Violation of area-law scaling for the entanglement entropy in spin 1/2 chains

Entanglement entropy obeys area law scaling for typical physical quantum systems. This may naively be argued to follow from locality of interactions. We show that this is not the case by constructing an explicit simple spin chain Hamiltonian with nearest neighbor interactions that presents an entanglement volume scaling law. This non-translational model is contrived to have couplings that force the accumulation of singlet bonds across the half chain. Our result is complementary to the known relation between non-translational invariant, nearest neighbor interacting Hamiltonians and QMA complete problems.Comment: 9 pages, 4 figure

Local temperature in quantum thermal states

We consider blocks of quantum spins in a chain at thermal equilibrium, focusing on their properties from a thermodynamical perspective. Whereas in classical systems the temperature behaves as an intensive magnitude, a deviation from this behavior is expected in quantum systems. In particular, we see that under some conditions the description of the blocks as thermal states with the same global temperature as the whole chain fails. We analyze this issue by employing the quantum fidelity as a figure of merit, singling out in detail the departure from the classical behavior. The influence in this sense of zero-temperature quantum phase transitions can be clearly observed within this approach. Then we show that the blocks can be considered indeed as thermal states with a high fidelity, provided an effective local temperature is properly identified. Such a result originates from typical properties of reduced sub-systems of energy-constrained Hilbert spaces. Finally, the relation between local and global temperature is analyzed as a function of the size of the blocks and the system parameters.Comment: 10 pages, 10 figures. New fidelity measure with similar result

Estudio de mejora de la calidad del agua para el olivar de riego de provincia de Jaén mediante la aplicación de herramientas SIG

El objetivo de este trabajo es el estudio, por medio de SIG, de la viabilidad de la utilización conjunta para el riego de olivar de aguas superficiales y subterráneas, para disminuir la salinización de acuíferos y los riesgos de contaminación por retornos de agua en la provincia de Jaén (sur de España). Se procede a evaluar las proporciones óptimas de los dos tipos de agua en función al umbral de salinidad a partil del cual puede afectar a la producción de la cosecha de olivar, y realizar mapas temáticos con el fin de evitar una acumulación excesiva de sal en el suelo. Se consideraron diferentes variables de la evaluación de riesgos, y un mapa temático para cada variable desarrollado por medio de análisis geoestadístico de los datos, utilizando el software de código abierto gvSIG. La herramienta basada en GIS fue una estrategia capaz de realizar mapas de mezcla de agua superficial y subterránea para disminuir los riesgos de salinización. Con este trabajo se expone la posibilidad de solucionar la afección de las superficies regadas en sus cuencas vertiente, desde las que la escorrentía superficial puede arrastrar sustancias contaminantes hacia áreas permeables a las que recarga, mediante la mezcla de agua de distinta procedencia, minimizando el riesgo de afección y vulnerabilidad de las escorrentías superficiales y aguas subterráneas frente a la contaminación

Economic cycles and environmental crisis in arid southeastern Spain. A historical perspective

The arid southeast region has been one of the areas with the oldest settlement in the Iberian Peninsula. Despite limitations imposed by lack of water and low soil fertility, a great number of dwellers have settled in this land for three thousand years thanks to its easy access to the commercial paths of the Mediter- ranean. The area is currently under great territorial and socioeconomic transformation activated by intensive agriculture through greenhouses and irrigation. The history of this territory offers a series of successful and downward cycles determined, from an ecological and economic point of view, by its integration in different stages of the globalization process. Most recently, in the 19th century an intensive deforestation process took place caused by the mining and iron industry. The deep economic and social crisis which followed the declining of this development model brought also about an ecological crisis. In the second half of the 20th century, negative environmental effects have continued and extended to the next generations with problems such as territorial saturation and aquifer depletion that characterize the new intensive agriculture under plastic. The current debate about the sustainability of this developmental model in such vulnerable environment can take advantage of some ecological lessons from the past

Scaling of entanglement support for Matrix Product States

The power of matrix product states to describe infinite-size translational-invariant critical spin chains is investigated. At criticality, the accuracy with which they describe ground state properties of a system is limited by the size $\chi$ of the matrices that form the approximation. This limitation is quantified in terms of the scaling of the half-chain entanglement entropy. In the case of the quantum Ising model, we find $S \sim {1/6}\log \chi$ with high precision. This result can be understood as the emergence of an effective finite correlation length $\xi_\chi$ ruling of all the scaling properties in the system. We produce five extra pieces of evidence for this finite-$\chi$ scaling, namely, the scaling of the correlation length, the scaling of magnetization, the shift of the critical point, and the scaling of the entanglement entropy for a finite block of spins. All our computations are consistent with a scaling relation of the form $\xi_\chi\sim \chi^{\kappa}$, with $\kappa=2$ for the Ising model. In the case of the Heisenberg model, we find similar results with the value $\kappa\sim 1.37$. We also show how finite-$\chi$ scaling allow to extract critical exponents. These results are obtained using the infinite time evolved block decimation algorithm which works in the thermodynamical limit and are verified to agree with density matrix renormalization group results.Comment: A new section comparing with previous results. Published version (small differences due to proof corrections

Toll-like receptors 2 and 4 modulate intestinal IL-10 differently in ileum and colon

Background: Inflammatory bowel diseases are consequence of an intestinal homeostasis breakdown in which innate immune dysregulation is implicated. Toll-like receptor (TLR)2 and TLR4 are immune recognition receptors expressed in the intestinal epithelium, the first physical-physiological barrier for microorganisms, to inform the host of the presence of Gram-positive and Gram-negative organisms. Interleukin (IL)-10 is an essential anti-inflammatory cytokine that contributes to maintenance of intestinal homeostasis. Aim: Our main aim was to investigate intestinal IL-10 synthesis and release, and whether TLR2 and TLR4 are determinants of IL-10 expression in the intestinal tract. Methods: We used Caco-2 cell line as an enterocyte-like cell model, and also ileum and colon from mice deficient in TLR2, TLR4 or TLR2/4 to test the involvement of TLR signaling. Results: Intestinal epithelial cells are able to synthesize and release IL-10 and their expression is increased after TLR2 or TLR4 activation. IL-10 regulation seems to be tissue specific, with IL-10 expression in the ileum regulated by a compensation between TLR2 and TLR4 expression, whereas in the colon, TLR2 and TLR4 affect IL-10 expression independently. Conclusions: Intestinal epithelial cells could release IL-10 in response to TLR activation, playing an intestinal tissue-dependent and critical intestinal immune role

De Piaget a Kohlberg: utilitat i vigència de l'ús de dilemes morals amb l'alumnat universitari

Ara que es compleixen els 90 anys del naixement de Lawrence Kohlberg, fóra de justícia rememorar la importància de les seues aportacions sobre el desenvolupament cognitiu moral de les persones. Però, el progrés d’aquesta teoria no hauria estat possible sense els estudis previs de Jean Piaget sobre el procés de construcció de la moral autònoma en l’infant. L’obra d’aquests dos autors ha tingut grans repercussions pedagògiques en el camí per a la construcció d’un pensament just i autònom. Una dels tècniques utilitzades per Kohlberg per fer progressar les persones en els estadis de desenvolupament moral per ell definits, és la dels dilemes morals. Entenem que aquesta tècnica contínua sent vàlida en l’actualitat, i així ho hem comprovat amb alumnat universitari, però hem pogut constatar que els dilemes hipotètics utilitzats per Kohlberg han quedat obsolets per tal com ha canviat el sistema de valors del nostre alumnat i del context social en què vivim. Per això hem hagut de construir nous dilemes adaptats a la nostra realitat actual, els quals s’han experimentat amb alumnat universitari fins a garantir- ne la validesa i l’eficàcia per complir els objectius previstos. Aquests nous dilemes constitueixen un material idoni per treballar amb l’alumnat perquè aprenguen la tècnica i puguen avançar cap a nivells superiors de desenvolupament cognitiu moral

Análisis correlatorio y espectral de los caudales del manantial de Iturriotz (Vizcaya): El sistema del barranco de Peñalba como ejemplo de un tipo de Karst de caraclerísticas mixtas

In order to define the structure of the time series of rainfall and discharge, and also to improve the knowledge of the Barranco Peñalba karstic system, a correlation and spectral analysis has been made of the Iturriotz spring and the Juncal pluviometer data (period: 6th August 1983 to 12th October 1985). Such analysis reveals a relatively important memory effect and a regulation time of 23,5 days. However, it has been made clear a very small modulation effect with a spectral band of 0.30-0.32. The cross correlation reveals a lag very small between the input and output signals, in spite of the existence of a some regulation power at the end of the impulsional answer. These results do not match exactly any of the type-model defined by Mangin (1982), but suggests a system with mixed characteristics. The apparently contradictory features inferred from this analysis can be atributed to the heterogeneity of the aquifer materials and to the complexity of the recharge mecanisms.Con objeto de definir la estructura de las series cronológicas de lluvias y caudales, así como para mejorar el conocimiento del sistema kárstico del barranco de Peñalba, se ha aplicado el análisis de correlación y espectral a los datos del manantial de Iturriotz y del pluviómetro del Juncal, del período 6 de Agosto de 1983 a 12 de Octubre de 1985. Dicho análisis revela un efecto memoria relativamente importante y un tiempo de regulación de 23,5 días; sin embargo, se pone de manifiesto un efecto de filtro muy reducido, con una banda espectral de 0.30-0.32; el correlograma cruzado evidencia un desfase muy corto entre las señales de entrada y salida, a pesar de que existe un cierto poder regulador al final de la respuesta impulsional. Estos resultados no corresponden exactamente a ninguno de los modelos-tipo definidos por Mangin (1982), sino que sugieren un sistema de características mixtas. Los rasgos aparentemente contradictorios que se deducen de este análisis pueden ser atribuidos a la heterogeneidad del material acuífero y a la complejidad de los mecanismos de recarga

Optimal Matrix Product States for the Heisenberg Spin Chain

We present some exact results for the optimal Matrix Product State (MPS) approximation to the ground state of the infinite isotropic Heisenberg spin-1/2 chain. Our approach is based on the systematic use of Schmidt decompositions to reduce the problem of approximating for the ground state of a spin chain to an analytical minimization. This allows to show that results of standard simulations, e.g. density matrix renormalization group and infinite time evolving block decimation, do correspond to the result obtained by this minimization strategy and, thus, both methods deliver optimal MPS with the same energy but, otherwise, different properties. We also find that translational and rotational symmetries cannot be maintained simultaneously by the MPS ansatz of minimum energy and present explicit constructions for each case. Furthermore, we analyze symmetry restoration and quantify it to uncover new scaling relations. The method we propose can be extended to any translational invariant Hamiltonian.Comment: 10 pages, 3 figures; typos adde