Self-organization of ultrasound in viscous fluids

We report the theoretical and experimental demonstration of pattern formation in acoustics. The system is an acoustic resonator containing a viscous fluid. When the system is driven by an external periodic force, the ultrasonic field inside the cavity experiences different pattern-forming instabilities leading to the emergence of periodic structures. The system is also shown to possess bistable regimes, in which localized states of the ultrasonic field develop. The thermal nonlinearity in the viscous fluid, together with the far-from-equilibrium conditions, are is the responsible of the observed effects

Spontaneous symmetry breaking as a resource for noncritically squeezed light

In the last years we have proposed the use of the mechanism of spontaneous symmetry breaking with the purpose of generating perfect quadrature squeezing. Here we review previous work dealing with spatial (translational and rotational) symmetries, both on optical parametric oscillators and four-wave mixing cavities, as well as present new results. We then extend the phenomenon to the polarization state of the signal field, hence introducing spontaneous polarization symmetry breaking. Finally we propose a Jaynes-Cummings model in which the phenomenon can be investigated at the single-photon-pair level in a non-dissipative case, with the purpose of understanding it from a most fundamental point of view.Comment: Review for the proceedings of SPIE Photonics Europe. 11 pages, 5 figures

Optics of Astigmatism and Retinal Image Quality

In the first part of this chapter, the optical condition of astigmatism is defined. The main causes and available classifications of ocular astigmatism are briefly described. The most relevant optical properties of image formation in an astigmatic eye are analysed and compared to that of an emmetropic eye and an eye with spherical ametropia. The spectacle prescription and axis notation for astigmatism are introduced, and the correction of astigmatism by means of lenses is briefly described. The formation of the retinal image for extended objects and the related blurring are also analysed, and the real limits of tolerance of uncorrected astigmatism are provided. Simulations of retinal images in astigmatic eyes, obtained by means of commercial optical design software, are also presented. Finally, the clinical assessment of retinal image quality by means of wavefront aberrometry and double-pass systems in eyes with astigmatism is presented, and current trends in research related to this topic are highlighted.Peer ReviewedPostprint (published version

A cloud-based integration platform for enterprise application integration: a model-driven engineering approach

This article addresses major information systems integration problems, approaches, technologies, and tools within the context of Model-Driven Software Engineering. The Guaraná integration platform is introduced as an innovative platform amongst state-of-the-art technologies available for enterprises to design and implement integration solutions. In this article, we present its domain-specific modeling language and its industrial cloud-based web development platform, which supports the design and implementation of integration solutions. A real-world case study is described and analyzed; then, we delve into its design and implementation, to finally disclose ten measures that empirically help estimating the amount of effort involved in the development of integration solutions.info:eu-repo/semantics/acceptedVersio

Theory of quantum fluctuations of optical dissipative structures and its application to the squeezing properties of bright cavity solitons

We present a method for the study of quantum fluctuations of dissipative structures forming in nonlinear optical cavities, which we illustrate in the case of a degenerate, type I optical parametric oscillator. The method consists in (i) taking into account explicitly, through a collective variable description, the drift of the dissipative structure caused by the quantum noise, and (ii) expanding the remaining -internal- fluctuations in the biorthonormal basis associated to the linear operator governing the evolution of fluctuations in the linearized Langevin equations. We obtain general expressions for the squeezing and intensity fluctuations spectra. Then we theoretically study the squeezing properties of a special dissipative structure, namely, the bright cavity soliton. After reviewing our previous result that in the linear approximation there is a perfectly squeezed mode irrespectively of the values of the system parameters, we consider squeezing at the bifurcation points, and the squeezing detection with a plane--wave local oscillator field, taking also into account the effect of the detector size on the level of detectable squeezing.Comment: 10 figure

Quadrature and polarization squeezing in a dispersive optical bistability model

We theoretically study quadrature and polarization squeezing in dispersive optical bistability through a vectorial Kerr cavity model describing a nonlinear cavity filled with an isotropic chi(3) medium in which self-phase and cross-phase modulation, as well as four--wave mixing, occur. We derive expressions for the quantum fluctuations of the output field quadratures as a function of which we express the spectrum of fluctuations of the output field Stokes parameters. We pay particular attention to study how the bifurcations affecting the non-null linearly polarized output mode squeezes the orthogonally polarized vacuum mode, and show how this produces polarization squeezing.Comment: 10 text pages + 12 figure

Preliminary study of the adaptation of Senegalese sole Solea senegalensis Kaup, 1858 to different salinities

Osmoregulatory and metabolic effects of adaptation to different water salinities (5, 15, 25, 42 and 55) were assessed during a period of 14 days in juveniles of Senegalese sole Solea senegalensis Kaup, 1858. The results showed a good capacity to adapt within the range of water salinities tested. Gill Na+,K+-ATPase activity showed a direct lineal relationship with regard to water salinity, whereas kidney Na+,K+-ATPase activity did not change. Plasma osmolality and ions levels did not present differences among the groups. Plasma cortisol, glucose and lactate were higher in the group maintained in the highest water salinity.El crecimiento del lenguado senegalés Solea senegalensis Kaup, 1858 está influido por diferentes variables, y una de ellas es la salinidad ambiental. En este trabajo, se estudian los efectos osmorreguladores y metabólicos de la aclimatación a distintas salinidades (5, 15, 25, 42 y 55) durante un periodo de 14 días en juveniles de esta especie. La actividad Na+,K+-ATPasa branquial presentó una relación lineal directa respecto a la salinidad ambiental, mientras que la actividad Na+,K+-ATPasa renal no experimentó variación alguna. Ni la osmolalidad ni los niveles de iones plasmáticos analizados mostraron diferencias significativas entre los diferentes grupos. El cortisol y los niveles de glucosa y lactato plasmático aumentaron en los ejemplares adaptados a la mayor salinidad. Los resultados mostraron una buena capacidad de aclimatación en el rango de salinidades ambientales analizado.Instituto Español de Oceanografí

Application surface of CPT, an advanced DInSAR displacement near Itoiz dam, Navarra, Spain

Itoiz reservoir is located in Navarra, northern Spain, being a newly constructed gravity dam that stores the water from the Irati and the Urrobi rivers. The dam has a total height of 121 m, a total length of 525 m and a maximum water storage volume of 410 hm3. The aim of this work is to study the surface displacement field during the impoundment of the Itoiz water reservoir. Orbital SAR Differential Interferometry (DInSAR) techniques have been proven to be a useful and powerful tool in tectonic areas for surveying subtle surface deformations over several years related to geodynamic phenomena. An advanced DInSAR observation technique, Coherent Pixel Technique (CPT), has been applied to study the existence of deformation in the dam area in order to obtain mean velocities and time series of deformation. We have studied the applicability of this technique to study the surface displacement field during the impoundment of the Itoiz water reservoir. Specifically, we focus on the analysis of the stability of the left slope of the reservoir. We have used ERS and ENVISAT descending and ascending images concerning to the 1992-2008 and 2003-2008 periods respectively. We compare the observation results with the displacement induced by water loading obtained using a theoretical model

Effects of offshore wind farms operational noise on bluefin tuna behaviour

The number of offshore wind farms is growing up quickly in the lasts years. Several studies about its environmental acoustic impacts have been developed at the same time the industry expands, most of them related to the high level impulsive noise produced during the pile diving process associated to the construction stage. Nevertheless, the study of the impact of the operational noise of turbines is very limited. In this paper we investigate the behavioural response of Bluefin tuna when exposed to the operation noise of a turbine. We analysed tuna reaction in terms of three parameters: depth of the school, swimming pattern and changes in the swimming direction. The experiment was developedin a fixed commercial tuna cage in the Mediterranean Sea. The usual behaviour of Bluefin tuna in captivity conditions was previously analysed using a continuous monitorization. Variations in depth were observed when feeding boat approaches, which could be interpreted as a consequence of the acoustical stimulus. The turbine noise was acoustically characterized, and reproduced using a broad-band underwater source. To monitor tuna behaviour two echosounders and a video system were simultaneously used. When exposed to short duration noise tuna behaviour does not exhibit clear disturbances. Nevertheless, with long duration emission tuna reacted: school reduced the radio of thecircular swimming region, moved up to the surface and some individuals were disorientated. Tuna seems to be habituated after several repetitions is short time.Proyecto AZIMUT. This work was financially support from Spanish Government by grant AP2009-4459. We thank both personal and material facilities provided by Grup Balfegó and Nuevo Tomás y Carmen crew

Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions

The generation of continuous-variable multipartite entangled states is important for several protocols of quantum information processing and communication, such as one-way quantum computation or controlled dense coding. In this article we theoretically show that multimode optical parametric oscillators can produce a great variety of such states by an appropriate control of the parametric interaction, what we accomplish by tailoring either the spatio-temporal shape of the pump, or the geometry of the nonlinear medium. Specific examples involving currently available optical parametric oscillators are given, hence showing that our ideas are within reach of present technology.Comment: 14 pages, 5 figure