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
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
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
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
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
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
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
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
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 light days at rest
frame \AA\ for microlenses with a mean mass of
. 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
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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