821 research outputs found

    Pre-Dispute Mandatory Arbitration Agreements and Title VII: Promoting Efficiency While Protecting Employee Rights - EEOC v. Luce, Forward, Hamilton & (and) Scripps

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    While the United States Supreme Court has repeatedly held that claims based on statutory rights may be vindicated by arbitration, the Court has yet to determine the validity of a pre-dispute mandatory arbitration agreement ( MAA ) that covers Title VII of the Civil Rights Act of 1964 ( Title VII ). The United States Court of Appeals for the Ninth Circuit, contrary to every other district court of appeals to have considered the matter, has held that Title VII claims may not be subjected to arbitration under an MAA. The instant case once again addresses the question of whether the Ninth Circuit will allow an employer to require its employees to sign an MAA covering Title VII claims as a condition of employment

    Microlensing Evidence That a Type 1 Quasar is Viewed Face-On

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    Using a microlensing analysis of 11 years of OGLE V-band photometry of the four image gravitational lens Q2237+0305, we measure the inclination i of the accretion disk to be cos i > 0.66 at 68% confidence. Very edge on (cos i < 0.39) solutions are ruled out at 95% confidence. We measure the V-band radius of the accretion disk, defined by the radius where the temperature matches the monitoring band photon emission, to be R_V = 5.8^+3.8_–2.3 × 10^15 cm assuming a simple thin disk model and including the uncertainties in its inclination. The projected radiating area of the disk remains too large to be consistent with the observed flux for a T α R ^–3/4 thin disk temperature profile. There is no strong correlation between the direction of motion (peculiar velocity) of the lens galaxy and the orientation of the disk

    The Transverse Peculiar Velocity of the Q2237+0305 Lens Galaxy and the Mean Mass of Its Stars

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    Using 11-years of OGLE V-band photometry of Q2237+0305, we measure the transverse velocity of the lens galaxy and the mean mass of its stars. We can do so because, for the first time, we fully include the random motions of the stars in the lens galaxy in the analysis of the light curves. In doing so, we are also able to correctly account for the Earth's parallax motion and the rotation of the lens galaxy, further reducing systematic errors. We measure a lower limit on the transverse speed of the lens galaxy, v_t > 338 km/s (68% confidence) and find a preferred direction to the East. The mean stellar mass estimate including a well-defined velocity prior is 0.12 <= 1.94 at 68% confidence, with a median of 0.52 Msun. We also show for the first time that analyzing subsets of a microlensing light curve, in this case the first and second halves of the OGLE V-band light curve, give mutually consistent physical results.Comment: 11 pages, 9 figures, 1 table; animated magnification pattern video can be found at http://www.astronomy.ohio-state.edu/~sdp/animation.avi; accepted for publication in Ap

    The Spatial Structure of An Accretion Disk

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    Based on the microlensing variability of the two-image gravitational lens HE1104-1805 observed between 0.4 and 8 microns, we have measured the size and wavelength-dependent structure of the quasar accretion disk. Modeled as a power law in temperature, T proportional to R^-beta, we measure a B-band (0.13 microns in the rest frame) half-light radius of R_{1/2,B} = 6.7 (+6.2 -3.2) x 10^15 cm (68% CL) and a logarithmic slope of beta=0.61 (+0.21 -0.17) for our standard model with a logarithmic prior on the disk size. Both the scale and the slope are consistent with simple thin disk models where beta=3/4 and R_{1/2,B} = 5.9 x 10^15 cm for a Shakura-Sunyaev disk radiating at the Eddington limit with 10% efficiency. The observed fluxes favor a slightly shallower slope, beta=0.55 (+0.03 -0.02), and a significantly smaller size for beta=3/4.Comment: 5 pages, 4 figures, submitted to Ap

    The Quasar Accretion Disk Size - Black Hole Mass Relation

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    We use the microlensing variability observed for nine gravitationally lensed quasars to show that the accretion disk size at 2500 Angstroms is related to the black hole mass by log(R_2500/cm) = (15.6+-0.2) + (0.54+-0.28)log(M_BH/10^9M_sun). This scaling is consistent with the expectation from thin disk theory (R ~ M_BH^(2/3)), but it implies that black holes radiate with relatively low efficiency, log(eta) = -1.29+-0.44 + log(L/L_E) where eta=L/(Mdot c^2). These sizes are also larger, by a factor of ~3, than the size needed to produce the observed 0.8 micron quasar flux by thermal radiation from a thin disk with the same T ~ R^(-3/4) temperature profile. More sophisticated disk models are clearly required, particularly as our continuing observations improve the precision of the measurements and yield estimates of the scaling with wavelength and accretion rate.Comment: 5 pages, 3 figures, submitted to ApJ

    The Optical, Ultraviolet, and X-ray Structure of the Quasar HE 0435-1223

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    Microlensing has proven an effective probe of the structure of the innermost regions of quasars, and an important test of accretion disk models. We present light curves of the lensed quasar HE 0435-1223 in the R band and in the ultraviolet, and consider them together with X-ray light curves in two energy bands that are presented in a companion paper. Using a Bayesian Monte Carlo method, we constrain the size of the accretion disk in the rest-frame near- and far-UV, and constrain for the first time the size of the X-ray emission regions in two X-ray energy bands. The R-band scale size of the accretion disk is about 10^15.23 cm (~23 r_g), slightly smaller than previous estimates, but larger than would be predicted from the quasar flux. In the UV, the source size is weakly constrained, with a strong prior dependence. The UV to R-band size ratio is consistent with the thin disk model prediction, with large error bars. In soft and hard X-rays, the source size is smaller than ~10^14.8 cm (~10 r_g) at 95% confidence. We do not find evidence of structure in the X-ray emission region, as the most likely value for the ratio of the hard X-ray size to the soft X-ray size is unity. Finally, we find that the most likely value for the mean mass of stars in the lens galaxy is ~0.3 M_sun, consistent with other studies.Comment: 13 pages, 7 figures. Replaced with version accepted to Ap

    Mid-IR Observations and a Revised Time Delay for the Gravitational Lens System Quasar HE 1104-1805

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    The mid-IR flux ratios F_A/F_B = 2.84 +/- 0.06 of the two images of the gravitationally lensed quasar HE 1104-1805 show no wavelength dependence to within 3% across 3.6-8.0 um, no time dependence over 6 months and agree with the broad emission line flux ratios. This indicates that the mid-IR emission likely comes from scales large enough to be little affected by microlensing and that there is little differential extinction between the images. We measure a revised time-delay between these two images of 152.2 +2.8-3.0 days from R and V-band data covering 1997 to 2006. This time-delay indicates that the lens has an approximately flat rotation curve over scales of 1-2 R_e. We also observed uncorrelated variations of ~0.05 mag/yr which we attribute to microlensing of the optical emission from the accretion disk. The optical colors have also changed significantly in the sense that image A is now redder than image B, rather than bluer as it was in 1993.Comment: 26 page, 6 figures; this version corrects table 1 which reported incorrect IRAC magnitudes; this change does not affect any result

    A Robust Determination of the size of quasar accretion disks using gravitational microlensing

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    Using microlensing measurements from a sample of 27 image-pairs of 19 lensed quasars we determine a maximum likelihood estimate for the accretion disk size of an {{\em}average} quasar of rs=4.03.1+2.4r_s=4.0^{+2.4}_{-3.1} light days at rest frame =1736=1736\AA\ for microlenses with a mean mass of =0.3M=0.3M_\odot. This value, in good agreement with previous results from smaller samples, is roughly a factor of 5 greater than the predictions of the standard thin disk model. The individual size estimates for the 19 quasars in our sample are also in excellent agreement with the results of the joint maximum likelihood analysis.Comment: 6 pages, 3 figures, submitted to Ap

    Alternative mechanism for bacteriophage adsorption to the motile bacterium Caulobacter crescentus

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    2D and 3D cryo-electron microscopy, together with adsorption kinetics assays of ϕCb13 and ϕCbK phage-infected Caulobacter crescentus, provides insight into the mechanisms of infection. ϕCb13 and ϕCbK actively interact with the flagellum and subsequently attach to receptors on the cell pole. We present evidence that the first interaction of the phage with the bacterial flagellum takes place through a filament on the phage head. This contact with the flagellum facilitates concentration of phage particles around the receptor (i.e., the pilus portals) on the bacterial cell surface, thereby increasing the likelihood of infection. Phage head filaments have not been well characterized and their function is described here. Phage head filaments may systematically underlie the initial interactions of phages with their hosts in other systems and possibly represent a widespread mechanism of efficient phage propagation
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