3,949 research outputs found

    Modeling the Effect of Traffic Calming on Local Animal Population Persistence

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    A steady growth in traffic volumes in industrialized countries with dense human populations is expected, especially on minor roads. As a consequence, the fragmentation of wildlife populations will increase dramatically. In human-dominated landscapes, typically minor roads occur in high densities, and animals encounter them frequently. Traffic calming is a new approach to mitigate negative impacts by reducing traffic volumes and speeds on minor roads at a regional scale. This leads to a distinction between roads with low volumes as being part of the traffic-calmed area, whereas roads with bundled traffic are located around this area. Within the traffic-calmed area, volumes and speeds can be decreased substantially; this is predicted to decrease the disturbance and mortality risk for animals. Thus far, data on the effects of traffic calming on wildlife population persistence remain scarce. Using metapopulation theory, we derived a model to estimate thresholds in the size of traffic-calmed areas and traffic volumes that may allow persistent populations. Our model suggests that traffic calming largely increases the persistence of roe deer in a landscape with a dense road network. Our modeling results show trade-offs between traffic volume on roads within the traffic-calmed area and both the area of habitat available for this species in the traffic-calmed area and the size of the traffic-calmed area. These results suggest ways to mitigate the fragmentation of wildlife habitat by road networks and their expected traffic volume

    Temporal variations of bicycle demand in the Netherlands: The influence of weather on cycling

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    The variability in bicycle demand depends strongly on weather. This paper describes a ‘weather’ model that makes demand forecasting possible. The model is based on flow time-series of many years, collected at 16 cycle paths in the Dutch cities of Gouda and Ede. The model is bi-level. The lower level describes how cyclists value the weather. The upper level is the relation between demand and this weather value. The observations show that most cyclists value the weather in a similar way, but recreational demand is much more sensitive to weather than utilitarian demand. Most fluctuations are described by the model, but a significant fraction is still not covered. From a correlation analysis of the residuals, we conclude that about 70% of the remaining variation is locally constrained, and can therefore not be described by a generic model. However, about 30% of this variation is not driven by local effects. The cause of this variation is not yet known. Besides uncovering trends in cycling, the model can also be employed to evaluate the effect of cycling policy interventions, and to correct flow measurements as input in traffic models

    Towards New Frontiers with B→πKB\to\pi K Decays

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    Exploring correlations between the CP asymmetries of Bd0→π0KSB^0_d\to\pi^0K_{\rm S} following from an isospin relation, we uncover new tensions with the Standard Model in data for neutral B→πKB\to\pi K decays. Should this intriguing picture originate from New Physics, a modified electroweak penguin sector provides a key scenario. It includes models with extra Zâ€ČZ' bosons, which offer attractive ways to resolve anomalies in B→K(∗)ℓ+ℓ−B\to K^{(*)}\ell^+\ell^- measurements. We present a new strategy to reveal the underlying physics, apply it to current B→πKB\to\pi K data, and discuss the excellent prospects for Belle II.Comment: 7 pages, 3 figure

    Planning and managing rural recreational traffic flows: why the future can’t be more like the past

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    The increasing popularity of rural tourism can cause traffic related problems at certain areas. Traffic congestion and parking problems are likely to occur as the infrastructure at these countryside destinations is seldom capable of dealing with the growing number of cars. Values which make the sites attractive to visitors can become under pressure and car traffic can also have negative effects on natural values. To prevent for such impacts, recreational traffic management is required. Recreational traffic management focuses on a smart organisation of recreational traffic flows. It has developed since the 1970s and to-day its character is influencing. Influencing takes place by offering tempting alternative opportunities and packages with varied facilities, based on specific desires of individual recreants. This requires detailed data on recreational use as well as an actor analysis, both on a regional and local scale

    Decoding (Pseudo)-Scalar Operators in Leptonic and Semileptonic BB Decays

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    We consider leptonic B−→ℓ−ΜˉℓB^-\to \ell^- \bar\nu_\ell and semileptonic Bˉ→πℓ−Μˉℓ\bar B \to \pi \ell^- \bar\nu_\ell, Bˉ→ρℓ−Μˉℓ\bar B \to \rho \ell^- \bar\nu_\ell decays and present a strategy to determine short-distance coefficients of New-Physics operators and the CKM element ∣Vub∣|V_{ub}|. As the leptonic channels play a central role, we illustrate this method for (pseudo)-scalar operators which may lift the helicity suppression of the corresponding transition amplitudes arising in the Standard Model. Utilising a new result by the Belle collaboration for the branching ratio of B−→Ό−ΜˉΌB^-\to \mu^- \bar\nu_\mu, we explore theoretically clean constraints and correlations between New Physics coefficients for leptonic final states with ÎŒ\mu and τ\tau leptons. In order to obtain stronger bounds and to extract ∣Vub∣|V_{ub}|, we employ semileptonic Bˉ→πℓ−Μˉℓ\bar B \to \pi \ell^- \bar\nu_\ell and Bˉ→ρℓ−Μˉℓ\bar B \to \rho \ell^- \bar\nu_\ell decays as an additional ingredient, involving hadronic form factors which are determined through QCD sum rule and lattice calculations. In addition to a detailed analysis of the constraints on the New Physics contributions following from current data, we make predictions for yet unmeasured decay observables, compare them with experimental constraints and discuss the impact of CP-violating phases of the New-Physics coefficients.Comment: 35 pages, 19 figures, matches published versio
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