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© 2010 The American Physical Society. Financial support was provided by the Spanish MICINN through Projects No. FIS2008-06078-C03-01 and No. FIS2008-06078-C03-03 and Consolider-Ingenio 2010 Program CPAN (CSD2007-00042) and by the Junta de Andalucía through Projects No. FQM2288 and No. FQM219. The authors want to thank S. Finazzi, S. Liberati, G. A. Mena Marugán, and R. Parentani for illuminating discussions., Fluctuations around a Bose-Einstein condensate can be described by means of Bogolubov theory leading to the notion of quasiparticle and antiquasiparticle familiar to nonrelativistic condensed-matter practitioners. On the other hand, we already know that these perturbations evolve according to a relativistic Klein-Gordon equation in the long-wavelength approximation. For shorter wavelengths, we show that this equation acquires nontrivial corrections which modify the Klein-Gordon product. In this approach, quasiparticles can also be defined (up to the standard ambiguities due to observer dependence). We demonstrate that-in the low-energy as well as in the high-energy regimes-both concepts of quasiparticle are actually the same, regardless of the formalism (Bogolubov or Klein-Gordon) used to describe them. These results also apply to any barotropic, inviscid, irrotational fluid, with or without quantum potential. Finally, we illustrate how the quantization of these systems of quasiparticles proceeds by analyzing a stationary configuration containing an acoustic horizon. We show that there are several possible choices of a regular vacuum state, including a regular generalization of the Boulware vacuum. Issues such us Hawking radiation crucially depend on this vacuum choice., Spanish MICINN, Junta de Andalucia, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2009 The American Physical Society. We kindly thank Stefano Liberati and Matt Visser for enlightening comments and discussions, and José Luis Jaramillo for very useful suggestions on the numerical aspects of this work. G. J. would also like to express his gratitude to Fernando Barbero, Daniel Gómez Vergel, and Lorenzo Sindoni for useful discussions, and SISSA (Trieste) for hospitality. Financial support was provided by the Spanish MEC through the projects FIS2005-05736- C03-01, FIS2005-05736-C03-02, and FIS2006-26387-E., We analyze the Hawking radiation process due to collapsing configurations in the presence of superluminal modifications of the dispersion relation. With such superluminal dispersion relations, the horizon effectively becomes a frequency-dependent concept. In particular, at every moment of the collapse, there is a critical frequency above which no horizon is experienced. We show that, as a consequence, the late-time radiation suffers strong modifications, both quantitative and qualitative, compared to the standard Hawking picture. Concretely, we show that the radiation spectrum becomes dependent on the measuring time, on the surface gravities associated with different frequencies, and on the critical frequency. Even if the critical frequency is well above the Planck scale, important modifications still show up., Spanish MEC, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 1998 The American Physical Society. We are very grateful to G.A. Mena Marugán, M. Moles and P.F. González-Díaz for helpful discussions and suggestions. C.B. was supported by a Spanish Ministry of Education and Culture (MEC) grant. C.B. is also grateful to J.B. Hartle and the Institute for Theoretical Physics (UCSB), where part of this work was done, for warm hospitality. This research was supported in part by the National Science Foundation under Grant No. PHY994–07194. L.J.G. was supported by funds provided by DGICYT and MEC (Spain) under Contract Adjunct to Project No. PB94–0107., We study the effects of asymptotically anti-de Sitter wormholes in low-energy field theory and give a general prescription for obtaining the local effective interaction terms induced by them. The choice of vacuum for the matter fields selects a basis of the Hilbert space of anti-de Sitter wormholes whose elements can be interpreted as states containing a given number of particles. This interpretation is subject to the same kind of ambiguity in the definition of a particle as that arising from quantum field theory in curved spacetime., National Science Foundation, DGICyT (Spain), MEC (Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2006 The American Physical Society. C. B. has been funded by the Spanish MEC under Project No. FIS2005-05736-C03-01 with a partial FEDER contribution. G. J. was supported by CSIC grants No. I3P-BGP2004 and No. I3P-BPD2005 of the I3P programme, cofinanced by the European Social Fund, and by the Spanish MEC under Project No. FIS2005-05736-C03- 02. L. J. G. was supported by the Spanish MEC under the same project and No. FIS2004-01912., We examine the linear stability of various configurations in Bose-Einstein condensates with steplike sonic horizons. These configurations are chosen in analogy with gravitational systems with a black hole horizon, a white hole horizon, and a combination of both. We discuss the role of different boundary conditions in this stability analysis, paying special attention to their meaning in gravitational terms. We highlight that the stability of a given configuration, not only depends on its specific geometry, but especially on these boundary conditions. Under boundary conditions directly extrapolated from those in standard general relativity, black hole configurations, white hole configurations, and the combination of both into a black hole-white hole configuration are shown to be stable. However, we show that under other (less stringent) boundary conditions, configurations with a single black hole horizon remain stable, whereas white hole and black hole-white hole configurations develop instabilities associated to the presence of the sonic horizons., Spanish MEC, CSIC, European Social Fund, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 1996 The American Physical Society. We are very grateful to Mariano Moles for helpful discussions and support. C.B. was supported by a Spanish Ministry of Education and Science (MEC) grant. L.J.G. was supported by the MEC and the British Council. P.G.-D. acknowledges DGICYT for financial support under Research Projects Nos. PB94-0107 and PB93-0139. G.A.M.M. was supported by funds provided by DGICYT and MEC under Contract Adjunct to the Project No. PB93-0139., Starting with a procedure for dealing with general asymptotic behavior, we construct a quantum theory for asymptotically anti-de Sitter wormholes. We follow both the path integral formalism and the algebraic quantization program proposed by Ashtekar. By adding suitable surface terms, the Euclidean action of the asymptoically anti-de Sitter wormholes can be seen to be finite and gauge invariant. This action determines an appropriate variational problem for wormholes. We also obtain the wormhole wave functions of the gravitational model and show that all the physical states of the quantum theory are superpositions of wormhole states., Spanish Ministry of Education and Science, British Council, DGICYT (Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© Int School Advanced Studies. The authors want to thank Renaud Parentani, Stefano Finazzi, Stefano Liberati, Iacopo Carusotto, Grigory Volovik and Matt Visser for illuminating discussions. Financial support was provided by the Spanish MICINN through the projects FIS2008-06078-C03-01 and FIS2008- 06078-C03-03 and by the Junta de Andalucía through the project FQM219. G.J. is supported by a FECYT postdoctoral mobility contract of the Spanish MEC/MICINN, and also acknowledges the Academy of Finland (Centers of Excellence Programme 2006- 2011, grant 218211) and the EU 7th Framework Programme (FP7/2007-2013, grant 228464 Microkelvin)., We use the avoidance of the trans-Planckian problem of Hawking radiation as a guiding principle in searching for a compelling scenario for the evaporation of black holes or black-hole-like objects. We argue that there exist only three possible scenarios, depending on whether the classical notion of long-lived horizon is preserved by high-energy physics and on whether the dark and compact astrophysical objects that we observe have long-lived horizons in the first place. Along the way, we find that i) a theory with high-energy superluminal signalling and a long-lived trapping horizon would be extremely unstable in astrophysical terms and that i i) stellar pulsations of objects hovering right outside but extremely close to their gravitational radius can result in a mechanism for Hawking-like emission., Spanish MICINN, Junta de Andalucia, Academy of Finland, EU, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© World Scientific. We are very grateful to Guillermo A. Mena Marugán, Mariano Moles and Pedro F. González-Díaz for helpful discussions and suggestions. C.B was supported by a Spanish Ministry of Education and Culture (MEC) grant. C.B. is also grateful to James Hartle and the Institute for Theoretical Physics (UCSB), where part of this work was done, for warm hospitality. This research was supported in part by the National Science Foundation under Grant No. PHY94–07194. L.J.G. was supported by funds provided by DGICYT and MEC under Contract Adjunct to the Project No. PB94–0107., The effects of asymptotically anti-de Sitter wormholes in low-energy field theory are calculated in full detail for three different matter contents: a conformal scalar field, an electromagnetic field and gravitons. There exists a close relation between the choice of vacuum for the matter fields and the selection of a basis of the Hilbert space of anti-de Sitter wormholes. In the presence of conformal matter (i.e., conformal scalar or electromagnetic fields), this relation allows us to interpret the elements of these bases as wormhole states containing a given number of particles. This interpretation is subject to the same kind of ambiguity in the definition of particle as that arising from quantum field theory in curved spacetime. In the case of gravitons, owing to the nonconformal coupling, it is not possible to describe wormhole states in terms of their particle content., National Science Foundation, DGICYT, MEC, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

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Changes in environmental conditions, whether related or not to human activities, are continuously modifying the geographic distribution of vectors, which in turn affects the dynamics and distribution of vector-borne infectious diseases. Determining the main ecological drivers of vector distribution and how predicted changes in these drivers may alter their future distributions is therefore of major importance. However, the drivers of vector populations are largely specific to each vector species and region. Here, we identify the most important human-activity-related and bioclimatic predictors affecting the current distribution and habitat suitability of the mosquito Culex pipiens and potential future changes in its distribution in Spain. We determined the niche of occurrence (NOO) of the species, which considers only those areas lying within the range of suitable environmental conditions using presence data. Although almost ubiquitous, the distribution of Cx. pipiens is mostly explained by elevation and the degree of urbanization but also, to a lesser extent, by mean temperatures during the wettest season and temperature seasonality. The combination of these predictors highlights the existence of a heterogeneous pattern of habitat suitability, with most suitable areas located in the southern and northeastern coastal areas of Spain, and unsuitable areas located at higher altitude and in colder regions. Future climatic predictions indicate a net decrease in distribution of up to 29.55%, probably due to warming and greater temperature oscillations. Despite these predicted changes in vector distribution, their effects on the incidence of infectious diseases are, however, difficult to forecast since different processes such as local adaptation to temperature, vector-pathogen interactions, and human-derived changes in landscape may play important roles in shaping the future dynamics of pathogen transmission.

Background & aims: Legumes, a low-energy, nutrient-dense and low glycemic index food, have shown beneficial effects on glycemic control and adiposity. As such, legumes are widely recommended in diabetic diets, even though there is little evidence that their consumption protects against type 2 diabetes. Therefore the aim of the present study was to examine the associations between consumption of total legumes and specific subtypes, and type 2 diabetes risk. We also investigated the effect of theoretically substituting legumes for other protein- or carbohydrate-rich foods. Methods: Prospective assessment of 3349 participants in the PREvención con DIeta MEDiterránea (PREDIMED) study without type 2 diabetes at baseline. Dietary information was assessed at baseline and yearly during follow-up. We used Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for type-2 diabetes incidence according to quartiles of cumulative average consumption of total legumes, lentils, chickpeas, dry beans and fresh peas. Results: During a median follow-up of 4.3 years, 266 new cases of type 2 diabetes occurred. Individuals in the highest quartile of total legume and lentil consumption had a lower risk of diabetes than those in the lowest quartile (HR: 0.65; 95% CI: 0.43, 0.96; P-trend = 0.04; and HR: 0.67; 95% CI: 0.46–0.98; P-trend = 0.05, respectively). A borderline significant association was also observed for chickpeas consumption (HR 0.68; 95% CI: 0.46, 1.00; P-trend = 0.06). Substitutions of half a serving/day of legumes for similar servings of eggs, bread, rice or baked potato was associated with lower risk of diabetes incidence. Conclusions: A frequent consumption of legumes, particularly lentils, in the context of a Mediterranean diet, may provide benefits on type 2 diabetes prevention in older adults at high cardiovascular risk. Trial registration: The trial is registered at http://www.controlled-trials.com (ISRCTN35739639). Registration dat