159 research outputs found

    Optical photometric and spectral study of the new FU Orionis object V2493 Cygni (HBC 722)

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    Aims. We present new results from optical photometric and spectroscopic observations of the eruptive pre-main sequence star V2493 Cyg (HBC 722). The object has continued to undergo significant brightness variations over the past few months and is an ideal target for follow-up observations. Methods. We carried out CCD BVRI photometric observations in the field of V2493 Cyg (“Gulf of Mexico”) from August 1994 to April 2012, i.e. at the pre-outburst states and during the phases of the outburst. We acquired high, medium, and low resolution spectroscopy of V2493 Cyg during the outburst. To study the pre-outburst variability of the target and construct its historical light curve, we searched for archival observations in photographic plate collections. Both CCD and photographic observations were analyzed using 15 comparison stars in the field of V2493 Cyg. Results. The pre-outburst photographic and CCD photometric observations of V2493 Cyg show low-amplitude light variations typical of T Tauri stars. The recent photometric data show a slow light decrease from October 2010 to June 2011 followed by an increase in brightness that continued until early 2012. The spectral observations of V2493 Cyg are typical of FU Orionis stars absorption spectra with strong P Cyg profiles of Hα and Na I D lines. On the basis of photometric monitoring performed over the past two years, the spectral properties at the maximal light, as well as the shape of long-term light curves, we confirm that the observed outburst of V2493 Cyg is of FU Orionis type

    YETI observations of the young transiting planet candidate CVSO 30 b

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    CVSO 30 is a unique young low-mass system, because, for the first time, a close-in transiting and a wide directly imaged planet candidates are found around a common host star. The inner companion, CVSO 30 b, is the first possible young transiting planet orbiting a previously known weak-lined T-Tauri star. With five telescopes of the 'Young Exoplanet Transit Initiative' (YETI) located in Asia, Europe and South America we monitored CVSO 30 over three years in a total of 144 nights and detected 33 fading events. In two more seasons we carried out follow-up observations with three telescopes. We can confirm that there is a change in the shape of the fading event between different observations and that the fading event even disappears and reappears. A total of 38 fading event light curves were simultaneously modelled. We derived the planetary, stellar, and geometrical properties of the system and found them slightly smaller but in agreement with the values from the discovery paper. The period of the fading event was found to be 1.36 s shorter and 100 times more precise than the previous published value. If CVSO 30 b would be a giant planet on a precessing orbit, which we cannot confirm, yet, the precession period may be shorter than previously thought. But if confirmed as a planet it would be the youngest transiting planet ever detected and will provide important constraints on planet formation and migration time-scales.Comment: 14 pages (20 with appendix), 7 figures (16 with appendix), 6 tables (7 with appendix

    Increased expression of integrin-linked kinase is associated with shorter survival in non-small cell lung cancer

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    BACKGROUND: Integrin-linked kinase (ILK) promotes tumor growth and invasion. Increased ILK expression is correlated with progression of several tumor types, but the expression of ILK has not been investigated in patients with non-small cell lung cancers (NSCLCs). METHODS: We investigated ILK expression in patients with NSCLC by means of immunohistochemistry. RESULTS: ILK expression was significantly associated with tumor grade, T status, lymph node metastasis and stage. (p = 0.0169 for tumor grade; p = 0.0006 for T status; p = 0.0002 for lymph node metastasis; p < 0.0001 for stage). The 5-year survival rates for patients with strong and weak or no ILK expression levels were 20% and 59%, respectively: the difference was statistically significant (p < 0.0001). A multivariate analysis of survival revealed that ILK expression, T status, N status and vascular invasion were statistically significant prognostic factors (p = 0.0218 for ILK; p = 0.0046 for T status; p < 0.0001 for N status; p < 0.0001 for vascular invasion). CONCLUSIONS: Our study demonstrates that increased expression of ILK is a poor prognostic factor in patients with NSCLC

    The composition of the protosolar disk and the formation conditions for comets

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    Conditions in the protosolar nebula have left their mark in the composition of cometary volatiles, thought to be some of the most pristine material in the solar system. Cometary compositions represent the end point of processing that began in the parent molecular cloud core and continued through the collapse of that core to form the protosun and the solar nebula, and finally during the evolution of the solar nebula itself as the cometary bodies were accreting. Disentangling the effects of the various epochs on the final composition of a comet is complicated. But comets are not the only source of information about the solar nebula. Protostellar disks around young stars similar to the protosun provide a way of investigating the evolution of disks similar to the solar nebula while they are in the process of evolving to form their own solar systems. In this way we can learn about the physical and chemical conditions under which comets formed, and about the types of dynamical processing that shaped the solar system we see today. This paper summarizes some recent contributions to our understanding of both cometary volatiles and the composition, structure and evolution of protostellar disks.Comment: To appear in Space Science Reviews. The final publication is available at Springer via http://dx.doi.org/10.1007/s11214-015-0167-

    Culture-independent molecular analysis of bacterial diversity in uranium-ore/-mine waste-contaminated and non-contaminated sites from uranium mines

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    Soil, water and sediment samples collected from in and around Jaduguda, Bagjata and Turamdih mines were analyzed for physicochemical parameters and cultured, and yet to be cultured microbial diversity. Culturable fraction of microbial community measured as Colony Forming Unit (CFU) on R2A medium revealed microbes between 104 and 109 CFU/g sample. Community DNA was extracted from all the samples; 16S rRNA gene amplified, cloned and subject to Amplified Ribosomal DNA Restriction Analysis. Clones representing each OTU were selected and sequenced. Sequence analyses revealed that non-contaminated samples were mostly represented by Acidobacteria, Bacteroidetes, Firmicutes and Proteobacteria (β-, γ-, and/or δ-subdivisions) along with less frequent phyla Nitrospira, Deferribacteres, Chloroflexi. In contrast, samples obtained from highly contaminated samples showed distinct abundance of β-,γ- and α-Proteobacteria along with Acidobacteria,Bacteroidetes and members of Firmicutes, Chloroflexi, Candidate division, Planctomycete, Cyanobacteria and Actinobacteria as minor groups. Our data represented the baseline information on bacterial community composition within non-contaminated samples which could potentially be useful for assessing the impact of metal and radionuclides contamination due to uranium mine activities
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