38 research outputs found
Consumers\u27 acceptance and use of personal health record systems: A theoretical model
Recently, there has been a growing trend towards consumer-based healthcare in which consumers are increasingly becoming partners in their own care. One way of accomplishing this is to provide consumers with access to their health records through the use of Personal Health Record (PHR) systems. In spite of their potential benefits, recent research has shown that PHRs are not yet popular or well known to consumers. The overall objective of this research is to investigate the influences of various personal, behavioral, and environmental factors on the adoption and use of PHR systems by Canadian consumers. Drawing on both the information systems and behavioral healthcare literatures such a model is developed and presented. The proposed model will be validated using a longitudinal design over a period of 16 months involving patients from two local clinics. The study participants will be introduced to an existing PHR system at those clinics. The system will subsequently be made available for their potential use. Users will be surveyed at various points in time regarding their perceptions about the system utilizing both close-ended and open-ended questions. Collected data will be analyzed using structure equation modeling and qualitative data analysis techniques
Interactions between the jet and disk wind in a nearby radio intermediate quasar III Zw 2
Disk winds and jets are ubiquitous in active galactic nuclei (AGN), and how
these two components interact remains an open question. We study the radio
properties of a radio-intermediate quasar III Zw 2. We detect two jet knots J1
and J2 on parsec scales, which move at a mildly apparent superluminal speed of
. Two -ray flares were detected in III Zw 2 in 2009--2010,
corresponding to the primary radio flare in late 2009 and the secondary radio
flare in early 2010. The primary 2009 flare was found to be associated with the
ejection of J2. The secondary 2010 flare occurred at a distance of 0.3
parsec from the central engine, probably resulting from the collision of the
jet with the accretion disk wind. The variability characteristics of III Zw 2
(periodic radio flares, unstable periodicity, multiple quasi-periodic signals
and possible harmonic relations between them) can be explained by the global
instabilities of the accretion disk. These instabilities originating from the
outer part of the warped disk propagate inwards and can lead to modulation of
the accretion rate and consequent jet ejection. At the same time, the wobbling
of the outer disk may also lead to oscillations of the boundary between the
disk wind and the jet tunnel, resulting in changes in the jet-wind collision
site. III Zw 2 is one of the few cases observed with jet-wind interactions, and
the study in this paper is of general interest for gaining insight into the
dynamic processes in the nuclear regions of AGN.Comment: accepted by Ap
Multi-wavelength temporal variability of the blazar PKS 1510-089
We perform correlation and periodicity search analyses on long-term
multi-band light curves of the FSRQ 1510-089 observed by the space-based
Fermi--Large Area Telescope in gamma-rays, the SMARTS and Steward Observatory
telescopes in optical and near-infrared (NIR) and the 13.7 m radio telescope in
Metsahovi Radio Observatory between 2008 and 2018. The z-transform discrete
correlation function method is applied to study the correlation and possible
time lags among these multi band light curves. Among all pairs of wavelengths,
the gamma-ray vs. optical/NIR and optical vs. NIR correlations show zero time
lags; however, both the gamma-ray and optical/NIR emissions precede the radio
radiation. The Generalized Lomb-Scargle periodogram, Weighted Wavelet
Z-transform, and REDFIT techniques are employed to investigate the
unresolved-core-emission dominated 37 GHz light curve and yield evidence for a
quasi-period around 1540 days, although given the length of the whole data set
it cannot be claimed to be significant. We also investigate the optical/NIR
color variability and find that this source shows a simple redder-when-brighter
behavior over time, even in the low flux state.Comment: Accepted for publication in ApJ; 20 pages, 9 figures, 4 table
Location of the Gamma-Ray Flaring Emission in the Parse-Scale Jet of the BL Lac Object AO 0235+164
We locate the gamma-ray and lower frequency emission in flares of the BL Lac
object AO 0235+164 at >12pc in the jet of the source from the central engine.
We employ time-dependent multi-spectral-range flux and linear polarization
monitoring observations, as well as ultra-high resolution (~0.15
milliarcsecond) imaging of the jet structure at lambda=7mm. The time
coincidence in the end of 2008 of the propagation of the brightest superluminal
feature detected in AO 0235+164 (Qs) with an extreme multi-spectral-range
(gamma-ray to radio) outburst, and an extremely high optical and 7mm (for Qs)
polarization degree provides strong evidence supporting that all these events
are related. This is confirmed at high significance by probability arguments
and Monte-Carlo simulations. These simulations show the unambiguous correlation
of the gamma-ray flaring state in the end of 2008 with those in the optical,
millimeter, and radio regime, as well as the connection of a prominent X-ray
flare in October 2008, and of a series of optical linear polarization peaks,
with the set of events in the end of 2008. The observations are interpreted as
the propagation of an extended moving perturbation through a re-collimation
structure at the end of the jet's acceleration and collimation zone.Comment: To be published in the proceedings of High Energy Phenomena in
Relativistic Outflows III (HEPRO III, IJMPCS). 6 page
On the Location of the Gamma-ray Emission in the 2008 Outburst in the BL Lacertae Object AO 0235+164 through Observations across the Electromagnetic Spectrum
We present observations of a major outburst at centimeter, millimeter,
optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO
0235+164. We analyze the timing of multi-waveband variations in the flux and
linear polarization, as well as changes in Very Long Baseline Array (VLBA)
images at 7mm with 0.15 milliarcsecond resolution. The association of the
events at different wavebands is confirmed at high statistical significance by
probability arguments and Monte-Carlo simulations. A series of sharp peaks in
optical linear polarization, as well as a pronounced maximum in the 7 mm
polarization of a superluminal jet knot, indicate rapid fluctuations in the
degree of ordering of the magnetic field. These results lead us to conclude
that the outburst occurred in the jet both in the quasi-stationary "core" and
in the superluminal knot, both parsecs downstream of the supermassive black
hole. We interpret the outburst as a consequence of the propagation of a
disturbance, elongated along the line of sight by light-travel time delays,
that passes through a standing recollimation shock in the core and propagates
down the jet to create the superluminal knot. The multi-wavelength light curves
vary together on long time-scales (months/years), but the correspondence is
poorer on shorter time-scales. This, as well as the variability of the
polarization and the dual location of the outburst, agrees with the
expectations of a multi-zone emission model in which turbulence plays a major
role in modulating the synchrotron and inverse Compton fluxes.Comment: Accepted for Publication in the Astrophysical Journal Letters. 7
pages (including 5 figures). Minor corrections with regard to previous
version, as proposed by the refere
VERITAS discovery of very high energy gamma-ray emission from S3 1227+25 and multiwavelength observations
We report the detection of very high energy gamma-ray emission from the
blazar S3 1227+25 (VER J1230+253) with the Very Energetic Radiation Imaging
Telescope Array System (VERITAS). VERITAS observations of the source were
triggered by the detection of a hard-spectrum GeV flare on May 15, 2015 with
the Fermi-Large Area Telescope (LAT). A combined five-hour VERITAS exposure on
May 16th and May 18th resulted in a strong 13 detection with a
differential photon spectral index, = 3.8 0.4, and a flux level
at 9% of the Crab Nebula above 120 GeV. This also triggered target of
opportunity observations with Swift, optical photometry, polarimetry and radio
measurements, also presented in this work, in addition to the VERITAS and
Fermi-LAT data. A temporal analysis of the gamma-ray flux during this period
finds evidence of a shortest variability timescale of = 6.2
0.9 hours, indicating emission from compact regions within the jet, and the
combined gamma-ray spectrum shows no strong evidence of a spectral cut-off. An
investigation into correlations between the multiwavelength observations found
evidence of optical and gamma-ray correlations, suggesting a single-zone model
of emission. Finally, the multiwavelength spectral energy distribution is well
described by a simple one-zone leptonic synchrotron self-Compton radiation
model.Comment: 18 pages, 6 figures. Accepted for publication in the Astrophysical
Journal (ApJ