| 1. |
- Algaba Brazalez, Astrid, 1983, et al.
(författare)
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Investigation of a Microstrip-to-Ridge Gap Waveguide transition by electromagnetic coupling
- 2012
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Ingår i: IEEE Antennas and Propagation Society, AP-S International Symposium (Digest). - 1522-3965. - 9781467304627 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- A transition from Microstrip to Ridge Gap Waveguide (RGW) has been studied and numerically analyzed in terms of S parameters. The RGW technology shows potential to be used up to THz frequencies. Therefore, good transitions are needed in order to make possible the measurements of RGW components at frequencies above 100 GHz.
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| 2. |
- Abe, H., et al.
(författare)
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Gamma-ray observations of MAXI J1820+070 during the 2018 outburst
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 517:4, s. 4736-4751
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Tidskriftsartikel (refereegranskat)abstract
- MAXIJ1820+070 is a low-mass X-ray binary with a black hole (BH) as a compact object. This binary underwent an exceptionally bright X-ray outburst from 2018 March to October, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 h of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy (HE) gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to similar to 500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential HE and very-HE gamma-ray emitting region should be located at a distance from the BH ranging between 10(11) and 10(13) cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA.
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| 3. |
- Adams, Camiel, 1992, et al.
(författare)
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AN ADAPTIVE ISOGEOMETRIC CONTINUUM SHELL ELEMENT FOR EFFICIENT MODELLING OF DELAMINATION GROWTH
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To accurately predict damage growth in large, thin-walled composite structures, it is required to have models that are both valid and computational efficient. In this respect, isogeometric continuum shell elements provide an interesting option. First of all, the higher order continuity achieved via isogeometric analysis yields an increased in-plane smoothness that enable the use of larger shell elements. In addition, the high in-plane continuity also leads to that in-plane derivatives of in-plane stresses are continuous across element edges, thereby allowing for element-local recovery procedures for the prediction of out-of-plane stresses [2, 3]. Furthermore, as shown by Hosseini et al. [1], it is in an isogeometric continuum shell modelling framework rather straightforward to modify the through-thickness kinematics to incorporate weak and strong discontinuities. By introducing weak discontinuities at ply interfaces, the through-thickness strain discontinuities at these locations are explicitly accounted for. This enables a much better 3D strain and stress prediction, something which is key for a good estimation of the amount of intralaminar damage. By introducing strong discontinuities, the element is also capable to represent initiation and growth of one or several delamination cracks. In the current contribution, we extend the shell formulation from [1] into an adaptive continuum shell that allows for an update of the through-thickness kinematics at any required time instant during the simulation. The adaptivity is facilitated by that the through-thickness kinematical enrichment can be achieved by so-called ”knot insertion”, a step which can be fully automated due to the hierarchical nature of the isogeometric approximation functions. As a result, the current shell provides a good basis for an accurate but also computationally efficient prediction of the progressive failure in laminates, without a-priory knowledge of where damage will occur. Results show that the adaptive modelling framework works well, both to predict the full 3D stress states in multiaxial laminates, but also to capture growth of delaminations. Furthermore, in comparison to a fully resolved model, the adaptive approach gives significant time savings even for simple analyses where significant parts of the domain exhibit delamination growth. This implies that computational efforts (time and memory) can be considerably reduced when using this adaptive concept in large-scale analyses where damage develop only in a confined, but initially unknown area of the structure. [1] S. Hosseini, J.J.C. Remmers, C.V. Verhoosel, and R. de Borst (2015) Int. J. Numer. Meth. Eng., 102, 159–179. [2] M. Fagerström and J.J.C Remmers (2017) Adaptive modelling of delmination growth using isogeometric continuum shell elements. Proc. ICCM21, Xian, China. [3] J.-E. Dufour, P. Antolin, G. Sangalli, F. Auricchio, A. Reali (2018) Composites Part B: Engineering, 138, 12-18.
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| 4. |
- Abdalla, H., et al.
(författare)
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HESS and MAGIC observations of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 in May 2016
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 648
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Tidskriftsartikel (refereegranskat)abstract
- The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behaviour and it is one of only a few FSRQs detected in very-high-energy (VHE, E>100 GeV) gamma rays. The VHE gamma -ray observations with H.E.S.S. and MAGIC in late May and early June 2016 resulted in the detection of an unprecedented flare, which revealed, for the first time, VHE gamma -ray intranight variability for this source. While a common variability timescale of 1.5 h has been found, there is a significant deviation near the end of the flare, with a timescale of similar to 20 min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, a curvature was detected in the VHE gamma -ray spectrum of PKS 1510-089, which can be fully explained by the absorption on the part of the extragalactic background light. Optical R-band observations with ATOM revealed a counterpart of the gamma -ray flare, even though the detailed flux evolution differs from the VHE gamma -ray light curve. Interestingly, a steep flux decrease was observed at the same time as the cessation of the VHE gamma -ray flare. In the high-energy (HE, E> 100 MeV) gamma -ray band, only a moderate flux increase was observed with Fermi-LAT, while the HE gamma -ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the gamma -ray spectrum indicates that the emission region is located outside of the BLR. Radio very-long-baseline interferometry observations reveal a fast-moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located similar to 50 pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this is indeed a true correlation, the VHE gamma rays must have been produced far down in the jet, where turbulent plasma crosses a standing shock.
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| 5. |
- Acciari, V. A., et al.
(författare)
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Gamma-Ray Observations of the Be/Pulsar Binary 1A 0535+262 During a Giant X-Ray Outburst
- 2011
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 733:2
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Tidskriftsartikel (refereegranskat)abstract
- Giant X-ray outbursts, with luminosities of about 1037 erg s–1, are observed roughly every five years from the nearby Be/pulsar binary 1A 0535+262. In this article, we present observations of the source with VERITAS at very high energies (VHEs;E >100 GeV) triggered by the X-ray outburst in 2009 December. The observations started shortly after the onset of the outburst and provided comprehensive coverage of the episode, as well as the 111 day binary orbit. No VHE emission is evident at any time. We also examined data from the contemporaneous observations of 1A 0535+262 with the Fermi/Large Area Telescope at high-energy photons (E > 0.1 GeV) and failed to detect the source at GeV energies. The X-ray continua measured with theSwift/X-Ray Telescope and the RXTE/PCA can be well described by the combination of blackbody and Comptonized emission from thermal electrons. Therefore, the gamma-ray and X-ray observations suggest the absence of a significant population of non-thermal particles in the system. This distinguishes 1A 0535+262 from those Be X-ray binaries (such as PSR B1259-63 and LS I +61°303) that have been detected at GeV-TeV energies. We discuss the implications of the results on theoretical models.
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| 6. |
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Fakta om maten och miljön : Konsumtionstrender,miljöpåverkan och livscykelanalyser
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vi äter mer och vi väljer andra livsmedel än tidigare. År 2000 konsumerade varje svensk ungefär 800 kg mat och dryck. Det är nästan 40 kg mer än för 10 år sedan. En allt mindre del av livsmedelskonsumtionen består av basmat tillagad i hemmet, dvs. kött, potatis, mjölk och bröd samtidigt som ”utrymmesmaten”,exempelvis läsk, godis, snacks mm. får allt större plats på bordet. En grov skattning visar att närmare 40 % av den mat vi äter kan vara importerad. Vad de nya valen och den ökade konsumtionen innebär för miljö och hälsa har vi begränsade kunskaper om.Naturvårdsverket har under lång tid intresserat sig för miljöpåverkan i livsmedelskedjan och har låtit genomföra flera studier för att skaffa sig kunskap i ämnet. Här redovisas det statistiska underlag som finns idag för att skildra miljöpåverkan från livsmedelssektorn och konsumtionsutvecklingen. Fokus har legat på energianvändning och koldioxidutsläpp och på handel ochindustri baserat på offentlig statistik. Utifrån detta underlag beskrivs den svenska livsmedelskedjans miljöbelastning för år 2000 och konsumtionens förändring över tid skildras. Dessutom sammanfattas kunskapsläget för miljöpåverkan från enskilda livsmedel genom hela kedjan.Rapporten visar att man kan göra intressanta sammanställningar över den svenska delen av livsmedelskedjan genom att kombinera befintliga data och komplettera vissa dataluckor. Rapporten ger inte bara svar utan väcker ävenfrågor som: – Vad betyder den förändrade livsmedelskonsumtion och den ökade importen för miljön? Hur kan man leva både miljöanpassat och hälsosamt?Rapporten vänder sig till främst till myndigheter, livsmedelsföretag och dagligvaruhandel samt andra som har intresse av att skaffa sig en överblick överlivsmedelskedjans miljöpåverkan. Rapporten kan utgöra underlag för beslut om initiativ för utredningar och om var åtgärder bör sättas in.
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| 7. |
- Fakoukakis, F. E., et al.
(författare)
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Ultra-Wideband butler matrix Fed MIMO antennas
- 2015
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Konferensbidrag (refereegranskat)abstract
- This work elaborates on the design of an Ultra-Wideband (UWB) Butler matrix fed antenna array, implementing a Multiple Input-Multiple Output (MIMO) configuration. The system aims at applications in future Long Term Evolution (LTE) and multifunctional Radar systems. Specifically, based on the results of our previous works, the research is extended towards the implementation of a MIMO beamforming scheme. Different beamforming scenarios are applied, in order to maximize system performance and minimize noise and interference. A comprehensive analysis and design procedure is presented, along with system simulation results.
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| 8. |
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Fakta för förvaltare: gäss och svanar : kunskapssammanställning om bete, övergödning, smittspridning och skyddsjakt
- 2018
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- GÄSSEN I SVERIGE blir allt fler. De flesta gåsarter ökar i antal och med växande populationer ökar också konflikterna mellan samhällsintressen och människor som berörs av gässen. Ändrade flyttningsmönster är ett annat exempel på hur förutsättningarna för förvaltningen av gäss och svanar påverkas. I den strategi för svensk viltförvaltning som Naturvårdsverket har tagit fram betonas en förvaltning byggd på kvalitetssäkrad kunskap och förvaltningen av gäss är ett bra exempel på vikten av aktuell kunskap när omständigheterna förändras. Viltstrategin beskriver de vägval som Naturvårdsverket avser att genomföra för att utveckla och stärka Sveriges viltförvaltning fram till år 2020. Bland annat ska arbetet med att förebygga skador och andra problem som vilt orsakar utvecklas, tillsammans med övriga berörda organisationer. Strategin betonar också att svensk viltförvaltning ska bygga på den bästa tillgängliga kunskapen och att Naturvårdsverket har ett stort ansvar för att se till att aktuell kunskap kommer till användning. Forskarna Johan Elmberg och Johan Månsson har på uppdrag av Naturvårdsverkets vetenskapliga kommitté för viltforskning gjort en litteraturöversikt om befintlig kunskap om gäss och om framtida kunskapsbehov. Kunskapssammanställningen ligger också till grund för ett större gåsforskningsprojekt under ledning av Johan Elmberg och Johan Månsson, med start 2017. I Naturvårdsverkets arbete med att ta fram vetenskapligt underlag till stöd för viltförvaltningen är gåsprojektet en viktig pusselbit som är tänkt att under de kommande åren kunna ge ytterligare kunskap till en gåsförvaltning i förändring. Författarna svarar ensamma för rapportens innehåll, slutsatser och rekommendationer
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| 9. |
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Fakta om nordiskt samarbete
- 1993
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Ingår i: Kulturmiljövård. - Stockholm : Riksantikvarieämbetet. - 1100-4800. ; :5, s. 54-55
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
- Fimbo, AM, et al.
(författare)
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Prevalence and Correlates of Lymphatic Filariasis Infection and Its Morbidity Following Mass Ivermectin and Albendazole Administration in Mkinga District, North-Eastern Tanzania
- 2020
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Ingår i: Journal of clinical medicine. - : MDPI AG. - 2077-0383. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Lymphatic filariasis (LF) is a neglected tropical disease targeted for elimination as public health problem through morbidity management and preventive annual mass drug administration (MDA). This cross-sectional community-based surveillance assessed the prevalence and correlates of LF infection in Mkinga district, Tanga-region, Tanzania. A total of 4115 individuals (49.7% males, 35.2% children) were screened for circulating filarial antigens (CFA), microfilaremia (mf) and disease manifestations in 15 villages between November 2018 and January 2019. MDA uptake in the previous year was assessed. Overall prevalence of CFA-positivity was 5.8% (239/4115; 95% CI: 5.1–6.6), with significant heterogeneity between villages (range 1.2% to 13.5%). CFA-positivity was higher in males (8.8%) than females (3.3%), and correlated with increasing age (p < 0.001). Prevalence of mf among CFA-positives was 5.2%. Only 60% of eligible inhabitants in the study area took MDA in the previous year, and CFA-positivity was 2-fold higher in those who missed MDA (p < 0.0001). Prevalence of scrotal enlargement, hydrocele, arms or legs swelling, lymphoedema and lymphadenopathy was 6.4%, 3.7%, 1.35%, 1.2% and 0.32%, respectively. Compared to baseline data, 16 years of MDA intervention significantly reduced LF transmission and morbidity, although the intended elimination target of <1% mf and <2% antigenemia to level where recrudescence is unlikely to occur by the year 2020 may not be attained. The finding of hotspots with ongoing transmission calls for intensified control measures.
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