4,987 research outputs found
The giant radio galaxy 8C0821+695 and its environment
We present new VLA and Effelsberg observations of the radio galaxy
8C0821+695. We have obtained detailed images in total intensity and
polarization of this 2 Mpc sized giant. The magnetic field has a configuration
predominantly parallel to the source main axis. We observe Faraday rotation at
low frequencies, most probably produced by an ionized medium external to the
radio source. The spectral index distribution is that typical of FR II radio
galaxies, with spectral indices gradually steepening from the source extremes
towards the core. Modeling the spectrum in the lobes using standard synchrotron
loss models yields the spectral age of the source and the mean velocity of the
jet-head with respect to the lobe material. The existence of a possible
backflow in the lobe is considered to relate spectral with dynamical
determinations of the age and the velocity with respect to the external medium.
Through a very simple model, we obtain a physical characterization of the jets
and the external medium in which the radio galaxy expands. The results in
8C0821+695 are consistent with a relativistic jet nourishing the lobes which
expand in a hot, low density halo. We infer a deceleration of the source
expansion velocity which we explain through a progressive increase in the
hot-spot size.Comment: 11 pages; 8 figures; accepted in A&
Minimal access surgery compared with medical management for gastro-oesophageal reflux disease : five year follow-up of a randomised controlled trial (REFLUX)
Peer reviewedPublisher PD
Where do graduates Develop their Enterprise Skills? The Value of the Contribution of Higher Education Institutions’ Context
This study investigates the value of the contribution of HEIs’ context in developing graduates enterprise skills. HEIs are under pressure to develop more enterprising graduates, particularly with the increasing numbers of graduates seeking employment and the growing dissatisfaction of employers. This study explores where graduates develop enterprise skills through investigating the impact of HE and employment contexts on their development. The paper draws on a qualitative study in the social constructionist paradigm within the pharmacy context, where interviews were conducted with pharmacy academics and employers. Results show that ability to demonstrate skills in one context does not necessarily mean ability to demonstrate them in another since the development and demonstration of enterprise skills is impacted by the contexts in which they are developed and demonstrated. The study adds value by highlighting the significant role of both HE and employment contexts in developing enterprise skills, while emphasising that these skills become more transferable through exposure to more contexts
Clinical and economic evaluation of laparoscopic surgery compared with medical management for gastro-oesophageal reflux disease : 5-year follow-up of multicentre randomised trial (the REFLUX trial)
Peer reviewedPublisher PD
Electronic transport, structure, and energetics of endohedral Gd@C82 metallofullerenes
Electronic structure and transport properties of the fullerene C and
the metallofullerene Gd@C are investigated with density functional
theory and the Landauer-Buttiker formalism. The ground state structure of
Gd@C is found to have the Gd atom below the C-C bond on the C
molecular axis of C. Insertion of Gd into C deforms the carbon
chain in the vicinity of the Gd atoms. Significant overlap of the electron
distribution is found between Gd and the C cage, with the transferred Gd
electron density localized mainly on the nearest carbon atoms. This charge
localization reduces some of the conducting channels for the transport, causing
a reduction in the conductivity of the Gd@C species relative to the
empty C molecule. The electron transport across the metallofullerene is
found to be insensitive to the spin state of the Gd atom.Comment: 13 pages, 7 figures, submitted Nano Let
Magnetic Fields in Quasar Cores II
Multi-frequency polarimetry with the Very Long Baseline Array (VLBA)
telescope has revealed absolute Faraday Rotation Measures (RMs) in excess of
1000 rad/m/m in the central regions of 7 out of 8 strong quasars studied (e.g.,
3C 273, 3C 279, 3C 395). Beyond a projected distance of ~20 pc, however, the
jets are found to have |RM| < 100 rad/m/m. Such sharp RM gradients cannot be
produced by cluster or galactic-scale magnetic fields, but rather must be the
result of magnetic fields organized over the central 1-100 pc. The RMs of the
sources studied to date and the polarization properties of BL Lacs, quasars and
galaxies are shown to be consistent so far with the predictions of unified
schemes. The direct detection of high RMs in these quasar cores can explain the
low fractional core polarizations usually observed in quasars at centimeter
wavelengths as the result of irregularities in the Faraday screen on scales
smaller than the telescope beam. Variability in the RM of the core is reported
for 3C 279 between observations taken 1.5 years apart, indicating that the
Faraday screen changes on that timescale, or that the projected superluminal
motion of the inner jet components samples a new location in the screen with
time. Either way, these changes in the Faraday screen may explain the dramatic
variability in core polarization properties displayed by quasars.Comment: Accepted to the ApJ. 27 pages, 9 figures including figure 6 in colo
Implications of a High Angular Resolution Image of the Sunyaev-Zel'dovich Effect in RXJ1347-1145
The most X-ray luminous cluster known, RXJ1347-1145 (z=0.45), has been the
object of extensive study across the electromagnetic spectrum. We have imaged
the Sunyaev-Zel'dovich Effect (SZE) at 90 GHz (3.3 mm) in RXJ1347-1145 at 10"
resolution with the 64-pixel MUSTANG bolometer array on the Green Bank
Telescope (GBT), confirming a previously reported strong, localized enhancement
of the SZE 20" to the South-East of the center of X-ray emission. This
enhancement of the SZE has been interpreted as shock-heated (> 20 keV) gas
caused by an ongoing major (low mass-ratio) merger event. Our data support this
interpretation. We also detect a pronounced asymmetry in the projected cluster
pressure profile, with the pressure just east of the cluster core ~1.6 times
higher than just to the west. This is the highest resolution image of the SZE
made to date.Comment: 9 pages, 7 figures; accepted for publication in The Astrophysical
Journa
International health and Hispanic culture
This research project focuses on the interrelations between health and culture in the Hispanic countries and their impact on individuals and communities. The research explores medical diseases and conditions, people\u27s traditions, beliefs, and perceptions related to concerns related to health issues, home remedies, behavior change, family and community, doctor-patient relationship, and social aspects of public health (ethnicity, gender, poverty). Students will have the opportunity to travel to the Dominican Republic with the researchers and participate in service learning activities to help Hispanic communities and collect data for this research project. CI students will lead the following research topics in the Dominican Republic: 1) self-medication, low-income population accessibility to medicines, and the governmental pharmacy system (Boticas Populares) (Caleb Addis); 2) domestic violence as a public health concern (Aliyah Anjarwalla); 3) how chronic diseases are promoted, prevented and controlled (Deepti Athavale); 4) hepatitis A as a public health concern (Thomas Cotton); 5) challenges/barriers of people with disabilities to access physical therapy services (Breci Davis) ; 6) cultural and socio-economic determinants of childhood obesity (Michelle Fuentes); 7)medical equipment maintenance at public health care settings: advantages and disadvantages of donated equipment (Hannah Haire); 8) challenges and opportunities for the implementation of the HIV Vertical Transmission Prevention Program (Ashley Jamison); and 9) a behavioral theory analysis of drug abuse (Katherine Orellana)
Observations of M87 and Hydra A at 90 GHz
This paper presents new observations of the AGNs M87 and Hydra A at 90 GHz
made with the MUSTANG bolometer array on the Green Bank Telescope at 8.5"
resolution. A spectral analysis is performed combining this new data and
archival VLA data on these objects at longer wavelengths. This analysis can
detect variations in spectral index and curvature expected from energy losses
in the radiating particles. M87 shows only weak evidence for steepening of the
spectrum along the jet suggesting either re-acceleration of the relativistic
particles in the jet or insufficient losses to affect the spectrum at 90 GHz.
The jets in Hydra A show strong steepening as they move from the nucleus
suggesting unbalanced losses of the higher energy relativistic particles. The
difference between these two sources may be accounted for by the different
lengths over which the jets are observable, 2 kpc for M87 and 45 kpc for Hydra
A.Comment: 11 pages, submitted to Ap
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