A planar extrapolation of the correlation problem that permits pairing

It was observed previously that an SU(N) extension of the Hubbard model is dominated, at large N, by planar diagrams in the sense of 't Hooft, but the possibility of superconducting pairing got lost in this extrapolation. To allow for this possibility, we replace SU(N) by U(N,q), the unitary group in a vector space of quaternions. At the level of the free energy, the difference between the SU(N)and U(N,q) extrapolations appears only to first nonleading order in N.Comment: 8 pages, 2 figure

The Black Hole Mass - Galaxy Bulge Relationship for QSOs in the SDSS DR3

We investigate the relationship between black hole mass and host galaxy velocity dispersion for QSOs in Data Release 3 of the Sloan Digital Sky Survey. We derive black hole mass from the broad Hbeta line width and continuum luminosity, and the bulge stellar velocity dispersion from the [OIII] narrow line width. At higher redshifts, we use MgII and [OII] in place of Hbeta and [OIII]. For redshifts z < 0.5, our results agree with the black hole mass - bulge velocity dispersion relationship for nearby galaxies. For 0.5 < z < 1.2, this relationship appears to show evolution with redshift in the sense that the bulges are too small for their black holes. However, we find that part of this apparent trend can be attributed to observational biases, including a Malmquist bias involving the QSO luminosity. Accounting for these biases, we find ~0.2 dex evolution in the black hole mass-bulge velocity dispersion relationship between now and redshift z ~ 1.Comment: Accepted by ApJ, 15 pages, 9 figure

A photometric and kinematic study of the stars and interstellar medium in the central two kpc of NGC 3379

HST images of NGC 3379 show that the V and I luminosity profiles in the inner 13 arcsec of this E1 galaxy are represented by two different components: a stellar bulge following a Sersic Law with exponent n = 2.36, and a central core (r < 0.7 arcsec) with a characteristic "cuspy" profile. Subtraction of the underlying stellar component represented by the fitted Sersic profile revealed the presence of a small (r ~ 105 pc) dust disk of about 150 solar masses, oriented at PA = 125 degrees and inclined ~ 77 degrees with respect to the line of sight. The same absorption structure is detected in the color-index (V-I) image. The stellar rotation in the inner 20 arcsec is well represented by a parametric planar disk model, inclined ~ 26 degrees relative to the plane of the sky, and apparent major axis along PA ~ 67 degrees. The gas velocity curves in the inner 5 arcsec show a steep gradient, indicating that the gas rotates much faster than the stars, although in the same direction. The velocity field of the gaseous system, however, is not consistent with the simple model of Keplerian rotation sustained by the large (7 x 10E9 solar masses within a radius of ~ 90 pc) central mass implied by the maximum velocity observed, but the available data precludes a more detailed analysis.Comment: 23 pages, LaTeX(aaspp4.sty), 9 figures included. Figs. 1 and 5 are colour plates. Accepted for publication in The Astrophysical Journal (part 1

Nest use is influenced by the positions of nests and drinkers in aviaries

The influence of the nest location and the placement of nipple drinkers on nest use by laying hens in a commercial aviary was assessed. Twenty pens in a laying hen house were equipped with the same commercial aviary system, but the pens differed in the nest location and the placement of nipple drinkers. Nests were placed along the walls in 10 pens, and nipple drinkers were installed in front of the nests in 5 of these pens. The other 10 pens were equipped with nests placed on a tier within the aviary (integrated nests). Nipple drinkers were installed in front of the nests in 5 of these pens. A total of 225 Lohmann Selected Leghorns were housed per pen. The hens were offered 4 nests per pen: 2 facing the service corridor of the laying hen house and 2 facing the outdoor area. The numbers of nest eggs and mislaid eggs were counted daily per pen. At 25, 36, and 43 wk of age, the nest platforms were videotaped and the behavior of laying hens in front of the nests was analyzed. The nest location affected the stationary and locomotive behaviors in front of the nests. Hens in front of the integrated nests and the nests with drinkers displayed more stationary behaviors than hens in front of wall-placed nests or nests without drinkers. No difference in the number of nest eggs could be detected, but the integration of the nests inside the aviary led to a more even distribution of hens while nest searching. In the pens with wall-placed nests, significantly more hens laid eggs in the nests at the wall near the service corridor than at the wall near the outdoor area. Due to this imbalance, crowding in front of the preferred nests occurred and pushing and agonistic interactions on the nest platforms were significantly more frequent. Placement of nipple drinkers in front of nests had no effect on the number of eggs laid in those nest

Hereditary hydrocephalus internus in a laboratory strain of golden hamsters (Mesocricetus auratus)

Golden hamsters of one common laboratory strain had a high incidence of hydrocephalus internus. When a severity score of hydrocephalus was used, a major autosomal recessive locus could be identified. However, when a binary score (hydrocephalus, no hydrocephalus) was used, no such major locus could be detected and results of test matings were not consistent with Mendelian inheritance. Golden hamsters with severe forms of hydrocephalus had a dorsally compressed and ventrally intact hippocampus. Implications for the behavior and well-being of affected hamsters are unknown but researchers using this strain should be aware of the likely presence of hydrocephalu

Accretion Disk Temperatures and Continuum Colors in QSOs

Accretion disks around supermassive black holes are widely believed to be the dominant source of the optical-ultraviolet continuum in many classes of active galactic nuclei (AGN). We study here the relationship between the continuum colors of AGN and the characteristic accretion disk temperature (T_max). Based on NLTE models of accrection disks in AGN computed as described by Hubeny et al. (2000), we find that continuum intensity ratios for several pairs of wavelengths between 1350 and 5100 A should show a trend of bluer colors for higher T_max, notwithstanding random disk inclinations. We compare this theoretical expectation with observed colors of QSOs in the Sloan Digital Sky Survey,deriving black hole mass and thence T_max from the width of the Mg II broad emission line. The observed colors generally do not show the expected trend and in some cases show a reverse trend of redder colors with increasing T_max. The cause of this discrepancy does not appear to be dust reddening or galaxy contamination but may relate to the accretion rate, as the offset objects are accreting above ~30 % of the Eddington limit. The derived disk temperature depends primarily on line width, with little or no dependence on luminosity.Comment: 7 pages, 7 figures, accepted for publication in ApJ, uses emulateapj.cl

Supermassive Black Holes and the Evolution of Galaxies

Black holes, an extreme consequence of the mathematics of General Relativity, have long been suspected of being the prime movers of quasars, which emit more energy than any other objects in the Universe. Recent evidence indicates that supermassive black holes, which are probably quasar remnants, reside at the centers of most galaxies. As our knowledge of the demographics of these relics of a violent earlier Universe improve, we see tantalizing clues that they participated intimately in the formation of galaxies and have strongly influenced their present-day structure.Comment: 20 pages, - This is a near-duplicate of the paper in Nature 395, A14, 1998 (Oct 1

Phase ordering and shape deformation of two-phase membranes

Within a coupled-field Ginzburg-Landau model we study analytically phase separation and accompanying shape deformation on a two-phase elastic membrane in simple geometries such as cylinders, spheres and tori. Using an exact periodic domain wall solution we solve for the shape and phase ordering field, and estimate the degree of deformation of the membrane. The results are pertinent to a preferential phase separation in regions of differing curvature on a variety of vesicles.Comment: 4 pages, submitted to PR

HI Observations of the Supermassive Binary Black Hole System in 0402+379

We have recently discovered a supermassive binary black hole system with a projected separation between the two black holes of 7.3 parsecs in the radio galaxy 0402+379. This is the most compact supermassive binary black hole pair yet imaged by more than two orders of magnitude. We present Global VLBI observations at 1.3464 GHz of this radio galaxy, taken to improve the quality of the HI data. Two absorption lines are found toward the southern jet of the source, one redshifted by 370 +/- 10 km/s and the other blueshifted by 700 +/- 10 km/s with respect to the systemic velocity of the source, which, along with the results obtained for the opacity distribution over the source, suggests the presence of two mass clumps rotating around the central region of the source. We propose a model consisting of a geometrically thick disk, of which we only see a couple of clumps, that reproduces the velocities measured from the HI absorption profiles. These clumps rotate in circular Keplerian orbits around an axis that crosses one of the supermassive black holes of the binary system in 0402+379. We find an upper limit for the inclination angle of the twin jets of the source to the line of sight of 66 degrees, which, according to the proposed model, implies a lower limit on the central mass of ~7 x 10^8 Msun and a lower limit for the scale height of the thick disk of ~12 pc .Comment: 20 pages, 7 figures. Accepted on the Astrophysical Journa