544 research outputs found

    Bistable and dynamic states of parametrically excited ultrasound in a fluid-filled cavity

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    In this paper we have considered the problem of parametric sound generation in an acoustic resonator flled with a fluid, taking explicitely into account the influence of the nonlinearly generated second harmonic. A simple model is presented, and its stationary solutions obtained. The main feature of these solutions is the appearance of bistable states of the fundamental field resulting from the coupling to the second harmonic. An experimental setup was designed to check the predictions of the theory. The results are consistent with the predicted values for the mode amplitudes and parametric thresholds. At higher driving values a self-modulation of the amplitudes is observed. We identify this phenomenon with a secondary instability previously reported in the frame of the theoretical model.Comment: 5 figures. Submitted to JAS

    Quadrature and polarization squeezing in a dispersive optical bistability model

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    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

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

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    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

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

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    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

    Positron Emission Tomography-Computed Tomography and Magnetic Resonance Imaging Assessments in a Mouse Model of Implant-Related Bone and Joint Staphylococcus aureus Infection.

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    Osteomyelitis is an infection of the bone, associated with an inflammatory process. Imaging plays an important role in establishing the diagnosis and the most appropriate patient management. However, data are lacking regarding the use of preclinical molecular imaging techniques to assess osteomyelitis progression in experimental models. This study aimed to compare structural and molecular imaging to assess disease progression in a mouse model of implant-related bone and joint infections caused by Staphylococcus aureus. In SWISS mice, the right femur was implanted with a resorbable filament impregnated with S. aureus (infected group, n = 10) or sterile culture medium (uninfected group, n = 6). Eight animals (5 infected, 3 uninfected) were analyzed with magnetic resonance imaging (MRI) at 1, 2, and 3 weeks postintervention, and 8 mice were analyzed with [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET)-computed tomography (CT) at 48 h and at 1, 2, and 3 weeks postintervention. In infected animals, CT showed bone lesion progression, mainly in the distal epiphysis, although some uninfected animals presented evident bone sequestra at 3 weeks. MRI showed a lesion in the articular area that persisted for 3 weeks in infected animals. This lesion was smaller and less evident in the uninfected group. At 48 h postintervention, FDG-PET showed higher joint uptake in the infected group than in the uninfected group (P = 0.025). Over time, the difference between groups increased. These results indicate that FDG-PET imaging was much more sensitive than MRI and CT for differentiating between infection and inflammation at early stages. FDG-PET clearly distinguished between infection and postsurgical bone healing (in uninfected animals) from 48 h to 3 weeks after implantation. IMPORTANCE Our results encourage future investigations on the utility of the model for testing different therapeutic procedures for osteomyelitis.We thank Yolanda Sierra, Alexandra de Francisco, and María de la Jara Felipe, from the Imaging Laboratory for Small Animals of the Instituto de Investigación Sanitaria, Gregorio Marañón, for their excellent work with animal preparation and imaging protocols. Additionally, we thank Daniel Calle, from the Advanced Imaging Unit of CNIC, for his help in imaging postprocessing. This study was partially supported by the Instituto de Salud Carlos III (grants PI20/ 01632 and PT20/00044), cofunded by the European Regional Development Fund (ERDF), A way to make Europe. This work was also supported by the Diagnosis and Treatment Follow-up of Severe Staphylococcal Infections with Anti-Staphylococcal Antibodies and Immune-PET project of the Grant Fundación BBVA a Equipos de Investigación Científica 2018, by the Fundación Ramón Areces, and by Comunidad de Madrid (S2022/BMD-7403 RENIM-CM). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación (MCIN), and the Pro CNIC Foundation, and it is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S, funded by MICIN/AEI/10.13039/501100011033).S

    Quantum squeezing of optical dissipative structures

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    We show that any optical dissipative structure supported by degenerate optical parametric oscillators contains a special transverse mode that is free from quantum fluctuations when measured in a balanced homodyne detection experiment. The phenomenon is not critical as it is independent of the system parameters and, in particular, of the existence of bifurcations. This result is a consequence of the spatial symmetry breaking introduced by the dissipative structure. Effects that could degrade the squeezing level are considered.Comment: 4 pages and a half, 1 fugure. Version to appear in Europhysics Letter

    Definition and Empirical Evaluation of Voters for Redundant Smart Sensor Systems Definición y Evaluación Empírica de Algoritmos de Voteo para Sistemas Redundantes de Sensado Inteligente

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    Abstract This study is the first attempt for integration voting algorithms with fault diagnosis devices. Voting algorithms are used to arbitrate between the results of redundant modules in fault-tolerant systems. Smart sensors are used for FDI (Fault Detection and Isolation) purposes by means of their built in intelligence. Integration of fault masking and FDI strategies is necessary in the construction of ultra-available/safe systems with on-line fault detection capability. This article introduces a range of novel software voting algorithms which adjudicate among the results of redundant smart sensors in a Triple Modular Redundant (TMR) system. Techniques to integrate replicated smart sensors and fault masking approach are discussed, and a classification of hybrid voters is provided based on result and confidence values, which affect the metrics of availability and safety.Thus, voters are classified into four groups: Independent-diagnostic safety-optimised voters, Integrated-diagnostic safety-optimised voters, Independent-diagnostic availability-optimised voters and Integrated-diagnostic availability-optimised voters. The properties of each category are explained and sample versions of each class as well as their possible application areas are discussed. Keywords: Ultra-Available System, Smart Sensor, Fault Masking, Triple Modular Redundancy. Resumen Este estudio es una primer aproximación para la integración de algoritmos de voteo con dispositivos de diagnóstico de fallas. Los algoritmos de voteo son usados para arbitrar entre los resultados de elementos redundantes en sistemas tolerantes a fallas. Los sensores inteligentes son usados para propositos de detección y separación de fallas (FDI) dada la capacidad su capacidad de inteligencia construida. La integración de enmascaramiento de fallas y las estrategias de FDI is necesaria en la construcción de sistemas altamente disponibles y seguros con la capacidad de detección de fallas en línea. Este artículo introduce un rango de algoritmos de voteo los cuales adjudican un resultado entre los resultados generados por los sensores inteligentes en un módulo de redundancia triple. Las técnicas para integrar los sensores inteligentes replicados y la aproximación de enmascaramiento de fallas son revisadas en este artículo. Una clasificación de algoritmos de voteo híbrido es provista con base en el resultado y los valores de confianza los cuales afectan las métricas de disponibilidad y seguridad de estos algoritmos. De hecho los algoritmos de voteo son clasificados en cuatro grupos: Diagnóstico-Independiente con seguridad-optimizada, Diagnóstico-Integrado con seguridad-optimizada, Diagnóstico-Independiente con disponibilidad-opitimizada y Diagnóstico-Integrado con disponibilidad-optimizada. Las propiedades de cada categoria son revisadas asi como muestras de sus implementaciones son discutidas

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

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    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

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

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    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
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