1,788 research outputs found

    High-contrast coronagraph for ground-based imaging of Jupiter-like planets

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    We propose a high-contrast coronagraph for direct imaging of young Jupiter-like planets orbiting nearby bright stars. The coronagraph employs a step-transmission filter in which the intensity is apodized with a finite number of steps of identical transmission in each step. It should be installed on a large ground-based telescope equipped with state-of-the-art adaptive optics systems. In that case, contrast ratios around 10^-6 should be accessible within 0.1 arc seconds of the central star. In recent progress, a coronagraph with circular apodizing filter has been developing, which can be used for a ground-based telescope with central obstruction and spider structure. It is shown that ground-based direct imaging of Jupiter-like planets is promising with current technology

    Masses, Radii, and Cloud Properties of the HR 8799 Planets

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    The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Some studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against observations of field L and T dwarfs, including the reddest L dwarfs. Unlike some previous studies we require mutually consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure thus yields plausible values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are not unusual but rather follow previously recognized trends, including a gravity dependence on the temperature of the L to T spectral transition--some reasons for which we discuss. We find the inferred mass of planet b is highly sensitive to whether or not we include the H and K band spectrum in our analysis. Solutions for planets c and d are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that, like in L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present an exploratory evolution calculation that accounts for this effect. Finally we recompute the the bolometric luminosity of all three planets.Comment: 52 pages, 12 figures, Astrophysical Journal, in press. v2 features minor editorial updates and correction

    Ladarixin, a dual CXCR1/2 inhibitor, attenuates experimental melanomas harboring different molecular defects by affecting malignant cells and tumor microenvironment.

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    CXCR1 and CXCR2 chemokine receptors and their ligands (CXCL1/2/3/7/8) play an important role in tumor progression. Tested to date CXCR1/2 antagonists and chemokine-targeted antibodies were reported to affect malignant cells in vitro and in animal models. Yet, redundancy of chemotactic signals and toxicity hinder further clinical development of these approaches. In this pre-clinical study we investigated the capacity of a novel small molecule dual CXCR1/2 inhibitor, Ladarixin (LDX), to attenuate progression of experimental human melanomas. Our data showed that LDX-mediated inhibition of CXCR1/2 abrogated motility and induced apoptosis in cultured cutaneous and uveal melanoma cells and xenografts independently of the molecular defects associated with the malignant phenotype. These effects were mediated by the inhibition of AKT and NF-kB signaling pathways. Moreover, systemic treatment of melanoma-bearing mice with LDX also polarized intratumoral macrophages to M1 phenotype, abrogated intratumoral de novo angiogenesis and inhibited melanoma self-renewal. Collectively, these studies outlined the pre-requisites of the successful CXCR1/2 inhibition on malignant cells and demonstrated multifactorial effects of Ladarixin on cutaneous and uveal melanomas, suggesting therapeutic utility of LDX in treatment of various melanoma types

    Matching signature whistles with photo-identification of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Inner Harbour, Western Australia

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    The Swan–Canning River System is home to an Indo-Pacific bottlenose dolphin (Tursiops aduncus) community of currently 17 adult and juvenile individuals. While a complete photo-identification catalogue exists, visual monitoring requires repeated boat-based surveys and is thus laborious and expensive. Bottlenose dolphins are known to emit individually distinctive signature whistles, and therefore, passive acoustic monitoring could be a reliable and more efficient tool. Archived acoustic and photographic data from the Fremantle Inner Harbour were reviewed for instances when dolphin whistles and individual identifying images were simultaneously available. As dolphin whistles are commonly used in social encounters, dolphins producing whistles in this study were always in groups. Consequently, to assess whether distinctive whistles could be attributed to individual dolphins, conditional probabilities for recording a specific whistle in the presence of certain individuals, as well as Bayesian posterior probabilities for encountering a specific individual at times of certain whistles were computed. While a larger sample size is needed to capture all individuals in diverse groupings, this study provides the first step in developing a passive acoustic program for monitoring this small dolphin community, in order to ultimately inform its conservation management. © 2020, Australian Acoustical Society

    Confiabilidade interobservadores do Pressure Ulcer Scale for Healing (PUSH), em pacientes com úlceras crônicas de perna

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    This study aimed to evaluate the inter rater reliability of the Pressure Ulcer Scale for Healing (PUSH), in its version adapted to the Portuguese language, in patients with chronic leg ulcers. Kappa index was used for the analysis. After accomplishing ethical issues, 41 patients with ulcers were examined. A total of 49% of the ulcers were located in the right leg and 36% of them were venous ulcers. The Kappa indices (0.97 to 1.00) obtained in the comparison between the observations of the clinical nurses and the stomal therapists for all sub-scales and for total score, confirmed the tool inter rater reliability, with statistical significance (pEl objetivo del estúdio fue probar la confiabilidad inter-observadores del Pressure Ulcer Scale for Healing (PUSH), en su versión adaptada al portugués, en pacientes con úlceras crónicas en la pierna. Para el análisis de concordancia se utilizó el Indice Kappa. Posterior a la aprobación del Comité de Ética, 41 pacientes con úlcera fueron examinados, siendo que 49% de las úlceras se localizaron a la derecha y 36% eran de etiología venosa. Los indices Kappa obtenidos (0,97 a 1,00), con un nivel significativo de pTestar a confiabilidade interobservadores do Pressure Ulcer Scale for Healing (PUSH), em sua versão adaptada para o português, em pacientes com úlceras crônicas de perna foi o objetivo deste estudo. Para a análise de concordância, utilizou-se o índice Kappa. Após aprovação pelo Comitê de Ética, pacientes com úlceras (41) úlceras foram examinados, sendo que 49% das úlceras localizavam-se à direita e 36% eram de etiologia venosa. Os índices Kappa obtidos (0,97 a 1,00), com significância estatística (

    THE INFLUENCE OF THE REMOTELY SENSED RAINFALL PRODUCTS’ SPATIAL RESOLUTION TO UNMASK EXTREME EVENTS IN NORTHEAST BRAZIL

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    This work presents the influence of the spatial resolution on precipitation samples to understand extreme events in the Agreste region of Pernambuco, northeast of Brazil. Among the materials used, the following sources of precipitation data (1998 to 2019) can be cited: The Tropical Rainfall Measuring Mission (TRMM), the Climatic Research Unit (CRU), and weather stations. In the process of validating the precipitation time series with the weather stations, the TRMM data showed a strong Pearson correlation (0.86 - 0.90) and the CRU data a moderate one (0.71 - 0.76). The relative bias (RB) and the standard deviation of observation ratio (RSR) were also calculated to identify the data’s trend, which showed an overestimation for both sources. The extreme events were identified through the calculation of the Standardized Precipitation Index (SPI), where the TRMM with strong correlation (0.80 - 0.91) obtained a better performance than the CRU data. The TRMM data were selected to understand the extreme drought events in the study area, where the cities with altitudes above 500m obtained maximum values of probability of occurrence with 19%. Conversely, for extreme humidity events, the maximum was 14% for those with altitudes below 200m
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