Phase ordering and symmetries of the Potts model

We have studied the ordering of the q-colours Potts model in two dimensions on a square lattice. On the basis of our observations we propose that if q is large enough the system is not able to break global and local null magnetisation symmetries at zero temperature: when q<4 the system forms domains with a size proportional to the system size while for q>4 it relaxes towards a non-equilibrium phase with energy larger than the ground state energy, in agreement with the previous findings of De Oliveira et al. (M. J. de Oliveira, A. Petri, T. Tome, Europhys. Lett., 65, 20 (2004)).Comment: 6 pages, 3 figures; minor text rewordings and changes in figures styl

Disclosing the Far East: Transpacific Encounters and the Beginnings of Global History in the Early Modern Iberian World (1565-1670)

This dissertation avers that the transpacific circulation of narrative artefacts - travel accounts, letters, relaciones, and illustrated codices- enabled the emergence of a new global history that departs from the ancient tradition of universal history. In the late 16th and early 17th centuries, Iberian missionaries and historians began to incorporate into their histories and chronicles of the Indies sources and material dealing with China, Japan and other regions of the Far East. The dissertation argues that this transpacific interaction enabled historians to produce synchronic modes of writing that were emancipated from ancient narrative models. To develop this argument, the dissertation examines how historians and missionaries gradually separated the reading of ancient books from their own modern experience of narrating the Far East. By incorporating sources and material produced mainly in Macau and Manila, scholars not only imported new knowledge related to East and Southeast Asia into the Iberian and European world, but they also transformed the genre of general and universal histories of the Indies developed during the 16th century in the New World. Instead of considering the gradual integration of America with Eurasia and Africa to be the main and only fact that defined the emergence of a new global history, this dissertation argues that it was the discovery of the Far East from the West Indies that enabled historians to create forms of writing global histories that departed from the tradition of universal history. The dissertation puts into dialogue coexisting models and methods of composing global histories that emerged in the late 16th and early 17th centuries. To do so, I examine the emergence of narratives that integrated the Far East into historical genres developed in the West Indies during the 16th century. In this part, I explore the writings of scholars who wrote about the Far East by projecting a perspective that emerged from their production developed in the West Indies: Martín de Rada (1533-78), Francisco Hernández (1517-1587), Juan González de Mendoza (1540-1617), José de Acosta (1540-1600), the authors of the Boxer codex (ca. 1590), Adriano de las Cortes (1577-1629), and Antonio de León Pinelo (1595-1660). Furthermore, the dissertation analyzes the emergence of global modes of writing by focusing on the writings of Jesuits who arrived in the Far East from the oriental Portuguese route, such as Matteo Ricci (1552-1610), Diego de Pantoja (1571-1618), and Nicolas Trigault (1577-1628). These correlated productions incorporated the Far East into the narratives of the Iberian world by redefining categories associated with the Orient and reformulating methods of historical writing. By building a corpus of sources that refer to the arrival of Iberians to the Far East, this dissertation advances the thesis that the creation of systems of exchange and the transpacific circulation of relaciones, letters, and codices made possible and shaped new forms of composing global histories in the early modern Iberian world

Relaxion Monodromy and the Weak Gravity Conjecture

The recently proposed relaxion models require extremely large trans-Planckian axion excursions as well as a potential explicitly violating the axion shift symmetry. The latter property is however inconsistent with the axion periodicity, which corresponds to a gauged discrete shift symmetry. A way to make things consistent is to use monodromy, i.e. both the axion and the potential parameters transform under the discrete shift symmetry. The structure is better described in terms of a 3-form field $C_{\mu \nu \rho}$ coupling to the SM Higgs through its field strength $F_4$. The 4-form also couples linearly to the relaxion, in the Kaloper-Sorbo fashion. The extremely small relaxion-Higgs coupling arises in a see-saw fashion as $g\simeq F_4/f$, with $f$ being the axion decay constant. We discuss constraints on this type of constructions from membrane nucleation and the Weak Gravity Conjecture. The latter requires the existence of membranes, whose too fast nucleation could in principle drive the theory out of control, unless the cut-off scale is lowered. This allows to constrain relaxion models on purely theoretical grounds. We also discuss possible avenues to embed this structure into string theory.Comment: 26 pages + appendices, 3 figures; v3: Corrected bounds on relaxion parameter spac

Exact solution of the p+ip pairing Hamiltonian and a hierarchy of integrable models

Using the well-known trigonometric six-vertex solution of the Yang-Baxter equation we derive an integrable pairing Hamiltonian with anyonic degrees of freedom. The exact algebraic Bethe ansatz solution is obtained using standard techniques. From this model we obtain several limiting models, including the pairing Hamiltonian with p+ip-wave symmetry. An in-depth study of the p+ip model is then undertaken, including a mean-field analysis, analytic and numerical solution of the Bethe ansatz equations, and an investigation of the topological properties of the ground-state wavefunction. Our main result is that the ground-state phase diagram of the p+ip model consists of three phases. There is the known boundary line with gapless excitations that occurs for vanishing chemical potential, separating the topologically trivial strong pairing phase and the topologically non-trivial weak pairing phase. We argue that a second boundary line exists separating the weak pairing phase from a topologically trivial weak coupling BCS phase, which includes the Fermi sea in the limit of zero coupling. The ground state on this second boundary line is the Moore-Read state.Comment: 65 pages, 11 figures, 3 table

IMPACT OF THE CAP REFORM ON THE SPANISH AGRICULTURAL SECTOR

This paper analyses the impact of the 2003 CAP reform on Spanish agricultural sector in the context of the recent CAP Health Check and high food prices, using PROMAPA, a positive mathematical programming model for representative farms. The analysis compares the model results for base year 2002 to the findings for a scenario with the CAP reform measures in place, taking into account recent modifications. The effect of adopting a full decoupling scheme instead of the present partial decoupling is also studied. Brief descriptions are given of the PROMAPA model, the representative farm considered and the assumptions about both price variations and the policy measures simulated. The findings showed that the farming area for cereals grew substantially after abolition of the compulsory set-aside and that the impact of transition to full decoupling was scant, except in the sheep and rearing cattle sub-sectors, where it considerably steepened the already sizeable decline in livestock numbers induced by the partial decoupling scheme.CAP reform, CAP Health Check, Decoupling, Spanish agricultural sector., Agricultural and Food Policy, Q10, Q12, Q18,

Breakfast Is a Marker for Cardiovascular Risk Prediction

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Entanglement of low-energy excitations in Conformal Field Theory

In a quantum critical chain, the scaling regime of the energy and momentum of the ground state and low lying excitations are described by conformal field theory (CFT). The same holds true for the von Neumann and Renyi entropies of the ground state, which display a universal logarithmic behaviour depending on the central charge. In this letter we generalize this result to those excited states of the chain that correspond to primary fields in CFT. It is shown that the n-th Renyi entropy is related to a 2n-point correlator of primary fields. We verify this statement for the critical XX and XXZ chains. This result uncovers a new link between quantum information theory and CFT.Comment: 4 pages, 3 figure