1/Nc1/N_c Expansion for Excited Baryons

We derive consistency conditions which constrain the possible form of the strong couplings of the excited baryons to the pions. The consistency conditions follow from requiring the pion-excited baryon scattering amplitudes to satisfy the large-N_c Witten counting rules and are analogous to consistency conditions used by Dashen, Jenkins and Manohar and others for s-wave baryons. The consistency conditions are explicitly solved, giving the most general allowed form of the strong vertices for excited baryons in the large-N_c limit. We show that the solutions to the large-N_c consistency conditions coincide with the predictions of the nonrelativistic quark model for these states, extending the results previously obtained for the s-wave baryons. The 1/N_c corrections to these predictions are studied in the quark model with arbitrary number of colors N_c.Comment: 56 pages, REVTeX; one new Appendix added containing a discussion of the results in the language of quark operator

SDSS J0806+2006 and SDSS J1353+1138: Two New Gravitationally Lensed Quasars from the Sloan Digital Sky Survey

We report the discoveries of two, two-image gravitationally lensed quasars selected from the Sloan Digital Sky Survey: SDSS J0806+2006 at z_s=1.540 and SDSS J1353+1138 at z_s=1.629 with image separations of 1.40" and 1.41" respectively. Spectroscopic and optical/near-infrared imaging follow-up observations show that the quasar images have identical redshifts and possess extended objects between the images that are likely to be lens galaxies at z_l~0.6 in SDSS J0806+2006 and z_l~0.3 in SDSS J1353+1138. The field of SDSS J0806+2006 contains several nearby galaxies that may significantly perturb the system, and SDSS J1353+1138 has an extra component near its Einstein ring that is probably a foreground star. Simple mass models with reasonable parameters reproduce the quasar positions and fluxes of both systems.Comment: 27 pages, 7 figures, The Astronomical Journal accepte

The redshift distribution of gravitational lenses revisited: Constraints on galaxy mass evolution

The redshifts of lens galaxies in known gravitational lens systems probe the volume distribution of lensing mass. Following earlier work by Kochanek, we re-derive the lens redshift probability distribution, allowing for mass and number density evolution of the lensing galaxies, and apply this test to a much enlarged sample of lens systems. From a literature survey of all known lenses, we have selected an unbiased sample of 15 lenses with complete redshift information. For a flat Universe and no lens evolution, we can only put an upper limit on the cosmological constant of Omega_lambda<0.89 at the 95% CL. Omega_lambda~0.7 and no evolution is consistent with the data. Allowing for evolution in an Omega_m=0.3, Omega_lambda=0.7 cosmology, we find that the best-fit evolution in sigma* (i.e., the characteristic velocity dispersion in a Schechter-like function) of early-type galaxies, in the redshift range z~0 to 1, is d[log sigma*(z)]/dz=-0.10+/-0.06. This is consistent with no evolution and implies that, at 95% CL, sigma* of early-type galaxies at z~1 was at least 63% of its current value. Alternatively, if there is no mass evolution, a present-day value of sigma*>175 km/s for elliptical galaxies is required (95% CL).Comment: 15 pages, MNRAS, in pres

The Reaction of Sle Antibodies with Native, Single Stranded Rna: Radioassay and Binding Specificities

Abstract Escherichia coli 3H-tRNA and MS2 phage 125I-RNA were prepared and used in a sensitive nitrocellulose filter assay. Antibodies that bound these RNA ligands occurred in the sera of several patients with SLE, but not in sera of patients with other connective tissue diseases. The antibody populations that bound polyribonucleotides (largely IgG) were distinct from antibody populations that bound polydeoxyribonucleotides. Competition experiments showed that the anti-RNA antibodies preferentially bound native ssRNA as compared with synthetic single and double stranded polyribonucleotides. There was increasing affinity with increasing m.w. of the ssRNA. The anti-tRNA population was of restricted heterogeneity (Sips index 0.83) and bound tRNA with an average association constant (Ko) of 9 × 106 1/mole at 4°C. The anti-MS2 RNA population was much more heterogeneous (Sips index 0.67) and bound MS2 RNA with a Ko of about 3 × 109 1/mole at 4°C. Whereas NZB/NZW mice spontaneously produce RNA reactive antibodies with conformation specificity for native tRNA, human SLE anti-RNA antibodies appear to have very little of this type of conformation specificity.</jats:p

Properties of tRNA-Specific Antibodies from NZB/NZW Mice

Abstract Antibodies that bind tRNA are produced spontaneously in New Zealand Black/New Zealand White (NZB/NZW) F1 hybrid female mice. An assay for the detection of these antibodies has been developed by using gel filtration and radioactive tRNA. This assay was found superior to the widely used ammonium sulfate precipitation assay because of the nature of the interaction between the protein and the tRNA. The antibodies bound native tRNA preferentially to tRNA denatured by cross-linking with formaldehyde. This conformational specificity was confirmed in competition experiments. The antibodies to native tRNA had an average association constant of 5 × 107 liter/mole at 4°C and could bind to more than one site per tRNA molecule. Experiments with immunoglobulin class-specific anti-mouse antisera, in solution and by radioimmunoelectrophoresis, showed that the antibodies were heterogeneous, but were predominantly of the IgG class. These antibodies may be useful for detection, localization, and conformational analysis of tRNA in solution as well as for understanding the pathogenesis of the lupus-like syndrome in these mice.</jats:p

Measurement of Antigen-Specific IgG Autoantibody Production <i>in Vitro</i>

Abstract This report describes the development of a direct, highly sensitive and reproducible microassay for measuring picogram amounts of IgG antibody produced in spleen cultures of NZB/NZW female mice and specific for a well defined nucleic acid antigen (native ssRNA). The spontaneously synthesized antibodies were extensively purified from the culture supernatants. The isolated IgG anti-RNA antibodies had a high affinity, limited heterogeneity, and were specific for RNA as compared with DNA. Spleen cell cultures produced quantities of anti-RNA antibodies sufficient to account for a large proportion of the circulating anti-RNA antibodies in the whole animal. However, our results provide no evidence for the recently published suggestion (Sawada et al., 1977. J. Immunol. 119:355) that autoreactive lymphocytes are released from normal immunoregulatory control during in vitro culture conditions.</jats:p

California Real Estate Finance, Fifth Edition

Roger Bernhardt, Stephen Dyer, and their new co authors, Daniel Bogart and Dan Schechter have fully updated their casebook on California Real Estate Finance in this revised fifth edition. California Real Estate Finance not only takes account of important changes in state and federal substantive and statutory law, but goes further and addresses the controversial and important real estate issues so widely discussed today, including predatory lending and the collapse of the subprime mortgage market. California law governing real estate is comprehensive and complex, fiercely so in the area of finance. Many California students will practice in this area, and the California Bar Exam does include finance as a subject area. Conventional law school real estate transactions courses often devote only a small fraction of their time to the important peculiarities of California doctrines, such as the one action and antideficiency rules. This book fills a critical need for students attending California law schools who intend to practice here. In order to fully explain the field of finance, the book regularly juxtaposes the rules and results in California with those in other jurisdictions, preparing students to carry their knowledge and newly acquired skills to other jurisdictions as well.https://digitalcommons.law.ggu.edu/monographs/1022/thumbnail.jp