Ground based γ-ray observations with Imaging Atmospheric Cherenkov Telescopes (IACTs) play a significant role in the discovery of very high energy (E > 100 GeV) γ-ray emitters. The analysis of IACT ...data demands a highly efficient background rejection technique, as well as methods to accurately determine the position of its source in the sky and the energy of the recorded γ-ray. We present results for background rejection and signal direction reconstruction from first studies of a novel data analysis scheme for IACT measurements. The new analysis is based on a set of Convolutional Neural Networks (CNNs) applied to images from the four H.E.S.S. phase-I telescopes. As the H.E.S.S. cameras pixels are arranged in a hexagonal array, we demonstrate two ways to use such image data to train CNNs: by resampling the images to a square grid and by applying modified convolution kernels that conserve the hexagonal grid properties.
The networks were trained on sets of Monte-Carlo simulated events and tested on both simulations and measured data from the H.E.S.S. array. A comparison between the CNN analysis to current state-of-the-art algorithms reveals a clear improvement in background rejection performance. When applied to H.E.S.S. observation data, the CNN direction reconstruction performs at a similar level as traditional methods. These results serve as a proof-of-concept for the application of CNNs to the analysis of events recorded by IACTs.
The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new ...observations from an unprecedented gamma-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (& GSIM;100 GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant gamma-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section (sigma v). Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach (sigma v) values of 3.7 x 10-26 cm3 s-1 for 1.5 TeV DM mass in the W+W- annihilation channel, and 1.2 x 10-26 cm3 s-1 for 0.7 TeV DM mass in the tau+tau- annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based gamma-ray observations thus probe (sigma v) values expected from thermal-relic annihilating TeV DM particles.
We report on broad multiwavelength observations of the 2010-2011 periastron passage of the γ-ray loud binary system PSR B1259−63. High-resolution interferometric radio observations establish extended ...radio emission trailing the position of the pulsar. Observations with the Fermi
Gamma-ray Space Telescope reveal GeV γ-ray flaring activity of the system, reaching the spin-down luminosity of the pulsar, around 30 d after periastron. There are no clear signatures of variability at radio, X-ray and TeV energies at the time of the GeV flare. Variability around periastron in the Hα emission line, can be interpreted as the gravitational interaction between the pulsar and the circumstellar disc. The equivalent width of the Hα grows from a few days before periastron until a few days later, and decreases again between 18 and 46 d after periastron. In near-infrared we observe the similar decrease of the equivalent width of Brγ line between the 40th and 117th day after the periastron. For the idealized disc, the variability of the Hα line represents the variability of the mass and size of the disc. We discuss possible physical relations between the state of the disc and GeV emission under assumption that GeV flare is directly related to the decrease of the disc size.
Myanmar represents an extreme example of the difficulties in optimally allocating resources for maximum public health benefit, on the basis of limited information. At the recent Myanmar Health Forum ...‘Investing in Health’ much of the discussion revolved around what to invest in, how health systems could be strengthened, and what research and capacity building areas the international donor community should prioritise for support. Funding for infectious disease control, particularly HIV and tuberculosis, is being channelled to the country at an unprecedented rate, but very little research has been conducted in recent years, and existing information has not yet been synthesised. This paper presents findings of the first systematic literature review on tuberculosis control and the health system in Myanmar, with the aim of informing the development of optimal research priorities and strategies. Medline and grey literature were searched for relevant papers. Inclusion criteria and analyses were structured to capture data on the Myanmar health system, healthcare delivery, financing, tuberculosis control indicators and information systems. A total of 77 papers were included in the analysis. The results indicate that there has been a large increase in the number of peer-reviewed articles published on tuberculosis in Myanmar over the past decade, although the absolute number of studies remains small. We identified several areas in which evidence to inform policy and resource allocation decisions is lacking, including research focused on rural and/or vulnerable populations, analyses of risk factors for TB and drug resistance that can inform prevention strategies and economic analyses for optimising resource allocation. The gaps in research to inform policy identified through this study may be relevant to other low resource settings with extremely limited research capacity.
Le Myanmar est l’illustration d’un exemple extrême de la difficulté de répartir les ressources de manière optimale pour un bénéfice maximal de la santé publique, sur la base d’informations limitées. Au cours du récent Forum sur la santé au Myanmar «Investir dans la santé», une grande partie des débats a porté sur les investissements, la manière de renforcer les systèmes de santé ainsi que les domaines de recherche et de renforcement des capacités auxquels la communauté internationale des donateurs devrait accorder la priorité. Le financement de la lutte contre les maladies infectieuses, en particulier le VIH et la tuberculose, s’est accéléré à un rythme sans précédent, mais très peu de recherches ont été menées ces dernières années et les informations existantes n’ont pas encore été synthétisées. Le présent article présente les résultats de la première revue systématique des publications sur la lutte contre la tuberculose et sur le système de santé au Myanmar, dans le but d’orienter l’élaboration des priorités et des stratégies de recherche optimales. Nous avons fouillé la base de données Medline et la littérature grise à la recherche d’articles pertinents. Les critères d’inclusion et les analyses ont été structurés de manière à recueillir des données sur le système de santé du Myanmar, la prestation et le financement des soins de santé, les indicateurs de la lutte contre la tuberculose et les systèmes d’information. Au total, 77 articles ont été inclus dans l’analyse. Les résultats indiquent qu’il ya eu une forte augmentation du nombre d’articles publiés sur la tuberculose au Myanmar au cours de la dernière décennie, bien que le nombre absolu d’études reste faible. Nous avons identifié plusieurs domaines dans lesquels il manque de données probantes pour éclairer les stratégies et les décisions relatives à l’allocation de ressources, notamment la recherche axée sur les populations rurales et/ou vulnérables, les analyses des facteurs de risque de tuberculose et de résistance aux médicaments qui peuvent aider les stratégies de prévention et les analyses économiques afin d’optimiser l’allocation des ressources. Dans le cadre de cette étude, les lacunes identifiées dans le domaine de la recherche devant éclairer les décideurs politiques peuvent être pertinentes pour d’autres milieux à faibles ressources dont la capacité de recherche est extrêmement limitée.
在信息有限的条件下, 优化资源配置实现公共卫生利益最大化 非常困难, 缅甸就是一个极端的实例。在近期举办的"卫生投 入"缅甸卫生论坛上, 大部分讨论都是围绕着投入哪些项目, 如 何强化卫生体系, 以及国际捐赠者应该如何确定优先支持哪些 领域的研究和能力建设。用于传染病尤其是HIV和结核控制 的资金正以前所未有的速度涌入缅甸, 但近年来进行的研究非 常少, 现有的信息也未经综合。本文为首篇关于缅甸结核控制 和卫生体系的系统文献综述, 旨在为制定最优研究优先顺序和 策略提供信息。在Medline和灰色文献中检索相关文章。纳入 标准和分析的目的是获取关于缅甸卫生体系、医疗服务、筹 资、结核控制指标和信息系统方面的数据。共纳入 77 篇文 献。结果显示, 过去十年, 关于缅甸结核病的同行评议文章数 量大幅增加, 尽管绝对数值仍然很小。我们发现若干领域仍然 缺乏指导政策和资源配置决策的证据, 包括以农村和/或弱势 人群为重点的研究、结核危险因素和耐药性分析, 这些研究可 以为预防策略和优化资源配置的经济学分析提供证据。本研 究发现的政策依据方面的研究空白可能也存在于其他研究能 力及其有限的资源匮乏国家。
Myanmar es un ejemplo extremo de las dificultades en la asignación óptima de los recursos para maximizar los beneficios para la salud pública, con base en la información limitada. En el reciente Foro de Salud en Myanmar "Invirtiendo en Salud", gran parte de la discusión giró alrededor de en qué invertir, cómo se podrían fortalecer los sistemas de salud y a qué áreas de investigación y creación de capacidades debería la comunidad internacional de donantes dar prioridad y apoyar. La financiación para el control de las enfermedades infecciosas, particularmente VIH y tuberculosis, está siendo canalizada al país a una tasa sin precedentes, pero en los últimos años se han realizado muy pocas investigaciones y aún no se ha sintetizado la información existente. Este artículo presenta los resultados de la primera revisión sistemática de la literatura sobre el control de la tuberculosis y el sistema de salud en Myanmar, con el objetivo de informar el desarrollo de prioridades y estrategias de investigación óptimas. Se buscaron artículos relevantes en Medline y en la literatura gris. Los criterios de inclusión y los análisis se estructuraron para recopilar datos sobre el sistema de salud de Myanmar, la prestación del cuidado de la salud, la financiación, los indicadores de control de la tuberculosis y los sistemas de información. Un total de 77 artículos fueron incluidos en el análisis. Los resultados indican que ha habido un gran aumento en el número de artículos evaluados por pares sobre tuberculosis en Myanmar durante la última década, aunque el número absoluto de estudios sigue siendo pequeño. Identificamos variasáreas en las cuales no existen evidencias para informar las decisiones de políticas y de asignación de recursos, incluyendo la investigación enfocada en poblaciones rurales y/o vulnerables, análisis de factores de riesgo de tuberculosis y resistencia a medicamentos que pueden informar estrategias de prevención y análisis económicos para optimizar la asignación de recursos. Las brechas en la investigación para informar las políticas identificadas a través de este estudio pueden ser relevantes para otros entornos de bajos recursos con una capacidad de investigaciónextremadamente limitada.
Background
The implementation of the ‘Surgical Safety Checklist’ caused a significant reduction in the incidence of complications and mortality among patients undergoing surgery. The aim of the ...present study was to evaluate perioperative safety standards and the quality of interprofessional cooperation before and after the introduction of a safety checklist from staff members' point of view.
Methods
Employees' attitude concerning safety‐relevant aspects of the perioperative period, work processes, and quality of interprofessional cooperation was surveyed before and 3 months after introducing an adapted form of the ‘Surgical Safety Checklist’ by a 19‐item questionnaire.
Results
After the implementation of the checklist, the cognizance of the names and functions of the individual operating room (OR) staff members, verification of the patient's written consent for surgery, indication for antibiotics before the surgical incision, and the quality of interprofessional cooperation were rated more positively. Traumatology physicians were more convinced that all artifacts had been removed from the surgical field. Finally, communication about intraoperative complications had improved.
Conclusions
Our attitude surveys demonstrate that from the OR staff's perspective, in the perioperative setting, safety‐relevant factors can be handled significantly better and with greater awareness by implementing a safety checklist as proposed by the World Health Organization.
Observations of the Crab nebula with HESS Aharonian, F.; Akhperjanian, A. G.; Bazer-Bachi, A. R. ...
Astronomy & astrophysics,
10/2006, Letnik:
457, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Context.The Crab nebula was observed with the HESS stereoscopic Cherenkov-telescope array between October 2003 and January 2005 for a total of 22.9 h (after data quality selection). This period of ...time partly overlapped with the commissioning phase of the experiment; observations were made with three operational telescopes in late 2003 and with the complete 4 telescope array in January–February 2004 and October 2004–January 2005. Aims.Observations of the Crab nebula are discussed and used as an example to detail the flux and spectral analysis procedures of HESS. The results are used to evaluate the systematic uncertainties in HESS flux measurements. Methods.The Crab nebula data are analysed using standard HESS analysis procedures, which are described in detail. The flux and spectrum of γ-rays from the source are calculated on run-by-run and monthly time-scales, and a correction is applied for long-term variations in the detector sensitivity. Comparisons of the measured flux and spectrum over the observation period, along with the results from a number of different analysis procedures are used to estimate systematic uncertainties in the measurements. Results.The data, taken at a range of zenith angles between $45^{\circ}$ and $65^{\circ}$, show a clear signal with over 7500 excess events. The energy spectrum is found to follow a power law with an exponential cutoff, with photon index $\Gamma = 2.39$ ± $0.03_{{\rm {stat}}}$ and cutoff energy $E_{\rm c} = (14.3 \pm 2.1_{{\rm {stat}}})~{\rm TeV}$ between 440 GeV and 40 TeV. The observed integral flux above 1 TeV is $(2.26 \pm 0.08_{{\rm {stat}}}) \times 10^{-11}~{{\rm cm}^{-2}~{\rm s}^{-1}}$. The estimated systematic error on the flux measurement is estimated to be 20%, while the estimated systematic error on the spectral slope is 0.1.
ABSTRACT
We report on a search for persistent radio emission from the one-off fast radio burst (FRB) 20190714A, as well as from two repeating FRBs, 20190711A and 20171019A, using the MeerKAT radio ...telescope. For FRB 20171019A, we also conducted simultaneous observations with the High-Energy Stereoscopic System (H.E.S.S.) in very high-energy gamma rays and searched for signals in the ultraviolet, optical, and X-ray bands. For this FRB, we obtain a UV flux upper limit of $1.39 \times 10^{-16}~{\rm erg\, cm^{-2}\, s^{-1}}$Å−1, X-ray limit of $\sim 6.6 \times 10^{-14}~{\rm erg\, cm^{-2}\, s^{-1}}$ and a limit on the very high energy gamma-ray flux $\Phi (E\gt 120\, {\rm GeV}) \lt 1.7\times 10^{-12}\, \mathrm{erg\, cm^{-2}\, s^{-1}}$. We obtain a radio upper limit of ∼15 $\mu$Jy beam−1 for persistent emission at the locations of both FRBs 20190711A and 20171019A with MeerKAT. However, we detected an almost unresolved (ratio of integrated flux to peak flux is ∼1.7 beam) radio emission, where the synthesized beam size was ∼ 8 arcsec size with a peak brightness of $\sim 53\, \mu$Jy beam−1 at MeerKAT and $\sim 86\, \mu$Jy beam−1 at e-MERLIN, possibly associated with FRB 20190714A at z = 0.2365. This represents the first detection of persistent continuum radio emission potentially associated with a (as-yet) non-repeating FRB. If the association is confirmed, one of the strongest remaining distinction between repeaters and non-repeaters would no longer be applicable. A parallel search for repeat bursts from these FRBs revealed no new detections down to a fluence of 0.08 Jy ms for a 1 ms duration burst.
The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the ...‘first stars’, which may have formed before galaxy formation began. Direct measurements are difficult and not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light. An alternative approach is to study the absorption features imprinted on the γ-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons. Here we report the discovery of γ-ray emission from the blazars H 2356 - 309 and 1ES 1101 - 232, at redshifts z = 0.165 and z = 0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies. The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources—in particular from the first stars formed. This result also indicates that intergalactic space is more transparent to γ-rays than previously thought.
Abstract
We report on the observations of four well-localized binary black hole (BBH) mergers by the High Energy Stereoscopic System (H.E.S.S.) during the second and third observing runs of Advanced ...LIGO and Advanced Virgo, O2 and O3. H.E.S.S. can observe 20 deg
2
of the sky at a time and follows up gravitational-wave (GW) events by “tiling” localization regions to maximize the covered localization probability. During O2 and O3, H.E.S.S. observed large portions of the localization regions, between 35% and 75%, for four BBH mergers (GW170814, GW190512_180714, GW190728_064510, and S200224ca). For these four GW events, we find no significant signal from a pointlike source in any of the observations, and we set upper limits on the very high energy (>100 GeV)
γ
-ray emission. The 1–10 TeV isotropic luminosity of these GW events is below 10
45
erg s
−1
at the times of the H.E.S.S. observations, around the level of the low-luminosity GRB 190829A. Assuming no changes are made to how follow-up observations are conducted, H.E.S.S. can expect to observe over 60 GW events per year in the fourth GW observing run, O4, of which eight would be observable with minimal latency.
We report on a survey of the inner part of the Galactic plane in very high energy gamma rays with the H.E.S.S. Cerenkov telescope system. The Galactic plane between +/-30° in longitude and +/-3° in ...latitude relative to the Galactic center was observed in 500 pointings for a total of 230 hr, reaching an average flux sensitivity of 2% of the Crab Nebula at energies above 200 GeV. Fourteen previously unknown sources were detected at a significance level greater than 4 σ after accounting for all trials involved in the search. Initial results on the eight most significant of these sources were already reported elsewhere (Aharonian and coworkers). Here we present detailed spectral and morphological information for all the new sources, along with a discussion on possible counterparts in other wavelength bands. The distribution in Galactic latitude of the detected sources appears to be consistent with a scale height in the Galactic disk for the parent population smaller than 100 pc, consistent with expectations for supernova remnants and/or pulsar wind nebulae.
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