Asthma mortality increased in Switzerland between 1980 and 1994. This study aimed to assess the economic burden of asthma in this country. Chart reviews were conducted for the last five patients seen ...for asthma in physician practices in 1996 and 1997. Direct expenditures and indirect costs for asthma-related morbidity were determined. A total of 589 patient charts were completely analysed, including 117 children's charts, obtained from 120 office-based physicians. The annual direct medical costs were CHF 1,778 and the mean annual indirect costs were CHF 1,019 per patient for all patients. The total estimated cost of asthma in Switzerland in 1997 was nearly CHF 1,252 million. Direct medical expenditures approached CHF 762 million, or 61% of the total. In 1997, the indirect costs for asthma were estimated to have exceeded CHF 490 million. Of these costs CHF 123 million (25%) was associated with morbidity and nearly CHF 368 million (75%) was associated with looking after asthmatic patients who had to be cared for at home. This study provides evidence that asthma is a major healthcare cost factor in Switzerland, amounting to approximately CHF 1,200 million per year. The data suggest that cost savings can be achieved by improving primary care for asthma in an ambulatory setting.
Aims. We report upper limits to the very high energy flux ($E>100$ GeV) of the flat spectrum radio quasar 3C 454.3 ($z=0.859$) derived by the Cherenkov telescope MAGIC during the high states of ...July/August and November/December 2007. We compare the upper limits derived in both time slots with the available quasi-simultaneous MeV-GeV data from the AGILE γ-ray satellite and interpret the observational results in the context of leptonic emission models. Methods. The source was observed with the MAGIC telescope during the active phases of July-August 2007 and November-December 2007 and the data were analyzed with the MAGIC standard analysis tools. For the periods around the ends of July and November, characterized by the most complete multifrequency coverage, we constructed the spectral energy distributions using our data together with nearly simultaneous multifrequency (optical, UV, X-ray and GeV) data. Results. Only upper limits can be derived from the MAGIC data. The upper limits, once corrected for the expected absorption by the extragalactic background light, together with nearly simultaneous multifrequency data, allow us to constrain the spectral energy distribution of 3C 454.3. The data are consistent with the model expectations based on inverse Compton scattering of the ambient photons from the broad line region by relativistic electrons, which robustly predicts a sharp cut-off above 20–30 GeV.
The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in ...short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.
The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies ...exceeding 10¹² electron volts and are bright sources of very-high-energy (VHE) γ-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE γ-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.
One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring the high-end region of a pulsar's spectrum would shed light on this question. By ...developing a new electronic trigger, we lowered the threshold of the Major Atmospheric γ-ray Imaging Cherenkov (MAGIC) telescope to 25 giga--electron volts. In this configuration, we detected pulsed γ-rays from the Crab pulsar that were greater than 25 giga--electron volts, revealing a relatively high cutoff energy in the phase-averaged spectrum. This indicates that the emission occurs far out in the magnetosphere, hence excluding the polar-cap scenario as a possible explanation of our measurement. The high cutoff energy also challenges the slot-gap scenario.
A measurement of the cosmic ray positron fraction e+/(e++e−) in the energy range of 1–30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space ...Shuttle flight in June 1998. A proton background suppression on the order of 106 is reached by identifying converted bremsstrahlung photons emitted from positrons.
FACT - The G-APD revolution in Cherenkov astronomy Bretz, T.; Anderhub, H.; Backes, M. ...
2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC),
10/2013
Conference Proceeding
Odprti dostop
Since two years, the FACT telescope is operating on the Canary Island of La Palma. Apart from its purpose to serve as a monitoring facility for the brightest TeV blazars, it was built as a major step ...to establish solid state photon counters as detectors in Cherenkov astronomy. The camera of the First G-APD Cherenkov Telesope comprises 1440 Geiger-mode avalanche photo diodes (G-APD), equipped with solid light guides to increase the effective light collection area of each sensor. Since no sense-line is available, a special challenge is to keep the applied voltage stable although the current drawn by the G-APD depends on the flux of night-sky background photons significantly varying with ambient light conditions. Methods have been developed to keep the temperature and voltage dependent response of the G-APDs stable during operation. As a cross-check, dark count spectra with high statistics have been taken under different environmental conditions. In this presentation, the project, the developed methods and the experience from two years of operation of the first G-APD based camera in Cherenkov astronomy under changing environmental conditions will be presented.
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