A dispersive wave pattern on Jupiter's fastest retrograde jet at 20∘20^\circS

A compact wave pattern has been identified on Jupiter's fastest retrograding jet at 20S (the SEBs) on the southern edge of the South Equatorial Belt. The wave has been identified in both reflected sunlight from amateur observations between 2010 and 2015, thermal infrared imaging from the Very Large Telescope and near infrared imaging from the Infrared Telescope Facility. The wave pattern is present when the SEB is relatively quiescent and lacking large-scale disturbances, and is particularly notable when the belt has undergone a fade (whitening). It is generally not present when the SEB exhibits its usual large-scale convective activity ('rifts'). Tracking of the wave pattern and associated white ovals on its southern edge over several epochs have permitted a measure of the dispersion relationship, showing a strong correlation between the phase speed (-43.2 to -21.2 m/s) and the longitudinal wavelength, which varied from 4.4-10.0 deg. longitude over the course of the observations. Infrared imaging sensing low pressures in the upper troposphere suggest that the wave is confined to near the cloud tops. The wave is moving westward at a phase speed slower (i.e., less negative) than the peak retrograde wind speed (-62 m/s), and is therefore moving east with respect to the SEBs jet peak. Unlike the retrograde NEBn jet near 17N, which is a location of strong vertical wind shear that sometimes hosts Rossby wave activity, the SEBs jet remains retrograde throughout the upper troposphere, suggesting the SEBs pattern cannot be interpreted as a classical Rossby wave. Cassini-derived windspeeds and temperatures reveal that the vorticity gradient is dominated by the baroclinic term and becomes negative (changes sign) in a region near the cloud-top level (400-700 mbar) associated with the SEBs, suggesting a baroclinic origin for this meandering wave pattern. [Abr]Comment: 19 pages, 11 figures, article accepted for publication in Icaru

Enhancing the significance of gravitational wave bursts through signal classification

The quest to observe gravitational waves challenges our ability to discriminate signals from detector noise. This issue is especially relevant for transient gravitational waves searches with a robust eyes wide open approach, the so called all- sky burst searches. Here we show how signal classification methods inspired by broad astrophysical characteristics can be implemented in all-sky burst searches preserving their generality. In our case study, we apply a multivariate analyses based on artificial neural networks to classify waves emitted in compact binary coalescences. We enhance by orders of magnitude the significance of signals belonging to this broad astrophysical class against the noise background. Alternatively, at a given level of mis-classification of noise events, we can detect about 1/4 more of the total signal population. We also show that a more general strategy of signal classification can actually be performed, by testing the ability of artificial neural networks in discriminating different signal classes. The possible impact on future observations by the LIGO-Virgo network of detectors is discussed by analysing recoloured noise from previous LIGO-Virgo data with coherent WaveBurst, one of the flagship pipelines dedicated to all-sky searches for transient gravitational waves

Prospects for intermediate mass black hole binary searches with advanced gravitational-wave detectors

We estimated the sensitivity of the upcoming advanced, ground-based gravitational-wave observatories (the upgraded LIGO and Virgo and the KAGRA interferometers) to coalescing intermediate mass black hole binaries (IMBHB). We added waveforms modeling the gravitational radiation emitted by IMBHBs to detectors' simulated data and searched for the injected signals with the coherent WaveBurst algorithm. The tested binary's parameter space covers non-spinning IMBHBs with source-frame total masses between 50 and 1050 $\text{M}_{\odot}$ and mass ratios between $1/6$ and 1$\,$. We found that advanced detectors could be sensitive to these systems up to a range of a few Gpc. A theoretical model was adopted to estimate the expected observation rates, yielding up to a few tens of events per year. Thus, our results indicate that advanced detectors will have a reasonable chance to collect the first direct evidence for intermediate mass black holes and open a new, intriguing channel for probing the Universe over cosmological scales.Comment: 9 pages, 4 figures, corrected the name of one author (previously misspelled

Comparação entre os índices espectrais EVI e EVI 2 para discriminação de pastagens plantadas e naturais.

A identificação e discriminação de espécies vegetais semelhantes, tais como pastagens plantadas (PP) e pastagens naturais (PN), constitui um desafio em decorrência da semelhança espectral entre essas classes. Assumindo-se uma premissa de que bandas espectrais na faixa do visível têm elevada correlação, os índices de vegetação (IVs) vêm contribuindo para a discriminação de classes. Portanto, este trabalho tem como objetivo analisar o comportamento do índice EVI 2 (índice de vegetação realçado, do inglês Enhanced Vegetation Index) na discriminação de alvos de PN e PP para dois períodos sazonais, comparando-o ao EVI. Para o desenvolvimento do trabalho, foram utilizadas 14 imagens do satélite TM/Landsat 5 em uma série temporal de sete anos, entre 2004 e 2010. De acordo com os resultados obtidos, pode-se concluir que, em geral, o EVI 2 mantém a correlação com dados do EVI, caracterizando sutilmente melhor a influência da sazonalidade nos dados

Avaliação de procedimento para correção de efeitos da atmosfera em ambiente tropical utilizando dados Landsat TM 5.

Os constituintes da atmosfera interferem nos valores de reflectância captados pelos sensores imageadores. Essa interferência decorre da interação dos gases e aerossóis com a radiação eletromagnética. Assim, comparamos respostas espectrais de alvos em imagem Landsat com e sem correção atmosférica, visando atestar a importância da correção. Para tanto, utilizamos dados de reflectância no sensor, influenciados pela atmosfera, e dados de reflectância na superfície, nos quais essa influência foi eliminada. A reflectância apresentou maiores valores no sensor que na superfície, principalmente nas bandas do visível (0,45 a 0,69 μm), devido aos efeitos de espalhamento. Portanto, a correção se mostra de grande importância, pois os dados corrigidos são mais fidedignos

A burst search for gravitational waves from binary black holes

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarisation for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios, and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated CBC waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set.Comment: 12 pages, 4 figures, 2 tables, submitted for publication in CQG in the special issue for the conference proceedings of GWDAW13; corrected some typos, addressed some minor reviewer comments one section restructured and references updated and correcte

Feedback cooling of the normal modes of a massive electromechanical system to submillikelvin temperature

We apply a feedback cooling technique to simultaneously cool the three electromechanical normal modes of the ton-scale resonant-bar gravitational wave detector AURIGA. The measuring system is based on a dc Superconducting Quantum Interference Device (SQUID) amplifier, and the feedback cooling is applied electronically to the input circuit of the SQUID. Starting from a bath temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the coolest normal mode. The same technique, implemented in a dedicated experiment at subkelvin bath temperature and with a quantum limited SQUID, could allow to approach the quantum ground state of a kilogram-scale mechanical resonator.Comment: 4 pages, 4 figure

Análise multiespectral de medidas de complexidade utilizando o software CompPlexus aplicado a dados do sensor ASTER.

Neste trabalho, será avaliado a eficiência do software CompPlexus na análise multiespectral de complexidade de alvos distintos utilizando bandas do sensor ASTER ? Advanced Spaceborne Thermal Emission and Reflection Radiometer

Landscape complexity analysis based on texture patterns and satellite image for a São Paulo's Cerrado site.

We analysed the spatial heterogeneity complexity of Cerrado vegetation of São Paulo. Spatial heterogeneity was obtained by quantity texture patterns on ASTER images for Jataí Ecological Station (JES; Luiz Antônio ‐ SP) conservation unit. Two hillsides of JES where cerradão physiognomy was present were analyzed, and for each of them we sampled three positions: base, medium and top. Vertical structure and canopy cover density varied along hillsides. For each site, we extracted the texture pattern for two spatial scales (150x150m and 75x75m). Spatial complexity were estimated by two landscape metrics, both based on informational entropy: a) maximum entropy (H/Hmax), in which high values of complexity are assigned to patterns more disordered; and b) convex function of entropy (LMC), which attribute high values of complexity to patterns situated in intermediate range between order and disorder. Comparing different sites of the same hillside, both metrics had identical results in relation to greatest and smallest values of complexity. In hillside 1, the top side showed greater values. In these area, the cerradão shows high trees with less density of canopy in comparison to others sites of this hillside, which provides more spatial heterogeneity. For the smaller values of complexity, there was difference in comparison of analyzed extensions in hillside 1: for 150 x 150m spatial scale, was attributed medium hillside site to smaller values of complexity; for 75 x 75m, the base had the smallest values. However, the value of complexity of medium and low hillsides for the same spatial extension were very close. In hillside 2, on the base of site, which shows a cerradão with shorter trees and lesser canopy cover density in relation to others sites of hillside, texture patterns had highest values of complexity for both entropy measures. The most homogeneity site, located in medium position of hillside and with presence of high trees and canopy density, smallest values were recorded. Based on our findings we can concluded that there is a tendency of sites situated in the top and in the base of hillside showed great values of complexity, while sites located in medium hillside tend to be less complex in terms of spatial heterogeneity. Also, for local scale, the canopy density is more relevant than tree vertical structure on determining the complexity of texture patterns of vegetation