The formation of spiral arms and rings in barred galaxies

In this and in a previous paper (Romero-Gomez et al. 2006) we propose a theory to explain the formation of both spirals and rings in barred galaxies using a common dynamical framework. It is based on the orbital motion driven by the unstable equilibrium points of the rotating bar potential. Thus, spirals, rings and pseudo-rings are related to the invariant manifolds associated to the periodic orbits around these equilibrium points. We examine the parameter space of three barred galaxy models and discuss the formation of the different morphological structures according to the properties of the bar model. We also study the influence of the shape of the rotation curve in the outer parts, by making families of models with rising, flat, or falling rotation curves in the outer parts. The differences between spiral and ringed structures arise from differences in the dynamical parameters of the host galaxies. The results presented here will be discussed and compared with observations in a forthcoming paper.Comment: 16 pages, 13 figures, accepted in A&A. High resolution version available at http://www.oamp.fr/dynamique/pap/merce.htm

Deep Strong Coupling Regime of the Jaynes-Cummings model

We study the quantum dynamics of a two-level system interacting with a quantized harmonic oscillator in the deep strong coupling regime (DSC) of the Jaynes-Cummings model, that is, when the coupling strength g is comparable or larger than the oscillator frequency w (g/w > 1). In this case, the rotating-wave approximation cannot be applied or treated perturbatively in general. We propose an intuitive and predictive physical frame to describe the DSC regime where photon number wavepackets bounce back and forth along parity chains of the Hilbert space, while producing collapse and revivals of the initial population. We exemplify our physical frame with numerical and analytical considerations in the qubit population, photon statistics, and Wigner phase space.Comment: Published version, note change of title: DSC regime of the JC mode

Evidences of evanescent Bloch waves in Phononic Crystals

We show both experimentally and theoretically the evanescent behaviour of modes in the Band Gap (BG) of finite Phononic Crystal (PC). Based on experimental and numerical data we obtain the imaginary part of the wave vector in good agreement with the complex band structures obtained by the Extended Plane Wave Expansion (EPWE). The calculated and measured acoustic field of a localized mode out of the point defect inside the PC presents also evanescent behaviour. The correct understanding of evanescent modes is fundamental for designing narrow filters and wave guides based on Phononic Crystals with defects.Comment: 8 pages, 3 figure

Detección de delaminaciones y otros defectos de unión en productos de acero multicapa Al/Al-Sn/Al llevando a cabo la monitorización con ondas guiadas EMAT

Rayleigh-Lamb, ultrasonic, guided wave modes were used to detect delamination, embedded steel debris and a brittle intermetallic Al-Fe diffusion bond layer at the interface between clad Al and steel, which were bonded together in a cold roll bonding (CRB) process. Multi-layered samples were produced, with artificially implanted defects of different sizes between the clad Al and steel layer to determine the sensitivity of the guided wave modes to qualitatively indicate the occurrence of defects based on signal attenuation caused by defects. Electromagnetic acoustic transducers (EMATs) were used to generate and detect the guided waves in the pitch and catch technique. Signals were measured in the as rolled and post rolling annealed state to determine the influence of the altered material properties on attenuation and Signal-to-Noise Ratio (SNR). Results show very good sensitivity of the S0 wave mode for delamination and embedded steel debris detection and a relation between attenuation, defect type, size and annealing state. However, detection of the presence of a brittle intermetallic Al-Fe diffusion layer was not possible due to the strong sensitivity to the material properties and thicknesses of the clad Al and steel materials. Micro sections of all samples were examined to explain the observations. The results suggest a promising use of Rayleigh-Lamb guided wave modes for online detection of bond defects in serial production of Al-Sn alloy/steel bimetal strips

Prevalence and predictors of inadequate patient medication knowledge

© 2016 John Wiley & Sons, Ltd. Objectives: To assess medication knowledge in adult patients and to explore its determinants. Method: Cross-sectional study. Medication knowledge was the primary outcome and was assessed using a previously validated questionnaire. A multivariate logistic regression analysis was performed to explore the association between medication knowledge and the factors included in the model. Results: Seven thousand two hundred seventy-eight patients participated in the study. 71.9% (n = 5234) (95% CI: 70.9%–73.0%) of the surveyed patients had an inadequate knowledge of the medication they were taking. The dimensions obtaining the highest level of knowledge were the ‘medication use process’ and ‘therapeutic objective of medication’. The items ‘frequency’ (75.4%), ‘dosage’ (74.5%) and ‘indication’ (70.5%) had the highest percentage of knowledge. Conversely, ‘medication safety’ represented the dimension with the lowest scores, ranging from 12.6% in the item “contraindications” to 15.3% in the item ‘side effects’. The odds ratio (OR) of having an inadequate medication knowledge increased for unskilled workers (OR: 1.33; 85% CI:1.00–1.78; P = 0.050), caregivers (OR:1.46; 95% CI:1.18–1.81; P < 0.001), patients using more than one medication (OR: 1.14; 95% CI: 1.00–1.31; P = 0.050) and patients who did not know the name of the medication they were taking (OR: 2.14, 95% CI: 1.71–2.68 P < 0.001). Conclusion: Nearly three quarters of the analysed patients had inadequate knowledge regarding the medicines they were taking. Unskilled workers and caregivers were at a higher risk of lacking of medication knowledge. Other factors that correlated with inadequate medication knowledge were the use of more than one drug and not knowing the name of the medication dispensed

On the origin of rR_1 ring structures in barred galaxies

We propose a new theory for the formation of rR_1 ring structures, i.e. for ring structures with both an inner and an outer ring, the latter having the form of ``8''. We propose that these rings are formed by material from the stable and unstable invariant manifolds associated with the Lyapunov orbits around the equilibrium points of a barred galaxy. We discuss the shape and velocity structure of the rings thus formed and argue that they are in agreement with the observed properties of rR_1 structures.Comment: 8 pages, 9 figures, accepted in Astronomy and Astrophysics. High quality figures are available upon reques

Invariant manifolds as building blocks for the formation of spiral arms and rings in barred galaxies

We propose a theory to explain the formation of spiral arms and of all types of outer rings in barred galaxies, extending and applying the technique used in celestial mechanics to compute transfer orbits. Thus, our theory is based on the chaotic orbital motion driven by the invariant manifolds associated to the periodic orbits around the hyperbolic equilibrium points. In particular, spiral arms and outer rings are related to the presence of heteroclinic or homoclinic orbits. Thus, R1 rings are associated to the presence of heteroclinic orbits, while R1R2 rings are associated to the presence of homoclinic orbits. Spiral arms and R2 rings, however, appear when there exist neither heteroclinic nor homoclinic orbits. We examine the parameter space of three realistic, yet simple, barred galaxy models and discuss the formation of the different morphologies according to the properties of the galaxy model. The different morphologies arise from differences in the dynamical parameters of the galaxy.Comment: 8 pages, 4 figures, in the proceedings of the conference: "Chaos in Astronomy", Athens, September 2007, G. Contopoulos and P.A. Patsis (eds), to be published by Springe

Transport and Entanglement Generation in the Bose-Hubbard Model

We study entanglement generation via particle transport across a one-dimensional system described by the Bose-Hubbard Hamiltonian. We analyze how the competition between interactions and tunneling affects transport properties and the creation of entanglement in the occupation number basis. Alternatively, we propose to use spatially delocalized quantum bits, where a quantum bit is defined by the presence of a particle either in a site or in the adjacent one. Our results can serve as a guidance for future experiments to characterize entanglement of ultracold gases in one-dimensional optical lattices.Comment: 14 pages, 6 figure