6,234 research outputs found

    Abandonment of land and the Scottish Coal case : was it Unprecedented?

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    The support of the Carnegie Trust for the Universities of Scotland in the provision of a research incentive grant that contributed to this note is gratefully acknowledged.Peer reviewedPostprin

    The Clem Lack Oration : Terrick Terrick: the Casey years, 1883-1892

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    Bose Hubbard model in the presence of Ohmic dissipation

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    We study the zero temperature mean-field phase diagram of the Bose-Hubbard model in the presence of local coupling between the bosons and an external bath. We consider a coupling that conserves the on-site occupation number, preserving the robustness of the Mott and superfluid phases. We show that the coupling to the bath renormalizes the chemical potential and the interaction between the bosons and reduces the size of the superfluid regions between the insulating lobes. For strong enough coupling, a finite value of hopping is required to obtain superfluidity around the degeneracy points where Mott phases with different occupation numbers coexist. We discuss the role that such a bath coupling may play in experiments that probe the formation of the insulator-superfluid shell structure in systems of trapped atoms.Comment: 5 pages, 2 figures. Error found in v1, now corrected, leads to qualitative changes in result

    Schwinger-Keldysh approach to out of equilibrium dynamics of the Bose Hubbard model with time varying hopping

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    We study the real time dynamics of the Bose Hubbard model in the presence of time-dependent hopping allowing for a finite temperature initial state. We use the Schwinger-Keldysh technique to find the real-time strong coupling action for the problem at both zero and finite temperature. This action allows for the description of both the superfluid and Mott insulating phases. We use this action to obtain dynamical equations for the superfluid order parameter as hopping is tuned in real time so that the system crosses the superfluid phase boundary. We find that under a quench in the hopping, the system generically enters a metastable state in which the superfluid order parameter has an oscillatory time dependence with a finite magnitude, but disappears when averaged over a period. We relate our results to recent cold atom experiments.Comment: 22 pages, 7 figure

    First evidence for interpersonal violence in Ukraine's Trypillian farming culture : Individual 3 from Verteba Cave, Bilche Zolote

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    This paper presents the initial stages of an interdisciplinary study of human skeletal remains interred at Verteba Cave, western Ukraine. This site has been described previously as a “ritual site of the Trypillian culture complex” by Nikitin et al. in Comprehensive site chronology and ancient mitochondrial DNA analysis from Verteba Cave – a Trypillian culture site of Eneolithic Ukraine, Interdisciplinaria Archaeologica: Natural Sciences in Archaeology 1, 9–18., and the material considered here is one of seven crania recovered during excavations at Verteba between 2008 and 2010. Palaeopathological analysis of the individual considered here indicates that this is a young adult female with evidence for peri-mortem injury, cranial surgery and into early stage Trypillia culture inter-personal interactions and burial ritual in this region of Ukraine. Paper published in Proceedings of the British Association for Biological Anthropology and Osteoarchaeology 13th and 14th Annual Conferences in Edinburgh (2nd-4th September 2011) and Bournemouth (14th–16th September 2012)

    Mitochondrial DNA analysis of eneolithic trypillians from Ukraine reveals neolithic farming genetic roots

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    The agricultural revolution in Eastern Europe began in the Eneolithic with the Cucuteni-Trypillia culture complex. In Ukraine, the Trypillian culture (TC) existed for over two millennia (ca. 5,400–2,700 BCE) and left a wealth of artifacts. Yet, their burial rituals remain a mystery and to date almost nothing is known about the genetic composition of the TC population. One of the very few TC sites where human remains can be found is a cave called Verteba in western Ukraine. This report presents four partial and four complete mitochondrial genomes from nine TC individuals uncovered in the cave. The results of this analysis, combined with the data from previous reports, indicate that the Trypillian population at Verteba carried, for the most part, a typical Neolithic farmer package of mitochondrial DNA (mtDNA) lineages traced to Anatolian farmers and Neolithic farming groups of central Europe. At the same time, the find of two specimens belonging to haplogroup U8b1 at Verteba can be viewed as a connection of TC with the Upper Paleolithic European populations. At the level of mtDNA haplogroup frequencies, the TC population from Verteba demonstrates a close genetic relationship with population groups of the Funnel Beaker/ Trichterbecker cultural complex from central and northern Europe (ca. 3,950–2,500 BCE)

    Lattice dynamics of incommensurate composite Rb-IV and a realization of the monatomic linear chain model

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    Longitudinal-acoustic (LA) phonons have been studied by inelastic x-ray scattering in the high-pressure incommensurate host-guest system Rb-IV in the pressure range of 16.3 to 18.4 GPa. Two LA-like phonon branches are observed along the direction of the incommensurate wave vector, which are attributed to separate lattice vibrations in the host and guest subsystems. The derived sound velocities for the host and the guest, nu(h) and nu(g), respectively, are similar in magnitude [nu(h)=nu(g)=3840(100) m/s at 18 GPa], but our results indicate rather different pressure dependences of dv(h)/dP=140(60) m/s GPa(-1) and d nu(g)/dP=280(80) m/s GPa(-1). The observations for the one-dimensional Rb guest chains are reproduced quantitatively on the basis of the monatomic linear chain model and the measured compressibility of the chains.</p
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