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| 2. |
- Aartsen, M. G., et al.
(författare)
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Multiwavelength follow-up of a rare IceCube neutrino multiplet
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 607
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Tidskriftsartikel (refereegranskat)abstract
- On February 17, 2016, the IceCube real-time neutrino search identified, for the first time, three muon neutrino candidates arriving within 100 s of one another, consistent with coming from the same point in the sky. Such a triplet is expected once every 13.7 years as a random coincidence of background events. However, considering the lifetime of the follow-up program the probability of detecting at least one triplet from atmospheric background is 32%. Follow-up observatories were notified in order to search for an electromagnetic counterpart. Observations were obtained by Swift's X-ray telescope, by ASAS-SN, LCO and MASTER at optical wavelengths, and by VERITAS in the very-high-energy gamma-ray regime. Moreover, the Swift BAT serendipitously observed the location 100 s after the first neutrino was detected, and data from the Fermi LAT and HAWC observatory were analyzed. We present details of the neutrino triplet and the follow-up observations. No likely electromagnetic counterpart was detected, and we discuss the implications of these constraints on candidate neutrino sources such as gamma-ray bursts, core-collapse supernovae and active galactic nucleus flares. This study illustrates the potential of and challenges for future follow-up campaigns.
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| 3. |
- Abeysekara, A. U., et al.
(författare)
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VERITAS and Fermi-LAT Observations of TeV Gamma-Ray Sources Discovered by HAWC in the 2HWC Catalog
- 2018
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing. - 0004-637X .- 1538-4357. ; 866:1
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Tidskriftsartikel (refereegranskat)abstract
- The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 sources are not associated with previously known teraelectronvolt (TeV) gamma-ray sources. We have studied 14 of these sources without known counterparts with VERITAS and Fermi-LAT. VERITAS detected weak gamma-ray emission in the 1 TeV-30 TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected 14 new HAWC sources from our analysis of Fermi-LAT data for energies higher than 10 GeV. During the search, we detected gigaelectronvolt (GeV) gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC, and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region.
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| 4. |
- Abdalla, H., et al.
(författare)
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TeV Emission of Galactic Plane Sources with HAWC and HESS
- 2021
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 917:1
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Tidskriftsartikel (refereegranskat)abstract
- The High Altitude Water Cherenkov (HAWC) observatory and the High Energy Stereoscopic System (H.E.S.S.) are two leading instruments in the ground-based very-high-energy gamma-ray domain. HAWC employs the water Cherenkov detection (WCD) technique, while H.E.S.S. is an array of Imaging Atmospheric Cherenkov Telescopes (IACTs). The two facilities therefore differ in multiple aspects, including their observation strategy, the size of their field of view, and their angular resolution, leading to different analysis approaches. Until now, it has been unclear if the results of observations by both types of instruments are consistent: several of the recently discovered HAWC sources have been followed up by IACTs, resulting in a confirmed detection only in a minority of cases. With this paper, we go further and try to resolve the tensions between previous results by performing a new analysis of the H.E.S.S. Galactic plane survey data, applying an analysis technique comparable between H.E.S.S. and HAWC. Events above 1 TeV are selected for both data sets, the point-spread function of H.E.S.S. is broadened to approach that of HAWC, and a similar background estimation method is used. This is the first detailed comparison of the Galactic plane observed by both instruments. H.E.S.S. can confirm the gamma-ray emission of four HAWC sources among seven previously undetected by IACTs, while the three others have measured fluxes below the sensitivity of the H.E.S.S. data set. Remaining differences in the overall gamma-ray flux can be explained by the systematic uncertainties. Therefore, we confirm a consistent view of the gamma-ray sky between WCD and IACT techniques.
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| 6. |
- Grassi, A., et al.
(författare)
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Association between incision technique for hamstring tendon harvest in anterior cruciate ligament reconstruction and the risk of injury to the infra-patellar branch of the saphenous nerve: a meta-analysis
- 2018
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Ingår i: Knee Surgery Sports Traumatology Arthroscopy. - : Springer Science and Business Media LLC. - 0942-2056 .- 1433-7347. ; 26:8, s. 2410-2423
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Tidskriftsartikel (refereegranskat)abstract
- To determine how the incision technique for hamstring tendon (HT) harvest in anterior cruciate ligament (ACL) reconstruction affects the risk of injury to the IPBSN and clinical outcome. A systematic literature search of the MEDLINE/Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL) and EBSCOhost electronic databases and clinicaltrials.gov for unpublished studies was performed to identify comparative studies investigating injury to the IPBSN after HT ACL reconstruction by comparing at least two different incision techniques. Data were extracted for the number of patients with evidence of any neurologic deficit corresponding to injury to the IPBSN, area of sensory deficit, the Lysholm score and patient satisfaction. The mean difference (MD) in study outcome between incision groups was assessed. The relative risk (RR) and the number needed to treat (NNT) were calculated. The Chi-square and Higgins' I (2) tests were applied to test heterogeneity. Data were pooled using a Mantel-Haenszel random-effects model if the statistical heterogeneity was > 50% and a fixed-effects model if the statistical heterogeneity was < 50%. The risk of bias was evaluated according to the Cochrane Database questionnaire and the quality of evidence was graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines. A total of eight studies (three randomized controlled trials (RCTs) and five comparative studies) were included, of which six compared vertical and oblique incisions, one horizontal and vertical incisions, and one compared all three techniques. HT harvest was performed through a vertical incision in 329 patients, through an oblique incision in 195 patients and through a horizontal incision in 151 patients. Considering the meta-analysis of the RCTs, the performance of a vertical incision significantly increased the risk of causing IPBSN deficiency compared with both oblique and horizontal incision [RR 1.65 (CI 1.10-2.49, p = 0.02) and RR 2.45 (CI 1.73-3.47, p < 0.0001), respectively]. A significantly larger area of sensory deficit was found with vertical incisions compared with oblique ones, with an MD of 22.91 cm(2) (95% CI 7.73-38.08; p = 0.04). No significant differences were found between the incision techniques in relation to patient-reported outcomes. The same trend was obtained after the performing a meta-analysis of all eight included studies. The quality of evidence in this meta-analysis was determined as "low" to "moderate", mostly due to inadequate methods of randomization and high heterogeneity among the included studies. The performance of a vertical incision to harvest HTs for ACL reconstruction significantly increased the risk of iatrogenic injury to the IPBSN compared with both oblique and horizontal incisions.
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| 7. |
- Illuminati, S., et al.
(författare)
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In-situ trace metal (Cd, Pb, Cu) speciation along the Po River plume (Northern Adriatic Sea) using submersible systems
- 2019
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 212, s. 47-63
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Tidskriftsartikel (refereegranskat)abstract
- Information on the distribution and speciation of trace metals is of critical importance for our ability to interpret the links between the bioavailability and uptake of an element, and its biogeochemical cycle in coastal environments. Within the framework of the European Project "In-situ automated Monitoring of Trace metal speciation in Estuaries and Coastal zones in relation with the biogeochemical processes (IMTEC)", the chemical speciation of Cd, Pb and Cu was carried out along the Po River plume in the period 27 October - 2 November 2002. During the cruise, five Voltammetric In-situ Profiling systems and one Multi Physical Chemical Profiler, as well as conventional voltammetric instruments, were successfully applied in order to evaluate the distribution of Cd, Pb and Cu between different fractions (free ion, dynamic, colloidal, dissolved and particulate fractions) and to assess the evolution of these fractions during estuarine mixing and in the water column. Dynamic concentrations were 0.05-0.2 nmol L-1 Cd, 0.02-0.2 nmol L-1 Pb, and 0.15-4.0 nmol L-1 Cu. Cd was mainly present as dynamic fraction (40-100% of the dissolved Cd). High proportions of Pb (similar to 70%) and Cu (similar to 80%) were present as colloids probably of biogenic origin. Principal components analysis reveals a strong influence of the Po River discharge on the spatial and vertical distributions of metal species. Almost all the metal fractions globally decreased following the salinity gradient. Metal concentrations are far below (at least one order of magnitude lower) the Environmental Quality Standard established by the Italian law. However, the Cu dynamic fraction showed concentrations likely to be toxic to sensitive phytoplankton community and to have negative effects on larva development of coastal macroinvertebrate species (toxicity data extracted from literature).
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| 8. |
- Romagnoli, F, et al.
(författare)
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Windstorm impacts on European forest-related systems: an interdisciplinary perspective
- 2023
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Ingår i: Forest Ecology and Management. - 1872-7042 .- 0378-1127. ; 541
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Tidskriftsartikel (refereegranskat)abstract
- Windstorms are considered the main disturbing abiotic agent in European forests. They affect a multiplicity of forest-related dimensions, such as forest ecology, forest operations, geomorphology, economy, and socio-cultural aspects. Due to the complex dynamics set off by windstorms, the design of post-windstorm forest management should be characterized by an interdisciplinary approach able to address multiple environmental and social needs. However, scientific literature investigating the impacts of windstorms on forests appears mainly focused on specific aspects. An interdisciplinary and more comprehensive approach is needed to cope with such multi-facet phenomena and to address future forest research.We reviewed current literature analyzing consequences of windstorms on European forests focusing on interconnections and cascade effects among forest-related dimensions in post-windstorm dynamics. We performed an in-depth review of 111 articles to detect most recurrent direct and indirect impacts as well as cascade effects among ecological, geomorphological, operational, economic, socio-cultural, and institutional forest-related dimensions. Our analysis aimed at providing a detailed analysis of the state of the art of windstorm impacts on European forests reported in literature, and suggesting an innovative approach to analyze windstorm consequences at a systemic level to acquire a comprehensive overview of post-windstorm dynamics.Our results showed that most of the studies dealt with interactions among ecological components of forests, but links between ecology, geomorphology, and society have been poorly studied. These knowledge gaps reduce the comprehension of windstorm impacts in the short and long terms and overlook the influence of societal-related aspects in post-windstorm forest management. Moreover, our analysis suggested the need of a post-windstorm management acting at systemic and comprehensive level, supported by forest policies that promotes multifunctionality to overcome challenges derived by natural disturbances intensification.
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| 9. |
- Romagnoli, Priscila, et al.
(författare)
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Making graphene visible in transparent dielectric substrates : Brewster angle imaging
- 2015
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Ingår i: Current Opinion in Chemical Engineering. - : Institute of Physics (IOP). - 2211-3398. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- The visibility of graphene is greatly increased by illuminating samples deposited on transparent dielectrics at the substrates’ Brewster angle. Using a commercial ellipsometer, the reflectivity of monolayers of CVD graphene is found to be up to 33 times higher than that of the substrate, i.e., an optical contrast as high as 3200% is obtained, more than 380 times higher than with standard optical microscopy. Also, with a simpler, homemade, experimental setup, a 1400% optical contrast was measured for a monolayer of CVD graphene and linear features as small as ~20 μm were visible in a monolayer, while ~6×17 μm2 trilayers could still be imaged in exfoliated samples. It is also shown that the reflectance/transmittance ratio increases quadratically with the number of graphene layers, which may allow for counting layer numbers and identifying wrinkles and folds in transferred samples.
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