Global bifurcation of homoclinic trajectories of discrete dynamical systems

We prove the existence of an unbounded connected branch of nontrivial homoclinic trajectories of a family of discrete nonautonomous asymptotically hyperbolic systems parametrized by a circle under assumptions involving the topological properties of the asymptotic stable bundles.Comment: 28 pages. arXiv admin note: text overlap with arXiv:1111.140

Perspectives on Interstellar Dust Inside and Outside of the Heliosphere

Measurements by dust detectors on interplanetary spacecraft appear to indicate a substantial flux of interstellar particles with masses exceeding 10^{-12}gram. The reported abundance of these massive grains cannot be typical of interstellar gas: it is incompatible with both interstellar elemental abundances and the observed extinction properties of the interstellar dust population. We discuss the likelihood that the Solar System is by chance located near an unusual concentration of massive grains and conclude that this is unlikely, unless dynamical processes in the ISM are responsible for such concentrations. Radiation pressure might conceivably drive large grains into "magnetic valleys". If the influx direction of interstellar gas and dust is varying on a ~10 yr timescale, as suggested by some observations, this would have dramatic implications for the small-scale structure of the interstellar medium.Comment: 13 pages. To appear in Space Science Review

A within farm clinical trial to compare two treatments (parenteral antibacterials and hoof trimming) for sheep lame with footrot

From observational studies, farmers who use parenteral antibacterials to promptly treat all sheep with footrot (FR) or interdigital dermatitis (ID) have a prevalence of lameness of <2% compared with a prevalence of 9% lameness reported by farmers who treat lame sheep by trimming affected feet. We tested the hypothesis that prompt treatment of sheep lame with naturally developing FR or ID with parenteral and topical antibacterials reduces the prevalence and incidence of lameness with these conditions compared with less frequent treatment with trimming of hoof horn and applying topical antibacterials. A further hypothesis was that reduction of ID and FR would improve productivity. A lowland sheep flock with 700 ewes was used to test these hypotheses in an 18-month within farm clinical trial with four groups of ewes: two intervention and two control. The duration and severity of lameness was used to categorise sheep into three weighted scores of lameness (WLS): never lame (WLS0), mildly lame/lame for <6 days (WLS1) and severely or chronically lame (WLS2). The intervention reduced the prevalence of lameness due to FR and ID in ewes and lambs and the incidence of lameness in ewes. The WLS was also significantly lower in sheep in the intervention groups. Ewes with a higher WLS were subsequently significantly more likely to have a body condition score <2.5 and to have lame lambs. Significantly more ewes lambed and successfully reared more lambs that were ready for slaughter at a younger age in the intervention versus control groups. There was an increase in the gross margin of £630/100 ewes mated in the intervention group, including the cost of treatment of £150/100 ewes mated. We conclude that prompt parenteral and topical antibacterial treatment of sheep lame with ID and FR reduced the prevalence and incidence of these infectious conditions and led to improved health, welfare and productivity

Creating the cultures of the future: cultural strategy, policy and institutions in Gramsci. Part two: Cultural strategy and institutions in Gramsci’s early writings and political practice

In this article, I consider Gramsci’s pre-prison writings and political practice in relation to questions of cultural strategy and institutions. I argue that the analysis of these early texts, which were written in the years in which Gramsci was active in party organisation and leadership, is fundamental not only for understanding the nature of Gramsci’s early and continued involvement with questions of cultural strategy and institutions, but also as a key for interpreting cultural policy themes that he later developed in the prison notebooks, and which originated in earlier debates

Exposure Path Perceptions and Protective Actions in Biological Water Contamination Emergencies

This study extends the Protective Action Decision Model, developed to address disaster warning responses in the context of natural hazards, to “boil water” advisories. The study examined 110 Boston residents’ and 203 Texas students’ expectations of getting sick through different exposure paths for contact with contaminated water. In addition, the study assessed respondents’ actual implementation (for residents) or behavioral expectations (for students) of three different protective actions – bottled water, boiled water, and personally chlorinated water – as well as their demo-graphic characteristics and previous experience with water contamination. The results indicate that people distinguish among the exposure paths, but the differences are small (one-third to one-half of the response scale). Nonetheless, the perceived risk from the exposure paths helps to explain why people are expected to consume (or actually consumed) bottled water rather than boiled or personally chlorinated water. Overall, these results indicate that local authorities should take care to communicate the relative risks of different exposure paths and should expect that people will respond to a boil water order primarily by consuming bottled water. Thus, they should make special efforts to increase supplies of bottled water in their communities during water contamination emergencies

Modelling spectral and timing properties of accreting black holes: the hybrid hot flow paradigm

The general picture that emerged by the end of 1990s from a large set of optical and X-ray, spectral and timing data was that the X-rays are produced in the innermost hot part of the accretion flow, while the optical/infrared (OIR) emission is mainly produced by the irradiated outer thin accretion disc. Recent multiwavelength observations of Galactic black hole transients show that the situation is not so simple. Fast variability in the OIR band, OIR excesses above the thermal emission and a complicated interplay between the X-ray and the OIR light curves imply that the OIR emitting region is much more compact. One of the popular hypotheses is that the jet contributes to the OIR emission and even is responsible for the bulk of the X-rays. However, this scenario is largely ad hoc and is in contradiction with many previously established facts. Alternatively, the hot accretion flow, known to be consistent with the X-ray spectral and timing data, is also a viable candidate to produce the OIR radiation. The hot-flow scenario naturally explains the power-law like OIR spectra, fast OIR variability and its complex relation to the X-rays if the hot flow contains non-thermal electrons (even in energetically negligible quantities), which are required by the presence of the MeV tail in Cyg X-1. The presence of non-thermal electrons also lowers the equilibrium electron temperature in the hot flow model to <100 keV, making it more consistent with observations. Here we argue that any viable model should simultaneously explain a large set of spectral and timing data and show that the hybrid (thermal/non-thermal) hot flow model satisfies most of the constraints.Comment: 26 pages, 13 figures. To be published in the Space Science Reviews and as hard cover in the Space Sciences Series of ISSI - The Physics of Accretion on to Black Holes (Springer Publisher

Modelling vehicles acceleration during overtaking manoeuvres

[EN] Abstract: Overtaking manoeuvre is a key issue for two-lane rural roads. These roads should provide sufficient overtaking sight distance (OSD) at certain locations to allow faster vehicles to pass slower ones. However, overtaking requires occupying the opposing lane, which represents a serious safety concern. Severity of overtaking related crashes is very high, compared with other manoeuvres. The development of advanced driver assistance systems (ADAS) for overtaking is being a complex task. Only few systems have been developed, but are not still in use. This research incorporated accurate data of real manoeuvres to improve the knowledge of the phenomenon. The trajectory of the overtaking vehicles on the left lane was observed. An instrumented vehicle measured the overtaking time and distance, the abreast position, and the initial and final speed of 180 drivers that passed it during a field experiment. Six different kinematic models (such as uniform acceleration or linear variation of acceleration) were calibrated. Generally, drivers started to accelerate before changing to the opposing lane. These models may be applied to ADAS, to estimate OSD and to improve microsimulation models.Part of this research was included in the project 'Desarrollo de modelos de distancias de visibilidad de adelantamiento', with reference code TRA2010-21736 and subsidised by the Spanish Ministery of Economy and Competitivity. The authors also thank Prof Dr Sayed, from University of British Columbia, for his valuable review.Llorca Garcia, C.; Moreno, AT.; García García, A. (2016). Modelling vehicles acceleration during overtaking manoeuvres. IET Intelligent Transport Systems. 10(3):206-215. https://doi.org/10.1049/iet-its.2015.0035S206215103Gray, R., & Regan, D. M. (2005). Perceptual Processes Used by Drivers During Overtaking in a Driving Simulator. Human Factors: The Journal of the Human Factors and Ergonomics Society, 47(2), 394-417. doi:10.1518/0018720054679443Basilio, N., Morice, A. H. P., Marti, G., & Montagne, G. (2015). High- and Low-Order Overtaking-Ability Affordances. Human Factors: The Journal of the Human Factors and Ergonomics Society, 57(5), 879-894. doi:10.1177/0018720815583581Morice, A. H. P., Diaz, G. J., Fajen, B. R., Basilio, N., & Montagne, G. (2015). An Affordance-Based Approach to Visually Guided Overtaking. Ecological Psychology, 27(1), 1-25. doi:10.1080/10407413.2015.991641Farah, H., Bekhor, S., & Polus, A. (2009). Risk evaluation by modeling of passing behavior on two-lane rural highways. Accident Analysis & Prevention, 41(4), 887-894. doi:10.1016/j.aap.2009.05.006Hassan, Y., Easa, S. M., & El Halim, A. O. A. (1996). Passing sight distance on two-lane highways: Review and revision. Transportation Research Part A: Policy and Practice, 30(6), 453-467. doi:10.1016/0965-8564(95)00032-1Wang, Y., & Cartmell, M. P. (1998). New Model for Passing Sight Distance on Two-Lane Highways. Journal of Transportation Engineering, 124(6), 536-545. doi:10.1061/(asce)0733-947x(1998)124:6(536)Sparks, G. A., Neudorf, R. D., Robinson, J. B. L., & Good, D. (1993). Effect of Vehicle Length on Passing Operations. Journal of Transportation Engineering, 119(2), 272-283. doi:10.1061/(asce)0733-947x(1993)119:2(272)Hanley, P. F., & Forkenbrock, D. J. (2005). Safety of passing longer combination vehicles on two-lane highways. Transportation Research Part A: Policy and Practice, 39(1), 1-15. doi:10.1016/j.tra.2004.09.001Khoury, J. E., & Hobeika, A. G. (2012). Integrated Stochastic Approach for Risk and Service Estimation: Passing Sight Distance Application. Journal of Transportation Engineering, 138(5), 571-579. doi:10.1061/(asce)te.1943-5436.0000366Jenkins, J. M., & Rilett, L. R. (2004). Application of Distributed Traffic Simulation for Passing Behavior Study. Transportation Research Record: Journal of the Transportation Research Board, 1899(1), 11-18. doi:10.3141/1899-02Rakha, H., Ahn, K., & Trani, A. (2004). Development of VT-Micro model for estimating hot stabilized light duty vehicle and truck emissions. Transportation Research Part D: Transport and Environment, 9(1), 49-74. doi:10.1016/s1361-9209(03)00054-3Polus, A., Livneh, M., & Frischer, B. (2000). Evaluation of the Passing Process on Two-Lane Rural Highways. Transportation Research Record: Journal of the Transportation Research Board, 1701(1), 53-60. doi:10.3141/1701-07Harwood, D. W., Gilmore, D. K., & Richard, K. R. (2010). Criteria for Passing Sight Distance for Roadway Design and Marking. Transportation Research Record: Journal of the Transportation Research Board, 2195(1), 36-46. doi:10.3141/2195-05Hegeman, G., Tapani, A., & Hoogendoorn, S. (2009). Overtaking assistant assessment using traffic simulation. Transportation Research Part C: Emerging Technologies, 17(6), 617-630. doi:10.1016/j.trc.2009.04.010Milanés, V., Llorca, D. F., Villagrá, J., Pérez, J., Fernández, C., Parra, I., … Sotelo, M. A. (2012). Intelligent automatic overtaking system using vision for vehicle detection. Expert Systems with Applications, 39(3), 3362-3373. doi:10.1016/j.eswa.2011.09.024Isermann, R., Mannale, R., & Schmitt, K. (2012). Collision-avoidance systems PRORETA: Situation analysis and intervention control. Control Engineering Practice, 20(11), 1236-1246. doi:10.1016/j.conengprac.2012.06.003Petrov, P., & Nashashibi, F. (2014). Modeling and Nonlinear Adaptive Control for Autonomous Vehicle Overtaking. IEEE Transactions on Intelligent Transportation Systems, 15(4), 1643-1656. doi:10.1109/tits.2014.2303995Llorca, C., & García, A. (2011). Evaluation of Passing Process on Two-Lane Rural Highways in Spain with New Methodology Based on Video Data. Transportation Research Record: Journal of the Transportation Research Board, 2262(1), 42-51. doi:10.3141/2262-05Llorca, C., Moreno, A. T., García, A., & Pérez-Zuriaga, A. M. (2013). Daytime and Nighttime Passing Maneuvers on a Two-Lane Rural Road in Spain. Transportation Research Record: Journal of the Transportation Research Board, 2358(1), 3-11. doi:10.3141/2358-01Llorca, C., Moreno, A. T., Pérez-Zuriaga, A. M., & García, A. (2013). Influence of age, gender and delay on overtaking dynamics. IET Intelligent Transport Systems, 7(2), 174-181. doi:10.1049/iet-its.2012.0147Khoury, J. E., & Hobeika, A. (2007). Incorporating Uncertainty into the Estimation of the Passing Sight Distance Requirements. Computer-Aided Civil and Infrastructure Engineering, 22(5), 347-357. doi:10.1111/j.1467-8667.2007.00491.xRakha, H., Snare, M., & Dion, F. (2004). Vehicle Dynamics Model for Estimating Maximum Light-Duty Vehicle Acceleration Levels. Transportation Research Record: Journal of the Transportation Research Board, 1883(1), 40-49. doi:10.3141/1883-05Fitzpatrick, K., Chrysler, S. T., & Brewer, M. (2012). Deceleration Lengths for Exit Terminals. Journal of Transportation Engineering, 138(6), 768-775. doi:10.1061/(asce)te.1943-5436.000038

Heavy quarkonium: progress, puzzles, and opportunities

A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the $B$-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

Towards good practice guidelines for the contour method of residual stress measurement

Accurate measurement of residual stress in metallic components using the contour method relies on the achievement of a good quality cut, on the appropriate measurement of the deformed cut surface and on the robust analysis of the measured data. There is currently no published standard or code of practice for the contour method. As a first step towards such a standard, this study draws on research investigations addressing the three main steps in the method: how best to cut the specimens; how to measure the deformation contour of the cut surface; and how to analyse the data. Good practice guidance is provided throughout the text accompanied by more detailed observations and advice tabulated in Appendi