47 research outputs found
Report from the third international consensus meeting to harmonise core outcome measures for atopic eczema/dermatitis clinical trials (HOME).
This report provides a summary of the third meeting of the Harmonising Outcome Measures for Eczema (HOME) initiative held in San Diego, CA, U.S.A., 6-7 April 2013 (HOME III). The meeting addressed the four domains that had previously been agreed should be measured in every eczema clinical trial: clinical signs, patient-reported symptoms, long-term control and quality of life. Formal presentations and nominal group techniques were used at this working meeting, attended by 56 voting participants (31 of whom were dermatologists). Significant progress was made on the domain of clinical signs. Without reference to any named scales, it was agreed that the intensity and extent of erythema, excoriation, oedema/papulation and lichenification should be included in the core outcome measure for the scale to have content validity. The group then discussed a systematic review of all scales measuring the clinical signs of eczema and their measurement properties, followed by a consensus vote on which scale to recommend for inclusion in the core outcome set. Research into the remaining three domains was presented, followed by discussions. The symptoms group and quality of life groups need to systematically identify all available tools and rate the quality of the tools. A definition of long-term control is needed before progress can be made towards recommending a core outcome measure
Fermi LAT observations of cosmic-ray electrons from 7 GeV to 1 TeV
We present the results of our analysis of cosmic-ray electrons using about 8
million electron candidates detected in the first 12 months on-orbit by the
Fermi Large Area Telescope. This work extends our previously-published
cosmic-ray electron spectrum down to 7 GeV, giving a spectral range of
approximately 2.5 decades up to 1 TeV. We describe in detail the analysis and
its validation using beam-test and on-orbit data. In addition, we describe the
spectrum measured via a subset of events selected for the best energy
resolution as a cross-check on the measurement using the full event sample. Our
electron spectrum can be described with a power law with no prominent spectral features within systematic uncertainties.
Within the limits of our uncertainties, we can accommodate a slight spectral
hardening at around 100 GeV and a slight softening above 500 GeV.Comment: 20 pages, 23 figures, 2 tables, published in Physical Review D 82,
092004 (2010) - contact authors: C. Sgro', A. Moisee
Fermi and Swift Observations of GRB 190114C: Tracing the Evolution of High-energy Emission from Prompt to Afterglow
We report on the observations of gamma-ray burst (GRB) 190114C by the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory. The prompt gamma-ray emission was detected by the Fermi GRB Monitor (GBM), the Fermi Large Area Telescope (LAT), and the Swift Burst Alert Telescope (BAT) and the long-lived afterglow emission was subsequently observed by the GBM, LAT, Swift X-ray Telescope (XRT), and Swift UV Optical Telescope. The early-time observations reveal multiple emission components that evolve independently, with a delayed power-law component that exhibits significant spectral attenuation above 40 MeV in the first few seconds of the burst. This power-law component transitions to a harder spectrum that is consistent with the afterglow emission observed by the XRT at later times. This afterglow component is clearly identifiable in the GBM and BAT light curves as a slowly fading emission component on which the rest of the prompt emission is superimposed. As a result, we are able to observe the transition from internal-shock- to external-shock-dominated emission. We find that the temporal and spectral evolution of the broadband afterglow emission can be well modeled as synchrotron emission from a forward shock propagating into a wind-like circumstellar environment. We estimate the initial bulk Lorentz factor using the observed high-energy spectral cutoff. Considering the onset of the afterglow component, we constrain the deceleration radius at which this forward shock begins to radiate in order to estimate the maximum synchrotron energy as a function of time. We find that even in the LAT energy range, there exist high-energy photons that are in tension with the theoretical maximum energy that can be achieved through synchrotron emission from a shock. These violations of the maximum synchrotron energy are further compounded by the detection of very high-energy (VHE) emission above 300 GeV by MAGIC concurrent with our observations. We conclude that the observations of VHE photons from GRB 190114C necessitates either an additional emission mechanism at very high energies that is hidden in the synchrotron component in the LAT energy range, an acceleration mechanism that imparts energy to the particles at a rate that is faster than the electron synchrotron energy-loss rate, or revisions of the fundamental assumptions used in estimating the maximum photon energy attainable through the synchrotron process
Fermi and Swift Observations of GRB 190114C: Tracing the Evolution of High-energy Emission from Prompt to Afterglow
We report on the observations of gamma-ray burst (GRB) 190114C by the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory. The prompt gamma-ray emission was detected by the Fermi GRB Monitor (GBM), the Fermi Large Area Telescope (LAT), and the Swift Burst Alert Telescope (BAT) and the long-lived afterglow emission was subsequently observed by the GBM, LAT, Swift X-ray Telescope (XRT), and Swift UV Optical Telescope. The early-time observations reveal multiple emission components that evolve independently, with a delayed power-law component that exhibits significant spectral attenuation above 40 MeV in the first few seconds of the burst. This power-law component transitions to a harder spectrum that is consistent with the afterglow emission observed by the XRT at later times. This afterglow component is clearly identifiable in the GBM and BAT light curves as a slowly fading emission component on which the rest of the prompt emission is superimposed. As a result, we are able to observe the transition from internal-shock- to external-shock-dominated emission. We find that the temporal and spectral evolution of the broadband afterglow emission can be well modeled as synchrotron emission from a forward shock propagating into a wind-like circumstellar environment. We estimate the initial bulk Lorentz factor using the observed high-energy spectral cutoff. Considering the onset of the afterglow component, we constrain the deceleration radius at which this forward shock begins to radiate in order to estimate the maximum synchrotron energy as a function of time. We find that even in the LAT energy range, there exist high-energy photons that are in tension with the theoretical maximum energy that can be achieved through synchrotron emission from a shock. These violations of the maximum synchrotron energy are further compounded by the detection of very high-energy (VHE) emission above 300 GeV by MAGIC concurrent with our observations. We conclude that the observations of VHE photons from GRB 190114C necessitates either an additional emission mechanism at very high energies that is hidden in the synchrotron component in the LAT energy range, an acceleration mechanism that imparts energy to the particles at a rate that is faster than the electron synchrotron energy-loss rate, or revisions of the fundamental assumptions used in estimating the maximum photon energy attainable through the synchrotron process
Fermi Large Area Telescope First Source Catalog
We present a catalog of high-energy gamma-ray sources detected by the Large
Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray
Space Telescope (Fermi), during the first 11 months of the science phase of the
mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL)
contains 1451 sources detected and characterized in the 100 MeV to 100 GeV
range. Source detection was based on the average flux over the 11-month period,
and the threshold likelihood Test Statistic is 25, corresponding to a
significance of just over 4 sigma. The 1FGL catalog includes source location
regions, defined in terms of elliptical fits to the 95% confidence regions and
power-law spectral fits as well as flux measurements in 5 energy bands for each
source. In addition, monthly light curves are provided. Using a protocol
defined before launch we have tested for several populations of gamma-ray
sources among the sources in the catalog. For individual LAT-detected sources
we provide firm identifications or plausible associations with sources in other
astronomical catalogs. Identifications are based on correlated variability with
counterparts at other wavelengths, or on spin or orbital periodicity. For the
catalogs and association criteria that we have selected, 630 of the sources are
unassociated. Care was taken to characterize the sensitivity of the results to
the model of interstellar diffuse gamma-ray emission used to model the bright
foreground, with the result that 161 sources at low Galactic latitudes and
toward bright local interstellar clouds are flagged as having properties that
are strongly dependent on the model or as potentially being due to incorrectly
modeled structure in the Galactic diffuse emission.Comment: 88 pages, 22 figures, submitted to Astrophysical Journal Supplement
Series. The 1FGL catalog is available at
http://fermi.gsfc.nasa.gov/ssc/data/access/lat/1yr_catalog
The On-orbit Calibrations for the Fermi Large Area Telescope
The Large Area Telescope (LAT) on--board the Fermi Gamma ray Space Telescope
began its on--orbit operations on June 23, 2008. Calibrations, defined in a
generic sense, correspond to synchronization of trigger signals, optimization
of delays for latching data, determination of detector thresholds, gains and
responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA),
measurements of live time, of absolute time, and internal and spacecraft
boresight alignments. Here we describe on orbit calibration results obtained
using known astrophysical sources, galactic cosmic rays, and charge injection
into the front-end electronics of each detector. Instrument response functions
will be described in a separate publication. This paper demonstrates the
stability of calibrations and describes minor changes observed since launch.
These results have been used to calibrate the LAT datasets to be publicly
released in August 2009.Comment: 60 pages, 34 figures, submitted to Astroparticle Physic
VizieR Online Data Catalog: Fermi LAT third source catalog (3FGL) (Acero+, 2015)
The data for the 3FGL catalog were taken during the period from 2008 August 4 (15:43 UTC) to 2012 July 31 (22:46 UTC), to covering close to 4yr. The LAT detects Îł-rays in the energy range from 20MeV to more than 300GeV. (4 data files). <P /