Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society

Disseminated herpes zoster with cauda equina symptoms

Herpes zoster is a common infection resulting from the reactivation of dormant varicella zoster virus in a posterior dorsal root ganglion. The typical dermatomal involvement includes the thoracic region, followed by the face and the cervical and lumbosacral regions, with 1% having disseminated disease. We present a rare case of an immunocompetent 85-year-old man presenting with herpes zoster at the L3-S2 dermatomes, that evolved to disseminated varicella zoster virus (dVZV), with radiologically and laboratory-confirmed lumbosacral plexopathy manifesting with cauda equina syndrome. Here we also discuss the diagnosis and complications of dVZV as well as treatment strategy. By maintaining a high degree of clinical suspicion and initiating early treatment, high-quality patient care and good outcomes are able to be achieved in cases like this

Applying design methods to promote older adults’ walking activities based on their hobbies and personal interests

People identify with their hobbies often which stimulate physical activity and participation in social activities, which in turn relate to higher levels of subjective well-being. Hobbies are potentially a powerful tool for design; however, it is unclear how to take hobbies into the design process for example to increase engagement. By creating and using the Leisure Time Canvas we identified older adults’ previous, current and potential future hobbies, and by closely collaborating with users we process these results into the design of a walking application called Ommetje. Thus, we demonstrate a design case to motivate physical activity. We present the design rationale of Ommetje and how we evaluated this smartphone walking application with 16 older adults for four months, and reflect on the design process of using hobbies as an ingredient for design. We show the power of hobbies in a design (process) as an intrinsic motivation to trigger people to be more socially and physically active

On the cognitive effectiveness of routing symbols in process modeling languages

Process models provide visual support for analyzing and improving complex organizational processes. In this paper, we discuss differences of process modeling languages using cognitive effectiveness considerations, to make statements about the ease of use and quality of user experience. Aspects of cognitive effectiveness are of importance for learning a modeling language, creating models, and understanding models. We identify the criteria representational clarity, perceptual discriminability, perceptual immediacy, visual expressiveness, and graphic parsimony to compare and assess the cognitive effectiveness of different modeling languages. We apply these criteria in an analysis of the routing elements of UML Activity Diagrams, YAWL, BPMN, and EPCs, to uncover their relative strengths and weaknesses from a quality of user experience perspective. We draw conclusions that are relevant to the usability of these languages in business process modeling projects