We use the clustering of galaxies around distant active-galactic nuclei (AGN) to derive an estimate of the relationship between galaxy and black hole mass that obtained during the ancient quasar epoch, at redshifts 2 < ∼ z < ∼ 3, when giant black holes accreted much of their mass. Neither the mean relationship nor its scatter differs significantly from what is observed in the local universe, at...

We study analytically the possibility that mergers of haloes are more highly clustered than the general population of haloes of comparable masses. We begin by investigating predictions for merger bias within the extended Press-Schechter formalism and discuss the limitations and ambiguities of this approach. We then postulate that mergers occur whenever two objects form within a (small) fixed di...

In order to solve the difficult questions such as in the presence of the cluster deviation and high dimensional data processing in traditional semi-supervised clustering algorithm, a semi-supervised clustering algorithm based on active learning was proposed, this algorithm can effectively solve the above two problems. Using active learning strategies in algorithm can obtain a large amount of in...

The auto-correlation function of the X-ray background in the range of angular scales 0. ◦3–20◦ is determined using the ROSAT All-Sky Survey. In the power-law approximation, our best fit estimate is w(θ) = (0. ◦0058/θ)1.1. At the small separation end, this is substantially above previous estimates based on ROSAT pointings. The present upward revision of the correlation amplitude results from var...

We present the two–point correlation function (2PCF) of narrow-line active galactic nuclei (AGN) selected within the First Data Release of the Sloan Digital Sky Survey. Using a sample of 13605 AGN in the redshift range 0.055 < z < 0.2, we find that the AGN auto–correlation function is consistent with the observed galaxy auto–correlation function on scales 0.2hMpc to > 100hMpc. The AGN hosts tra...

Radio continuum emission at 1.4 GHz was used to identify active galaxies in a sample of 20 nearby Abell clusters. The radio emission indicates either an active galactic nucleus or current star formation, and optical spectroscopy was used to evaluate which of these dominates for each of the radio-selected galaxies. In an analysis which parallels the blue fractions of Butcher-Oemler studies, we c...

OBJECTIVES/HYPOTHESIS To determine whether patients with Menière's disease can be grouped into distinct subtypes based on a cluster analysis of distinct disease parameters. STUDY DESIGN Prospective study at a tertiary center associated with a university hospital. METHODS The study included 153 patients diagnosed with unilateral definite Menière's disease. The main variables employed were ta...