A search for new hot subdwarf stars by means of Virtual Observatory tools

Hot subdwarf stars are faint, blue objects, and are the main contributors to the far-UV excess observed in elliptical galaxies. They offer an excellent laboratory to study close and wide binary systems, and to scrutinize their interiors through asteroseismology, as some of them undergo stellar oscillations. However, their origins are still uncertain, and increasing the number of detections is crucial to undertake statistical studies. In this work, we aim at defining a strategy to find new, uncatalogued hot subdwarfs. Making use of Virtual Observatory tools we thoroughly search stellar catalogues to retrieve multi-colour photometry and astrometric information of a known sample of blue objects, including hot subdwarfs, white dwarfs, cataclysmic variables and main sequence OB stars. We define a procedure to discriminate among these spectral classes, particularly designed to obtain a hot subdwarf sample with a low contamination factor. In order to check the validity of the method, this procedure is then applied to two test sky regions: the Kepler FoV and to a test region of around (RA:225, DEC:5) deg. As a result, we obtained 38 hot subdwarf candidates, 23 of which had already a spectral classification. We have acquired spectroscopy for three other targets, and four additional ones have an available SDSS spectrum, which we used to determine their spectral type. A temperature estimate is provided for the candidates based on their spectral energy distribution, considering two-atmospheres fit for objects with clear infrared excess. Eventually, out of 30 candidates with spectral classification, 26 objects were confirmed to be hot subdwarfs, yielding a contamination factor of only 13%. The high rate of success demonstrates the validity of the proposed strategy to find new uncatalogued hot subdwarfs. An application of this method to the entire sky will be presented in a forthcoming work.Comment: 13 pages, 7 figure

Intestinal colonization due to Escherichia coli ST131: Risk factors and prevalence

Background Escherichia coli sequence type 131 (ST131) is a successful clonal group that has dramatically spread during the last decades and is considered an important driver for the rapid increase of quinolone resistance in E. coli. Methods Risk factors for rectal colonization by ST131 Escherichia coli (irrespective of ESBL production) were investigated in 64 household members (18 were colonized) and 54 hospital contacts (HC; 10 colonized) of 34 and 30 index patients with community and nosocomial infection due to these organisms, respectively, using multilevel analysis with a p limit of < 0.1. Result Colonization among household members was associated with the use of proton-pump inhibitors (PPI) by the household member (OR = 3.08; 95% CI: 0.88–10.8) and higher age of index patients (OR = 1.05; 95% CI; 1.01–1.10), and among HC, with being bed-ridden (OR = 21.1; 95% CI: 3.61–160.0) and having a urinary catheter (OR = 8.4; 95% CI: 0.87–76.9). Conclusion Use of PPI and variables associated with higher need of person-to-person contact are associated with increased risk of rectal colonization by ST131. These results should be considered for infection control purposes.Plan Nacional de I + D + i 2013-2016Ministerio de Economía y Competitividad (España)European Development Regional Fund REIPI RD12/0015/0010 REIPI RD16/0016/0001Instituto de Salud Carlos III 070190 AC16/000076-MODERN AC16/AC16/00072-ST131TSJunta de Andalucía CTS5259 CTS21

Parabolic curves for diffeomorphisms in C2

We give a simple proof of the existence of parabolic curves for diffeomorphisms in (C 2 , 0) tangent to the identity with isolated fixed point

Accumulation and distribution of diterpenic acids in leaves of Montanoa tomentosa

Montanoa tomentosa has been used for at least last five centuries in traditional medicine in Mexico as a remedy for reproductive impairments. The accumulation of diterpenic acids in M. tomentosa leaves was determined. Using Scanning Electron Microscopy, the type and distribution of glandular trichomes (GTs) was observed on the abaxial and adaxial sides of leaves. GTs and non-glandular trichomes (NGTs) were observed on leaf surface, but the latter are confined to the leaves abaxial side. On the adaxial surface, only non-glandular trichomes were observed. Accumulation in GTs and leaf lamina of kaurenoic (KA) and grandiflorenic (GFA) acids was determined by Gas Chromatography coupled to an Electron Impact Mass Spectrometric Detector (GC/EI-MSD). GC-MSD analysis indicated that GTs accumulated KA and GFA, with KA accumulation being at a higher level than GFA in these structures. Attention on GFA and KA is due to their importance as plant growth regulator precursors with potential pharmacological applications.Colegio de Farmacéuticos de la Provincia de Buenos Aire