8,540 research outputs found
Dual-frequency GPS survey for validation of a regional DTM and for the generation of local DTM data for sea-level rise modelling in an estuarine salt marsh
Global average temperatures have risen by an average of 0.07°C per decade over the last
100 years, with a warming trend of 0.13°C per decade over the last 50 years.
Temperatures are predicted to rise by 2°C - 4.4°C by 2100 leading to global average sealevel
rise (SLR) of 2 – 6mm per year (20 – 60cms in total) up to 2100 (IPCC 2007) with
impacts for protected coastal habitats in Ireland.
Estuaries are predominantly sedimentary environments, and are characterised by shallow
coastal slope gradients, making them sensitive to even modest changes in sea-level. The
Shannon estuary is the largest river estuary in Ireland and is designated as a Special Area
of Conservation (SAC) under the EU Habitats Directive (EU 1992) providing protection
for listed habitats within it, including estuarine salt marsh.
Trends in Shannon estuary tidal data from 1877 – 2004 suggest an average upward SLR
trend of 4 - 5mm/yr over this period. A simple linear extension of this historical trend
would imply that local SLR will be in the region of 40 - 45cm by 2100. However, this
may underestimate actual SLR for the estuary by 2100, since it takes no account of
predicted climate-driven global SLR acceleration (IPCC 2007) up to 2100
A desire for immersion: the panorama to the Oculus Rift
The paper argues that the experience of viewing 360° historical scenes, either within the "real" environment of the panorama or contemporary "virtual" environments, arises in part from the attraction of the affecting experience. Tracing a line from ancient Greece and Rome through to contemporary technological innovations in Virtual Reality, we explore an idea that what links all of these experiences is not solely a response to social, political or historical streams but a manifestation of a pan-historical human desire for the Dionysiac.
Using texts by theorists as diverse as Nietzsche, Baudrillard, Rheingold, Gibson and Shaviro, we suggest that the impetus for viewing historical scenes within 360° environments is at least partly involved in wanting to go beyond spectatorship and intellectual curiousity, towards presence and intoxication. Attempts to tease out the ideological content of an immersive experience must be done in the context of the craving of audience members for the sensual, the sensational, the being present, and other "illegitimate" forms of impetus to view and experiences. These always already exist alongside and perhaps even before the more legitimate goals of gaining knowledge, historical perspective, education and information.
Charlton and Moar explore the idea that this desire for immersion impels us to submerge ourselves in historical scenes. Thus immersion is the link between panoramas and new panoramic experiences afforded by new technologies such as the Oculus Rift
VR and the dramatic theatre: are they fellow creatures?
This paper describes an experimental project that aims to investigate the scope of methodological and technical possibilities of using 360° videos for experiencing authored drama. In particular, it examines how a work written for the medium of theatre, with a traditional audience-drama relationship of viewer invisibility and non-participation, might translate into a viewing experience as a VR drama. The technical and dramaturgical issues arising from this are discussed. Specifically, the shared voyeuristic quality of both media is examined. Is the invisible viewer of VR drama in the invidious role of Glaucon’s iniquitous shepherd Gyges, or does the medium give invisibility a cloak of aesthetic value
Performance of three-photon PET imaging: Monte Carlo simulations
We have recently introduced the idea of making use of three-photon positron
annihilations in positron emission tomography. In this paper the basic
characteristics of the three-gamma imaging in PET are studied by means of Monte
Carlo simulations and analytical computations. Two typical configurations of
human and small animal scanners are considered. Three-photon imaging requires
high energy resolution detectors. Parameters currently attainable by CdZnTe
semiconductor detectors, the technology of choice for the future development of
radiation imaging, are assumed. Spatial resolution is calculated as a function
of detector energy resolution and size, position in the field of view, scanner
size, and the energies of the three gamma annihilation photons. Possible ways
to improve the spatial resolution obtained for nominal parameters: 1.5 cm and
3.2 mm FWHM for human and small animal scanners, respectively, are indicated.
Counting rates of true and random three-photon events for typical human and
small animal scanning configurations are assessed. A simple formula for minimum
size of lesions detectable in the three-gamma based images is derived.
Depending on the contrast and total number of registered counts, lesions of a
few mm size for human and sub mm for small animal scanners can be detected
Debye Potentials for Maxwell and Dirac Fields from a Generalisation of the Killing-Yano Equation
By using conformal Killing-Yano tensors, and their generalisations, we obtain
scalar potentials for both the source-free Maxwell and massless Dirac
equations. For each of these equations we construct, from conformal
Killing-Yano tensors, symmetry operators that map any solution to another.Comment: 35 pages, plain Te
A New Look at Stratospheric Sudden Warmings. Part I: Climatology and Modeling Benchmarks
Stratospheric sudden warmings are the clearest and strongest manifestation of dynamical coupling in the stratosphere–troposphere system. While many sudden warmings have been individually documented in the literature, this study aims at constructing a comprehensive climatology: all major midwinter warming events are identified and classified, in both the NCEP–NCAR and 40-yr ECMWF Re-Analysis (ERA-40) datasets. To accomplish this a new, objective identification algorithm is developed. This algorithm identifies sudden warmings based on the zonal mean zonal wind at 60°N and 10 hPa, and classifies them into events that do and do not split the stratospheric polar vortex.
Major midwinter stratospheric sudden warmings are found to occur with a frequency of approximately six events per decade, and 46% of warming events lead to a splitting of the stratospheric polar vortex. The dynamics of vortex splitting events is contrasted to that of events where the vortex is merely displaced off the pole. In the stratosphere, the two types of events are found to be dynamically distinct: vortex splitting events occur after a clear preconditioning of the polar vortex, and their influence on middle-stratospheric temperatures lasts for up to 20 days longer than vortex displacement events. In contrast, the influence of sudden warmings on the tropospheric state is found to be largely insensitive to the event type.
Finally, a table of dynamical benchmarks for major stratospheric sudden warming events is compiled. These benchmarks are used in a companion study to evaluate current numerical model simulations of the stratosphere
Identification of diverse database subsets using property-based and fragment-based molecular descriptions
This paper reports a comparison of calculated molecular properties and of 2D fragment bit-strings when used for the selection of structurally diverse subsets of a file of 44295 compounds. MaxMin dissimilarity-based selection and k-means cluster-based selection are used to select subsets containing between 1% and 20% of the file. Investigation of the numbers of bioactive molecules in the selected subsets suggest: that the MaxMin subsets are noticeably superior to the k-means subsets; that the property-based descriptors are marginally superior to the fragment-based descriptors; and that both approaches are noticeably superior to random selection
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