New Michigan Tick (Acari: Ixodidae) and Flea (Siphonaptera: Ceratophyllidae) Records From Colonial Nesting Birds

Banding and censusing large numbers of gull chicks over a 30-year period on Great Lakes islands has produced a collection of five individual ticks from two Herring Gull (Larus argentatus) chicks. The tick species, Hemaphysalis leporispalustris, found on the gulls is commonly found on Snowshoe Hares (Lepus americanus). Although this represents an apparently uncom­mon record on Herring Gulls, this host could be an important source of aerial vector dispersal during regular cyclic hare/tick population peaks. Populations of the flea, Ceratophyllus lari, have increased rapidly in ground nesting Double-crested Cormorant (Phalacrocorax auritus) colonies from none 16 years ago. The possibilities of disease transmission by both of these hematophagus ectoparasites are assessed with evidence from the literature. The tick and flea distributions reported here are new host records, and the flea is a new species record for Michigan

Geographic Distribution of Siphonaptera Collected From Small Mammals on Lake Michigan Islands

The distribution of ten flea species collected from five small mammal host species on 13 Lake Michigan islands is described. Four new eastern and southern records for Hystrichopsylla dippiei Rothschild are given. Speculative suggestions are made regarding dispersal routes of some of the small mammal host species, and the distribution of flea species from Peromyscus maniculatus gracilis LeConte is dis- cussed in the context of island biogeography theory

Additional Siphonaptera Records From Small Mammals in the Central Upper Peninsula of Michigan

Fleas were collected from mammals during the period 1990-1992 in two upper peninsula counties. Identified specimens were compared to existing distribution records for both parasite and host. Only those records which are newly documented for county, upper peninsula or Michigan are listed. We report one previously unknown flea species and five new host records for Michigan. One host record is new for the upper peninsula. In addition, seven new host/parasite combinations are recorded for two central upper peninsula counties

ON THE MEASUREMENT OF A COSMOLOGICAL DIPOLE IN THE PHOTON NUMBER COUNTS OF GAMMA-RAY BURSTS

If gamma-ray bursts are cosmological or in a halo distribution their properties are expected to be isotropic (at least to 1st order). However, our motion with respect to the burst parent population (whose proper frame is expected to be that of the Cosmic Microwave Background (CMB), or that of a static halo) will cause a dipole effect in the distribution of bursts and in their photon number counts (together termed a Compton-Getting effect). We argue that the photon number count information is necessary to distinguish a genuine Compton-Getting effect from some other anisotropy and to fully test the proper frame isotropy of the bursts. Using the 2B burst catalogue and the dipole determined from the CMB, we find the surprising result that although the number weighted distribution is consistent with isotropy, the fluence weighted dipole has a correlation with the CMB dipole that has a probability of occuring only 10% of the time for an isotropic photon distribution. Furthermore, the photon and number dipoles are inconsistent under the hypothesis of isotropy, at the 2-sigma level. This could be an indication that a non-negligible fraction of gamma-ray bursts originate in the local, anisotropic universe. (shortened Abstract)Comment: Accepted by ApJ. Self-unpacking (use csh), uuencoded, compressed Postscript, 16 pages + 4 Figures (5 files

The Chandra Fornax Survey - I: The Cluster Environment

We present the first results of a deep Chandra survey of the inner 1 degree of the Fornax cluster of galaxies. Ten 50 ksec pointings were obtained in a mosaic centered on the giant elliptical galaxy NGC 1399 at the nominal cluster center. Emission and temperature maps of Fornax are presented, and an initial study of 771 detected X-ray point sources is made. Regions as small as 100pc are resolved. The intra-cluster gas in Fornax exhibits a highly asymmetric morphology and temperature structure, dominated by a 180 kpc extended ``plume'' of low surface brightness, cool, ~1 keV) gas to the North-East of NGC 1399 with a sharper edge to the South West. The elliptical galaxy NGC 1404 also exhibits a cool halo of X-ray gas within the cluster, with a highly sharpened leading edge as it presumably falls into the cluster, and a cometary-like tail. We estimate that some ~200-400 point sources are physically associated with Fornax. Confirming earlier works, we find that the globular cluster population in NGC 1399 is highly X-ray active, extending to globulars which may in fact be intra-cluster systems. We have also found a remarkable correlation between the location of giant and dwarf cluster galaxies and the presence of X-ray counterparts, such that systems inhabiting regions of low gas density are more likely to show X-ray activity. Not only does this correlate with the asymmetry of the intra-cluster gas but also with the axis joining the center of Fornax to an infalling group 1 Mpc to the South-West. We suggest that Fornax may be experiencing an intergalactic ``headwind'' due to motion relative to the surrounding large-scale structure.Comment: 35 pages, 15 figures, submitted to ApJ. Most figures not included owing to severe compression degradation - we strongly recommend downloading the full resolution paper from http://www.astro.columbia.edu/~caleb/ms_highres.pdf (1.9Mb

Siphonaptera Records and Host Associations From the Central and Eastern Upper Peninsula of Michigan

Fleas were collected from birds and mammals over a five year period in four upper peninsula counties. Identified specimens were compared to published records of distribution for the parasite species and its host species, and only those records which are new county distributions for host or parasite are listed. Four new host records for Michigan, four new flea distribution records for the upper peninsula, and 26 new county records are listed

The evolution of the cluster X-ray scaling relations in the WARPS sample at 0.6<z<1.0

The X-ray properties of a sample of 11 high-redshift (0.6<z<1.0) clusters observed with Chandra and/or XMM are used to investigate the evolution of the cluster scaling relations. The observed evolution of the L-T and M-L relations is consistent with simple self-similar predictions, in which the properties of clusters reflect the properties of the universe at their redshift of observation. When the systematic effect of assuming isothermality on the derived masses of the high-redshift clusters is taken into account, the high-redshift M-T and Mgas-T relations are also consistent with self-similar evolution. Under the assumption that the model of self-similar evolution is correct and that the local systems formed via a single spherical collapse, the high-redshift L-T relation is consistent with the high-z clusters having formed at a significantly higher redshift than the local systems. The data are also consistent with the more realistic scenario of clusters forming via the continuous accretion of material. The slope of the L-T relation at high-redshift (B=3.29+/-0.38) is consistent with the local relation, and significantly steeper then the self-similar prediction of B=2. This suggests that the non-gravitational processes causing the steepening occurred at z>1 or in the early stages of the clusters' formation, prior to their observation. The properties of the intra-cluster medium at high-redshift are found to be similar to those in the local universe. The mean surface-brightness profile slope for the sample is 0.66+/-0.05, the mean gas mass fractions within R2500 and R200 are 0.073+/-0.010 and 0.12+/-0.02 respectively, and the mean metallicity of the sample is 0.28+/-0.16 solar.Comment: 23 pages, 17 figures. Accepted for publication in MNRAS. Revised to match accepted version: reanalysed data with latest calibrations, several minor changes. Conclusions unchange

Liming Missouri soils (2000)

Reviewed February 2000