488 research outputs found

    Adaptive driver modelling in ADAS to improve user acceptance: A study using naturalistic data

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    Accurate understanding of driver behaviour is crucial for future Advanced Driver Assistance Systems (ADAS) and autonomous driving. For user acceptance it is important that ADAS respect individual driving styles and adapt accordingly. Using data collected during a naturalistic driving study carried out at the University of Southampton, we assess existing models of driver acceleration and speed choice during car following and when cornering. We observe that existing models of driver behaviour that specify a preferred inter-vehicle spacing in car-following situations appear to be too prescriptive, with a wide range of acceptable spacings visible in the naturalistic data. Bounds on lateral acceleration during cornering from the literature are visible in the data, but appear to be influenced by the minimum cornering radii specified in design codes for UK roadway geometry. This analysis of existing driver models is used to suggest a small set of parameters that are sufficient to characterise driver behaviour in car-following and curve driving, which may be estimated in real-time by an ADAS to adapt to changing driver behaviour. Finally, we discuss applications to adaptive ADAS with the objectives of improving road safety and promoting eco-driving, and suggest directions for future researc

    Systems Theoretic Accident Model and Process (STAMP) applied to a Royal Navy Hawk jet missile simulation exercise

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    The Royal Navy uses Hawk jets to simulate sea-skimming missile attacks against vessels as part of their training regulations. To best achieve these goals, pilots of the Hawk are required to fly at approximately 50 feet above sea level to accurately mimic the flight path of a missile. Despite this need the Hawk is not equipped with a radar altimeter and instead relies upon pilot skill to ensure the safe completion of the operation. Incidents whereby the Hawk jets have struck the water are however recorded, risking pilot safety. This paper explores the Hawk missile simulation task using a Systems Theoretic Accident Model and Process (STAMP) and its corresponding hazard analysis Systems-Theoretic Process Analysis (STPA) methodology to map the key stakeholders within this operation. In doing so, the method explores areas of potential risk in the system and recommends how overall systemic safety of the operation can be improved

    Learning in a Facebook environment : the writing is on the wall.

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    Ph. D. University of KwaZulu-Natal, Durban 2014.This thesis explores how students learn in a Facebook learning environment. While e-learning environments offer many new opportunities to engage in learning, these new spaces are still largely unexplored and the purview of students more than lecturers. This is even more so the case when it comes to the recent emergence of Web 2.0 technologies and specifically Social Network Systems. These spaces, originally conceived for social agendas, are increasingly being applied to a variety of other uses. Recently the application of not designed- for-learning environments to formal learning has begun to be explored. Most notable amongst these emergent spaces is Facebook, the largest single website, with over 1 billion users. Facebook, unlike traditional e-learning environments, represents a departure both technologically and paradigmatically from what is normally used by universities. Technologically Facebook is not institutionally hosted or controlled. Paradigmatically it is built around conversations and not organisation and artefacts. Using an affordance theoretical framing based on the Latourian concept of actants, the actant action opportunities arising from the students’ use of Facebook are explored. This analysis revealed the existence of a dynamic web of interacting affordances that push and pull against each other as students use the environment. This conversation-based approach to learning shifts learning from correct content to correcting content, from artefact to conversation, and from prospective to retrospective sense. The key tenets of learning in a Facebook environment, as identified through the Latourianbased lens, exist in the notion of “between”. In addition to the affordance tensions the students navigate, is the interplay between a learning discourse and a power discourse. The learning discourse itself is also framed by the interplay between vulnerability and validation. Students make themselves vulnerable through posts, and thereby open up opportunities to learn through the validation of subsequent comments. At the same time the learning discourse is interwoven with the power discourse, where decisions and actions are no longer autocratically or democratically enacted, but rather homeocratically through retrospective sanction of small evolving actions. Using Facebook as a learning environment signals the emergence of a new theoretical perspective for learning, one that is founded, not on organised, deterministic, artefactual principles, but rather on networks of retrospective conversation-based learning. These new environments which challenge not only our conceptions of the place of learning, but also our paradigms of learning, operate in a realm of uncertainty, something that in most respects is foreign to university learning environments

    Estrada de Ferro Madeira-Mamoré : história trågica de uma expedição

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    Tradução de: Recollections of an ill-fated expedition to the readwathers of the madeira river in BrasilFINEPUFRJFUJBIBEPFAPERJME

    Dynamic deformation of volcanic ejecta from the Toba caldera: Possible relevance to Cretaceous/Tertiary boundary phenomena

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    Plagioclase and biotite phenocrysts in ignimbrites erupted from the Toba caldera, Sumatra, show microstructures and textures indicative of shock stress levels higher than 10 GPa. Strong dynamic deformation has resulted in intense kinking in biotite and, with increasing shock intensity, the development in plagioclase of planar features, shock mosaicism, incipient recrystallization, and possible partial melting. Microstructures in quartz indicative of strong shock deformation are rare, however, and many shock lamellae, if formed, may have healed during post-shock residence in the hot ignimbrite; they might be preserved in ash falls. Peak shock stresses from explosive silicic volcanism and other endogenous processes may be high and if so would obviate the need for extraterrestrial impacts to produce all dynamically deformed structures, possibly including shock features observed near the Cretaceous/Tertiary boundary

    Adaptive driver modelling in ADAS to improve user acceptance: a study using naturalistic data

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    Accurate understanding of driver behaviour is crucial for future Advanced Driver Assistance Systems (ADAS) and autonomous driving. For user acceptance it is important that ADAS respect individual driving styles and adapt accordingly. Using data collected during a naturalistic driving study carried out at the University of Southampton, we assess existing models of driver acceleration and speed choice during car following and when cornering. We observe that existing models of driver behaviour that specify a preferred inter-vehicle spacing in car-following situations appear to be too prescriptive, with a wide range of acceptable spacings visible in the naturalistic data. Bounds on lateral acceleration during cornering from the literature are visible in the data, but appear to be influenced by the minimum cornering radii specified in design codes for UK roadway geometry. This analysis of existing driver models is used to suggest a small set of parameters that are sufficient to characterise driver behaviour in car-following and curve driving, which may be estimated in real-time by an ADAS to adapt to changing driver behaviour. Finally, we discuss applications to adaptive ADAS with the objectives of improving road safety and promoting eco-driving, and suggest directions for future research

    Novel Magnetic Resonance Imaging strategy targeting Neurotensin Receptors in detection of Prostate Cancer [preprint]

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    Prostate cancer is the second leading cause of all male cancer deaths. One of the factors present in malignant prostate cells and shown to support its metastatic growth is the neuropeptide neurotensin (NT). The primary goal of the present study was to establish the feasibility of using a newly developed paramagnetic receptor ligand for NT and non-invasive ultrahigh-field magnetic resonance (MR) imaging to visualize prostate cancer in rodents. Orthotropic xenografts were initiated in six-week old male BALB/c nu/nu athymic mice (n = 28) by intra-prostatic (ventral lobe) inoculation of human prostate cancer cells (10 ÎŒL of PC3 cells (10^6/100 ÎŒL)). Palpable tumors developed within 30-60 days. A micro-imager utilized in these studies was an actively shielded 9.4T, 89 mm bore, Oxford superconducting magnet with a 100 gauss/cm gradient system. Prior to contrast injection, T2 weighted anatomy scans were done to localize the tumor with a spin-echo multi-slice sequence with TR: 2000 TE: 40 and NEX: 1 in both coronal and axial planes. The paramagnetic ligand data sets were collected with a spin-echo, T1 weighted pulse sequence (MSME): TR 300 msec; TE 5 msec; NEX 4 in both axial and coronal planes. The data sets were taken initially at 5-min intervals post contrast injection for the first half hour and then at 15 min intervals for the next 1.5-2 hours for a time series analyses. The temporal distribution of MR signal intensity in various regions were determined in the absence and presence of NT. Our results confirm that the novel NT molecule was protected from enzymatic degradation and capable of forming a high-affinity paramagnetic NT ligand with an extended half-life. During the imaging studies, the signal intensity increased by 200% in the region of the tumor. This increase in signal intensity approached maximum binding within 30 minutes and remained visible for 1-hour post-injection of the contrast agent. Taken together, these findings suggest that it is feasible to detect and image prostate cancer using a paramagnetic NT ligand and the emergence of the NT receptor ligand that may be used as a diagnostic marker for prostate cancer in humans

    Long-term trends in invertebrate-habitat relationships under protected and fished conditions

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    Few studies examine the long-term effects of changing predator size and abundance on the habitat associations of resident organisms despite that this knowledge is critical to understand the ecosystem effects of fishing. Marine reserves offer the opportunity to determine ecosystem-level effects of manipulated predator densities, while parallel monitoring of adjacent fished areas allows separating these effects from regional-scale change. Relationships between two measures of benthic habitat structure (reef architecture and topographic complexity) and key invertebrate species were followed over 17years at fished and protected subtidal rocky reefs associated with two southern Australian marine reserves. Two commercially harvested species, the southern rock lobster (Jasus edwardsii) and blacklip abalone (Haliotis rubra) were initially weakly associated with habitat structure across all fished and protected sites. The strength of association with habitat for both species increased markedly at protected sites 2years after marine reserve declaration, and then gradually weakened over subsequent years. The increasing size of rock lobster within reserves apparently reduced their dependency on reef shelters as refuges from predation. Rising predation by fish and rock lobster in the reserves corresponded with weakening invertebrate-habitat relationships for H. rubra and sea urchins (Heliocidaris erythrogramma). These results emphasise that animal-habitat relationships are not necessarily stable through time and highlight the value of marine reserves as reference sites. Our work shows that fishery closures to enhance populations of commercially important and keystone species should be in areas with a range of habitat features to accommodate shifting ecological requirements with ontogenesis

    Lung cancer treatment costs, including patient responsibility, by disease stage and treatment modality, 1992 to 2003

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    AbstractObjectivesThe objective of this analysis was to estimate costs for lung cancer care and evaluate trends in the share of treatment costs that are the responsibility of Medicare beneficiaries.MethodsThe Surveillance, Epidemiology, and End Results (SEER)-Medicare data from 1991–2003 for 60,231 patients with lung cancer were used to estimate monthly and patient-liability costs for clinical phases of lung cancer (prediagnosis, staging, initial, continuing, and terminal), stratified by treatment, stage, and non-small- versus small-cell lung cancer. Lung cancer-attributable costs were estimated by subtracting each patient's own prediagnosis costs. Costs were estimated as the sum of Medicare reimbursements (payments from Medicare to the service provider), co-insurance reimbursements, and patient-liability costs (deductibles and “co-payments” that are the patient's responsibility). Costs and patient-liability costs were fit with regression models to compare trends by calendar year, adjusting for age at diagnosis.ResultsThe monthly treatment costs for a 72-year-old patient, diagnosed with lung cancer in 2000, in the first 6 months ranged from 2687(noactivetreatment)to2687 (no active treatment) to 9360 (chemo-radiotherapy); costs varied by stage at diagnosis and histologic type. Patient liability represented up to 21.6% of care costs and increased over the period 1992–2003 for most stage and treatment categories, even when care costs decreased or remained unchanged. The greatest monthly patient liability was incurred by chemo-radiotherapy patients, which ranged from 1617to1617 to 2004 per month across cancer stages.ConclusionsCosts for lung cancer care are substantial, and Medicare is paying a smaller proportion of the total cost over time
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