| 1. |
- Abadie, J., et al.
(författare)
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Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts
- 2012
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 539
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Tidskriftsartikel (refereegranskat)abstract
- Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with similar to 50% or better probability with a few pointings of wide-field telescopes.
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| 2. |
- Meyer, E., et al.
(författare)
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The state of the art in beyond 5G distributed massive multiple-input multiple-output communication system solutions
- 2022
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Ingår i: Open Research Europe. - : F1000 Research Ltd. - 2732-5121. ; 2
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Forskningsöversikt (refereegranskat)abstract
- Beyond fifth generation (5G) communication systems aim towards data rates in the tera bits per second range, with improved and flexible coverage options, introducing many new technological challenges in the fields of network architecture, signal pro- cessing, and radio frequency front-ends. One option is to move towards cell-free, or distributed massive Multiple-Input Multiple-Output (MIMO) network architectures and highly integrated front-end solutions. This paper presents an outlook on be- yond 5G distributed massive MIMO communication systems, the signal processing, characterisation and simulation challenges, and an overview of the state of the art in millimetre wave antennas and electronics.
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| 3. |
- Bouter, K. E. C., et al.
(författare)
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Differential metabolic effects of oral butyrate treatment in lean versus metabolic syndrome subjects article
- 2018
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Ingår i: Clinical and Translational Gastroenterology. - : Ovid Technologies (Wolters Kluwer Health). - 2155-384X. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Gut microbiota-derived short-chain fatty acids (SCFAs) have been associated with beneficial metabolic effects. However, the direct effect of oral butyrate on metabolic parameters in humans has never been studied. In this first in men pilot study, we thus treated both lean and metabolic syndrome male subjects with oral sodium butyrate and investigated the effect on metabolism. Methods: Healthy lean males (n = 9) and metabolic syndrome males (n = 10) were treated with oral 4 g of sodium butyrate daily for 4 weeks. Before and after treatment, insulin sensitivity was determined by a two-step hyperinsulinemic euglycemic clamp using [6,6-2H2]-glucose. Brown adipose tissue (BAT) uptake of glucose was visualized using 18F-FDG PET-CT. Fecal SCFA and bile acid concentrations as well as microbiota composition were determined before and after treatment. Results: Oral butyrate had no effect on plasma and fecal butyrate levels after treatment, but did alter other SCFAs in both plasma and feces. Moreover, only in healthy lean subjects a significant improvement was observed in both peripheral (median Rd: from 71 to 82 μmol/kg min, p < 0.05) and hepatic insulin sensitivity (EGP suppression from 75 to 82% p < 0.05). Although BAT activity was significantly higher at baseline in lean (SUVmax: 12.4 ± 1.8) compared with metabolic syndrome subjects (SUVmax: 0.3 ± 0.8, p < 0.01), no significant effect following butyrate treatment on BAT was observed in either group (SUVmax lean to 13.3 ± 2.4 versus metabolic syndrome subjects to 1.2 ± 4.1). Conclusions: Oral butyrate treatment beneficially affects glucose metabolism in lean but not metabolic syndrome subjects, presumably due to an altered SCFA handling in insulin-resistant subjects. Although preliminary, these first in men findings argue against oral butyrate supplementation as treatment for glucose regulation in human subjects with type 2 diabetes mellitus. © 2018 The Author(s).
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| 4. |
- Montalescot, Gilles, et al.
(författare)
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Prehospital Ticagrelor in ST-Segment Elevation Myocardial Infarction
- 2014
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Ingår i: New England Journal of Medicine. - : Massachusetts Medical Society. - 0028-4793 .- 1533-4406. ; 371:11, s. 1016-1027
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND The direct-acting platelet P2Y(12) receptor antagonist ticagrelor can reduce the incidence of major adverse cardiovascular events when administered at hospital admission to patients with ST-segment elevation myocardial infarction (STEMI). Whether prehospital administration of ticagrelor can improve coronary reperfusion and the clinical outcome is unknown. METHODS We conducted an international, multicenter, randomized, double-blind study involving 1862 patients with ongoing STEMI of less than 6 hours duration, comparing prehospital (in the ambulance) versus in-hospital (in the catheterization laboratory) treatment with ticagrelor. The coprimary end points were the proportion of patients who did not have a 70% or greater resolution of ST-segment elevation before percutaneous coronary intervention (PCI) and the proportion of patients who did not have Thrombolysis in Myocardial Infarction flow grade 3 in the infarct-related artery at initial angiography. Secondary end points included the rates of major adverse cardiovascular events and definite stent thrombosis at 30 days. RESULTS The median time from randomization to angiography was 48 minutes, and the median time difference between the two treatment strategies was 31 minutes. The two coprimary end points did not differ significantly between the prehospital and in-hospital groups. The absence of ST-segment elevation resolution of 70% or greater after PCI (a secondary end point) was reported for 42.5% and 47.5% of the patients, respectively. The rates of major adverse cardiovascular events did not differ significantly between the two study groups. The rates of definite stent thrombosis were lower in the prehospital group than in the in-hospital group (0% vs. 0.8% in the first 24 hours; 0.2% vs. 1.2% at 30 days). Rates of major bleeding events were low and virtually identical in the two groups, regardless of the bleeding definition used. CONCLUSIONS Prehospital administration of ticagrelor in patients with acute STEMI appeared to be safe but did not improve pre-PCI coronary reperfusion.
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| 5. |
- Amani, Navid, 1985, et al.
(författare)
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Array Configuration Effect on the Spatial Correlation of MU-MIMO Channels in NLoS Environments
- 2020
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Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020. ; 2020:March
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Konferensbidrag (refereegranskat)abstract
- In this paper, three different base-station antenna (BSA) configurations are compared in terms of inter-user spatial correlation in a two dimensional (2D) non-line-of-sight (NLoS) environment. The three configurations are: (i) a regular uniform linear array (ULA); (ii) a periodic sparse array; and (iii) an aperiodic sparse array. Electromagnetic modeling of the NLoS channel is proposed where scatterers are considered as resonant dipoles confined in clusters of scatterers (CoSs). While the probability of facing highly correlated user-equipments (UEs) in a multi-user multiple-input multiple-output (MU-MIMO) system is decreasing as the richness of mutipath increases, the sparsity (increased inter-element spacing) is seen to be capable of reducing this probability as well. This is due to the larger spatial variations experienced by the sparse array. Moreover, the results show that further improvement can be achieved by deploying an aperiodic distribution of antenna elements into the sparse antenna aperture.
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| 6. |
- Farsaei, A., et al.
(författare)
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On the Outage Performance of Line-Of-Sight Massive MIMO with a Fixed-Length Uniform Linear Sparse Array
- 2019
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Ingår i: Proceedings of the 2019 9th IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, APWC 2019. ; , s. 345-348
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Konferensbidrag (refereegranskat)abstract
- Increasing the inter-element spacing of a uniform linear sparse array results in reducing the mutual coupling and simplifying the heat dissipation control of the array. However, increasing the inter-element spacing may result in the appearance of grating lobes in the field-of-view (FoV). In this paper, 0.05-outage capacity is used as the performance metric to optimize the inter-element spacing for a given array size in line-of-sight scenarios. For the case of two users, we propose to increase the inter-element spacing as long as the 0.05-outage capacity does not reduce more than 1% compared to the capacity achieved when the two users have orthogonal channel vectors. Radiated power at the base station is adjusted to have the same effective isotropic radiated power for different arrays. Simulation results for an array size of 40λ show that for FoVs of 60° to 120°, the inter-element spacing can be increased from 0.5λ to more than 1.14λ.
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| 7. |
- Keskin, Furkan, 1988, et al.
(författare)
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Peak Sidelobe Level Based Waveform Optimization for OFDM Joint Radar-Communications
- 2021
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Ingår i: EuRAD 2020 - 2020 17th European Radar Conference. ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- We propose a novel joint radar communication waveform design method based on OFDM spectrum allocation to trade off radar and communication performance. The proposed approach combines the water filling optimization to maximize the communication rate for slow fading channels with windowing to reduce pulse compression peak sidelobe level (PSL) for the radar. A trade-off between communication and radar performance is demonstrated by modifying the constraints of the optimization problem. The results show that, depending on the channel response, the proposed optimization method can significantly reduce PSL with limited impact on the data rate.
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