Vehicle Steering control: A model of learning

A hierarchy of strategies were postulated to describe the process of learning steering control. Vehicle motion and steering control data were recorded for twelve novices who drove an instrumented car twice a week during and after a driver training course. Car-driver describing functions were calculated, the probable control structure determined, and the driver-alone transfer function modelled. The data suggested that the largest changes in steering control with learning were in the way the driver used the lateral position cue

Is HIV short-sighted? Insights from a multistrain nested model

An important component of pathogen evolution at the population level is evolution within hosts. Unless evolution within hosts is very slow compared to the duration of infection, the composition of pathogen genotypes within a host is likely to change during the course of an infection, thus altering the composition of genotypes available for transmission as infection progresses. We develop a nested modeling approach that allows us to follow the evolution of pathogens at the epidemiological level by explicitly considering within-host evolutionary dynamics of multiple competing strains and the timing of transmission. We use the framework to investigate the impact of short-sighted within-host evolution on the evolution of virulence of human immunodeficiency virus (HIV), and find that the topology of the within-host adaptive landscape determines how virulence evolves at the epidemiological level. If viral reproduction rates increase significantly during the course of infection, the viral population will evolve a high level of virulence even though this will reduce the transmission potential of the virus. However, if reproduction rates increase more modestly, as data suggest, our model predicts that HIV virulence will be only marginally higher than the level that maximizes the transmission potential of the virus

ITS implementation plan for the Gold Coast area

ITS needs to be used to reinforce the planned major changes to the road functional hierarchy in the District, namely: • the use of Southport-Burleigh Rd. (SBR) as the major regional corridor; • the removal of through traffic from the GCH; • the use of Oxley Dr./Olsen Av./Ross St./NBR as another major north-south by-pass; • the use of Smith St.; NSR/Queen St.; NBR and Reedy Creek Rd. – West Burleigh Road as the major east-west access corridors. There is a need to integrate the proposed ITS measures into the current related plans for the Pacific Motorway and into the overall traffic control strategies for the area as a whole. In addition, the staging of the proposed plan needs to take into account the planned DMR capital Works Program. An index representing the degree of priority to be attached to each network link was developed to assist in the phased implementation of ITS technologies over the next 5 years. 'ITS Index' is made up of five variables, namely: • Accident rate factor • AADT • Volume/Capacity ratio • Delay • % Commercial Vehicles The main components of the ITS plan are shown diagrammatically in Figure 1. The latter assumes that the high level of ITS implementation on the Pacific Motorway will be extended in time to the remainder of that Highway. To assist in the implementation of the road hierarchy system, a new static signage plan should be implemented. This plan needs to reinforce the changes by clearly assigning single road names to corridors and by placing new signs at appropriate locations. Capturing Traffic Data The following corridors should be equipped with automatic traffic monitoring capability in priority order: High Priority ? SBR corridor from Smith St. connection to Reedy Creek Rd. ? Smith St. from Pacific Highway to High St. ? GCH from Pacific Highway to North St. Medium Priority ? Nerang-Broadbeach Rd/Ross St. to Nerang-Southport Rd. ? Nerang-Southport Rd from Pacific Highway to SBR ? Nerang-Broadbeach Rd from Pacific Highway to SBR The Smith St. link from the Pacific Motorway to Olsen Ave. should be considered as a freeway for monitoring purposes. The GCH along the coastal strip needs to be treated as a local distributor rather than as the major corridor. As a result, the future traffic surveillance priority should be low. At least one permanent environmental (vehicle emissions) monitoring station should be set up as part of the ITS plan. The most appropriate site for such a station would seem to be on the SBR corridor at the vicinity of Hooker Blv. intersection. Pacific Highway The Pacific Motorway project will set the benchmark for freeway incident detection and traffic management in the State. The high level of ITS implementation on the Motorway section will create a significant gap in performance and expectation, relative to the remainder of the Highway. It is recommended that the southern sections of the Pacific Highway be equipped to the equivalent level of traffic data collection and surveillance as the newly upgraded Motorway section, under a staged program. Travel Time Savings The travel time benefits of the full implementation of ITS over the network are likely to be of the order of at least 5 percent of vehicle-hours travelled on the affected links. At a discount rate of 6 percent, the total present value of the gross travel time benefit over 10 years is of the order of $200 million

Origins of the avian neural crest: the role of neural plate-epidermal interactions

We have investigated the lineage and tissue interactions that result in avian neural crest cell formation from the ectoderm. Presumptive neural plate was grafted adjacent to non-neural ectoderm in whole embryo culture to examine the role of tissue interactions in ontogeny of the neural crest. Our results show that juxtaposition of non-neural ectoderm and presumptive neural plate induces the formation of neural crest cells. Quail/chick recombinations demonstrate that both the prospective neural plate and the prospective epidermis can contribute to the neural crest. When similar neural plate/epidermal confrontations are performed in tissue culture to look at the formation of neural crest derivatives, juxtaposition of epidermis with either early (stages 4–5) or later (stages 6–10) neural plate results in the generation of both melanocytes and sympathoadrenal cells. Interestingly, neural plates isolated from early stages form no neural crest cells, whereas those isolated later give rise to melanocytes but not crest-derived sympathoadrenal cells. Single cell lineage analysis was performed to determine the time at which the neural crest lineage diverges from the epidermal lineage and to elucidate the timing of neural plate/epidermis interactions during normal development. Our results from stage 8 to 10+ embryos show that the neural plate/neural crest lineage segregates from the epidermis around the time of neural tube closure, suggesting that neural induction is still underway at open neural plate stages

A systematic review of reported reassortant viral lineages of influenza A

BACKGROUND: Most previous evolutionary studies of influenza A have focussed on genetic drift, or reassortment of specific gene segments, hosts or subtypes. We conducted a systematic literature review to identify reported claimed reassortant influenza A lineages with genomic data available in GenBank, to obtain 646 unique first-report isolates out of a possible 20,781 open-access genomes. RESULTS: After adjusting for correlations, only: swine as host, China, Europe, Japan and years between 1997 and 2002; remained as significant risk factors for the reporting of reassortant viral lineages. For swine H1, more reassortants were observed in the North American H1 clade compared with the Eurasian avian-like H1N1 clade. Conversely, for avian H5 isolates, a higher number of reported reassortants were observed in the European H5N2/H3N2 clade compared with the H5N2 North American clade. CONCLUSIONS: Despite unavoidable biases (publication, database choice and upload propensity) these results synthesize a large majority of the current literature on novel reported influenza A reassortants and are a potentially useful prerequisite to inform further algorithmic studies. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12879-015-1298-9) contains supplementary material, which is available to authorized users

Aerosol scattering of ultraviolet sunlight in the tropical maritime atmosphere

The effects of atmospheric aerosol scattering on the vertical profile of solar ultraviolet radiation are investigated. Measurements of diffuse and total ultraviolet radiation were made using a rocketborne optical sonde in the marine atmosphere of Antigua. During observations, the sun was at zenith. Vertical profiles of directly transmitted solar radiation were calculated by subtraction of the diffuse component from the total radiance. Using these values of direct downward solar UV-flux, the optical thickness of the atmosphere was derived as a function of altitude. Absorption by ozone was also considered. In the troposphere the values of observed optical thickness were in general equal to or lower than those expected theoretically from Rayleigh scattering alone. The measured radiation profiles were compared with those computed for a multiple scattering model atmosphere. Some computations regarding the interaction of UV-sunlight with maritime aerosols are presented

Topological soliton-polaritons in 1D systems of light and fermionic matter

Quantum nonlinear optics is a quickly growing field with large technological promise, at the same time involving complex and novel many-body phenomena. In the usual scenario, optical nonlinearities originate from the interactions between polaritons, which are hybrid quasi-particles mixing matter and light degrees of freedom. Here we introduce a type of polariton which is intrinsically nonlinear and emerges as the natural quasi-particle in presence quantum degenerate fermionic matter. It is a composite object made of a fermion trapped inside an optical soliton forming a topological defect in a spontaneously formed crystalline structure. Each of these soliton-polaritons carries a $\textbf{Z}_2$ topological quantum number, as they create a domain wall between two crystalline regions with opposite dimerization so that the fermion is trapped in an interphase state. These composite objects are formally equivalent to those appearing in the Su-Schrieffer-Heeger (SSH) model for electrons coupled to lattice phonons.Comment: Edited version. 6+7 pages, 3 figure