The ATESP 5 GHz radio survey IV. 19, 38, and 94 GHz observations and radio spectral energy distributions

It is now established that the faint radio population is a mixture of star-forming galaxies and faint active galactic nuclei (AGNs), with the former dominating below S(1.4GHz) \sim 100 muJy and the latter at larger flux densities. The faint radio AGN component can itself be separated into two main classes, mainly based on the host-galaxy properties: sources associated with red/early-type galaxies (like radio galaxies) are the dominant class down to \sim 100 muJy; quasar/Seyfert--like sources contribute an additional 10-20\%. One of the major open questions regarding faint radio AGNs is the physical process responsible for their radio emission. This work aims at investigating this issue, with particular respect to the AGN component associated with red/early-type galaxies. Such AGNs show, on average, flatter radio spectra than radio galaxies and are mostly compact (<= 30 kpc in size). Various scenarios have been proposed to explain their radio emission. For instance they could be core/core-jet dominated radio galaxies, low-power BL LACs, or advection-dominated accretion flow (ADAF) systems. We used the Australia Telescope Compact Array (ATCA) to extend a previous follow-up multi-frequency campaign to 38 and 94 GHz. (abridged)Comment: 16 pages, 7 figures, 6 tables. Accepted for publication in A&

The core fundamental plane of B2 radio galaxies

The photometric, structural and kinematical properties of the centers of elliptical galaxies, harbor important information of the formation history of the galaxies. In the case of non active elliptical galaxies these properties are linked in a way that surface brightness, break radius and velocity dispersion of the core lie on a fundamental plane similar to that found for their global properties. We construct the Core Fundamental Plane (CFP) for a sizeable sample of low redshift radio galaxies and compare it with that of non radio ellipticals. To pursue this aim we combine data obtained from high resolution HST images with medium resolution optical spectroscopy to derive the photometric and kinematic properties of ~40 low redshift radio galaxies. We find that the CFPs of radio galaxies is indistinguishable from that defined by non radio elliptical galaxies of similar luminosity. The characteristics of the CFP of radio galaxies are also consistent (same slope) with those of the Fundamental Plane (FP) derived from the global properties of radio (and non radio) elliptical galaxies. The similarity of CFP and FP for radio and non radio ellipticals suggests that the active phase of these galaxies has minimal effects for the structure of the galaxies.Comment: 8 pages, 4 figures, accepted for publication in Astronomy and Astrophysic

The lives of FR I radio galaxies

After a brief introduction to the morphological properties of FRI radio sources, we discuss the possibility that FRI jets are relativistic at their bases and decelerate quickly to non-relativistic velocities. From two-frequency data we determine spectral index distributions and consequently the ages of FRI sources. We show that in the large majority of cases synchrotron theory provides unambiguous and plausible answers; in a few objects re-acceleration of electrons may be needed. The derived ages are of the order 10^7-10^8 years, 2-4 times larger than the ages inferred from dynamical arguments and a factor 5-10 larger than the ages of FRII sources. The linear sizes of FRI and FRII sources make it unlikely that many FRII's evolve into FRI's. A brief discussion is given of the possibility that radio sources go through different cycles of activity.Comment: 19 pages, including 13 figures, to appear in `Life Cycles of Radio Galaxies', ed. J. Biretta et al., New Astronomy Review

Comparison of registration strategies for USCT–MRI image fusion: preliminary results

Comparing Ultrasound Computer Tomography (USCT) to the well-known Magnetic Resonance Imaging (MRI) is an essential step in evaluating the clinical value of USCT. Yet the different conditions of the breast either embedded in water (USCT) or in air (MRI) prevent direct comparison. In this work we compare two strategies for image registration based on biomechanical modeling to automatically establish spatial correspondence: a) by applying buoyancy to the MRI, or b) by removing buoyancy from the USCT. The registration was applied to 9 datasets from 8 patients. Both registration strategies revealed similar registration accuracies (MRI to USCT: mean = 5.6 mm, median = 5.6 mm, USCT to MRI: mean = 6.6 mm, median = 5.7 mm). Image registration of USCT and MRI allows to delineate corresponding tissue structures in both modalities in the same or nearby slices. Our preliminary results indicate that both simulation strategies seem to perform similarly. Yet the newly developed deformation of the USCT volume is less computationally demanding: As the breast is subjected to buoyancy it can thereby serve as the unloaded state while for the contrary strategy we have to solve an inverse problem

Cognitive and social delays in the initiation of conversational repair

The exact timing of a conversational turn conveys important information to a listener. Most turns are initiated within 250ms after the previous turn. However, interlocutors take longer to initiate certain types of turns: those that either require more cognitive processing or are socially dispreferred. Many dispreferred turns are also cognitively demanding, so it is difficult to attribute specific conversational delays to social or cognitive mechanisms. In this paper, we evaluate the relative contribution of cognitive and social variables to the timing of utterances in conversation. We focus on a type of turn that is socially dispreferred, cognitively demanding, and generally delayed: other-initiations of repair (OIRs). OIRs occur when a listener notices and decides to signal a comprehension problem (e.g., "What?"). We analyzed the Floor Transfer Offsets of 456 OIRs, and found that interlocutors initiated OIRs later when trouble sources had weaker discourse context or were shorter, and when the OIR was more face-threatening. Our results suggest that both cognitive and social variables contribute to the timing of delayed utterances in conversation. We discuss how attention, prediction, planning, and social preference manifest in the timing of turns