669 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
Simultaneous spectra and radio properties of BL Lac's
We present the results of nine years of the blazar observing programme at the
RATAN-600 radio telescope (2005-2014). The data were obtained at six frequency
bands (1.1, 2.3, 4.8, 7.7, 11.2, 21.7 GHz) for 290 blazars, mostly BL Lacs. In
addition, we used data at 37 GHz obtained quasi-simultaneously with the
Metsahovi radio observatory for some sources. The sample includes blazars of
three types: high-synchrotron peaked (HSP), low-synchrotron peaked (LSP), and
intermediate-synchrotron peaked (ISP). We present several epochs of flux
density measurements, simultaneous radio spectra, spectral indices and
properties of their variability. The analysis of the radio properties of
different classes of blazars showed that LSP and HSP BL Lac blazars are quite
different objects on average. LSPs have higher flux densities, flatter spectra
and their variability increases as higher frequencies are considered. On the
other hand, HSPs are very faint in radio domain, tend to have steep low
frequency spectra, and they are less variable than LSPs at all frequencies.
Another result is spectral flattening above 7.7 GHz detected in HSPs, while an
average LSP spectrum typically remains flat at both the low and high frequency
ranges we considered.Comment: 14 pages, 6 figures. Accepted for publication in Astronomische
Nachrichte
Simultaneous Planck, Swift, and Fermi observations of X-ray and gamma-ray selected blazars
We present simultaneous Planck, Swift, Fermi, and ground-based data for 105 blazars belonging to three samples with flux limits in the soft X-ray, hard X-ray, and gamma-ray bands, with additional 5GHz flux-density limits to ensure a good probability of a Planck detection. We compare our results to those of a companion paper presenting simultaneous Planck and multi-frequency observations of 104 radio-loud northern active galactic nuclei selected at radio frequencies. While we confirm several previous results, our unique data set allows us to demonstrate that the selection method strongly influences the results, producing biases that cannot be ignored. Almost all the BL Lac objects have been detected by the Fermi Large Area Telescope (LAT), whereas 30% to 40% of the flat-spectrum radio quasars (FSRQs) in the radio, soft X-ray, and hard X-ray selected samples are still below the gamma-ray detection limit even after integrating 27 months of Fermi-LAT data. The radio to sub-millimetre spectral slope of blazars is quite flat, with similar to 0 up to about 70GHz, above which it steepens to similar to -0.65. The BL Lacs have significantly flatter spectra than FSRQs at higher frequencies. The distribution of the rest-frame synchrotron peak frequency (nu(S)(peak)) in the spectral energy distribution (SED) of FSRQs is the same in all the blazar samples with = 10(13.1+.1) Hz, while the mean inverse Compton peak frequency, , ranges from 10(21) to 10(22) Hz. The distributions of nu(S)(peak) and nu(S)(peak) of BL Lacs are much broader and are shifted to higher energies than those of FSRQs; their shapes strongly depend on the selection method. The Compton dominance of blazars, defined as the ratio of the inverse Compton to synchrotron peak luminosities, ranges from less than 0.2 to nearly 100, with only FSRQs reaching values larger than about 3. Its distribution is broad and depends strongly on the selection method, with gamma-ray selected blazars peaking at similar to 7 or more, and radio-selected blazars at values close to 1, thus implying that the common assumption that the blazar power budget is largely dominated by high-energy emission is a selection effect. A comparison of our multi-frequency data with theoretical predictions shows that simple homogeneous SSC models cannot explain the simultaneous SEDs of most of the gamma-ray detected blazars in all samples. The SED of the blazars that were not detected by Fermi-LAT may instead be consistent with SSC emission. Our data challenge the correlation between bolometric luminosity and nu(S)(peak) predicted by the blazar sequence. --author-supplied descriptio
Urban wireless traffic evolution: the role of new devices and the effect of policy
The emergence of new wireless technologies, such as the Internet of Things,
allows digitalizing new and diverse urban activities. Thus, wireless traffic
grows in volume and complexity, making prediction, investment planning, and
regulation increasingly difficult. This article characterizes urban wireless
traffic evolution, supporting operators to drive mobile network evolution and
policymakers to increase national and local competitiveness. We propose a
holistic method that widens previous research scope, including new devices and
the effect of policy from multiple government levels. We provide an analytical
formulation that combines existing complementary methods on traffic evolution
research and diverse data sources. Results for a centric area of Helsinki
during 2020-2030 indicate that daily volumes increase, albeit a surprisingly
large part of the traffic continues to be generated by smartphones. Machine
traffic gains importance, driven by surveillance video cameras and connected
cars. While camera traffic is sensitive to law enforcement policies and data
regulation, car traffic is less affected by transport electrification policy.
High-priority traffic remains small, even under encouraging autonomous vehicle
policies. We suggest that 5G small cells might be needed around 2025, albeit
the utilization of novel radio technology and additional mid-band spectrum
could delay this need until 2029. We argue that mobile network operators
inevitably need to cooperate in constructing a single, shared small cell
network to mitigate the high deployment costs of massively deploying small
cells. We also provide guidance to local and national policymakers for
IoT-enabled competitive gains via the mitigation of five bottlenecks. For
example, local monopolies for mmWave connectivity should be facilitated on
space-limited urban furniture or risk an eventual capacity crunch, slowing down
digitalization
Results from the Blazar Monitoring Campaign at the Whipple 10m Gamma-ray Telescope
In September 2005, the observing program of the Whipple 10 m gamma-ray
telescope was redefined to be dedicated almost exclusively to AGN monitoring.
Since then the five Northern Hemisphere blazars that had already been detected
at Whipple are monitored routinely each night that they are visible. Thanks to
the efforts of a large number of multiwavelength collaborators, the first year
of this program has been very successful. We report here on the analysis of
Markarian 421 observations taken from November, 2005 to May, 2006 in the
gamma-ray, X-ray, optical and radio bands.Comment: 4 pages; contribution to the 30th International Cosmic Ray
Conference, Merida, Mexico, July 200
Frequency dependent core shifts and parameter estimation for the blazar 3C 454.3
We study the core shift effect in the parsec scale jet of the blazar 3C 454.3
using the 4.8 GHz - 36.8 GHz radio light curves obtained from three decades of
continuous monitoring. From a piecewise Gaussian fit to each flare, time lags
between the observation frequencies and spectral indices
based on peak amplitudes are determined. From the fit , indicating equipartition between
the magnetic field energy density and the particle energy density. From the fit
, is in the range to . A mean
magnetic field strength at 1 pc, G, and at the core,
mG, are inferred, consistent with previous
estimates. The measure of core position offset is
pc GHz when averaged over all frequency pairs. Based on the
statistical trend shown by the measured core radius as a
function of , we infer that the synchrotron opacity model may not be valid
for all cases. A Fourier periodogram analysis yields power law slopes in the
range to describing the power spectral density shape and gives
bend timescales in the range yr. This result, and both positive
and negative , indicate that the flares originate from multiple shocks
in a small region. Important objectives met in our study include: the
demonstration of the computational efficiency and statistical basis of the
piecewise Gaussian fit; consistency with previously reported results; evidence
for the core shift dependence on observation frequency and its utility in jet
diagnostics in the region close to the resolving limit of very long baseline
interferometry observations.Comment: 12 pages, 11 figures (23 sub-figures), 5 tables. Accepted for
publication in MNRA
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