1,753 research outputs found

    Herb Wharton, Aboriginal stockman and author, Mount Isa, Queensland, 1994 /

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    Title devised by cataloguer from information provided by photographer.; Part of: Cattle Camp series of portraits of Aboriginal drovers, Mount Isa, Queensland, 1994.; Mode of access: Online

    A non-stationary model for spatially dependent circular response data based on wrapped Gaussian processes

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    Circular data can be found across many areas of science, for instance meteorology (e.g., wind directions), ecology (e.g., animal movement directions), or medicine (e.g., seasonality in disease onset). The special nature of these data means that conventional methods for non-periodic data are no longer valid. In this paper, we consider wrapped Gaussian processes and introduce a spatial model for circular data that allow for non-stationarity in the mean and the covariance structure of Gaussian random fields. We use the empirical equivalence between Gaussian random fields and Gaussian Markov random fields which allows us to considerably reduce computational complexity by exploiting the sparseness of the precision matrix of the associated Gaussian Markov random field. Furthermore, we develop tunable priors, inspired by the penalized complexity prior framework, that shrink the model toward a less flexible base model with stationary mean and covariance function. Posterior estimation is done via Markov chain Monte Carlo simulation. The performance of the model is evaluated in a simulation study. Finally, the model is applied to analyzing wind directions in Germany

    Non-stationary spatial regression for modelling monthly precipitation in Germany

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    It is widely accepted that spatial dependencies have to be acknowledged appropriately in data that are spatially aligned. However, most spatial models still assume that the dependence structure does not vary over space, i.e., it is stationary. While assuming stationarity considerably facilitates estimation, it is often too restrictive when describing atmospheric phenomena such as precipitation. Nonetheless, the applicability of non-stationary models is often hindered, as their use reveals to be cumbersome and improvements over stationary models can be hard to identify. The stochastic partial differential equation (SPDE) approach to spatial modelling allows for flexible specifications of non-stationary models. In particular, given the German orographic diversity, it makes sense to investigate potential non-stationarity in precipitation patterns. Taking such potential non-stationarities into account may, in particular, leads to improved smoothing of the observed precipitation pattern taken on a finite set of measurement stations, and therefore to improved inputs to hydrological models. We suggest an SPDE-based model where the mean and dependence structure are allowed to vary with elevation, as well as a more flexible non-parametric alternative based on multivariate B-Splines. As factors such as wind may cause higher dependence in a given direction, we include anisotropy in the model. Results show that, according to the widely applicable Bayesian information criterion, a non-stationary model provides a better fit to the data. Taking German monthly precipitation as a motivation, we set up a simulation study to explore the ability of the elevation and spline-based models to correctly identify non-stationarity

    Car drivers’ preferences for ISA policy measures

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    Intelligent Speed Adaptation (ISA), an in-vehicle system that can either warn the driver or directly limit the vehicle’s speed when the speed limit is reached, is generally believed to have a large potential to increase road safety. However, policy makers hesitate to take policy measures that may increase ISA use. Public acceptance of ISA or policy makers’ perception of it is regarded to play an important role in this. This paper aims to increase this insight by reporting car drivers’ preferences for ISA policy measures based on stated choice experiment conducted in the Netherlands. Respondents made choices between various implementation strategies (mandatory ISA and voluntary ISA with financial incentives) given a chosen policy measure. The policy measure describes which drivers group (speed offenders, professional drivers or all drivers) is targeted and which ISA type (warning or limiting) is stimulated. The results point out that car drivers especially prefer that policy makers would impose ISA on speed offenders and to a lesser extent also on professional drivers, while they prefer a voluntary ISA for themselves. Use of voluntary ISA can be stimulated by offering financial incentives, of which purchase subsidy is preferred above annual tax cuts. Furthermore, car drivers prefer warning ISA for themselves and also for professional drivers, while they prefer limiting ISA for speed offenders. In addition, the results indicate that females and the older age group prefer ISA policy measures more than males and young drivers, but overall car drivers’ preferences seem to be rather homogeneous.Engineering, Systems and ServicesTechnology, Policy and Managemen

    A dual infection of infectious salmon anaemia (ISA) virus and a togavirus-like virus in ISA of Atlantic salmon Salmo salar in New Brunswick, Canada

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    Two viruses, infectious salmon anaemia (ISA) virus and a novel togavirus-like virus, were isolated from ISA disease outbreaks that were first reported as a new syndrome, haemorrhagic kidney syndrome (HKS) affecting farmed Atlantic salmon Salmo salar L. on the East coast of Canada. Laboratory confirmation of ISA diagnosis was initially complicated by isolation of only the togavirus-like agent using the CHSE-214 cell line. Here we demonstrate that a clinical sample from a disease outbreak of ISA contained a mixture of ISA virus and togavirus-like virus. Reverse transcriptase-polymerase chain reaction (RT-PCR) confirmed the presence of both viruses during serial passage of cultures in SHK-1 and CHSE-214 cells. Virus harvested at passage level 3 in both cell lines caused high mortalities and severe gross pathology consistent with ISA virus infection in experimentally inoculated Atlantic salmon parr (approximately 35 g) in freshwater, beginning 12 d post inoculation. ISA virus was detected by virus isolation from kidney and liver tissues of all dead or moribund fish tested. A comparison of virus isolation, 1-step procedure RT-PCR and RNA dot-blot hybridization for detection of ISA virus (ISAV) in fish tissues showed virus isolation to have 100% sensitivity, followed by RT-PCR (66 and 28% sensitivity in kidney and liver, respectively), with RNA dot-blot hybridization as the least sensitive method (20 and 10% sensitivity in kidney and liver, respectively). No togavirus-like virus was detected in these samples by virus isolation. Moreover, another togavirus-like virus isolate grown in CHSE-214 cells in the absence of any other detectable pathogen was non-pathogenic in experimentally inoculated fish. This study confirms that the original ISA outbreaks in New Brunswick, Canada, were caused solely by ISAV

    Isa Lake on the Continental Divide, Yellowstone National Park.

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    Isa Lake on the Continental Divide, Yellowstone National Park

    Transition to ISA: Changes in Audit Documentation Practice

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    Th e article considers the eff ects of transition to ISA in audit documenting. Th e author analyzes base audit documenting problems, existing before the transition to ISA, discloses ISA specifi c features, refl ected in the change of approach to audit documenting, explores the main results the transition to ISA in formation of auditor working papers.</jats:p

    What drives the Acceptability of Intelligent Speed Assistance (ISA)?

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    To have knowledge about the acceptability of Intelligent Transport systems (ITS) is most beneficial for the development of supported implementation strategies. So far, different theories and methods, also stemming from other domains, have been used to define and conceptualize the notion of acceptability. In a previous paper, we developed a theoretical concept to define acceptability of ISA based on different theories and methods used in ITS & ISA research. In the current paper we aim to find out which predefined indicators are relevant to define the acceptability of ISA. Background factors, contextual issues and ISA-device related factors are used as indicators to predict the level of acceptability. Structural Equation Modelling (SEM) is used to define the direct and indirect effects.Infrastructures, Systems and ServicesTechnology, Policy and Managemen

    GSQ Mt Isa Southwest elevation grid geodetic

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    Maintenance and Update Frequency: notPlannedStatement: This GSQ Mt Isa Southwest elevation grid geodetic is elevation data for the Mount Isa South West, Qld, 2006 acquired under the project No. 1111 for the geological survey of QLD. The grid has a cell size of 0.00083 degrees (approximately 88m). This grid contains the ground elevation values relative to the geoid for the Mount Isa South West, Qld, 2006. It represents the vertical distance from a location on the Earth's surface to the geoid. The data are given in units of meters. The processed data are checked by GA geophysicists using standard methods for assessing quality to ensure that the final data are fit-for-purpose.Digital Elevation data record the terrain height variations from the processed point- or line-located data recorded during a geophysical survey. This GSQ Mt Isa Southwest elevation grid geodetic is elevation data for the Mount Isa South West, Qld, 2006. This survey was acquired under the project No. 1111 for the geological survey of QLD. The grid has a cell size of 0.00083 degrees (approximately 88m). This grid contains the ground elevation relative to the geoid for the Mount Isa South West, Qld, 2006. It represents the vertical distance from a location on the Earth's surface to the geoid. The data are given in units of meters. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose
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