The Growth of Red Sequence Galaxies in a Cosmological Hydrodynamic Simulation

We examine the cosmic growth of the red sequence in a cosmological hydrodynamic simulation that includes a heuristic prescription for quenching star formation that yields a realistic passive galaxy population today. In this prescription, halos dominated by hot gas are continually heated to prevent their coronae from fueling new star formation. Hot coronae primarily form in halos above \sim10^12 M\odot, so that galaxies with stellar masses \sim10^10.5 M\odot are the first to be quenched and move onto the red sequence at z > 2. The red sequence is concurrently populated at low masses by satellite galaxies in large halos that are starved of new fuel, resulting in a dip in passive galaxy number densities around \sim10^10 M\odot. Stellar mass growth continues for galaxies even after joining the red sequence, primarily through minor mergers with a typical mass ratio \sim1:5. For the most massive systems, the size growth implied by the distribution of merger mass ratios is typically \sim2\times the corresponding mass growth, consistent with observations. This model reproduces mass-density and colour-density trends in the local universe, with essentially no evolution to z = 1, with the hint that such relations may be washed out by z \sim 2. Simulated galaxies are increasingly likely to be red at high masses or high local overdensities. In our model, the presence of surrounding hot gas drives the trends with both mass and environment.Comment: 15 pages, 8 figures. MNRAS accepte

Survey for Etomopathogenic Nematodes and Entomopathogenic Fungi in Alfalfa Snout Beetle, \u3ci\u3eOtiorhynchus Ligustici\u3c/i\u3e (L.) (Coleoptera: Curculionidae), Infested Fields in Hungary and in New York State

A survey for etomopathogenic nematodes and fungi in alfalfa snout beetle Otiorhynchus ligustici (L.) infested fields was conducted in Hungary, where this beetle is native, and in New York State, where the alfalfa snout beetle is an invasive species. Soil samples were collected in Hungary and in New York in alfalfa snout beetle infested alfalfa fields in spring 2002. Galleria mellonella (L.) larvae were used as bait insects. The entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae were found in Hungary and New York. The frequency of plots with entomopathogenic fungi was not significantly different between locations in Hungary and New York. The entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis sp. were found in Hungary and New York and S. feltiae was only found in Hungary. The frequency of plots with entomopathogenic nematodes was not significantly different between locations in Hungary and New York. S. carpocapsae and S. feltiae were found in coexistence at one location in Hungary

Field Persistence of \u3ci\u3eSteinernema Carpocapsa\u3c/i\u3e Weiser (Ny001), \u3ci\u3eSteinernema Feltiae\u3c/i\u3e Filipjev (Valko) and \u3ci\u3eHeterorhabditis Bacteriophora\u3c/i\u3e Poinar (Oswego) in Alfalfa Fields

The long term field persistence of Steinernema carpocapsae Weiser, strain NY001, S. feltiae Filipjev, strain Valko and Heterorhabditis bacteriophora Poinar, strain Oswego was investigated in an alfalfa field infested by the alfalfa snout beetle, Otiorhynchus ligustici L. Nematodes were applied in single-species, two-species and three-species combinations at a total of 2.5 × 109 infective juveniles per hectare. Soil samples were taken approximately every two weeks from mid/late May to late October in 2004 and 2005. Two soil samplings were conducted in 2006 at the end of May and in early July. All nematodes persisted in the field at the time of the last sampling in July 2006, over two years after application suggesting long term persistence of these nematodes and the potential to coexist in combinations. Steinernema feltiae Valko was not detected in the three-species combination after June 8, 2005, approximately one year after nematode application suggesting that S. feltiae Valko cannot compete effectively when a specialized ambusher nematode (S. carpocapsae NY001) and a specialized cruiser nematode (H. bacteriophora Oswego) are present simultaneously. In 2006, two years after nematode application, a marked movement of nematodes into experimental plots where they were not applied was observed. S. carpocapsae NY001 was found in the highest number of plots where it wasn’t applied. Given the ambusher behavior of S. carpocapsae NY001, it is suspected that its movement occurred via infected, but still live adult alfalfa snout beetles

An investigation of particle mixing in a gas-fluidized bed

Mechanism for particle movement in gas-fluidized beds was studied both from the theoretical and experimental points of view. In a two-dimensional fluidized bed particle trajectories were photographed when a bubble passed through

Schur properties of convolutions of gamma random variables

Sufficient conditions for comparing the convolutions of heterogeneous gamma random variables in terms of the usual stochastic order are established. Such comparisons are characterized by the Schur convexity properties of the cumulative distribution function of the convolutions. Some examples of the practical applications of our results are given