798 research outputs found

    Redshift constraints for RGB 0136+391 and PKS 0735+178 from deep optical imaging

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    We present the results of deep I-band imaging of two BL Lacerate objects, RGB 0136+391 and PKS 0735+178, during an epoch when the optical nucleus was in a faint state in both targets. In PKS 0735+178 we find a significant excess over a point source, which, if fitted by the de Vaucouleurs model, corresponds to a galaxy with I = 18.64 +- 0.11 and r_eff = 1.8 +- 0.4 arcsec. Interpreting this galaxy as the host galaxy of PKS 0735+178 we derive z = 0.45 +- 0.06 using the host galaxy as a "standard candle". We also discuss the immediate optical environment of PKS 0735+178 and the identity of the MgII absorber at z = 0.424. Despite of the optimally chosen epoch and deep imaging we find the surface brightness profile of RGB 0136+391 to be consistent with a point source. By determining a lower limit for the host galaxy brightness by simulations, we derive z > 0.40 for this target.Comment: 6 pages, 5 figures, accepted for publication in Astronomy & Astrophysic

    Multiband optical polarimetry of BL Lac objects with the Nordic Optical Telescope

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    Optical polarization of seven selected BL Lac objects in UBVRI bands was studied with the Nordic Optical Telescope from December 10-14, 1999. Two of them, 3C 66A and PKS 0735+178, were monitored for 4 nights for a total integration time of 4.75 and 5.5 hours, respectively. Other objects (1Jy 0138-097, H 0414+009, PKS 0823-223, OJ287 and BL Lac) were observed sparsely during the run. Apart from PKS 0823-223 (more polarized than observed in the past), the sources show levels of flux and polarization consistent with results at previous epochs. 3C 66A and PKS 0735+178 were intensively observed during December 11 and 12 and exhibited variability of polarization, both on internight and intranight time scales. Wavelength dependence of polarization has been investigated, as well as circular polarization. The results are discussed within the standard model for BL Lacs.Comment: 11 pages, 7 figures, accepted to Astronomy & Astrophysic

    Adherence to host extracellular matrix and serum components by Enterococcus faecium isolates of diverse origin.

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    Enterococcus faecium has emerged as an important cause of nosocomial infections over the last two decades. We recently demonstrated collagen type I (CI) as a common adherence target for some E. faecium isolates and a significant correlation was found to exist between acm-mediated CI adherence and clinical origin. Here, we evaluated 60 diverse E. faecium isolates for their adherence to up to 15 immobilized host extracellular matrix and serum components. Adherence phenotypes were most commonly observed to fibronectin (Fn) (20% of the 60 isolates), fibrinogen (17%) and laminin (Ln) (13%), while only one or two of the isolates adhered to collagen type V (CV), transferrin or lactoferrin and none to the other host components tested. Adherence to Fn and Ln was almost exclusively restricted to clinical isolates, especially the endocarditis-enriched nosocomial genogroup clonal complex 17 (CC17). Thus, the ability to adhere to Fn and Ln, in addition to CI, may have contributed to the emergence and adaptation of E. faecium, in particular CC17, as a nosocomial pathogen

    Sonoelectrochemical degradation of formic acid using Ti/Ta2O5-SnO2 electrodes

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    AbstractAdvanced oxidation processes (AOPs) are modern methods using highly reactive hydroxyl radicals for the oxidation of persistent organic (sometimes inorganic) compounds in aqueous phase. Among AOPs, sonoelectrochemical degradation is a technique employing electrochemistry and ultrasound as the main source of energy without the need for additional chemicals for the process. The annual production of formic acid (FA) is around 800,000tons and is a constituent in wastewaters from tannery, chemical, pharmaceutical, dyeing industries etc. Thus far sonoelectrochemical methods have never been applied to FA decomposition. The aim of this paper is to investigate the sonoelectrochemical decomposition of FA, optimize the sonochemical and electrochemical parameters involved in FA degradation and compare the results with other existing AOPs. Sonoelectrochemical degradation of FA was found to be either comparable or better than other AOPs in terms of time and degradation efficiency. The highest 97% mineralization of FA was obtained using 1176kHz ultrasonic irradiation combined with 20mA electrolysis in 120min. The fastest FA degradation kinetics with a rate constant of 0.0374min−1 were generated at 381kHz at 20mA at an ultrasonic power of 0.02W/cm3

    Observation of shot-noise-induced asymmetry in the Coulomb blockaded Josephson junction

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    We have investigated the influence of shot noise on the IV-curves of a single mesoscopic Josephson junction. We observe a linear enhancement of zero-bias conductance of the Josephson junction with increasing shot noise power. Moreover, the IV-curves become increasingly asymmetric. Our analysis on the asymmetry shows that the Coulomb blockade of Cooper pairs is strongly influenced by the non-Gaussian character of the shot noise.Comment: 4 pages, 5 figures, RevTE

    Mesoscopic Josephson junction as a noise detector

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    Small Josephson junctions are known to be very susceptible to noise. We have utilized this property in developing methods to measure noise as well as environmental resonance modes in mesoscopic systems. We review recent results on tunnel junction systems and show also that higher order moments of shot noise can be addressed with the present method based on the noise-induced modification of incoherent tunneling of Cooper pairs.Peer reviewe
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