On the behavior in time of solutions to motion of Non-Newtonian fluids

We study the behavior on time of weak solutions to the non-stationary motion of an incompressible fluid with shear rate dependent viscosity in bounded domains when the initial velocity u∈ L2. Our estimates show the different behavior of the solution as the growth condition of the stress tensor varies. In the “dilatant” or “shear thickening” case we prove that the decay rate does not depend on u, then our estimates also apply for irregular initial velocity

Inconstant Planck's constant

Motivated by the Dirac idea that fundamental constant are dynamical variables and by conjectures on quantum structure of spacetime at small distances, we consider the possibility that Planck constant $\hbar$ is a time depending quantity, undergoing random gaussian fluctuations around its measured constant mean value, with variance $\sigma^2$ and a typical correlation timescale $\Delta t$. We consider the case of propagation of a free particle and a one--dimensional harmonic oscillator coherent state, and show that the time evolution in both cases is different from the standard behaviour. Finally, we discuss how interferometric experiments or exploiting coherent electromagnetic fields in a cavity may put effective bounds on the value of $\tau= \sigma^2 \Delta t$.Comment: To appear on the International Journal of Modern Physics

Transmittivity measurements by means of squeezed vacuum light

A method for measuring the transmittivity of optical samples by using squeezed--vacuum radiation is illustrated. A squeezed vacuum field generated by a below--threshold optical parametric oscillator is propagated through a nondispersive medium and detected by a homodyne apparatus. The variance of the detected quadrature is used for measuring the transmittivity. With this method it is drastically reduced the number of photons passing through the sample during the measurement interval. The results of some tests are reported.Comment: 14 pages, 8 figure

Experimental pre-assessing entanglement in Gaussian states mixing

We suggest and demonstrate a method to assess entanglement generation schemes based on mixing of Gaussian states at a beam splitter (BS). Our method is based on the fidelity criterion and represents a tool to analyze the effect of losses and noise before the BS in both symmetric and asymmetric channels with and without thermal effects. More generally, our scheme allows one to pre-assess entanglement resources and to optimize the design of BS-based schemes for the generation of continuous variable entanglement.Comment: 10 pages, 15 figure

Quantum tomography as a tool for the characterization of optical devices

We describe a novel tool for the quantum characterization of optical devices. The experimental setup involves a stable reference state that undergoes an unknown quantum transformation and is then revealed by balanced homodyne detection. Through tomographic analysis on the homodyne data we are able to characterize the signal and to estimate parameters of the interaction, such as the loss of an optical component, or the gain of an amplifier. We present experimental results for coherent signals, with application to the estimation of losses introduced by simple optical components, and show how these results can be extended to the characterization of more general optical devices

Effects of ocean acidification on macroalgal communities

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Use of information and communication technology and tools in the internazionalization department of a higher education institution

El uso de nuevas herramientas tecnológicas (TICS) es necesario a fin de que una Oficina de Proyectos internacionales trabaje de una manera más eficiente. Las TICS pueden usarse para apoyar la presentación de una propuesta (sitios para seguir los próximos llamados, herramientas para crear redes de trabajo) así como para el gerenciamiento del proyecto en sí  (herramientas para gerenciar el proyecto, para desarrollar reuniones virtuales, para facilitar el trabajo virtual en equipos).Asimismo, las TICS favorecen la investigación (brindan acceso a información pública y especializada) y el entrenamiento  (eLearning). Las comunicaciones internas y externas se ven mejoradas por las herramientas de comunicación sincrónicasy asincrónicas. La evaluación de las actividades se beneficia a través de las encuestas en línea, y la administración financiera de un proyecto se facilita con los sistemas contables. Las TICs están cambiando completamente la forma en que los proyectos internacionales se llevan adelante, haciendo posible y habituales realidades que antes eran inimaginables (por ejemplo, las reuniones virtuales). Este trabajo brinda una mirada a todos los posibles usos de las TICS en un Proyecto Internacional, y hace sugerencias sobre las herramientas a usar, basadas en la experiencia de los autores

Full characterization of Gaussian bipartite entangled states by a single homodyne detector

We present the full experimental reconstruction of Gaussian entangled states generated by a type--II optical parametric oscillator (OPO) below threshold. Our scheme provides the entire covariance matrix using a single homodyne detector and allows for the complete characterization of bipartite Gaussian states, including the evaluation of purity, entanglement and nonclassical photon correlations, without a priori assumptions on the state under investigation. Our results show that single homodyne schemes are convenient and robust setups for the full characterization of OPO signals and represent a tool for quantum technology based on continuous variable entanglement.Comment: 4 pages, 3 figures, slightly longer version of published PR