259 research outputs found

    Applications of Phase-Based Motion Processing

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    Image pyramids provide useful information in determining structural response at low cost using commercially available cameras. The current effort applies previous work on the complex steerable pyramid to analyze and identify imperceptible linear motions in video. Instead of implicitly computing motion spectra through phase analysis of the complex steerable pyramid and magnifying the associated motions, instead present a visual technique and the necessary software to display the phase changes of high frequency signals within video. The present technique quickly identifies regions of largest motion within a video with a single phase visualization and without the artifacts of motion magnification, but requires use of the computationally intensive Fourier transform. While Riesz pyramids present an alternative to the computationally intensive complex steerable pyramid for motion magnification, the Riesz formulation contains significant noise, and motion magnification still presents large amounts of data that cannot be quickly assessed by the human eye. Thus, user-friendly software is presented for quickly identifying structural response through optical flow and phase visualization in both Python and MATLAB

    The identification of Late Holocene bog bursts at Littleton bog, Ireland: ecohydrological changes display complex climatic and non-climatic drivers

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    In order to clearly understand the response of raised mires to past climate change, it is important to consider the full range of drivers and responses of these ecohydrological archives. To this end, a high resolution ecohydrological record from Littleton bog, Co. Tipperary, Ireland, was generated utilizing a combination of plant macrofossils, testate amoebae, and humification analysis. Chronological control for this record was provided by a Bayesian age-depth model based on AMS radiocarbon dates. Testate amoebae-derived reconstructed peatland water tables indicate a series of sudden shifts to dry bog surface conditions at c.3140, c.2510, and c.1540 cal BP. These events display a distinctive palaeoecological signal and chronological tempo that is best explained as a result of a series of bog burst events, and which seem inconsistent with other explanations. The chronological correspondence between the bog bursts at Littleton and a set of similar events at Derryville bog, c.5km to the north, is noted, as is the broad correspondence of these events with wet-shifts indicated in regional peatland water table compilations from Britain and Ireland. A range of possible driving mechanisms for these events is proposed, including anthropogenic disturbance of the bog surface, non-linear response to climate forcing, internal bog dynamics, vegetation succession, or a combination of factors. We illustrate the need for further multi-proxy investigations to fully understand these phenomena

    From findspot to site: a spatial examination of the Mesolithic resource in Surrey

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    Surrey has a diverse range of Mesolithic occupation evidence, spanning the Early Mesolithic, Horsham period and the Later Mesolithic. This paper collates these data and then quantitatively analyses the relationships between the geographical distributions of Mesolithic material and a range of environmental characteristics. The distribution of material is also analysed using a GIS to understand where ‘hotspots’ (and ‘coldspots’) of activity may be located and takes into account variations in collecting activity and modern discovery opportunities. There is evidence that the environment may have been important in determining the spatial extent of Mesolithic hunter-gatherer behaviour, and this is assessed through comparison of the Mesolithic resource and a range of environmental variables. The record shows a prevalence of hunting-type assemblages in the south-west of the county, where the majority of microliths and points were identified, together with sites with evidence for occupation (often excavated as such, or with evidence for domestic activities such as burning). There was also evidence that records identified on higher elevations and steeper slopes appeared to represent items used, discarded or lost on hunting trips and potentially highlighted the importance of these regions as lookout or observation locations; however, there was a lack of occupation sites based near these optimal viewing locations. The majority of occupation sites were located across an east--west Greensand band, and situated within 5km of the Clay-with-Flints outcrops. These were wet/dry marginal regions, probably conducive to settlement owing to the benefits these locations may have had for hunting and gathering. A lower density of records from north-west and south-east Surrey appear to indicate these areas were used primarily for the processing of material while people were moving across the landscape. The overall high proportion of findspots and scatters within the dataset may result from the nature of hunter-gatherer living, with high levels of mobility within the landscape alongside ephemeral occupation and activity sites

    The Morphology of Steve

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    This report is part of Project Steve. Project Steve is, among other things, the first scientific analysis of the sex, geographic location, and body size of scientists named Steve. We performed this research for the best of all reasons: we discovered that we had lots of data. No scientist can resist the opportunity to analyze data, regardless of where that data came from or why it was gathered

    New insights into late Devensian late glacial and early Holocene environmental change: two high-resolution case studies from SE England

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    The Late Devensian Lateglacial to early Holocene transition across north-west Europe was characterized by a rapid shift in climate from the cold, harsh conditions of the Loch Lomond Stadial to the warmer climate of the early postglacial. However, our knowledge of this transition in south-east England has been hampered by the paucity of mires with sedimentary records spanning this period. We present two new high-resolution paleoenvironmental records from Langshot Bog and Elstead Bog B (Surrey, UK), which provide a clear signature of vegetation succession and fire history. Organic sedimentation at Langshot Bog commenced prior to 12,640–12,410 cal. BP (95% probability) and continued until 8430–8350 cal. BP (95% probability). Providing a robust chronology for Elstead Bog B proved to be problematic, although available dates suggest sediment accumulation commenced prior to 11,820–11,400 cal. BP (WM-168, 2σ). The sites are characterized by similar vegetation records, indicating a regional signal from locations over 20 km apart. Scrubby tundra-style vegetation is characteristic of cold conditions associated with the Lateglacial. The identification of Alnus and Corylus, taxa not normally associated with this period, indicates that microclimates may have permitted the survival of these species. Expansion of Betula followed by Pinus dates to the onset of the Holocene, forming mixed coniferous-deciduous woodland, during a period which is punctuated by short climatic events identified from stable isotope analysis. Subsequent expansion of thermophilous taxa Corylus, Ulmus and Quercus results in the formation of deciduous woodland. A rise in micro-charcoal, heathland and herbaceous taxa indicates development of heathy-scrubby clearings within this Holocene landscape

    Pre-Hispanic terrace agricultural practices and long-distance transfer of plant taxa in the southern-central Peruvian Andes revealed by phytolith and pollen analysis

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    The archaeological excavation of two abandoned prehispanic agricultural terraces (Infiernillo and Tocotoccasa) in the Chicha-Soras Valley (Apurimac) in southern-central Peru revealed the presence of palaeosols. The palaeosols represent soil that developed following construction of agricultural terraces during the Middle Horizon. The soil profiles at the current surface developed following reconstruction of the terraces during the Late Intermediate Period. Phytolith analysis revealed an unexpected presence of Arecaceae (palm family) and Marantaceae (arrowroot family) in both terraces, which has been attributed to local cultivation and/or transportation and use of soil, dung, plant material or implements (made of Arecaceae) on the terrace surfaces. Pollen analysis of a nearby wetland (Ayapampa) did not provide evidence for Arecaceae or Marantaceae. Both phytolith and pollen analysis of the terraces and wetland (respectively) indicated that Zea mays was cultivated locally during the Middle Horizon and Late Intermediate Period, although phytoliths of maize are absent from the wetland record during the Middle Horizon. The presence of Solanaceae and Chenopodiaceae/Amaranthaceae pollen in the wetland may be indicative of cultivation of further important taxa during the Middle Horizon and Late Intermediate Period, which continued into the Late Horizon together with Zea mays
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