| 1. |
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| 2. |
- Bombarda, F., et al.
(författare)
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Runaway electron beam control
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 61:1
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Tidskriftsartikel (refereegranskat)
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| 3. |
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- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
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Tidskriftsartikel (refereegranskat)
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| 4. |
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| 5. |
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| 6. |
- Veres, P., et al.
(författare)
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Observation of inverse Compton emission from a long gamma-ray burst
- 2019
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Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 575:7783, s. 459-
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Tidskriftsartikel (refereegranskat)abstract
- Long-duration gamma-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectron volt-to-mega electronvoltband, which is probably produced within the jet and lasts from milliseconds to minutes, known as the prompt emission(1,2). Subsequently, the interaction of the jet with the surrounding medium generates shock waves that are responsible for the afterglow emission, which lasts from days to months and occurs over a broad energy range from the radio to the gigaelectronvolt bands(1-6). The afterglow emission is generally well explained as synchrotron radiation emitted by electrons accelerated by the external shock(7-9). Recently, intense long-lasting emission between 0.2 and 1 teraelectronvolts was observed from GRB 190114C(10,11). Here we report multifrequency observations of GRB 190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from 5 x 10(-6) to 10(12) electronvolts. We find that the broadband spectral energy distribution is double-peaked, with the teraelectronvolt emission constituting a distinct spectral component with power comparable to the synchrotron component. This component is associated with the afterglow and is satisfactorily explained by inverse Compton up-scattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed teraelectronvolt component are typical for GRBs, supporting the possibility that inverse Compton emission is commonly produced in GRBs.
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| 7. |
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| 8. |
- Abdo, A. A., et al.
(författare)
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Gamma-ray flaring activity from the gravitationally lensed blazar PKS 1830-211 observed by Fermi LAT
- 2015
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 799:2
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Tidskriftsartikel (refereegranskat)abstract
- The Large Area Telescope ( LAT) on board the FermiGamma- ray Space Telescope routinely detects the MeV- peaked flat- spectrum radio quasar PKS 1830- 211 ( z = 2.507). Its apparent isotropic. - ray luminosity ( E > 100 MeV), averaged over 3 years of observations and peaking on 2010 October 14/ 15 at 2.9 x 1050 erg s- 1, makes it among the brightest high- redshift Fermi blazars. No published model with a single lens can account for all of the observed characteristics of this complex system. Based on radio observations, one expects time- delayed variability to follow about 25 days after a primary flare, with flux about a factor of 1.5 less. Two large. - ray flares of PKS 1830- 211 have been detected by the LAT in the considered period, and no substantial evidence for such a delayed activity was found. This allows us to place a lower limit of about 6 on the. - ray flux ratio between the two lensed images. Swift XRT observations from a dedicated Target of Opportunity program indicate a hard spectrum with no significant correlation of X- ray flux with the. - ray variability. The spectral energy distribution can be modeled with inverse Compton scattering of thermal photons from the dusty torus. The implications of the LAT data in terms of variability, the lack of evident delayed flare events, and different radio and. - ray flux ratios are discussed. Microlensing effects, absorption, size and location of the emitting regions, the complex mass distribution of the system, an energy- dependent inner structure of the source, and flux suppression by the lens galaxy for one image path may be considered as hypotheses for understanding our results.
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| 9. |
- Franz, D, et al.
(författare)
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Towards long-term standardised carbon and greenhouse gas observations for monitoring Europe´s terrestrial ecosystems: a review
- 2018
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Ingår i: International Agrophysics. - : Walter de Gruyter GmbH. - 0236-8722 .- 2300-8725. ; 32, s. 439-455
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Tidskriftsartikel (refereegranskat)abstract
- Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO2, CH4, N2O, H2O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Koike, M., et al.
(författare)
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Year-Round In Situ Measurements of Arctic Low-Level Clouds : Microphysical Properties and Their Relationships With Aerosols
- 2019
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Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 124:3, s. 1798-1822
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Tidskriftsartikel (refereegranskat)abstract
- Two years of continuous in situ measurements of Arctic low-level clouds have been made at the Mount Zeppelin Observatory (78 degrees 56N, 11 degrees 53E), in Ny-angstrom lesund, Spitsbergen. The monthly median value of the cloud particle number concentration (N-c) showed a clear seasonal variation: Its maximum appeared in May-July (658cm(-3)), and it remained low between October and March (87cm(-3)). At temperatures warmer than 0 degrees C, a clear correlation was found between the hourly N-c values and the number concentrations of aerosols with dry diameters larger than 70nm (N-70), which are proxies for cloud condensation nuclei (CCN). When clouds were detected at temperatures colder than 0 degrees C, some of the data followed the summertime N-c to N-70 relationship, while other data showed systematically lower N-c values. The lidar-derived depolarization ratios suggested that the former (CCN-controlled) and latter (CCN-uncontrolled) data generally corresponded to clouds consisting of supercooled water droplets and those containing ice particles, respectively. The CCN-controlled data persistently appeared throughout the year at Zeppelin. The aerosol-cloud interaction index (ACI=dlnN(c)/(3dlnN(70))) for the CCN-controlled data showed high sensitivities to aerosols both in the summer (clean air) and winter-spring (Arctic haze) seasons (0.220.03 and 0.250.02, respectively). The air parcel model calculations generally reproduced these values. The threshold diameters of aerosol activation (D-act), which account for the N-c of the CCN-controlled data, were as low as 30-50nm when N-70 was less than 30cm(-3), suggesting that new particle formation can affect Arctic cloud microphysics.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Dall'Osto, Manuel, et al.
(författare)
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Simultaneous measurements of aerosol size distributions at three sites in the European high Arctic
- 2019
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 19:11, s. 7377-7395
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Tidskriftsartikel (refereegranskat)abstract
- Aerosols are an integral part of the Arctic climate system due to their direct interaction with radiation and indirect interaction through cloud formation. Understanding aerosol size distributions and their dynamics is crucial for the ability to predict these climate relevant effects. When of favourable size and composition, both long-rangetransported - and locally formed particles - may serve as cloud condensation nuclei (CCN). Small changes of composition or size may have a large impact on the low CCN concentrations currently characteristic of the Arctic environment. We present a cluster analysis of particle size distributions (PSDs; size range 8-500 nm) simultaneously collected from three high Arctic sites during a 3-year period (20132015). Two sites are located in the Svalbard archipelago: Zeppelin research station (ZEP; 474 m above ground) and the nearby Gruvebadet Observatory (GRU; about 2 km distance from Zeppelin, 67 m above ground). The third site (Villum Research Station at Station Nord, VRS; 30 m above ground) is 600 km west-northwest of Zeppelin, at the tip of northeastern Greenland. The GRU site is included in an inter-site comparison for the first time. K-means cluster analysis pro- vided eight specific aerosol categories, further combined into broad PSD classes with similar characteristics, namely pristine low concentrations (12 %-14 % occurrence), new particle formation (16 %-32 %), Aitken (21 %-35 %) and accumulation (20 %-50 %). Confined for longer time periods by consolidated pack sea ice regions, the Greenland site GRU shows PSDs with lower ultrafine-mode aerosol concentrations during summer but higher accumulation-mode aerosol concentrations during winter, relative to the Svalbard sites. By association with chemical composition and cloud condensation nuclei properties, further conclusions can be derived. Three distinct types of accumulation-mode aerosol are observed during winter months. These are associated with sea spray (largest detectable sizes, > 400 nm), Arctic haze (main mode at 150 nm) and aged accumulation-mode (main mode at 220 nm) aerosols. In contrast, locally produced particles, most likely of marine biogenic origin, exhibit size distributions dominated by the nucleation and Aitken mode during summer months. The obtained data and analysis point towards future studies, including apportioning the relative contribution of primary and secondary aerosol formation processes and elucidating anthropogenic aerosol dynamics and transport and removal processes across the Greenland Sea. In order to address important research questions in the Arctic on scales beyond a singular station or measurement events, it is imperative to continue strengthening international scientific cooperation.
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| 19. |
- Devito, Fiorella, et al.
(författare)
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Evaluation of endothelial function and cardiovascular risk in non-obese patients with slight degree of obstructive sleep apnea syndrome
- 2017
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Ingår i: Monaldi Archives for Chest Disease. - : Fondazione Salvatore Maugeri. - 1122-0643 .- 2532-5264. ; 87:3, s. 112-118
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Tidskriftsartikel (refereegranskat)abstract
- Recently, it has been clearly described an independent relationship between obstructive sleep apnea syndrome (OSAS) and cardiovascular risk, with underlying mechanisms also including endothelial dysfunction. We enrolled 32 consecutive non-obese patients (mean age of 39.5 +/- 11.5 years), of which 16 with mild OSAS and 16 snoring without OSAS. Mild OSAS is defined by an AHI index between 5 and 15. We have investigated if whether there was a relationship between mild OSAS, endothelial function and carotid intima-media thickness (C-IMT). The population was divided into two groups: Group 1 (16 simple snorer patients with an average age of 39.4 +/- 12.1 years) and Group 2 (16 subjects with mild OSAS with an average age of 39.6 +/- 11.2 years). Each group underwent cardiovascular investigation including measurement of flow-mediated dilation (FMD) of the brachial artery and C-IMT. Both groups comprised non-obese subjects. Patients with mild OSAS had serum total cholesterol values statistically significantly higher than simple snores patients (178.6 +/- 24.9 vs 159.2 +/- 25.3; p=0.038). OSAS patients had also a trend towards higher values of maximum C-IMT compared to simple snorer patients (0.70 +/- 0.15 vs 0.65 +/- 0.16), although below the level of significance. Between the two groups, no difference was found for FMD values. The present results on mild OSAS strengthen the importance of a diagnosis of OSAS as soon as possible, in order to encourage all primary prevention interventions to correct risk factors responsible for disease progression and the occurrence of cardiovascular diseases, not excluding the use of therapies of non-invasive ventilation even in the early stages of the disease.
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| 20. |
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| 21. |
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| 22. |
- Vitale, Cristiana, et al.
(författare)
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Heart Failure Association/European Society of Cardiology position paper on frailty in patients with heart failure
- 2019
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Ingår i: European Journal of Heart Failure. - : WILEY. - 1388-9842 .- 1879-0844. ; 21:11, s. 1299-1305
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Tidskriftsartikel (refereegranskat)abstract
- Heart failure (HF) and frailty are two distinct yet commonly associated conditions. The interplay between the two conditions is complex, due to overlaps in underlying mechanisms, symptoms and prognosis. The assessment of frailty in patients with HF is crucial, as it is associated with both unfavourable outcomes and reduced access and tolerance to treatments. However, to date a consensus definition of frailty in patients with HF remains lacking and the need for a validated assessment score, for identifying those HF patients with frailty, is high and timely. This position paper proposes a new definition of frailty for use by healthcare professionals in the setting of HF and creates a foundation for the design of a tailored and validated score for this common condition.
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