59 research outputs found

    Human observations of late Quaternary coastal change: examples from Australia, Europe and the Pacific Islands

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    In the aftermath of the last ice age, when sea level rose along most of the world's coastline, the activities of coastal peoples were impacted by coastal submergence, land loss and sometimes isolation as offshore islands formed. In some parts of the world, there is clear evidence that people encoded their observations of postglacial sea-level rise into oral traditions that were communicated across hundreds of generations to reach us today in an intelligible form. In other contexts, people's observations of rising sea level are likely to have formed the foundations of ‘legends’ about undersea places and the peoples inhabiting them. For a selection of coastal sites in Australia and northwest Europe, this study discusses a range of contrasting situations in which culturally-grounded stories about coastal submergence, land loss and isolation plausibly recollect the nature and effects of postglacial sea-level rise. Using science-based histories of postglacial sea-level change, minimum ages are determined for each group of site-specific stories; in the case of Australia, these range from 7000–11,500 BP, for northwest Europe from 5500 to 9500 BP. For selected sites in the Pacific Islands, where human settlement about 3000 years BP post-dated the end of postglacial sea-level rise, localized submergence is recalled in traditional stories of local people. It is argued that studies of late Quaternary coastal evolution can often be filled out by adding details from stories preserved in local cultures, something which leads to a clearer picture of the human-societal impacts of coastal submergence and land loss than can be obtained from palaeoenvironmental reconstructions and geological evidence alone

    On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes

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    The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic

    THE RATE OF BINARY BLACK HOLE MERGERS INFERRED FROM ADVANCED LIGO OBSERVATIONS SURROUNDING GW150914

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    A transient gravitational-wave signal, GW150914, was identi fi ed in the twin Advanced LIGO detectors on 2015 September 2015 at 09:50:45 UTC. To asse ss the implications of this discovery, the detectors remained in operation with unchanged con fi gurations over a period of 39 days around the time of t he signal. At the detection statistic threshold corresponding to that observed for GW150914, our search of the 16 days of simultaneous two-detector observational data is estimated to have a false-alarm rate ( FAR ) of < ́ -- 4.9 10 yr 61 , yielding a p -value for GW150914 of < ́ - 210 7 . Parameter estimation follo w-up on this trigger identi fi es its source as a binary black hole ( BBH ) merger with component masses ( )( ) = - + - + mm M ,36,29 12 4 5 4 4 at redshift = - + z 0.09 0.04 0.03 ( median and 90% credible range ) . Here, we report on the constraints these observations place on the rate of BBH coalescences. Considering only GW150914, assuming that all BBHs in the universe have the same masses and spins as this event, imposing a search FAR threshold of 1 per 100 years, and assuming that the BBH merger rate is constant in the comoving frame, we infer a 90% credible range of merger rates between – -- 2 53 Gpc yr 31 ( comoving frame ) . Incorporating all search triggers that pass a much lower threshold while accounting for the uncerta inty in the astrophysical origin of each trigger, we estimate a higher rate, ranging from – -- 13 600 Gpc yr 31 depending on assumptions about the BBH mass distribution. All together, our various rate estimat es fall in the conservative range – -- 2 600 Gpc yr 31

    Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra

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    The use of Jadammina macrescens (Brady) and Balticammina pseudomacrescens Bronnimann, Lutze and Whittaker (Protozoa: Foraminiferida) as sea-level indicators.

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    In studies of foraminiferal distributions in saltmarshes in New England and Atlantic Canada, Balticammina pseudomacrescens and Jadammina macrescens have formerly been grouped as Trochammina macrescens. This study recognises them as distinct species and shows that they have significantly different distributions on the surface of saltmarshes in Maine. Here, relative abundances of J. macrescens correlate with tidal elevation (
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