On Gravitational Waves in Spacetimes with a Nonvanishing Cosmological Constant

We study the effect of a cosmological constant $\Lambda$ on the propagation and detection of gravitational waves. To this purpose we investigate the linearised Einstein's equations with terms up to linear order in $\Lambda$ in a de Sitter and an anti-de Sitter background spacetime. In this framework the cosmological term does not induce changes in the polarization states of the waves, whereas the amplitude gets modified with terms depending on $\Lambda$. Moreover, if a source emits a periodic waveform, its periodicity as measured by a distant observer gets modified. These effects are, however, extremely tiny and thus well below the detectability by some twenty orders of magnitude within present gravitational wave detectors such as LIGO or future planned ones such as LISA.Comment: 8 pages, 4 figures, accepted for publication in Physical Review

Uma metodologia de apoio à seleção de softwares educativos para o ensino de matemática

En virtud del intenso desarrollo de productos de software educativos hoy, la selección de esos productos por los maestros ha se tornado una tarea cada vez más difícil. Argumentamos en este trabajo que mismo existiendo innúmeras estrategias de evaluación ellas no son efectivamente aplicadas para realizar una selección basada en la comparación de los rasgos de los productos de software evaluados. En este sentido, presentamos un nuevo abordaje para la evaluación de productos de software educativo. En este abordaje proponemos una metodología que tiene como objectivo principal permitir la selección de productos de software educativo que tengan rasgos funcionales semejantes, por medio del uso de métricas definidas por el propio evaluador y que son basadas en la teoría de los campos conceptuales y formalizadas utilizando la técnica de puntos de casos de uso.Em virtude ao intenso desenvolvimento de produtos de software educativo atualmente, a seleção desses produtos pelos professores tem se tornado uma tarefa cada vez mais difícil. Argumentamos nesse trabalho que mesmo existindo inúmeras estratégias de avaliação elas não são efetivamente aplicadas para realizar uma seleção baseada na comparação das características dos produtos de software avaliados. Nesse sentido, apresentamos uma nova abordagem para a avaliação de produtos de software educativo. Nessa abordagem propomos uma metodologia que tem como objetivo principal permitir a seleção de produtos de software educativo que possuam características funcionais semelhantes, através da utilização de métricas definidas pelo próprio avaliador e que são baseadas na teoria dos campos conceituais e formalizadas utilizando a técnica de pontos de casos de uso.Due to the intense product development educational software currently, the selection of these products by the teachers has become an increasingly difficult task. We argue in this paper that even though there are numerous assessment strategies they are not effectively applied to filter based on the comparison of the characteristics of software products evaluated. In this sense, we present a new approach for the evaluation of educational software products. In this approach we propose a methodology that aims to allow the selection of educational software products that have similar functional characteristics through the use of metrics defined by the evaluator itself and that are based on the theory of conceptual fields and formalized using the point technique use cases

Transverse magnetization and torque in asymmetrical mesoscopic superconductors

We show that asymmetrical mesoscopic superconductors bring new insight into vortex physics where we found the remarkable coexistence of long and short vortices. We study an asymmetrical mesoscopic sphere, that lacks one of its quadrants, and obtain its three-dimensional vortex patterns by solving the Ginzburg-Landau theory. We find that the vortex patterns are asymmetric whose effects are clearly visible and detectable in the transverse magnetization and torque.Comment: 4 pages, 4 figures (low resolution

Improvement of multilateration(MLAT) accuracy and convergence for airport surveillance

AbstractIn this paper, westudy, evaluate and develop the use of regularization methods to solve the location problem in multilateration systems using Mode-S signals. The Tikhonov method has been implemented as a first applicationto solve the classical system of hyperbolic equations in multilateration systems. Some simulations are obtained and the results are compared with those obtained by the well established Taylor linearization and with the Cramér-Rao Lower Bound analysis. Significant improvements are found for the applicationof Tikhonov method

Improving indoor conditions in an Italian historical Church: the case study of Donnaregina Vecchia

Preserving the historical and artistic heritage is a topic of central interest, especially in countries that have particularly old heritage such as Italy. This study concerns the monitoring of environmental conditions of an ancient church in the center of Naples, a beautiful example of Italian Gothics, which, besides the absolute value of the architecture, even preserves works of art of special significance. The measurement campaign, performed during two typical winter weeks, was necessary to calibrate a dynamic energy model of the church. Then, a radiant floor was designed, to provide a space heating service for the Choir, used for conferences and events, so that the improvement of microclimatic conditions, in winter, can contribute to preserving artifacts (e.g., too cold conditions can induce cracks of wooden materials) and improve occupants' thermal comfort, without compromising the historical/artistic value of the church. The monitoring revealed that the indoor microclimatic conditions do not satisfy the ideal ranges for the conservation of the artistic heritage, and that the indoor environment is uncomfortable for the occupants. The positive effects of the new heating systems were also evaluated, by means of simulations performed starting from the calibrated energy model

Quantum states of elementary three-geometry

We introduce a quantum volume operator $K$ in three--dimensional Quantum Gravity by taking into account a symmetrical coupling scheme of three SU(2) angular momenta. The spectrum of $K$ is discrete and defines a complete set of eigenvectors which is alternative with respect to the complete sets employed when the usual binary coupling schemes of angular momenta are considered. Each of these states, that we call quantum bubbles, represents an interference of extended configurations which provides a rigorous meaning to the heuristic notion of quantum tetrahedron. We study the generalized recoupling coefficients connecting the symmetrical and the binary basis vectors, and provide an explicit recursive solution for such coefficients by analyzing also its asymptotic limit.Comment: 15 pages, LaTe

Optical properties of polystyrene-ZnO nanocomposite scattering layer to improve light extraction in organic light-emitting diode

In this work, experimental measurements on polystyrene-ZnO nanocomposite scattering films and on organic light-emitting device with and without the scattering layers are presented. The results are also compared with Henyey-Greenstein radiative-transfer model to narrow down the parameters that can be important in the identification of more suitable scattering layers. As a result, an increase of efficiency of about 30% has been obtained that it can be translated in 60% of outcoupled light in respect to the total generated amount

Irreversibility at zero temperature from the perspective of the environemnt

We address the emergence of entropy production in the non-equilibrium process of an open quantum system from the viewpoint of the environment. By making use of a dilation-based approach akin to Stinespring theorem, we derive an expression for the entropy production that comprises two fundamental contributions. The first is linked to the rate of creation of correlations between system and environment whereas the second highlights the possibility for the environment to modify its state in light of its coupling to the system. Both terms are shown to be associated with irreversible currents within the system and the environment, which pinpoint the emergence of irreversibility in the Markovian limit. Finally, we discuss how such a change of perspective in the study of entropy production has fecund implications for the study of non-Markovian open-system dynamics

Beam heat load analysis with COLDDIAG: a cold vacuum chamber for diagnostics

The knowledge of the heat intake from the electron beam is essential to design the cryogenic layout of superconducting insertion devices. With the aim of measuring the beam heat load to a cold bore and understanding the responsible mechanisms, a cold vacuum chamber for diagnostics (COLDDIAG) has been built. The instrumentation comprises temperature sensors, pressure gauges, mass spectrometers and retarding field analyzers, which allow to study the beam heat load and the influence of the cryosorbed gas layer. COLDDIAG was installed in the storage ring of the Diamond Light Source from September 2012 to August 2013. During this time measurements were performed for a wide range of machine conditions, employing the various measuring capabilities of the device. Here we report on the analysis of the measured beam heat load, pressure and gas content, as well as the low energy charged particle flux and spectrum as a function of the electron beam parameters

＜翻訳＞ 言語学と情報化社会

翻訳者 : 藤村, 昌昭原著者 : Mauro, T. D