxides is a major source of the HOx radical family (OH + peroxy radicals) in convective outflow. The timescale for decay of the convective enhancement of peroxides in the upper troposphere is determined using CH3I as a chemical clock and is interpreted using photochemical model calculations. Decline of CH3OOH takes place on a timescale of a 1-2 days, but the resulting HOx converts to H2O2, so H2O2 mixing ratios show no decline for ∼5 days following a convective event. The perturbation to HOx at 8-12 km altitude from deep convective injection of peroxides decays on a timescale of 2-3 days for the PEM-Tropics A conditions. Copyright 1999 by the American Geophysical Union

Preferred levels for background ducking to produce esthetically pleasing audio for TV with clear speech

In audio production, background ducking facilitates speech intelligibility while allowing the background to fulfill its purpose, e.g., to create ambience, set the mood, or convey semantic cues. Technical details for recommended ducking practices are not currently documented in the literature. Hence, we first analyzed common practices found in TV documentaries. Second, a listening test investigated the preferences of 22 normal-hearing participants on the Loud- ness Difference (LD) between commentary and background during ducking. Highly personal preferences were observed, highlighting the importance of object-based personalization. Sta- tistically significant difference was found between non-expert and expert listeners. On average, non-experts preferred LDs that were 4 LU higher than the ones preferred by experts. A sta- tistically significant difference was also found between Commentary over Music (CoM) and Commentary over Ambience (CoA). Based on the test results, we recommend at least 10 LU difference for CoM and at least 15 LU for CoA. Moreover, a computational method based on the Binaural Distortion-Weighted Glimpse Proportion (BiDWGP) was found to match the median preferred LD for each item with good accuracy (mean absolute error = 1.97 LU ± 2.50)