The magnetic environment of the Orion-Eridanus superbubble as revealed by Planck

Using the 353-GHz polarization observations by the Planck satellite we characterize the magnetic field in the Orion-Eridanus superbubble, a nearby expanding structure that spans more than 1600 square degrees in the sky. We identify a region of both low dispersion of polarization orientations and high polarization fraction associated with the outer wall of the superbubble identified in the most recent models of the large-scale shape of the region. We use the Davis-Chandrasekhar-Fermi method to derive plane-of-the-sky magnetic field strengths of tens of microGauss toward the southern edge of the bubble. The comparison of these values with existing Zeeman splitting observations of HI in emission suggests that the large-scale magnetic field in the region was primarily shaped by the expanding superbubble.Comment: 7 pages, 8 figures. Accepted for publication as a Letter in A&A, section 1. Letters to the Editor (08/12/2017

Magnetised Polish doughnuts revisited

We discuss a procedure to build new sequences of magnetised, equilibrium tori around Kerr black holes which combines two approaches previously considered in the literature. For simplicity we assume that the test-fluid approximation holds, and hence we neglect the self-gravity of the fluid. The models are built assuming a particular form of the angular momentum distribution from which the location and morphology of equipotential surfaces can be computed. This ansatz includes, in particular, the constant angular momentum case originally employed in the construction of thick tori - or Polish doughnuts - and it has already been used to build equilibrium sequences of purely hydrodynamical models. We discuss the properties of the new models and their dependence on the initial parameters. These new sequences can be used as initial data for magnetohydrodynamical evolutions in general relativity.Comment: 9 pages, 6 figures. Accepted for publication in Astronomy & Astrophysics July 12, 201

The MICE luminosity monitor

The MICE experiment will provide the first measurement of ionisation cooling, a technique suitable for reducing the transverse emittance of a tertiary muon beam in a future neutrino factory accelerator facility. MICE is presently in the final stages of commissioning its beam line. The MICE luminosity monitor has proved an invaluable tool throughout this process, providing independent measurements of particle rate from the MICE target, normalisation for beam line detectors and verification of simulation codes

Kelvin-Helmholtz instability in partially ionized compressible plasmas

The Kelvin-Helmholtz Instability (KHI) has been observed in the solar atmosphere. Ion-neutral collisions may play a relevant role for the growth rate and evolution of the KHI in solar partially ionized plasmas as in, e.g., solar prominences. Here, we investigate the linear phase of the KHI at an interface between two partially ionized magnetized plasmas in the presence of a shear flow. The effects of ion-neutral collisions and compressibility are included in the analysis. We obtain the dispersion relation of the linear modes and perform parametric studies of the unstable solutions. We find that in the incompressible case the KHI is present for any velocity shear regardless the value of the collision frequency. In the compressible case, the domain of instability depends strongly on the plasma parameters, specially the collision frequency and the density contrast. For high collision frequencies and low density contrasts the KHI is present for super-Alfvenic velocity shear only. For high density contrasts the threshold velocity shear can be reduced to sub-Alfvenic values. For the particular case of turbulent plumes in prominences, we conclude that sub-Alfvenic flow velocities can trigger the KHI thanks to the ion-neutral coupling.Comment: Accepted for publication in Ap

Coexistence of periods in a bisecting bifurcation

The inner structure of the attractor appearing when the Varley-Gradwell-Hassell population model bifurcates from regular to chaotic behaviour is studied. By algebraic and geometric arguments the coexistence of a continuum of neutrally stable limit cycles with different periods in the attractor is explained.Comment: 13 pages, 5 figure

Density functional simulation of small Fe nanoparticles

We calculate from first principles the electronic structure, relaxation and magnetic moments in small Fe particles, applying the numerical local orbitals method in combination with norm-conserving pseudopotentials. The accuracy of the method in describing elastic properties and magnetic phase diagrams is tested by comparing benchmark results for different phases of crystalline iron to those obtained by an all-electron method. Our calculations for the bipyramidal Fe_5 cluster qualitatively and quantitatively confirm previous plane-wave results that predicted a non-collinear magnetic structure. For larger bcc-related (Fe_35) and fcc-related (Fe_38, Fe_43, Fe_62) particles, a larger inward relaxation of outer shells has been found in all cases, accompanied by an increase of local magnetic moments on the surface to beyond 3 mu_B.Comment: 15 pages with 6 embedded postscript figures, updated version, submitted to Eur.Phys.J.

Pleomorphic adenoma of the nasal septum : a case report

Polypoid nasal lesions are commonly encountered in clinical practice and all should be examined histologically. The authors report a case of pleomorphic adenoma arising in the nasal septum in salivary-type tissue. The interest of this case is both in the relative rarity of the condition, and also in its being the first such report in local practice.peer-reviewe