On the biology of the European flying squid Todarodes sagittatus (Lamarck, 1798) (Cephalopoda: Ommastrephidae) in the central eastern Atlantic

A total of 206 specimens of the ommastrephid squid Todarodes sagittatus, obtained from three areas of the central eastern Atlantic (Canary Islands/African coast, Madeira, and the Gettysburg Bank area south of Portugal) were examined. New information on size, mass, length-mass relationships, reproductive biology, and diet of the squid from a hitherto not very well studied area is supplied. Females dominated the samples (78%) and attained larger size and mass than males. Dorsal mantle lengths of T. sagittatus in the Canary Islands/African coast samples and in the Madeira region were similar, 167 – 348 mm for females and 175 – 269 mm for males. From the Gettysburg Bank all specimens were immature, females ranging between 71 and 276 mm and males from 98 to 233 mm. Mature females were found mainly during winter and mature males nearly year-round, indicating that they mature earlier than females and at a smaller size. Prey consisted mainly offish (54.9%), decapods (18.8%) and cephalopods (12.1%). Otoliths and fish bones identified from stomach contents suggest that myctophids were the most common and diverse prey

Reducing computational time via order reduction of a class of reaction–diffusion systems

In this paper, we consider a class of reaction– diffusion PDEs. For this class, a suitable state transformation allows conversion to a heat equation together with a lower order PDE set. By giving an explicit solution to the heat equation we are able to obtain a complete solution to the original PDE. By focusing on the computational load, we give a comparison of the pure numerical, analytical/numerical, analytical/approximated, and approximated methods of solving the PDE. In some examples, we note an almost order of magnitude improvement in computational load

Anomalous rotational properties of Bose-Einstein condensates in asymmetric traps

We study the rotational properties of a Bose-Einstein condensate confined in a rotating harmonic trap for different trap anisotropies. Using simple arguments, we derive expressions for the velocity field of the quantum fluid for condensates with or without vortices. While the condensed gas describes open spiraling trajectories, on the frame of reference of the rotating trap the motion of the fluid is against the trap rotation. We also find explicit formulae for the angular momentum and a linear and Thomas-Fermi solutions for the state without vortices. In these two limits we also find an analytic relation between the shape of the cloud and the rotation speed. The predictions are supported by numerical simulations of the mean field Gross-Pitaevskii model.Comment: 4 RevTeX pages, 2 EPS figures; typos fixed, reference adde

Split vortices in optically coupled Bose-Einstein condensates

We study a rotating two-component Bose-Einstein condensate in which an optically induced Josephson coupling allows for population transfer between the two species. In a regime where separation of species is favored, the ground state of the rotating system displays domain walls with velocity fields normal to them. Such a configuration looks like a vortex split into two halves, with atoms circulating around the vortex and changing their internal state in a continuous way.Comment: 4 EPS pictures, 4 pages; Some errata have been corrected and thep resentation has been slightly revise

Exploring Li-ion conductivity in cubic, tetragonal and mixed-phase Al-substituted Li7La3Zr2O12 using atomistic simulations and effective medium theory

Garnet Li7La3Zr2O12 (LLZO) is a promising solid electrolyte candidate for solid-state Li-ion batteries, but at room temperature it crystallizes in a poorly Li-ion conductive tetragonal phase. To this end, partial substitution of Li+ by Al3+ ions is an effective way to stabilize the highly conductive cubic phase at room temperature. Yet, fundamental aspects regarding this aliovalent substitution remain poorly understood. In this work, we use molecular dynamics and advanced hybrid Monte Carlo methods for systematic study of the room temperature Li-ion diffusion in tetragonal and cubic LLZO to shed light on important open questions. We find that Al substitution in tetrahedral sites of the tetragonal LLZO allows previously inaccessible sites to become available, which enhances Li-ion conductivity. In contrast, in the cubic phase Li-ion diffusion paths become blocked in the vicinity of Al ions, resulting in a decrease of Li-ion conductivity. Moreover, combining the conductivities of individual phases through an effective medium approximation allowed us to estimate the conductivities of cubic/tetragonal phase mixtures that are in good agreement with those reported in several experimental works. This suggests that phase coexistence (due to phase equilibrium or gradients in Al content within a sample) could have a significant impact on the conductivity of Al-substituted LLZO, particularly at low contents of Al3+. Overall, by making a thorough comparison with reported experimental data, the theoretical study and simulations of this work advance our current understanding of Li-ion mobility in Al-substituted LLZO garnets and might guide future in-depth characterization experiments of this relevant energy storage material.MINECO ENE2016-81020-R. SGI/IZO-SGIker UPV/EHU. the i2BASQUE academic network. Barcelona Supercomputer Center (QCM-2016-450 3-0002)

Three-dimensional vortex configurations in a rotating Bose Einstein condensate

We consider a rotating Bose-Einstein condensate in a harmonic trap and investigate numerically the behavior of the wave function which solves the Gross Pitaevskii equation. Following recent experiments [Rosenbuch et al, Phys. Rev. Lett., 89, 200403 (2002)], we study in detail the line of a single quantized vortex, which has a U or S shape. We find that a single vortex can lie only in the x-z or y-z plane. S type vortices exist for all values of the angular velocity Omega while U vortices exist for Omega sufficiently large. We compute the energy of the various configurations with several vortices and study the three-dimensional structure of vortices