► The standard test statistic of TeV astronomy (Li and Ma (1983), Eq. (17)) is generalized. ► The derived formulae can provide a significance estimation in all reasonable observation cases. ► I ...discuss the relation to the current test statistic, and present several further possible generalizations. ► This result is particularly useful for skymapping purposes, fits on skymaps, or for scans of large sky areas.
Astrophysical sources of TeV gamma rays are usually established by Cherenkov telescope observations. These counting type instruments have a field of view of few degrees in diameter and record large numbers of particle air showers via their Cherenkov radiation in the atmosphere. The showers are either induced by gamma rays or diffuse cosmic ray background. The commonly used test statistic to evaluate a possible gamma-ray excess is Li and Ma 6, Eq. (17), which can be applied to independent on- and off-source observations, or scenarios that can be approximated as such. This formula however is unsuitable if the data are taken in so-called “wobble” mode (pointing to several offset positions around the source), if at the same time the acceptance shape is irregular or even depends on operating parameters such as the pointing direction or telescope multiplicity. To provide a robust test statistic in such cases, this paper explores a possible generalization of the likelihood ratio concept on which the formula of Li and Ma is based. In doing so, the multi-pointing nature of the data and the typically known instrument point spread function are fully exploited to derive a new, semi-numerical test statistic. Due to its flexibility and robustness against systematic uncertainties, it is not only useful for detection purposes, but also for skymapping and source shape fitting. Simplified Monte Carlo simulations are presented to verify the results, and several applications and further generalizations of the concept are discussed.
Context. It has been suggested that the bow shocks of runaway stars are sources of high-energy gamma rays (E > 100 MeV). Theoretical models predicting high-energy gamma-ray emission from these ...sources were followed by the first detection of non-thermal radio emission from the bow shock of BD+43°3654 and non-thermal X-ray emission from the bow shock of AE Aurigae. Aims. We perform the first systematic search for MeV and GeV emission from 27 bow shocks of runaway stars using data collected by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. Methods. We analysed 57 months of Fermi-LAT data at the positions of 27 bow shocks of runaway stars extracted from the Extensive stellar BOw Shock Survey catalogue (E-BOSS). A likelihood analysis was performed to search for gamma-ray emission that is not compatible with diffuse background or emission from neighbouring sources and that could be associated with the bow shocks. Results. None of the bow shock candidates is detected significantly in the Fermi-LAT energy range. We therefore present upper limits on the high-energy emission in the energy range from 100 MeV to 300 GeV for 27 bow shocks of runaway stars in four energy bands. For the three cases where models of the high-energy emission are published we compare our upper limits to the modelled spectra. Our limits exclude the model predictions for ζ Ophiuchi by a factor ≈5.
Federal authorization of the use of Clinical Laboratory Improvement Amendments of 1988 (CLIA) waived point-of-care tests for SARS-CoV-2 by pharmacists during the pandemic resulted in a dramatic rise ...in the number of community pharmacies that became CLIA-waived test sites. Now as we exit the pandemic, the wide-ranging expansion of the scope of practice facilitated currently by the PREP Act is set to expire in fall 2024. As a result, American pharmacists’ ability to offer CLIA-waived testing services will revert to a patchwork of state laws.
This study aims to examine both the number of pharmacies in the United States with CLIA Certificates of Waiver before and after the SARS-CoV-2 pandemic and the state-by-state differences in the percentage of pharmacies with CLIA Certificates of Waiver.
Data were collected from the U.S. Centers for Disease Control and Prevention CLIA Laboratory Search website on May 3rd, 2015, August 4th, 2019, November 26th, 2020, October 6th, 2021, November 23rd, 2022, and December 4th, 2023. The website allows for the exportation of demographic data on all CLIA-waived facilities by state.
The total number of pharmacies with a CLIA-waiver grew from 10,626 (17.9%) locations in 2015 to 12,157 (21.4%) locations in 2019, to 15,671 (27.6%) locations in 2020, and to 29,011 (51.6%) locations in 2023. States demonstrated considerable variability in the percentage of pharmacies possessing a CLIA certificate of waiver in 2023, with a range of 10.7%–87.9%.
Use of CLIA-waived tests in pharmacies has grown by 140% since 2019. The time period from 2019 to 2021 witnessed a 92.5% increase in pharmacies that possessed a certificate of waiver which was largely driven by the pandemic. Interestingly, from 2021 to 2023 the was continued growth in the market of 31.6%. This suggests that pharmacies continue to see opportunity in offering CLIA-waived testing services beyond those that had been extended as a result of the pandemic.
The Clinical Laboratory Improvement Amendments of 1988 (CLIA) enabled greater access to low-risk tests by allowing their use in facilities with a Certificate of Waiver in the U.S. Recently, the 2019 ...novel coronavirus (COVID-19) pandemic has shined a spotlight on CLIA-waived diagnostic testing. To meet this increased patient demand for diagnostic testing, the U.S. Department of Health and Human Services (HHS) authorized licensed pharmacists to order and administer FDA authorized COVID-19 tests.
This study aims to update the previous national benching report and examine both the number of pharmacies in the United States with CLIA Certificates of Waiver before and after the SARS-CoV-2 pandemic and the state-by-state differences in the percentage of pharmacies with CLIA Certificates of Waiver.
Data were collected from the U.S. Centers for Disease Control and Prevention CLIA Laboratory Search website May 3rd, 2015, August 4th, 2019 and November 26th, 2020. The website allows for exportation of demographic data on all CLIA-waived facilities by state.
Pharmacies exhibited the largest growth both in number (4865 new locations) and by percent (45%) of CLIA-waived facilities between 2015 and 2020. The total number of pharmacies with a CLIA-waiver grew from 10,626 (17.94%) locations in 2015 to 12,157 (21.43%) locations in 2019, to 15,671 (27.63%) locations in 2020. States demonstrated considerable variability in the percentage of pharmacies with a CLIA-waiver, with a range of 2.92%–56.52%.
Pharmacies have become an increasingly important location for patients to access CLIA-waived tests in the United States, now serving as the second largest provider of CLIA-waived tests by the total number of locations. Most of this growth occurred between 2019 and 2020 due to the COVID-19 pandemic, and concentrated efforts will be necessary to sustain this momentum.
Source detection in counting type experiments such as Cherenkov telescopes often involves the application of the classical Eq. (17) from the paper of Li & Ma (1983) to discrete on- and off-source ...regions. The on-source region is typically a circular area with radius θ in which the signal is expected to appear with the shape of the instrument point spread function (PSF). This paper addresses the question of what is the θ that maximises the probability of detection for a given PSF width and background event density. In the high count number limit and assuming a Gaussian PSF profile, the optimum is found to be at ζ∞2≈2.51 times the squared PSF width σPSF392. While this number is shown to be a good choice in many cases, a dynamic formula for cases of lower count numbers, which favour larger on-source regions, is given. The recipe to get to this parametrisation can also be applied to cases with a non-Gaussian PSF. This result can standardise and simplify analysis procedures, reduce trials and eliminate the need for experience-based ad hoc cut definitions or expensive case-by-case Monte Carlo simulations.
Massive star-forming regions assemble a large number of young stars with remnants of stellar evolution and a very dense environment. Therefore, particles accelerated in supernova remnants and pulsar ...wind nebulae encounter optimal conditions for interacting with target material and photon fields, and thus produce gamma-ray emission. However, observations are challenging because multiple phenomena may appear entangled within the resolution of current gamma-ray telescopes. We report on MAGIC observations aimed to understand the nature of the emission from the star-forming region W51 and the unidentified source HESS J1857+026. While gamma-ray emission from W51 is dominated by the interaction of the supernova remnant W51C with dense molecular clouds, HESS J1857+026 is associated to the pulsar wind nebula from PSR J1856+0245. However, an additional source is resolved north of HESSJ1857+026, with sufficient separation to determine that it cannot be powered by the same pulsar. We search for multiwavelength data to determine the origin of the new source.
We report on observations of the Crab pulsar with the MAGIC telescopes. Our data were taken in both monoscopic (> 25 GeV) and stereoscopic (> 50 GeV) observation modes. Two peaks were detected with ...both modes and phase-resolved energy spectra were calculated. By comparing with Fermi-LAT measurements, we find that the energy spectrum of the Crab pulsar does not follow a power law with an exponential cutoff, but has an additional hard component, extending up to at least 400 GeV. This suggests that the emission above 25 GeV is not dominated by curvature radiation, as suggested in the standard scenarios of the OG and SG models.
The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep ...exposure of 210 hours. Three sources of different types were detected: the pulsar wind nebula of the most energetic pulsar known, N 157B; the radio-loud supernova remnant N 132D; and the largest nonthermal x-ray shell, the superbubble 30 Dor C. The unique object SN 1987A is, unexpectedly, not detected, which constrains the theoretical framework of particle acceleration in very young supernova remnants. These detections reveal the most energetic tip of a γ-ray source population in an external galaxy and provide via 30 Dor C the unambiguous detection of γ-ray emission from a superbubble.
IceTop: The surface component of IceCube Abbasi, R.; Aguilar, J.A.; Ahlers, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2013, Volume:
700
Journal Article
Peer reviewed
Open access
IceTop, the surface component of the IceCube Neutrino Observatory at the South Pole, is an air shower array with an area of 1km2. The detector allows a detailed exploration of the mass composition of ...primary cosmic rays in the energy range from about 100TeV to 1EeV by exploiting the correlation between the shower energy measured in IceTop and the energy deposited by muons in the deep ice. In this paper we report on the technical design, construction and installation, the trigger and data acquisition systems as well as the software framework for calibration, reconstruction and simulation. Finally the first experience from commissioning and operating the detector and the performance as an air shower detector will be discussed.
The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100 MeV < E < 100 GeV) γ-ray band, which is continuously monitored with Fermi-LAT. During two ...periods of high activity in April 2014 and June 2015 target-of-opportunity observations were undertaken with the High Energy Stereoscopic System (H.E.S.S.) in the very-high-energy (VHE, E > 100 GeV) γ-ray domain. While the observation in 2014 provides an upper limit, the observation in 2015 results in a signal with 8.7σ significance above an energy threshold of 66 GeV. No VHE variability was detected during the 2015 observations. The VHE photon spectrum is soft and described by a power-law index of 4.2 ± 0.3. The H.E.S.S. data along with a detailed and contemporaneous multiwavelength data set provide constraints on the physical parameters of the emission region. The minimum distance of the emission region from the central black hole was estimated using two plausible geometries of the broad-line region and three potential intrinsic spectra. The emission region is confidently placed at r ≳ 1.7 × 1017 cm from the black hole, that is beyond the assumed distance of the broad-line region. Time-dependent leptonic and lepto-hadronic one-zone models were used to describe the evolution of the 2015 flare. Neither model can fully reproduce the observations, despite testing various parameter sets. Furthermore, the H.E.S.S. data were used to derive constraints on Lorentz invariance violation given the large redshift of 3C 279.
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