Chemical distribution of HII regions towards the Galactic anticentre

We study the physical and chemical properties of a sample of HII regions located at RG >11 kpc and present the radial distribution of abundances towards the Galaxy anticentre. We carried out optical spectroscopic observations of nine HII regions with the WHT. The sample was increased by searching the literature for optical observations of regions towards the Galactic anticentre, re-analysing them to obtain a single sample of 23 objects covering the Galactocentric radius from 11 kpc to 18 kpc to be processed in a homogeneous and consistent manner. Accurate electron densities and temperatures of several ionic species were derived in 13 HII regions. These physical parameters were applied to the spectra to determine direct total chemical abundances. For those regions without direct estimations of temperature, chemical abundances were derived by performing tailor-made photoionisation models and/or by using an empirical relation obtained from radio recombination and optical temperatures. We performed weighted least-squares fits to the distribution of the derived abundances along the Galactocentric distances to study the radial gradients of metallicity. The distributions O/H, N/H, S/H, and Ar/H towards the anticentre can be represented by decreasing linear radial gradients, while in the case of N/O abundances the radial distribution is better fitted with a two-zone model. The He/H radial gradient is presented here for the first time; we find a slope that is not significantly different from zero. The derived gradient for oxygen shows a clear decrease with distance with a slope of -0.053dex/kpc. Although a shallower slope at large Galactocentric distances is suggested by our data, the flattening of the distribution cannot be confirmed and more objects towards the anticentre need to be studied in order to establish the true form of the metallicity gradient.Comment: Accepted for publication in Section 5. Galactic structure, stellar clusters and populations of Astronomy and Astrophysics. The official date of acceptance is 13/09/2016. 19 pages, 15 figures and 10 table

LAS INTERVENCIONES ANTRÓPICAS EN EL CURSO BAJO DEL GUADALETE Y EN SAN PEDRO DURANTE LA EDAD MODERNA

Se documentan en este trabajo las obras antrópicas realizadas durante la Edad Moderna en el curso bajo del río Guadalete y en el río San Pedro, en los términos municipales de Jerez de la Frontera y El Puerto de Santa María. Después de situar espacial y cronológicamente los embarcaderos del Guadalete -La Corta, El Portal, Puerto Franco, Sidueña y El Puerto-, estudiamos las tres principales obras efectuadas en ambos cursos fluviales, que originaron largos conflictos entre Jerez y El Puerto a causa de los intereses enfrentados entre una ciudad realenga y otra de régimen señorial: la excavación por Jerez de un canal que comunicó el Guadalete con el San Pedro (1648); la apertura en el Guadalete, en lugar inmediato a la ciudad de El Puerto, del Caño del Molino (1701); y la excavación de un nuevo cauce del Guadalete -el que ha llegado a nuestros días- desde el San Pedro (1722).Finalmente, anotamos los proyectos, nunca ejecutados (1766-1859), que pretendieron verter las aguas del Guadalete a su paso por El Puerto hasta el San Pedro, con el fin de evitar la colmatada y peligrosa barra de su desembocadura

Anthropic interventions on the lower course of Guadalente and San Pedro rivers during the Modern Age

El artículo documenta las obras antrópicas realizadas durante la Edad Moderna en el curso bajo del río Guadalete y en el río San Pedro, en los términos municipales de Jerez de la Frontera y El Puerto de Santa María. Después de situar espacial y cronológicamente los embarcaderos del Guadalete –La Corta, El Portal, Puerto Franco, Sidueña y El Puerto – estudiamos las tres principales obras efectuadas en ambos cursos fluviales, que originaron largos conflictos entre Jerez y El Puerto a causa de los intereses enfrentados entre una ciudad realenga y otra de régimen señorial: la excavación por Jerez de un canal que comunicó el Guadalete con el San Pedro (1648); la apertura en el Guadalete, en lugar inmediato a la ciudad de El Puerto de Santa María, del Caño del Molino (1701), y la excavación de un nuevo cauce del Guadalete desde el San Pedro (1722), el que ha llegado a nuestros días. Finalmente, anotamos los proyectos, nunca ejecutados (1766-1859), que pretendieron verter las aguas del Guadalete a su paso por El Puerto hasta el San Pedro con el fin de evitar la colmatada y peligrosa barra de su desembocadura.The article documents the anthropic works carried out during the Modern Age in the lower course of the Guadalete and San Pedro rivers, within then municipal boundaries of Jerez de la Frontera and El Puerto de Santa María. After placing the docks of the Guadalete river –La Corta, El Portal, Puerto Franco, Sidueña and El Puerto –spatially and chronologically, we study the three main works carried out on both rivers, which led to long lasting conflicts between Jerez and El Puerto due to the conflicting interests of a royal and a seigniorial city: the opening of a channel in Jerez to communicate the Guadalete with the San Pedro river (1648); the opening of Caño del Molino (1701) next to El Puerto de Santa María on the Guadalete and the excavation of a new course for the Guadalete from San Pedro river (1722) which still exists today. Finally, we list the projects, never accomplished (1766-1859), that were supposed to transfer water from the Guadalete as it flowed past El Puerto to the San Pedro river in order to avoid the abundant and dangerous sediments of its estuary44 pp

Number conserving particle-hole RPA for superfluid nuclei

TheAuthor(s) - .Published by Elsevier B.V. "This is an open access article under the CCBY license (http://creativecommons.org/licenses/by/4.0/).Funded by SCOAP"We present a number conserving particle-hole RPA theory for collective excitations in the transition from normal to superfluid nuclei. The method derives from an RPA theory developed long ago in quantum chemistry using antisymmetric geminal powers, or equivalently number projected HFB states, as reference states. We show within a minimal model of pairing plus monopole interactions that the number conserving particle-hole RPA excitations evolve smoothly across the superfluid phase transition close to the exact results, contrary to particle-hole RPA in the normal phase and quasiparticle RPA in the superfluid phase that require a change of basis at the broken symmetry point. The new formalism can be applied in a straightforward manner to study particle-hole excitations on top of a number projected HFB state.Consejería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía (Spain) FQM-160 and FQM-370Fondo Europeo de Desarrollo Regional (ERDF), ref. SOMM17/6105/UGRMinisterio de Ciencia, Innovación y Universidades and the ERDF under Projects No. FIS2015-63770-P, FIS2017-88410-P and PGC2018-094180-B-I00CEAFMC and Universidad de Huelva High Performance Computer (HPC@UHU) funded by FEDER/MINECO project UNHU-15CE-284

Number conserving particle-hole RPA for superfluid nuclei

TheAuthor(s) - .Published by Elsevier B.V. "This is an open access article under the CCBY license (http://creativecommons.org/licenses/by/4.0/).Funded by SCOAP"We present a number conserving particle-hole RPA theory for collective excitations in the transition from normal to superfluid nuclei. The method derives from an RPA theory developed long ago in quantum chemistry using antisymmetric geminal powers, or equivalently number projected HFB states, as reference states. We show within a minimal model of pairing plus monopole interactions that the number conserving particle-hole RPA excitations evolve smoothly across the superfluid phase transition close to the exact results, contrary to particle-hole RPA in the normal phase and quasiparticle RPA in the superfluid phase that require a change of basis at the broken symmetry point. The new formalism can be applied in a straightforward manner to study particle-hole excitations on top of a number projected HFB state.Consejería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía (Spain) FQM-160 and FQM-370Fondo Europeo de Desarrollo Regional (ERDF), ref. SOMM17/6105/UGRMinisterio de Ciencia, Innovación y Universidades and the ERDF under Projects No. FIS2015-63770-P, FIS2017-88410-P and PGC2018-094180-B-I00CEAFMC and Universidad de Huelva High Performance Computer (HPC@UHU) funded by FEDER/MINECO project UNHU-15CE-284

A hydrated ion model of [UO2]2+ in water: Structure, dynamics, and spectroscopy from classical molecular dynamics

A new ab initio interaction potential based on the hydrated ion concept has been developed to obtain the structure, energetics, and dynamics of the hydration of uranyl in aqueous solution. It is the first force field that explicitly parameterizes the interaction of the uranyl hydrate with bulk water molecules to accurately define the second-shell behavior. The [UO2(H2O)5 ] 2+ presents a first hydration shell U–O average distance of 2.46 Å and a second hydration shell peak at 4.61 Å corresponding to 22 molecules using a coordination number definition based on a multisite solute cavity. The second shell solvent molecules have longer mean residence times than those corresponding to the divalent monatomic cations. The axial regions are relatively de-populated, lacking direct hydrogen bonding to apical oxygens. Angle-solved radial distribution functions as well as the spatial distribution functions show a strong anisotropy in the ion hydration. The [UO2(H2O)5 ] 2+ solvent structure may be regarded as a combination of a conventional second hydration shell in the equatorial and bridge regions, and a clathrate-like low density region in the axial region. Translational diffusion coefficient, hydration enthalpy, power spectra of the main vibrational modes, and the EXAFS spectrum simulated from molecular dynamics trajectories agree fairly well with the experiment.Junta de Andalucía de España, Proyecto de Excelencia-P11-FQM 760

Connection between decoherence and excited state quantum phase transitions

In this work we explore the relationship between an excited state quantum phase transition (ESQPT) and the phenomenon of quantum decoherence. For this purpose, we study how the decoherence is affected by the presence of a continuous ESQPT in the environment. This one is modeled as a two level boson system described by a Lipkin Hamiltonian. We will show that the decoherence of the system is maximal when the environment undergoes a continuous ESQPT

A general study of actinyl hydration by molecular dynamics simulations using ab initio force fields

A set of new ab initio force fields for aqueous [AnO2] 2+/+ (An = Np(VI,V), Pu(VI), Am(VI)) has been developed using the Hydrated Ion (HI) model methodology previously used for [UO2] 2+. Except for the non-electrostatic contribution of the HI-bulk water interaction, the interaction potentials are individually parameterized. Translational diffusion coefficients, hydration enthalpies, and vibrational normal mode frequencies were calculated from the MD simulations. Physico-chemical properties satisfactorily agree with experiments validating the robustness of the force field strategy. The solvation dynamics and structure for all hexavalent actinoids are extremely similar and resemble our previous analysis of the uranyl cation. This supports the idea of using the uranyl cation as a reference for the study of other minor actinyls. The comparison between the NpO2+ 2 and NpO+ 2 hydration only provides significant differences in first and second shell distances and second-shell mean residence times. We propose a single general view of the [AnO2] 2+/+ hydration structure: aqueous actinyls are amphiphilic anisotropic solutes which are equatorially conventional spherically symmetric cations capped at the poles by clathrate-like water structures.Junta de Andalucía de España, Plan Andaluz de Investigación-FQM-28