669 research outputs found

    Consumers\u27 acceptance and use of personal health record systems: A theoretical model

    Get PDF
    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

    Full text link
    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

    Get PDF
    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

    Full text link
    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

    Full text link
    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

    Full text link
    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 Δt\Delta t between the observation frequencies ν\nu and spectral indices α\alpha based on peak amplitudes AA are determined. From the fit Δtν1/kr\Delta t \propto \nu^{1/k_r}, kr=1.10±0.18k_r = 1.10 \pm 0.18 indicating equipartition between the magnetic field energy density and the particle energy density. From the fit AναA \propto \nu^\alpha, α\alpha is in the range 0.24-0.24 to 1.521.52. A mean magnetic field strength at 1 pc, B1=0.5±0.2B_1 = 0.5 \pm 0.2 G, and at the core, Bcore=46±16B_{\rm core} = 46 \pm 16 mG, are inferred, consistent with previous estimates. The measure of core position offset is Ωrν=6.4±2.8\Omega_{r\nu} = 6.4 \pm 2.8 pc GHz1/kr^{1/k_r} when averaged over all frequency pairs. Based on the statistical trend shown by the measured core radius rcorer_{\rm core} as a function of ν\nu, 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 1.6-1.6 to 3.5-3.5 describing the power spectral density shape and gives bend timescales in the range 0.520.66 0.52 - 0.66~yr. This result, and both positive and negative α\alpha, 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
    corecore