Cosmic magnetic fields and dark energy in extended electromagnetism

We discuss an extended version of electromagnetism in which the usual gauge fixing term is promoted into a physical contribution that introduces a new scalar state in the theory. This new state can be generated from vacuum quantum fluctuations during an inflationary era and, on super-Hubble scales, gives rise to an effective cosmological constant. The value of such a cosmological constant coincides with the one inferred from observations as long as inflation took place at the electroweak scale. On the other hand, the new state also generates an effective electric charge density on sub-Hubble scales that produces both vorticity and magnetic fields with coherent lengths as large as the present Hubble horizon.Comment: 4 pages, 2 figures. Contribution to the proceedings of Spanish Relativity Meeting 2010, Granada, Spain, 6-10 September 201

The Peierls substitution in an engineered lattice potential

Artificial gauge fields open new possibilities to realize quantum many-body systems with ultracold atoms, by engineering Hamiltonians usually associated with electronic systems. In the presence of a periodic potential, artificial gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here, we describe a one-dimensional lattice derived purely from effective Zeeman-shifts resulting from a combination of Raman coupling and radiofrequency magnetic fields. In this lattice, the tunneling matrix element is generally complex. We control both the amplitude and the phase of this tunneling parameter, experimentally realizing the Peierls substitution for ultracold neutral atoms.Comment: 6 pages, 5 figure

Nuestra Experiencia en el Estudio con Ultrasonografía en la Cadera Neonatal

Se estudian mediante ultrasonografía las caderas de 112 recién nacidos (224 caderas) con signos clínicos de displasia luxante de cadera. Los resultados se comparan con los datos de exploración clínica y estudio radiográ- fico poniendo en evidencia las limitaciones diagnósticas de las maniobras exploratorias clásicas y la radiografía. Concluye que la ultrasonografía es el método más seguro e inocuo para el diagnóstico precoz de la displasia luxante de cadera en el recién nacido.The authors are studied by ultrasonography 112 newborns (224 hips) with clinical signs of congenital dysplasia and dislocation of the hip. The results obtained are compared with clinical findings and radiographic study emphasizing the diagnostic limitations of the clasics maneuvistes of physical examination and radiography. They conclude that the ultrasonography is the most sure method and innocuous to the early diagnosis of the congenital dysplasia and dislocation of the hip at the newborn

Quantum tomography via equidistant states

We study the possibility of performing quantum state tomography via equidistant states. This class of states allows us to propose a non-symmetric informationally complete POVM based tomographic scheme. The scheme is defined for odd dimensions and involves an inversion which can be analytically carried out by Fourier transform

Los Ultrasonidos en la Cadera Neonatal

Los autores describen la técnica de Estudio mediante Ecografía de la cadera neonatal, las imágenes normales, los métodos de mediciones y las características de los distintos grados de displasiaThe authors describe the technique of the study by ultrasound examination of neonatal hip, normal images, methods of measurement and characteristics of differents degrees of dysplasi