53,383 research outputs found

    Detectors and Concepts for sub-100 ps timing with gaseous detectors

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    We give a short compendium of the main ongoing detectors and concepts capable of performing accurate sub-100 ps timing at high particle fluxes and on large areas, through technologies based on gaseous media. We briefly discuss the state-of-the-art, technological limitations and prospects, and a new bizarre idea

    Cluster of galaxies around seven radio-loud QSOs at 1<z<1.6: K-band images

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    We have conducted a NIR study of the environments of seven radio-loud quasars at redshifts 1<z<1.6. In present paper we describe deep KK band images obtained for the fields of ~6X6 arcmin around the quasars with 3σ\sigma limiting magnitudes of K~20.5. These fields were previously studied using deep B and R band images (Sanchez & Gonzalez-Serrano 1999). Using together optical and NIR data, it has been found a significant excess of galaxies which optical-NIR colours, luminosity, spatial scale, and number of galaxies are compatible with clusters at the redshift of the quasar. We have selected a sample of cluster candidates analyzing the R-K vs. K diagram. A ~25% of the candidates present red optical-NIR colours and an ultraviolet excess. This population has been also found in clusters around quasars at the same redshifts (Tanaka et al. 2000; Haines et al. 2001). These galaxies seem to follow a mixed evolution: a main passive evolution plus late starformation processes. The quasars do not inhabit the core of the clusters, being found in the outer regions. This result agrees with the hypothesis that the origin/feeding mechanism of the nuclear activity were merging processes. The quasars inhabit the region were a collision is most probably to produce a merger.Comment: 15 pages. A&A, accepted for publishin

    Internet sources for nursing and allied health

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    Lists and describes available Internet resources for nursing and allied health professionals. Procedure for subscribing and unsubscribing from the discussion lists; Newsgroups available for nurses; Accessing to gopher servers