2,445 research outputs found

    Archaeological identification of fragmented nuts and fruits from key Asia-Pacific economic tree species using anatomical criteria: comparative analysis of Canarium, Pandanus and Terminalia

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    The fats, protein and carbohydrates afforded by tree nuts and fruits are key resources for communities from Southeast Asia, through Melanesia, Australia and across Oceania. They are important in long-distance marine trade networks, large-scale ceremonial gatherings, and are core resources in a wide range of subsistence economies, including foraging systems, horticulture and swidden agriculture. Recent archaeobotanical evidence has also shown their deep-time importance, being amongst the earliest foods used in the colonisation of novel environments in Australia and New Guinea, as well as the later colonisation of Near and Remote Oceania. The archaeobotanical methods used to identify fruit and nut-derived plant macrofossils have been largely limited to use of morphological characters of near whole or exceptionally preserved remains, most commonly endocarps, the hard, nutshell-like interior layer of the fruit protecting the seed. Here we detail how anatomical characteristics of endocarps, visible in light and scanning electron microscopy (SEM), can be used with surviving morphological features to identify confidently the use of key Asia-Pacific economic trees, in this case, Canarium, Pandanus and Terminalia. Systematic anatomical description allows the identification of these important economic taxa, and separation from the remains of others such as Aleurites and Cocos, when found in a range of archaeological assemblages. This includes the often highly fragmented charred assemblages that can be recovered routinely from most sites with appropriate fine-sieving and flotation methods. These methods provide the basis for a more representative and nuanced understanding of ancient plant use, economy and social systems operating in the region and, being particularly useful in tropical regions, will broaden the archaeobotanical database on ancient foods globally.Introduction Background - Definition of tree fruits and nuts - Structure and use of Canarium - Structure and use of Pandanus - Structure and use of Terminalia - Archaeological visibility Methods - Archaeobotanical analysis of modern comparative material - Archaeobotanical analysis of archaeological material Results - Canarium - Pandanus - Terminalia Discussion Conclusio

    Early Ceramics in Anatolia: Implications for the Production and Use of the Earliest Pottery. The Evidence from Boncuklu Höyük

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    Fragments of possible fired clay found at Boncuklu Höyük, central Turkey, appear to derive from rudimentary vessels, despite the later ninth- and early eighth-millennium cal. bc and thus ‘Aceramic’ dates for the site. This paper will examine the evidence for such fired clay vessels at Boncuklu and consider their implications as examples of some of the earliest pottery in Anatolia. The discussion will examine contextual evidence for the role of these fragments and consider their relative rarity at the site and the implications for the marked widespread adoption of pottery in southwest Asia c. 7000–6700 cal. bc

    Effective action and semiclassical limit of spin foam models

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    We define an effective action for spin foam models of quantum gravity by adapting the background field method from quantum field theory. We show that the Regge action is the leading term in the semi-classical expansion of the spin foam effective action if the vertex amplitude has the large-spin asymptotics which is proportional to an exponential function of the vertex Regge action. In the case of the known three-dimensional and four-dimensional spin foam models this amounts to modifying the vertex amplitude such that the exponential asymptotics is obtained. In particular, we show that the ELPR/FK model vertex amplitude can be modified such that the new model is finite and has the Einstein-Hilbert action as its classical limit. We also calculate the first-order and some of the second-order quantum corrections in the semi-classical expansion of the effective action.Comment: Improved presentation, 2 references added. 15 pages, no figure

    3d Spinfoam Quantum Gravity: Matter as a Phase of the Group Field Theory

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    An effective field theory for matter coupled to three-dimensional quantum gravity was recently derived in the context of spinfoam models in hep-th/0512113. In this paper, we show how this relates to group field theories and generalized matrix models. In the first part, we realize that the effective field theory can be recasted as a matrix model where couplings between matrices of different sizes can occur. In a second part, we provide a family of classical solutions to the three-dimensional group field theory. By studying perturbations around these solutions, we generate the dynamics of the effective field theory. We identify a particular case which leads to the action of hep-th/0512113 for a massive field living in a flat non-commutative space-time. The most general solutions lead to field theories with non-linear redefinitions of the momentum which we propose to interpret as living on curved space-times. We conclude by discussing the possible extension to four-dimensional spinfoam models.Comment: 17 pages, revtex4, 1 figur

    Black hole and brane production in TeV gravity: A review

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    In models with large extra dimensions particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate non-perturbative gravitational objects such as black holes and branes. The formation and the subsequent decay of these super-Planckian objects would be detectable in particle colliders and high energy cosmic ray detectors, and have interesting implications in cosmology and astrophysics. In this paper we present a review of black hole and brane production in TeV-scale gravity.Comment: 40 pages, 14 figures, submitted to the Int. Jou. Mod. Phys.

    The Zero Age Main Sequence of WIMP burners

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    We modify a stellar structure code to estimate the effect upon the main sequence of the accretion of weakly interacting dark matter onto stars and its subsequent annihilation. The effect upon the stars depends upon whether the energy generation rate from dark matter annihilation is large enough to shut off the nuclear burning in the star. Main sequence WIMP burners look much like protostars moving on the Hayashi track, although they are in principle completely stable. We make some brief comments about where such stars could be found, how they might be observed and more detailed simulations which are currently in progress. Finally we comment on whether or not it is possible to link the paradoxically young OB stars found at the galactic centre with WIMP burners.Comment: 4 pages, 3 figs. Matches published versio

    Temporal variation of coupling constants and nucleosynthesis

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    We investigate the triple-alpha process and the Oklo phenomenon to obtain constraints on possible cosmological time variations of fundamental constants. Specifically we study cosmological temporal constraints for the fine structure constant and nucleon and meson masses.Comment: 4 pages. Proceedings of the Nuclear Physics in Astrophysics Conference, Debrecen, Hungary, September 30 - October 3, 2002. To be published in Nuc. Phys.
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