On the origin of relativistic particles and gamma-rays in quasars

A model for a class of quasars and active galactic nuclei is proposed in which a shock around a massive black hole randomizes the infall kinetic energy of spherically accreting matter producing a nonthermal spectrum of high energy protons. It is suggested that these protons are responsible for the secondary production (via proton decay) of the radio emitting high energy electrons and also of high energy gamma-rays (via proton decay and inverse Compton interactions of the electrons). The correlation between radio and gamma-ray emission implied by the model is in good agreement with observations of 3C273. Observation of the flux of high energy neutrinos from quasars may provide a test for the model

Relativistic particles and gamma-ray in quasars and active galactic nuclei

A model for a class of quasars and active galactic nuclei is described in which a shock around a massive black hole randomizes the infall kinetic energy of spherically accreting matter producing a nonthermal spectrum of high energy protons. These protons may be responsible for the secondary production (via tau + or - decay) of the radio emitting high energy electrons and also of high energy gamma rays (via pi decay and inverse Compton interactions of the electrons). The correlation between radio and gamma ray emission implied by the model is in good agreement with observations of 3C273. Observation of the flux of high energy neutrinos from quasars may provide a test for the model

Active galaxies and the diffuse Gamma-Ray background

A model for the origin of relativistic particles and gamma rays in active galactic nuclei and quasars, together with recent HEAO-1 observations of the spectra of active galaxies from 2 to 165 keV, provide the basis for a reexamination of the nature of the extragalactic gamma ray background. Active galaxies account for the observed background if their X-ray spectra steepen to E.021 above 100 keV, as observed in Cen-A, together with a further steepening to E.021 as a result of absorption of gamma rays by photon-photon pair production interactions with X-ray photons. The compactness of active galaxies required to give this steepening is consistent with estimates of their typical luminosity and radius

Interactions of UHE cosmic ray nuclei with radiation during acceleration: consequences on the spectrum and composition

In this paper, we study the diffusive shock acceleration of cosmic-ray protons and nuclei, taking into account all the relevant interaction processes with photon backgrounds. We investigate how the competition between protons and nuclei is modified by the acceleration parameters such as the acceleration rate, its rigidity dependence, the photon density and the confinement capability of the sources. We find that in the case of interaction-limited acceleration processes protons are likely to be accelerated to higher energies than nuclei, whereas for confinement-limited acceleration nuclei are accelerated to higher energies than protons. Finally, we discuss our results in the context of possible astrophysical accelerators, and in the light of recent cosmic-ray data.Comment: 14 pages, 11 figures A few paragraphs and one figure added for clarity, figures slightly redesigned, no changes in the result

Search for synchrotron emission from secondary leptons in dense cold starless cores

We report radio continuum observations with the Australia Telescope Compact Array of two molecular clouds. The impetus for these observations is a search for synchrotron radiation by cosmic ray secondary electrons/positrons in a region of enhanced density and possibly high magnetic field. We present modelling which shows that there should be an appreciable flux of synchrotron above the more diffuse, galactic synchrotron background. The starless core G333.125-0.562 and infrared source IRAS 15596-5301 were observed at 1384 and 2368 MHz. For G333.125-0.562, we find no significant levels of radio emission from this source at either frequency, nor any appreciable polarisation: we place an upper limit on the radio continuum flux from this source of 0.5 mJy per beam at both 1384 and 2368 MHz. Due to the higher than expected flux density limits, we also obtained archival ATCA data at 8640 MHz for this cloud and place an upper limit on the flux density of 50 micro-Jy per beam. Assuming the cosmic ray spectrum is similar to that near the Sun, and given the cloud's molecular density and mass, we place an upper limit on the magnetic field of 500 micro-G. IRAS 15596-5301, with an RMS of 50 micro-Jy per beam at 1384 MHz, shows an HII region consistent with optically thin free-free emission already detected at 4800 MHz. We use the same prescription as G333 to constrain the magnetic field from this cloud to be less than 500 micro-G. We find that these values are not inconsistent with the view that magnetic field values scale with the average density of the molecular cloud.Comment: 6 pages, 5 pdf figures, accepted for publication in PAS

Cosmic ray antimatter: Is it primary or secondary?

The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic ray antiprotons, including the low energy measurement of Buffington, were examined. It is concluded that the cosmic ray antiproton data may be strong evidence for antimatter galaxies and baryon symmetric cosmology. The present antiproton data are consistent with a primary extragalactic component having antiproton/proton approximately equal to .0032 + or - 0.7

Cosmic ray antimatter and baryon symmetric cosmology

The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic-ray antiprotons, including the new low-energy measurement of Buffington, et al. We conclude that the cosmic-ray antiproton data may be evidence for antimatter galaxies and baryon symmetric cosmology. The present bar P data are consistent with a primary extragalactic component having /p=/equiv 1+/- 3.2/0.7x10 = to the -4 independent of energy. We propose that the primary extragalactic cosmic ray antiprotons are most likely from active galaxies and that expected disintegration of bar alpha/alpha ban alpha/alpha. We further predict a value for ban alpha/alpha =/equiv 10 to the -5, within range of future cosmic ray detectors

Bounds on Relic Neutrino Masses in the Z-burst Model

Neutrinos from far-away sources annihilating at the Z resonance on relic neutrinos may give origin to the extreme-energy cosmic rays (EECR). If ``Z-bursts'' are responsible for the EECR events, then we show that the non-observation of cosmic ray events at energies above 2 x 10^20 eV by the AGASA Collaboration implies a lower bound around 0.3 eV on the relic neutrino mass. Since this mass exceeds the mass-squared differences inferred from oscillation physics, the bound in fact applies to all three neutrino masses. Together with the upper bound provided by comparisons of the CMB anisotropy with large-scale structure, this bound leaves only a small interval for neutrino masses around 0.3 eV, if Z-bursts are to explain the existing EECR events.Comment: 19 pages, including 4 figure

Health Literacy, Diabetes Prevention, and Self-Management

International audienceOBJECTIVE:To identify the factors that can predict physicians' use of electronic prescribing.DESIGN:All primary care physicians who practised in a single geographic region in Quebec were invited to use a free, advanced, research-based electronic prescribing and drug management system. This natural experiment was studied with an expansion of the Technology Acceptance Model (TAM), which was used to explain early adopters' use of this electronic prescribing technology.SETTING:Quebec city region.PARTICIPANTS:A total of 61 primary care physicians who practised in a single geographic region where there was no electronic prescribing.MAIN OUTCOME MEASURES:Actual use of electronic prescribing; physicians' perceptions of and intentions to use electronic prescribing; physician and practice characteristics.RESULTS:During the 9-month study period, 61 primary care physicians located in 26 practice sites used electronic prescribing to write 15 160 electronic prescriptions for 18 604 patients. Physician electronic prescribing rates varied considerably, from a low of 0 to a high of 75 per 100 patient visits, with a mean utilization rate of 30 per 100 patient visits. Overall, 34% of the variance in the use of electronic prescribing was explained by the expanded TAM. Computer experience (P=.001), physicians' information-acquisition style (P=.01), and mean medication use in the practice (P=.02) were significant predictors. Other TAM factors that generally predict new technology adoption (eg, intention to use, perceived ease of use, and perceived usefulness) were not predictive in this study.CONCLUSION:The adoption of electronic prescribing was a highly challenging task, even among early adopters. The insight that this pilot study provides into the determinants of the adoption of electronic prescribing suggests that novel physician-related factors (eg, information-acquisition style) and practice-related variables (eg, prevalence of medication use) influence the adoption of electronic prescribing