Speakers use their own discourse model to determine referents' accessibility during the production of referring expressions.

We report two experiments that investigated the widely-held assumption that speakers use the addressee's discourse model when choosing referring expressions, by manipulating whether the addressee could hear the immediately preceding linguistic context. Experiment 1 showed that speakers increased pronoun use (relative to definite NPs) when the referent was mentioned in the immediately preceding sentence compared to when it was not, but whether their addressee heard that the referent was mentioned had no effect, indicating that speakers use their own, privileged discourse model when choosing referring expressions. The same pattern of results was found in Experiment 2. Speakers produced fewer pronouns when the immediately preceding sentence mentioned a referential competitor than when it mentioned the referent, but this effect did not differ depending on whether the sentence was shared with their addressee. Thus, we conclude that choice of referring expression is determined by the referent's accessibility in the speaker’s own discourse model rather than the addressee's

QPOs from Random X-ray Bursts around Rotating Black Holes

We continue our earlier studies of quasi-periodic oscillations (QPOs) in the power spectra of accreting, rapidly-rotating black holes that originate from the geometric "light echoes" of X-ray flares occurring within the black hole ergosphere. Our present work extends our previous treatment to three-dimensional photon emission and orbits to allow for arbitrary latitudes in the positions of the distant observers and the X-ray sources in place of the mainly equatorial positions and photon orbits of the earlier consideration. Following the trajectories of a large number of photons we calculate the response functions of a given geometry and use them to produce model light curves which we subsequently analyze to compute their power spectra and autocorrelation functions. In the case of an optically-thin environment, relevant to advection-dominated accretion flows, we consistently find QPOs at frequencies of order of ~kHz for stellar-mass black hole candidates while order of ~mHz for typical active galactic nuclei (~10^7 Msun) for a wide range of viewing angles (30 to 80deg) from X-ray sources predominantly concentrated toward the equator within the ergosphere. As in our previous treatment, here too, the QPO signal is produced by the frame-dragging of the photons by the rapidly-rotating black hole, which results in photon "bunches" separated by constant time-lags, the result of multiple photon orbits around the hole. Our model predicts for various source/observer configurations the robust presence of a new class of QPOs, which is inevitably generic to curved spacetime structure in rotating black hole systems.Comment: 26 pages, 8 b/w figs, accepted to Ap

Evolution of ferromagnetic circular dichroism coincident with magnetization and anomalous Hall effect in Co-doped rutile TiO2

Magnetic circular dichroism (MCD) of rutile Ti1-xCoxO2-d is systematically examined with various x and d to reveal a phase diagram for the appearance of ferromagnetism at higher carrier concentration and Co content. The phase diagram exactly matches with that determined from anomalous Hall effect (AHE). The magnetic field dependence of MCD also shows good coincidence with those of the magnetization and AHE. The coincidence of these independent measurements strongly suggests single and intrinsic ferromagnetic origin.Comment: 9 pages, 4 figure

Role of charge carriers for ferromagnetism in cobalt-doped rutile TiO2

Electric and magnetic properties of a high temperature ferromagnetic oxide semiconductor, cobalt-doped rutile TiO2, are summarized. The cobalt-doped rutile TiO2 epitaxial thin films with different electron densities and cobalt contents were grown on r-sapphire substrates with laser molecular beam epitaxy. Results of magnetization, magnetic circular dichroism, and anomalous Hall effect measurements were examined for samples with systematically varied electron densities and cobalt contents. The samples with high electron densities and cobalt contents show the high temperature ferromagnetism, suggesting that charge carriers induce the ferromagnetism.Comment: 14 pages, 12 figure

Toward a Unified AGN Structure

We present a unified model for the structure and appearance of accretion powered sources across their entire luminosity range from galactic X-ray binaries to luminous quasars, with emphasis on AGN and their phenomenology. Central to this model is the notion of MHD winds launched from the accretion disks that power these objects. These winds provide the matter that manifests as blueshifted absorption features in the UV and X-ray spectra of a large fraction of these sources; furthermore, their density distribution in the poloidal plane determines the "appearance" (i.e. the column and velocity structure of these absorption features) as a function of the observer inclination angle. This work focuses on just the broadest characteristics of these objects; nonetheless, it provides scaling laws that allow one to reproduce within this model the properties of objects spanning a very wide luminosity range and viewed at different inclination angles, and trace them to a common underlying dynamical structure. Its general conclusion is that the AGN phenomenology can be accounted for in terms of three parameters: The wind mass flux in units of the Eddington value, $\dot m$, the observer's inclination angle $\theta$ and the logarithmic slope between the O/UV and X-ray fluxes $\alpha_{OX}$. However, because of a significant correlation between $\alpha_{OX}$ and UV luminosity, we conclude that the AGN structure depends on only two parameters. Interestingly, the correlations implied by this model appear to extend to and consistent with the characteristics of galactic X-ray sources, suggesting the presence of a truly unified underlying structure for accretion powered sources.Comment: submitted to the Astronomical Review, 32pg, 8 fig

Development of audience design in children with and without ASD

We examined 2 hypotheses concerning the development of audience design by contrasting children with and without autistic spectrum disorder (ASD) in referential communication. The 2-stage hypothesis predicts that the ability to use contrastive size adjectives for ambiguity avoidance develops separately from and faster than the ability to avoid perspective-inappropriate descriptions for their addressee. The single-stage hypothesis assumes that both abilities reflect speakers' perspective-taking, and they should develop in tandem with each other. Experiment 1 found that 6-to 10-year-olds with and without ASD produced disambiguating size adjectives ("small door") equally often when the size-contrasting competitor (large door) was in the visual context shared with their addressee. When the competitor was hidden from their addressee, that is, it was part of children's privileged context, children with ASD produced more perspective-inappropriate size adjectives than those without ASD, providing support for the 2-stage model. Experiment 2 showed a similar pattern of results with 11-to 16-year-old adolescents. Compared with adults, 6-to 10-year-olds without ASD produced more perspective-inappropriate size adjectives in the privileged context, while producing fewer disambiguating size adjectives in the shared context, demonstrating more "egocentric" behaviors than adults. Importantly, whereas 11-to 16-yearolds without ASD produced disambiguating adjectives nearly as often as adults in the shared context, they produced perspective-inappropriate adjectives more than adults in the privileged context. This indicated that even in non-ASD, the ability to avoid perspective-inappropriate descriptions develops more slowly than the ability to avoid ambiguous descriptions, delaying the onset of adult-like audience design, consistent with the 2-stage hypothesis