391 research outputs found

    Satellite triangulation in Europe from WEST and ISAGEX data

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    Observational data that was acquired during the West European Satellite Triangulation (WEST) program and the International Satellite Geodesy Experiment (ISAGEX) campaign was obtained for the purpose of performing a geometric solution to improve the present values of coordinates of the European stations in the OSU WN14 solutions, adding some new stations and assessing the quality of the WN14 solution with the help of the additional data available. The status of the data as received, the preprocessing required and the preliminary tests carried out for the initial screening of the data are described. The adjustment computations carried out and the results of the adjustments are discussed

    The mega-events database: systematising the evidence on mega-event outcomes

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    Although events such as the Olympic Games and World’s Fairs are among the largest of mega-projects, there is little systematic data to evaluate their outcomes over a longer period of time and across multiple sites. This research note describes the first longitudinal database on mega-event outcomes. It lays out the rationale and major goals of the database, its methodological approach and content, and its challenges and limitations. The database allows analysing larger patterns of mega-event contexts and outcomes, and helps evaluating mega-events as public policies. © 2021 Informa UK Limited, trading as Taylor & Francis Group.Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF: PP00P1_172891The Swiss National Science Foundation (SNSF) funded the research of this paper under the grant ‘Mega-events: growth and impacts’, grant number PP00P1_172891

    Helical Jet in the Gravitationally Lensed Blazar PKS1830-211

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    Recent radio VLBI observations of the complex gravitationally lensed system PKS1830-211 have thrown up some questions with regard to the processes occuring at the heart of the blazar source at a redshift of 2.51, which is viewed almost straight down the jet axis. This work links, by a model of a helical jet tracked by ballistically ejected plasmons from a precessing nozzle, observations on the scale of tens of microarcseconds to those on the scale of milliarcseconds. An observed jet precession period of 1.08 years is inferred from the model, translating to an intrinsic period of 30.8 years for a source at redshift 2.51 and an assumed jet bulk velocity of 0.99 c. This fits well with the picture of an active galactic nucleus hosting a binary black hole system at its centre, with the jet emitted by one member of the system, and the precession as being due to its orbital motion around its companion.Comment: Accepted for publication in the MNRA

    A Treatment with a Protease Inhibitor Recombinant from the Cattle Tick (Rhipicephalus Boophilus microplus) Ameliorates Emphysema in Mice

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    Aims: To determine whether a serine protease inhibitor treatment can prevent or minimize emphysema in mice.Methods: C57BL/6 mice were subjected to porcine pancreatic elastase (PPE) nasal instillation to induce emphysema and were treated with a serine protease inhibitor (rBmTI-A) before (Protocol 1) and after (Protocol 2) emphysema development. in both protocols, we evaluated lung function to evaluate the airway resistance (Raw), tissue damping (Gtis) and tissue elastance (Htis). the inflammatory profile was analyzed in the bronchoalveolar lavage (BALF) and through the use of morphometry; we measured the mean linear intercept (Lm) (to verify alveolar enlargement), the volume proportion of collagen and elastic fibers, and the numbers of macrophages and metalloprotease 12 (MMP-12) positive cells in the parenchyma. We showed that at both time points, even after the emphysema was established, the rBmTI-A treatment was sufficient to reverse the loss of elastic recoil measured by Htis, the alveolar enlargement and the increase in the total number of cells in the BALF, with a primary decrease in the number of macrophages. Although, the treatment did not control the increase in macrophages in the lung parenchyma, it was sufficient to decrease the number of positive cells for MMP-12 and reduce the volume of collagen fibers, which was increased in PPE groups. These findings attest to the importance of MMP-12 in PPE-induced emphysema and suggest that this metalloprotease could be an effective therapeutic target.Laboratorios de Investigacao Medica do Hospital das Clinicas da Faculdade de Medicina da USP (LIM/HC)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Univ São Paulo, Dept Med, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biol Sci, São Paulo, BrazilUNIFESP EPM, Dept Bioquim, São Paulo, BrazilUFABC, Ctr Ciencias Nat & Humanas, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biol Sci, São Paulo, BrazilUNIFESP EPM, Dept Bioquim, São Paulo, BrazilWeb of Scienc

    Ultra-low noise supercontinuum source for ultra-high resolution optical coherence tomography at 1300 nm

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    Supercontinuum (SC) sources are of great interest for many applications due to their ultra-broad optical bandwidth, good beam quality and high power spectral density [1]. In particular, the high average power over large bandwidths makes SC light sources excellent candidates for ultra-high resolution optical coherence tomography (UHR-OCT) [2-5]. However, conventional SC sources suffer from high pulse-to-pulse intensity fluctuations as a result of the noise-sensitive nonlinear effects involved in the SC generation process [6-9]. This intensity noise from the SC source can limit the performance of OCT, resulting in a reduced signal-to-noise ratio (SNR) [10-12]. Much work has been done to reduce the noise of the SC sources for instance with fiber tapers [7,8] or increasing the repetition rate of the pump laser for averaging in the spectrometer [10,12]. An alternative approach is to use all-normal dispersion (ANDi) fibers [13,14] to generate SC light from well-known coherent nonlinear processes [15-17]. In fact, reduction of SC noise using ANDi fibers compared to anomalous dispersion SC pumped by sub-picosecond pulses has been recently demonstrated [18], but a cladding mode was used to stabilize the ANDi SC. In this work, we characterize the noise performance of a femtosecond pumped ANDi based SC and a commercial SC source in an UHR-OCT system at 1300 nm. We show that the ANDi based SC presents exceptional noise properties compared to a commercial source. An improvement of ~5 dB in SNR is measured in the UHR-OCT system, and the noise behavior resembles that of a superluminiscent diode. This preliminary study is a step forward towards development of an ultra-low noise SC source at 1300 nm for ultra-high resolution OCT
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