660 research outputs found

    Gauge and Lorentz transformation placed on the same foundation

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    In this note we show that a "dynamical" interaction for arbitrary spin can be constructed in a straightforward way if gauge and Lorentz transformations are placed on the same foundation. As Lorentz transformations act on space-time coordinates, gauge transformations are applied to the gauge field. Placing these two transformations on the same ground means that all quantized field like spin-1/2 and spin-3/2 spinors are functions not only of the coordinates but also of the gauge field components. This change of perspective solves a couple of problems occuring for higher spin fields like the loss of causality, bad high-energy properties and the deviation of the gyromagnetic ratio from its constant value g=2 for any spin, as caused by applying the minimal coupling. Starting with a "dynamical" interaction, a non-minimal coupling can be derived which is consistent with causality, the expectation for the gyromagnetic ratio, and well-behaved for high energies. As a consequence, on this stage the (elektromagnetic) gauge field has to be considered as classical field. Therefore, standard quantum field theory cannot be applied. Despite this inconvenience, such a common ground is consistent with an old dream of physicists almost a century ago. Our approach, therefore, indicates a straightforward way to realize this dream.Comment: 12 pages, no figures, published version. arXiv admin note: substantial text overlap with arXiv:0908.376

    D8.2 Dissemination Plan (DIGIART - The Internet of Historical Things and Building New 3D Cultural Worlds)

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    This document outlines the dissemination activities carried out by project partners. It sets out what has already been achieved, and provides an outline of what is planned. Main activities will centre around the workshops (co-)organised and/or (co-)financed by DigiArt to ensure that activities and materials under the DigiArt development are extensively disseminated and promoted within the research community and related external communities, widely announced via appropriate channels, and fully grasped by targeted stakeholders. An overview is given of all dissemination opportunities identified through traditional communication channels such as event attendance (e.g. conferences, seminars, workshops, etc.), project publications (e.g. leaflets, press releases as well as conference papers, articles in professional journals etc.) and project presentations (e.g. to local stakeholders, etc.). This is complemented also by online activities based around the project website, and through the main social platforms (e.g. Twitter, Facebook, etc.). The dissemination activities have been designed to target the key audiences and stakeholders and to maximize awareness of DigiArt’s objectives and training activities

    Characterizing Evulsion in the Later Stone Age Maghreb: age, sex and effects on mastication

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    This paper assesses the earliest evidence for widespread dental modification in Northwest Africa. The intentional modification of teeth has implications for an individual’s appearance, sense of identity and perceived status. The range of modifications reported varies from alterations of shape or color to the complete removal of healthy teeth (evulsion or ablation). The availability of well-dated collections reveals that Northwest Africa was the first region where the custom of tooth evulsion was widely practiced. Analysis of Iberomaurusian (Late Stone Age, n=77) and Capsian dental material (n=12) shows that evulsion was present in most male and female individuals (>94%). The most common Iberomaurusian practice involved removal of both upper central incisors (around 65%) although removal of fewer, none and more teeth was also recorded. Observations of the extent of alveolar remodeling of different sockets revealed that teeth were frequently removed at different ages, suggesting that the cultural significance was age transgressive and may have related to an event that individuals experienced more than once. During the Capsian period the prevalence of evulsion was lower in males than in females, but when present more teeth were removed with evulsion frequently involving both mandible and maxilla. Tooth wear analysis shows that evulsion affected not only the appearance of the individual but also the functioning of the masticatory complex

    Behavioral inferences from the high levels of dental chipping in Homo naledi

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    Objectives: A variety of mechanical processes can result in ante-mortem dental chipping. In this study, chipping data in the teeth of Homo naledi are compared with those of other pertinent dental samples to give insight into their etiology. Materials and Methods: Permanent teeth with complete crowns evidencing occlusal wear were examined macroscopically. The location, number, and severity of fractures were recorded and compared to those found in samples of two other South African fossil hominin species, as well as in samples of non-human primates (n= 3) and recent humans (n= 7). Results: With 44% of teeth affected, Homo naledi exhibits far higher rates of chipping than the other fossil hominin samples. Specifically, 50% of posterior teeth and 31% of anterior teeth display at least one chip. The maxillary teeth are more affected than the mandibular teeth (45% vs. 43%, respectively), 73% of molar chipping occurs on interproximal surfaces, and right teeth are more often affected than left teeth (50% vs. 38%). Discussion: Results indicate that the teeth of H. naledi were exposed to acute trauma on a regular basis. Because interproximal areas are more affected than buccal, and posterior teeth more than anterior, it is unlikely that non-masticatory cultural behavior was the cause. A diet containing hard and resistant food, or contaminants such as grit, is more likely. The small chip size, as well as steep occlusal wear and cupped dentine on some molars is supportive of the latter possibility. This pattern of chipping suggests H. naledi differed considerably – in terms of diet, environment, and/or specialized masticatory processing— relative to other African fossil hominins

    Assessing Size and Strength of the Clavicle for its usefulness for Sex Estimation in a British Medieval Sample.

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    The construction of the biological profile from human skeletal remains is the foundation of anthropological examination. However, remains may be fragmentary and the elements usually employed, such as the pelvis and skull, are not available. The clavicle has been successfully used for sex estimation in samples from Iran and Greece. In the present study the aim was to test the suitability of the measurements used in those previous studies on a British Medieval population. In addition, the project tested whether discrimination between sexes was due to size or clavicular strength. The sample consisted of 23 females and 25 males of pre-determined sex from two medieval collections: Poulton and Gloucester. Six measurements were taken using an osteometric board, sliding callipers and graduate tape. In addition, putty rings and bi-planar radiographs were made and robusticity measures calculated. The resulting variables were used in stepwise discriminant analyses. The linear measurements allowed correct sex classification in 89.6% of all individuals. This demonstrates the applicability of the clavicle for sex estimation in British populations. The most powerful discriminant factor was maximum clavicular length and the best combination of factors was maximum clavicular length and circumference. This result is similar to that obtained by other studies. To further investigate the extent of sexual dimorphism of the clavicle, the biomechanical properties of the polar second moment of area J and the ratio of maximum to minimum bending rigidity are included in the analysis. These were found to have little influence when entered into the discriminant function analysis

    Oral health in Late Pleistocene and Holocene North West Africa

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    Archaeological sites in North West Africa have yielded a rich record of human occupation, including well dated human burials from the Late Pleistocene Iberomaurusian and early Holocene Capsian periods. The transition broadly coincides with climatic amelioration at the end of the Holocene enabling expansion into slighter dryer inland areas. Here we investigate possible changes in oral health and subsistence behaviours during the transition between the Iberomaurusian (n = 109 individuals) and the Capsian (n = 19 individuals), based on the study of dental remains. Frequencies in oral pathologies (caries, abscesses, periodontal disease and antemortem tooth loss) were studied to assess possible differences between the late Pleistocene and early Holocene. The Late Pleistocene Iberomaurusians were characterised by high caries frequencies (60% of observed teeth). The Capsians displayed very similar patterns in oral pathologies but a slightly lower percentage of carious teeth (49%). The similarity in oral health in Iberomaurusian and Capsian populations is consistent with similarities in diet and oral hygiene. The implication of cultural and biological continuity between the Iberomaurusian and Capsian periods is supported by indicators, such as exploitation of wild plants and snails, tooth evulsion and craniofacial and dental morphology. © 201

    An outcrop of Eemian and Early Weichselian deposits at Beernem (N.W. Belgium)

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    The authors study the sedimentological and paleobotanical characteristics of a continuous succession of Eemian and Weichselian deposits older than 50.000 y, B.F. It forms the major part of the Quaternary cover in a tributary valley of the Upper-Pleistocene Flemish-Valley-Belgian Coastal Plain complex at Beernem. They recognize an alluvial Eemian deposit covering the E4a, E4b, E5 and E6 pollenzones; a quick paleoclimatic transition and Weichselian deposits of a fluvio-periglacial and niveo-colluvial nature with numerous peat layers, one of which is linked with a buried paleopodzol (paleosol of Beernem) and correlatedwith the Amersfoort interstadial. The pre-Amersfoort peats are of EW I type, the post-Amersfoort ones of a PW type. The numerous syngenetic cryoturbation levels, suggest that all over the pre-Moershoofd Weichselian mean annual temperatures fell below -5°C, at least during successive rather long periods. They contrast the paleobotanical, chronological and sedimentological interpretations

    Prehistory of the British Isles: A tale of coming and going

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    It is now recognised that Britain has not always been geographically isolated from Europe and, for most of the last one million years, formed an extension of the northwest European landmass. During most of this time, Britain was accessible to migrating humans and animals, although climatic conditions varied greatly from Mediterranean-like through to glaciations and extreme cold, making Britain a difficult place to settle for any length of time. The oldest evidence for humans in Britain dates to between about 850,000 and 1 million years ago. Recovered lithic artefacts suggest that hominin species occupied and deserted the British Isles at least nine times. This article reviews the prehistory of the British Isles and presents the main sites and time periods
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