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Triatomine bugs carry the parasitic protozoa Trypanosoma cruzi, the causal agent of Chagas disease. It is known that both the parasite and entomopathogenic fungi can decrease bug survival, but the combined effect of both pathogens is not known, which is relevant for biological control purposes. Herein, the survival of the triatomine Meccus pallidipennis (Stal, 1872) was compared when it was coinfected with the fungus Metarhizium anisopliae (Metschnikoff) and T. cruzi, and when both pathogens acted separately. The immune response of the insect was also studied, using phenoloxidase activity in the bug gut and hemolymph, to understand our survival results. Contrary to expectations, triatomine survival was higher in multiple than in single challenges, even though the immune response was lower in cases of multiple infection. We postulate that T. cruzi exerts a protective effect and/or that the insect reduced the resources allocated to defend itself against both pathogens. Based on the present results, the use of M. anisopliae as a control agent should be re-considered.
The presence of a carbonate platform that interfingers towards the west with slope facies allows for the identification of an ancient lower Palaeozoic continental margin in the Western Precordillera of Argentina. The Los Sombreros Formation is essential for the interpretation of the continental slope of the Precordillera, which accreted to Gondwana as part of the Cuyania Terrane in the early Palaeozoic. The age of these slope deposits is controversial; therefore, a precise biostratigraphic scheme is critical to reveal the evolution of the South American continental margin of Gondwana. The study of lithic deposits of two sections of the Los Sombreros Formation, the El Salto and Los Túneles sections, provides important information for further understanding the depositional history of the slope. At El Salto section, the conodonts recovered from an allochthonous block refer to the Cordylodus proavus Zone (upper Furongian). The conodonts recovered from the matrix of a calclithite bed of the Los Sombreros Formation in the Los Túneles section are assigned to the Lenodus variabilis Zone (early Darriwilian), providing a minimum age for this stratigraphic unit. In addition, clasts from this sample yielded conodonts from the Paltodus deltifer − Macerodus dianae zones (upper Tremadocian). The contrasting conodont colour alterations and preservation states from the elements of two latter records, coming from the same sample, argue the reworked clasts originated in the carbonate platform and later transported to the slope during the accretion process of the Precordilleran Terrane to the South American Gondwanan margin during the Middle–Late Ordovician.
In this work we present high resolution spectroscopic data of the giant star-forming region of N11, obtained with the GIRAFFE instrument at the Very Large Telescope. By using this data set, we find that most of the Hα emission lines profiles in this complex can be fitted by a single Gaussian, however, multiple emission line profiles can be observed in the central region of N11. By adding all the spectra, we derive the integrated Hα profile of this complex, which displays a width (σ) of about 12 km s−1 (corrected by instrumental and thermal width). We find that a single Gaussian fit on the integrated Hα profile leaves remaining wings, which can be fitted by a secondary broad Gaussian component. In addition, we find high velocity features, which spatially correlate with soft diffuse X-ray emission.
The meeting was attended by the President and Vice-President of the Commission, along with approximately 15 other members. The President reported on the election of new officers that took place at the end of March 2012, for four new members of the Organizing Committee as well as a new Vice-President, and thanked the outgoing members. Tomaz Zwitter (Slovenia) was elected as the new VP (2012–2015), and the new OC members for the period 2012–2018 are Alceste Bonanos (Greece), Alain Jorissen (Belgium), David Katz (France), and Matthias Steinmetz (Germany). The current VP, Dimitri Pourbaix, became the President through 2015.
Commission 42 (C42) co-organized, together with Commission 27 (C27) and Division V (Div V) as a whole, a full day of science and business sessions that were held on 24 August 2012. The program included time slots for discussion of business matters related to Div V, C27 and C42, and two sessions of 2 hours each devoted to science talks of interest to both C42 and C27. In addition, we had a joint session between Div IV and Div V motivated by the proposal to reformulate the division structure of the IAU and the possible merger of the two divisions into a new Div G. The current report gives an account of the matters discussed during the business session of C42.
The present report covers the main developments in the field of close binaries during the triennium 2009-2012. In addition to scientific publications, there have been several opportunities for direct interaction of researchers working on close binaries. A number of meetings focused on more or less specific topics have taken place during this past years but the highlight for Commission 42 is arguably IAU Symposium 282 held in 2011 in Slovakia. The meeting exploited a strong connection in the methodology and tools used by close binary studies and the rapidly advancing field of exoplanet research. After all, exoplanetary systems are mostly discovered and studied using techniques employed by analyses of close binaries for decades. Modelling of exoplanet radial velocity curves and transiting planet light curves are just particular cases of single-lined and eclipsing binary systems, respectively, with very unequal component properties. As shown by IAU Symposium 282, the synergies between the two fields are strong and potentially very useful. Found below is a summary of the main scientific topics and conclusions from this very successful Symposium.
The past three-year period has seen steady efforts to collect large numbers of radial-velocity (RV) measurements, as well as important applications of radial velocities to astrophysics. Improvements in precision continue to be driven largely by exoplanet research. A workshop entitled “Astronomy of Exoplanets with Precise Radial Velocities” took place in August of 2010 at Penn State University (USA), and was attended by some 100 researchers from around the world. The meeting included thorough discussions of the current capabilities and future potential of the radial velocity technique, as well as data analysis algorithms to improve precision at visible and near-infrared wavelengths.
Division IX provides a forum for astronomers engaged in the planning, development, construction, and calibration of optical and infrared telescopes and instrumentation, as well as observational procedures including data processing. A few years ago, discussions were started about changes in the structure of Division IX, with the aim of bringing it more in line with today's world of large coordinated projects and multi-national observatories. The course of this process, and further steps to be taken in the period from 2009 to 2012, were at the focus of the deliberations at the business meeting of Division IX at the IAU General Assembly in Rio de Janeiro.
During the commission business session, the past President presented the new Organizing Committee which was selected by the OC through a e-mail vote conducted during the months before the Rio de Janeiro General Assembly. The new OC will consist of Ignasi Ribas (President), Mercedes Richards (Vice President), and Slavek Rucinski (Past President) with the members: David Bradstreet, Petr Harmanec, Janusz Kaluzny, Joanna Mikolajewska, Ulisse Munari, Panos Niarchos, Katalin Olah, Theo Pribulla, Colin Scarfe and Guillermo Torres.
Division IX provides a forum for astronomers engaged in the planning, development, construction, and calibration of optical and infrared telescopes and instrumentation, as well as observational procedures including data processing.
This three-year period has seen considerable activity in the Commission, with a wide range of applications of radial velocities as well as a significant push toward higher precision. The latter has been driven in large part by the exciting research on extrasolar planets. This field is now on the verge of detecting Earth-mass bodies around nearby stars, as demonstrated by recent work summarized below, and radial velocities continue to play a central role.
Two meetings of interest to close binaries took place during the reporting period: A full day session on short-period binary stars – mostly CV's – (Milone et al. 2008) during the 2006 AAS Spring meeting in Calgary and the very broadly designed IAU Symposium No. 240 on Binary Stars as Critical Tools and Tests in Contemporary Astrophysics in Prague, 2006, with many papers on close binaries [Hartkopf et al. 2007]. In addition, the book by Eggleton (2006), which is a comprehensive summary of evolutionary processes in binary and multiple stars, was published.
The SB9 Working Group of Commission 30 aims at compiling the 9th Catalogue of Orbits of Spectroscopic Binaries. By definition, this is a never ending task as orbits of newly discovered systems keep appearing in the literature. Despite this, the working group tries to catch up with the delay as nothing was done in between 1989 when the 8th catalogue by Batten et al. and 2000 when the WG was settled. In 2006, at its business meeting, the WG decided to focus on the completeness of systems rather than on completeness of orbits. If the latter is a valuable objective, only the former is useful to any statistical investigation of spectroscopic binaries.
With 40 or more transiting exoplanets now known, the time is ripe to seek patterns and correlations among their observed properties, which may give important insights into planet formation, structure, and evolution. This task is made difficult by the widely different methodologies that have been applied to measure their properties in individual cases. Furthermore, in many systems our knowledge of the planet properties is limited by the knowledge of the properties of the parent stars. To address these difficulties we have undertaken the first comprehensive analysis of the data for 23 transiting planets using a uniform methodology. We revisit several of the recently proposed correlations, and find new ones involving the metallicity of the parent stars.
The recently discovered transiting very hot Jupiter, HAT-P-7b, a planet detected by the telescopes of HATNet, turned out to be among the ones subjected to the highest irradiation from the parent star. In order to best characterize this particular planet, we carried out an analysis based on a complete and simultaneous Monte-Carlo solution using all available data. We included the discovery light curves, partial follow-up light curves, the radial velocity data, and we used the stellar evolution models to infer the stellar properties.
This self-consistent way of modeling provides the most precise estimate of the a posteriori distributions of all of the system parameters of interest, and avoids making assumptions on the values and uncertainties of any of the internally derived variables describing the system. This analysis demonstrates that even partial light curve information can be valuable. This may become very important for future discoveries of planets with longer periods – and therefore longer transit durations – where the chance of observing a full event is small.
The current content of the database was presented, emphasising the substantial progress accomplished since the IAU XXIV General Assembly in Manchester, 2000. More than 1 200 stellar systems have been added to the 8th Catalogue over the past six years, for a total of 540 papers compiled. A first paper was published to make the community aware of this facility (Pourbaix et al. 2004).