Antiferromagnetic Ising model in an imaginary magnetic field

We study the two-dimensional antiferromagnetic Ising model with a purely imaginary magnetic field, which can be thought of as a toy model for the usual $\theta$ physics. Our motivation is to have a benchmark calculation in a system which suffers from a strong sign problem, so that our results can be used to test Monte Carlo methods developed to tackle such problems. We analyze here this model by means of analytical techniques, computing exactly the first eight cumulants of the expansion of the effective Hamiltonian in powers of the inverse temperature, and calculating physical observables for a large number of degrees of freedom with the help of standard multi-precision algorithms. We report accurate results for the free energy density, internal energy, standard and staggered magnetization, and the position and nature of the critical line, which confirm the mean-field qualitative picture, and which should be quantitatively reliable, at least in the high-temperature regime, including the entire critical line

Soil carbon sequestration rates under Mediterranean woody crops using recommended management practices : A meta-analysis

This work was supported by the projects: CARBOLIVAR (P11-RNM-7186) funded by Consejería de Innovación, Ciencia y Empresa of Junta de Andalucía and GEISpain project (CGL2014‐52838‐C2‐1‐R) funded by Ministerio de Economía y Competitividad, both including European Union ERDF funds. This work was also supported by the FPU 2012 grant program of the Ministerio de Educación, Cultura y Deporte of Spain. Dr. Roberto Garcia-Ruiz and Eduardo Aguilera gratefully acknowledge support by the Sustainable Farm Systems project (SSHRC 895-2011-1020) funded by the Canadian Social Sciences and Humanities Research Council.Peer reviewedPostprin

Massive Schwinger model at finite θ\theta

Using the approach developed in [V. Azcoiti, G. Di Carlo, A. Galante, V. Laliena, \textit{Phys. Lett.} \textbf{B563}, (2003) 117], we are able to reconstruct the behavior of the massive 1-flavor Schwinger model with a $\theta$ term and a quantized topological charge. We calculate the full dependence of the order parameter with $\theta$. Our results at $\theta = \pi$ are compatible with Coleman's conjecture on the phase diagram of this model.Comment: 8 pages, 8 figure

El tiempo a través del tiempo

El presente ensayo pretende ser una introducción general al problema filosófico del tiempo desde sus muy diferentes formas y posibilidades de ser abordado. En este sentido, el artículo recorre el problema desde diferentes puntos de vista y da breve cuenta de la pluralidad y diversidad de los tiempos que se encuentran en las diferentes definiciones filosóficas, en los diferentes estratos del saber, en las diferentes épocas y culturas, y también en los diferentes instrumentos que miden el propio tiempo.The present essay is designed to be a general introduction to the philosophical problem of time from its very different forms and ways of approaching. In this sense, the article covers the problem from different perspectives and gives a brief account of the plurality and diversity of the time found in the different philosophical definitions, in the different layers of knowledge, in different periods and cultures and also in the different instruments used to measure time itself

Family farming in the agricultural census of 2006: the legal mark and the options for their identification.

(Agricultura familiar no censo agropecuário 2006: o marco legal e as opções para sua identificação). Visando delimitar a agricultura familiar no Censo Agropecuário 2006, o Ministério do Desenvolvimento Agrário (MDA) e o Instituto Brasileiro de Geografia e Estatística (IBGE) elaboraram metodologia para construção de uma variável identificando os estabelecimentos agropecuários recenseados e que se ajustam ao conceito previsto na Lei n.11.326, de 24 de julho de 2006. O texto apresenta os passos metodológicos utilizados e alguns resultados

Frustration in Lattice Gauge Theory

We introduce a U(1) lattice gauge theory which incorporates explicit frustration in $d>2$. We show, by identifying an appropiate order parameter and through computer simulations, the existence of a frustrated region in the phase diagram of the model. We study this phase diagram and the nature of the transition lines.Comment: 3 pages, Latex, 5 figures, espcrc2.sty needed, Talk presented by E. Follana at LATTICE 9

Las huellas de la oralidad en siete cuentos de la narrativa del treinta

Seguir las huellas de la oralidad en algunos cuentos de la narrativa ecuatoriana de los treinta es, sin duda, una tarea compleja, porque no se trata de textos que se inscriben dentro de lo que Walter J. Ong llama oralidad primaria, es decir, “a la oralidad de una cultura que carece de todo conocimiento de la escritura o de la impresión”,1 sino de la literatura (letra) hecha, precisamente, por letrados, por escritores y constituida por textos fijados, hasta cierto punto, por la escritura, es decir, de la oralidad secundaria, de aquella que depende de la impresión y en general de la tecnología. Por lo tanto es necesario considerar, para este estudio, tanto la oralidad como la escritura –oralidad primaria y oralidad secundaria– como dos niveles dialógicos de análisis e interpretación, no excluyentes sino complementarios. Por esta razón sería más apropiado hablar de los efectos de la oralidad en textos escritos, que modelizan un tipo de cultura, en este caso, la del montubio de las primeras décadas del siglo XX – la de la época del cacao–. Entonces, la pregunta básica a la que vamos a tratar de responder es: ¿cómo se representa dicha cultura oral en los textos seleccionados? (“El cholo del cuerito e venao” y “El cholo que se castró”, de Demetrio Aguilera Malta; “El Guaraguao” y “La salvaje”, de Joaquín Gallegos Lara; “Mardecido llanto” y “El malo”, de Enrique Gil Gilbert; y “Banda de pueblo”, de José de la Cuadra.