5,919 research outputs found

    The XO Planetary Survey Project - Astrophysical False Positives

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    Searches for planetary transits find many astrophysical false positives as a by-product. There are four main types analyzed in the literature: a grazing-incidence eclipsing binary star, an eclipsing binary star with a small radius companion star, a blend of one or more stars with an unrelated eclipsing binary star, and a physical triple star system. We present a list of 69 astrophysical false positives that had been identified as candidates of transiting planets of the on-going XO survey. This list may be useful in order to avoid redundant observation and characterization of these particular candidates independently identified by other wide-field searches for transiting planets. The list may be useful for those modeling the yield of the XO survey and surveys similar to it. Subsequent observations of some of the listed stars may improve mass-radius relations, especially for low-mass stars. From the candidates exhibiting eclipses, we report three new spectroscopic double-line binaries and give mass function estimations for 15 single lined spectroscopic binaries.Comment: 13 pages, 4 figures, accepted to ApJ

    Gap plasmon polariton structure for very efficient micro to nano scale interfacing

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    The seamless transition between micro-scale photonics and nano-scale plasmonics requires the mitigation between different waveguiding mechanisms as well as between few orders of magnitude in the field lateral size, down to a small fraction of a wavelength. By exploiting gap plasmon polariton waves both at the micro and nano scale, very high power transfer efficiency (>60%) can be achieved using an ultrashort (few microns) non adiabatic tapered gap plasmon waveguide. Same mechanism may be used to harvest impinging light waves and direct them into a nano hole or slit, to exhibit an anomalous transmission - without the conventional periodic structures. The special interplay of plasmonic and oscillating modes is analyzed.Comment: Submitted to PRL. Part of the work was presented at IPRA-2005 conference, paper JWA

    Public Libraries’ Perceptions of Future Collaborations for the Development of Smart Cities and Communities: Understanding Influential Factors

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    Recently, the concept of smart city has been adopted by many communities as a strategy to find alternative solutions to increasingly complex social, economic, and environmental issues. Different local actors, including public libraries, are already playing an important role in developing smart cities and communities either by themselves or in collaboration with other organizations. However, most public libraries are not currently collaborating for smart community development. Therefore, this paper analyzes the factors that influence public libraries’ perceptions about future collaborations in developing smart cities and communities as well as their potential benefits. The results show that consequential incentives, the nature of the task, preexisting relationships, an agreement on initial aims, and a collaborative and supportive leader all have a significant positive impact on the extent, effectiveness, and benefits of public libraries’ future collaborations to develop smart cities and communities

    Tailor-made molecularly imprinted polymers for dimethoate and deltamethrin recognition: synthesis, characterization and chromatographic evaluation

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    This work concerns the development of molecularly imprinted polymers (MIPs) for the selective extraction of dimethoate (dmt) and deltamethrin (dm) from food matrices. To achieve this goal, the non-covalent methodology has been applied for the preparation of MIPs using metacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) and triethylene glycol dimethacrylate (TEGDMA) as cross-linkers in order to evaluate the influence of the nature of the cross-linker on the efficiency and selectivity of those MIPs for the target pesticides. Non-imprinted polymers (NIPs), which do not contain template, have been also prepared in parallel with the MIP synthesis using the same synthetic protocol to assess the specificity of the interactions. Chemical and physical characterization was carried out using conventional techniques, such as Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis (TGA). Morphological characterization of MIPs and NIPs has been also performed using scanning electron microscopy (SEM) in order to assess the polymer’s surface topography. The performance of each polymer was evaluated by conducting binding property measurements, namely imprinting factor determinations and adsorption studies using high performance liquid chromatography (HPLC)

    H2 reformation in post-shock regions

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    H2 formation is an important process in post-shock regions, since H2 is an active participant in the cooling and shielding of the environment. The onset of H2 formation therefore has a strong effect on the temperature and chemical evolution in the post shock regions. We recently developed a model for H2 formation on a graphite surface in warm conditions. The graphite surface acts as a model system for grains containing large areas of polycyclic aromatic hydrocarbon structures. Here this model is used to obtain a new description of the H2 formation rate as a function of gas temperature that can be implemented in molecular shock models. The H2 formation rate is substantially higher at high gas temperatures as compared to the original implementation of this rate in shock models, because of the introduction of H atoms which are chemically bonded to the grain (chemisorption). Since H2 plays such a key role in the cooling, the increased rate is found to have a substantial effect on the predicted line fluxes of an important coolant in dissociative shocks [O I] at 63.2 and 145.5 micron. With the new model a better agreement between model and observations is obtained. Since one of the goals of Herschel/PACS will be to observe these lines with higher spatial resolution and sensitivity than the former observations by ISO-LWS, this more accurate model is very timely to help with the interpretation of these future results.Comment: 12 pages, 3 figures, 1 table, accepted in MNRAS Letter

    Gilberto Freyre e a Inglaterra: uma história de amor

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    Gilberto Freyre era um anglófilo confesso. Este artigo procura, de um lado, apontar para os traços da cultura britânica que mais o cativaram e, de outro, chamar a atenção para a grande importância do ensaísta britânico, Walter Pater, na trajetória intelectual do autor de Casa-grande & Senzala. Será argumentado que foi nesse autor vitoriano que Freyre encontrou inspiração para a forma ensaística de sua obra e para o tema da casa como elemento central para a compreensão da cultura brasileira. A parte final do artigo explora o impacto da obra de Freyre em Asa Briggs, um dos únicos intelectuais britânicos que reconhece o valor de suas idéias para o estudo de outras sociedades.Gilberto Freyre was a confessed anglophile. This article aims, on the one side, at pointing out the traits of British culture which most captivated him, and, on the other side, at calling attention to the importance of the British essayist Walter Paterr in the intellectual trajectory of the author of The master and the slaves. It will be argued that it was in this Victorian writer that Freyre found inspiration for the essay form of his work and for the theme of the house as a central element for the understanding of Brazilian culture. The final part of the article explores the impact of Freyre’s work on Asa Briggs, one of the rare British intellectuals who recognizes the value of his ideas for the study of other societies

    Prediction of Phenotypic Antimicrobial Resistance Profiles From Whole Genome Sequences of Non-typhoidal Salmonella enterica

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    Surveillance of antimicrobial resistance (AMR) in non-typhoidal Salmonella enterica (NTS), is essential for monitoring transmission of resistance from the food chain to humans, and for establishing effective treatment protocols. We evaluated the prediction of phenotypic resistance in NTS from genotypic profiles derived from whole genome sequencing (WGS). Genes and chromosomal mutations responsible for phenotypic resistance were sought in WGS data from 3,491 NTS isolates received by Public Health England’s Gastrointestinal Bacteria Reference Unit between April 2014 and March 2015. Inferred genotypic AMR profiles were compared with phenotypic susceptibilities determined for fifteen antimicrobials using EUCAST guidelines. Discrepancies between phenotypic and genotypic profiles for one or more antimicrobials were detected for 76 isolates (2.18%) although only 88/52,365 (0.17%) isolate/antimicrobial combinations were discordant. Of the discrepant results, the largest number were associated with streptomycin (67.05%, n = 59). Pan-susceptibility was observed in 2,190 isolates (62.73%). Overall, resistance to tetracyclines was most common (26.27% of isolates, n = 917) followed by sulphonamides (23.72%, n = 828) and ampicillin (21.43%, n = 748). Multidrug resistance (MDR), i.e., resistance to three or more antimicrobial classes, was detected in 848 isolates (24.29%) with resistance to ampicillin, streptomycin, sulphonamides and tetracyclines being the most common MDR profile (n = 231; 27.24%). For isolates with this profile, all but one were S. Typhimurium and 94.81% (n = 219) had the resistance determinants blaTEM-1, strA-strB, sul2 and tet(A). Extended-spectrum β-lactamase genes were identified in 41 isolates (1.17%) and multiple mutations in chromosomal genes associated with ciprofloxacin resistance in 82 isolates (2.35%). This study showed that WGS is suitable as a rapid means of determining AMR patterns of NTS for public health surveillance
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