888 research outputs found

    Virtual Reality Flight Environments May Tax Working Memory and Disrupt Prospective Memory

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    While vivid virtual reality (VR) environments may afford better performance for some flight tasks, it is possible that enhanced stimuli could overload some cognitive resources. Prospective memory (PM) is a cognitive factor sensitive to working memory and visual processing demands, and it may be a performance factor either adversely affected or enhanced by VR factors. Forty-seven pilots flew a VR flight simulation scenario, which included an auditory cue-based PM task. Self-ratings of psychological experiences in VR revealed three factors with relationships to PM: fluency, presence, and interactivity. Path analyses examined the relation of each of these factors with PM, and with two types of working memory, based on Level 1 SA. Higher fluency ratings were associated with lower PM, whereas greater presence and interactivity were correlated with better PM. Working memory also significantly mediated the effects of fluency on PM

    Encoding hybridised institutions into first order logic

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    "First published online: 12 November 2014"A ‘hybridization’ of a logic, referred to as the base logic, consists of developing the characteristic features of hybrid logic on top of the respective base logic, both at the level of syntax (i.e. modalities, nominals, etc.) and of the semantics (i.e. possible worlds). By ‘hybridized institutions’ we mean the result of this process when logics are treated abstractly as institutions (in the sense of the institution theory of Goguen and Burstall). This work develops encodings of hybridized institutions into (many-sorted) first order logic (abbreviated FOL) as a ‘hybridization’ process of abstract encodings of institutions into FOL, which may be seen as an abstraction of the well known standard translation of modal logic into first order logic. The concept of encoding employed by our work is that of comorphism from institution theory, which is a rather comprehensive concept of encoding as it features encodings both of the syntax and of the semantics of logics/institutions. Moreover we consider the so-called theoroidal version of comorphisms that encode signatures to theories, a feature that accommodates a wide range of concrete applications. Our theory is also general enough to accomodate various constraints on the possible worlds semantics as well a wide variety of quantifications. We also provide pragmatic sufficient conditions for the conservativity of the encodings to be preserved through the hybridization process, which provides the possibility to shift a formal verification process from the hybridized institution to FOL.We thank both Till Mossakowski and Andrzej Tarlecki for the technical suggestion of using the predicates D. The work of the first author has been supported by a grant of the Romanian National Authority for Scientific Research, CNCS-UEFISCDI, project number PN-II-ID-PCE-2011-3-0439. The work of the second author was funded by the European Regional Development Fund through the COMPETE Programme, and by the Portuguese Foundation for Science and Technology through the projects FCOMP-01-0124-FEDER-028923 and NORTE-01-0124-FEDER-000060

    The impact of rainfall and school break time policies on physical activity in 9-10 year old British children: a repeated measures study.

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    BACKGROUND: The weather may be a driver of seasonal patterns in children's physical activity (PA). A better understanding of the relationships between weather and PA may help increase children's PA. This study aims to examine the association between PA and rainfall in 9-10 year old children, and how it may be modified by school policies. METHODS: 1794 participants in the SPEEDY study in Norfolk, UK recorded PA using ActiGraph accelerometers over up to six days in the summer term of 2007. Multilevel regression models were used to determine the day-by-day association between rainfall and minutes spent sedentary, in moderate-to-vigorous PA (MVPA), and average counts per minute (cpm) over the whole day (07:00-21:00) and the lunchtime period (12:00-14:00). School policies for break times in bad weather were fitted as interaction terms with rainfall. RESULTS: Relative to days with no rain, children spent 9.4 minutes (95%CI 7.0 to 11.9) fewer in MVPA, were sedentary for 13.6 minutes (8.8 to 18.4) more, and accumulated 85.9 cpm (66.2 to 105.5) fewer over the whole day on the wettest days. Children allowed to play outside in wet weather showed the lowest lunchtime PA levels on the wettest days, undertaking 9.8 minutes (6.2 to 13.5) fewer MVPA, 16.1 minutes (10.3 to 21.9) more sedentary, and accumulating 408.0 cpm (250.9 to 565.1) fewer than those allowed to be active indoors. CONCLUSIONS: Rainfall is negatively associated with PA in primary school children, but providing indoor physical activities in wet weather may help children maintain physical activity levels irrespective of rainfall.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

    Unintentional F doping of the surface of SrTiO3(001) etched in HF acid -- structure and electronic properties

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    We show that the HF acid etch commonly used to prepare SrTiO3(001) for heteroepitaxial growth of complex oxides results in a non-negligible level of F doping within the terminal surface layer of TiO2. Using a combination of x-ray photoelectron spectroscopy and scanned angle x-ray photoelectron diffraction, we determine that on average ~13 % of the O anions in the surface layer are replaced by F, but that F does not occupy O sites in deeper layers. Despite this perturbation to the surface, the Fermi level remains unpinned, and the surface-state density, which determines the amount of band bending, is driven by factors other than F doping. The presence of F at the STO surface is expected to result in lower electron mobilities at complex oxide heterojunctions involving STO substrates because of impurity scattering. Unintentional F doping can be substantially reduced by replacing the HF-etch step with a boil in deionized water, which in conjunction with an oxygen tube furnace anneal, leaves the surface flat and TiO2 terminated.Comment: 18 pages, 7 figure

    Managing CO2 storage resources in a mature CCS future

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    This paper summarises the potential for surface and subsurface interactions which might occur during CO2 storage operations. We discuss possible options for managing these interactions to provide timely storage capacity, illustrated with a regional case study from the Southern North Sea. The case study evaluates storage site options to provide storage capacity for CO2 supplied to the region until 205

    Fire, climate and the origins of agriculture: micro-charcoal records of biomass burning during the Last Glacial Interglacial Transition in Southwest Asia

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    This study investigates changes in climate, vegetation, wildfire and human activity in Southwest Asia during the transition to Neolithic agriculture between ca. 16 and ca. 9 ka. In order to trace the fire history of this region, we use microscopic charcoal from lake sediment sequences, and present two new records: one from south central Turkey (Akgo¨ l) and the other from the southern Levant (Hula). These are interpreted primarily as the result of regional-scale fire events, with the exception of a single large event ca. 13 ka at Akgo¨ l, which phytolith analysis shows was the result of burning of the local marsh vegetation. Comparison between these and other regional micro-charcoal, stable isotope and pollen records shows that wildfires were least frequent when the climate was cold and dry (glacial, Lateglacial Stadial) and the vegetation dominated by chenopod–Artemisia steppe, and that they became more frequent and/or bigger at times of warmer, wetter but seasonally dry climate (Lateglacial Interstadial, early Holocene). Warmer and wetter climates caused an increase in biomass availability, with woody matter appearing to provide the main fuel source in sites from the Levant, while grass fires predominated in the interior uplands of Anatolia. Southwest Asia’s grasslands reached their greatest extent during the early Holocene, and they were maintained by dry-season burning that helped to delay the spread of woodland by up to 3 ka, at the same time as Neolithic settlement became established across this grass parkland landscape. Although climatic changes appear to have acted as the principal ‘pacemaker’ for fire activity through the last glacial–interglacial climatic transition (LGIT), human actions may have amplified shifts in biomass burning. Fire regimes therefore changed markedly during this time period, and both influenced, and were influenced by, the cultural-economic transition from hunter-foraging to agriculture and village lif
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