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Wide-field surveys of galaxies and clusters are an indispensable tool for studying large scale structure in the universe. The Abell catalogue (Abell 1958), Zwicky catalogue (Zwicky et. al. 1961-1968), and the Lick survey (Shane and Wirtanen 1967, Seldner et. al. 1977) have provided many statistical results of key importance to our understanding of galaxy formation and clustering (see e.g. Peebles 1980). However, these surveys were constructed more than 20 years ago. Since then, there have been major technological developments in photographic emulsions, automatic scanning machines and computers. It is therefore possible to improve significantly on earlier surveys by generating deep galaxy catalogues with high photometric precision and uniformity over wide areas of sky. Over the last four years, we have taken advantage of these developments to construct a new survey of several million galaxies.
We positionally match sources observed by the Sloan Digital Sky Survey (SDSS), the Two Micron All Sky Survey (2MASS), and the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey. Practically all 2MASS sources are matched to an SDSS source within 2 arcsec; ~11% of them are optically resolved galaxies and the rest are dominated by stars. About 1/3 of FIRST sources are matched to an SDSS source within 2 arcsec; ~80% of these are galaxies and the rest are dominated by quasars. Based on these results, we project that by the completion of these surveys the matched samples will include about 107 stars and 106 galaxies observed by both SDSS and 2MASS, and about 250,000 galaxies and 50,000 quasars observed by both SDSS and FIRST. Here we present a preliminary analysis of the optical, infrared and radio properties for the extragalactic sources from the matched samples. In particular, we find that the fraction of quasars with stellar colors missed by the SDSS spectroscopic survey is probably not larger than ~10%, and that the optical colors of radio-loud quasars are ~0.05 mag. redder (with 4σ significance) than the colors of radio-quiet quasars.
We describe preliminary measurements of the pairwise velocity dispersion (PVD) of galaxies in the Galaxy and Mass Assembly (GAMA) survey as a function of projected separation and galaxy luminosity. Due to the faint magnitude limit (r < 19.8) and highly-complete spectroscopic sampling of the GAMA survey, we are able to measure the PVD to smaller scales and for lower-luminosity galaxies than previous SDSS-based work. We see no strong scale-dependence at most luminosities in the quasi-linear regime. We observe an apparent drop in PVD towards very small scales (below ≈ 0.1h−1 Mpc), but this could in part be due to a restriction of the streaming model employed. At intermediate scales, the PVD is highest (~ 500 km/s) at intermediate luminosities, dropping at both fainter and brighter luminosities.
We describe modifications to the joint stepwise maximum likelihood method of Cole (2011) in order to simultaneously fit the GAMA-II galaxy luminosity function (LF), corrected for radial density variations, and its evolution with redshift. The whole sample is reasonably well-fit with luminosity (Q) and density (P) evolution parameters Q, P ≈ 0.8, 1.7. Red galaxies show larger luminosity but smaller density evolution than blue galaxies, as expected.
A heuristic greedy algorithm is developed for efficiently tiling spatially dense redshift surveys. In its first application to the Galaxy and MassAssembly (GAMA) redshift survey we find it rapidly improves the spatial uniformity of our data, and naturally corrects for any spatial bias introduced by the 2dF multi-object spectrograph. We make conservative predictions for the final state of the GAMA redshift survey after our final allocation of time, and can be confident that even if worse than typical weather affects our observations, all of our main survey requirements will be met.
This case illustrates the surgical use of wire localization, a well tried technique from a different field of surgery, in the removal of an ultrasound-detected, impalpable deep lower cervical lymph node in a high-risk patient. A localization needle with an echogenic tip was placed freehand
under ultrasound guidance, immediately before surgery. The imaging and marking of the impalpable cervical lymph node resulted in a precise surgical dissection and a reduction in operating time whilst minimizing risks to the patient and staff.
The spectra of the Sloan Digital Sky Survey (SDSS) are being used to construct a catalogue of QSO absorption lines, for use in studies of abundances, relevant radiation fields, number counts as a function of redshift, and other matters, including the evolution of these parameters. The catalogue includes intervening, associated, and BAL absorbers, in order to allow a clearer definition of the relationships between these three classes. We describe the motivation for and the data products of the project to build the SDSS QSO absorption line catalogue.
Observations of order–disorder phenomena at high pressure in hydrous phases are reinterpreted with the results of Rietveld analysis and neutron-diffraction data. The reported partial amorphization of the hydrogen sublattice in β-Co(OD)2 at 11.2 GPa was not confirmed in powder-diffraction data collected with the Paris-Edinburgh cell to 15.5 GPa. The diffraction data, and perhaps the spectroscopic data on which the observations of amorphization are based, are consistent with an increase in the H…H repulsion with pressure. The structural consequences of competition between H…H repulsion and H-bond (O—H…O) formation is observed in the M(OH)2 compounds in general. It is also observed in the dense high-pressure phases recovered from high-pressure synthetic experiments.
The hydrogen bond (X—H… Y) is one of the most studied bond geometries in the mineralogical, biological, and solid-state organic chemical communities [1, 2]. For nonmineral and mineral structures alike, the published literature, consisting mainly of crystal-structure determinations at ambient pressure, provides a means to study the bond as donor (X) and acceptor (Y) vary over a variety of structures and chemistries [3, 4]. The secondary environment, however, is important in considering the effects of structure on H-bond geometry ; in many cases gross changes in this environment from one structure type to the next make it difficult to separate the effects of the relatively weak H bonding from the steric effects because of the framework making up the remainder of the structure .
A disturbed calcium homeostasis characterizes diabetic pregnancy. This study documents changes in bone mineral composition in diabetic pregnant rats and examines the effect of insulin replacement. Control pregnant (CP), diabetic pregnant (DP) and insulin-treated DP (DPi) rats were assessed for femoral calcium and magnesium content, bone mineral density (BMD) and the ratio of hypertrophic to maturing and proliferative cells in the femoral growth plate. DP rats showed a significantly (P < 0·01) lower body weight, femoral weight and length than CP rats. Femoral calcium and magnesium content was also significantly (P < 0·05) lower in DP rats, as was ash weight. When calcium and magnesium were normalized for ash weight no signficant differences were apparent. A significantly (P < 0·05) lower total BMD at the distal femur was seen in DP rats. This comprised a significantly (P < 0·01) lower trabecular BMD with no significant change in cortical BMD. A significantly (P < 0·05) higher ratio of hypertrophic to maturing and proliferative cells of the femoral growth plate was evident in DP animals. DPi rats showed normal blood glucose concentrations and femoral growth plate histology. DPi rats also showed normal femoral weight and length but only partially restored femoral ash weight and mineral content. Insulin failed to normalize total or trabecular BMD. Diabetes mellitus clearly has a marked effect on bone growth and mineral content in pregnancy which may be relevant to overall calcium homeostasis. The lower bone growth, bone calcium content and trabecular BMD may be unfortunate consequences of the marked hypercalciuria reported elsewhere in diabetes and may serve to maintain normocalcaemia in the disease.
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