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Sökning: WFRF:(Maggiolo F)

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1.
  • Niemi, MEK, et al. (författare)
  • 2021
  • swepub:Mat__t
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4.
  • Borges, A. H., et al. (författare)
  • Nonnucleoside Reverse-transcriptase Inhibitor- vs Ritonavir-boosted Protease Inhibitor-based Regimens for Initial Treatment of HIV Infection: A Systematic Review and Metaanalysis of Randomized Trials
  • 2016
  • Ingår i: Clinical Infectious Diseases. - : Oxford University Press (OUP). - 1058-4838 .- 1537-6591. ; 63:2, s. 268-280
  • Tidskriftsartikel (refereegranskat)abstract
    • Background. Previous studies suggest that nonnucleoside reverse-transcriptase inhibitors (NNRTIs) cause faster virologic suppression, while ritonavir-boosted protease inhibitors (PI/r) recover more CD4 cells. However, individual trials have not been powered to compare clinical outcomes. Methods. We searched databases to identify randomized trials that compared NNRTI-vs PI/r-based initial therapy. A meta-analysis calculated risk ratios (RRs) or mean differences (MDs), as appropriate. Primary outcome was death or progression to AIDS. Secondary outcomes were death, progression to AIDS, and treatment discontinuation. We calculated RR of virologic suppression and MD for an increase in CD4 cells at week 48. Results. We included 29 trials with 9047 participants. Death or progression to AIDS occurred in 226 participants in the NNRTI arm and in 221 in the PI/r arm (RR, 1.03; 95% confidence interval, .87-1.22; 12 trials; n = 3825), death in 205 participants in the NNRTI arm vs 198 in the PI/r arm (1.04; 0.86-1.25; 22 trials; n = 8311), and progression to AIDS in 140 participants in the NNRTI arm vs 144 in the PI/r arm (1.00; 0.80-1.25; 13 trials; n = 4740). Overall treatment discontinuation (1.12; 0.93-1.35; 24 trials; n = 8249) and from toxicity (1.21; 0.87-1.68; 21 trials; n = 6195) were comparable, but discontinuation due to virologic failure was more common with NNRTI (1.58; 0.91-2.74; 17 trials; n = 5371). At week 48, there was no difference between NNRTI and PI/r in virologic suppression (RR, 1.03; 0.98-1.09) or CD4(+) recovery (MD, -4.7 cells; -14.2 to 4.8). Conclusions. We found no difference in clinical and viro-immunologic outcomes between NNRTI-and PI/r-based therapy.
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5.
  • Gunell, H, et al. (författare)
  • Acceleration of ions and nano dust at a comet in the solar wind
  • 2015
  • Ingår i: Planetary and Space Science. - : Elsevier. - 0032-0633 .- 1873-5088. ; 119, s. 13-23
  • Tidskriftsartikel (refereegranskat)abstract
    • A quasi-neutral hybrid simulation of the interaction of the solar wind with the atmosphere of a comet is used together with a test particle simulation of cometary ions and dust to compute trajectories and velocity distribution functions of charged particles, starting outside the diamagnetic cavity at 150 km cometocentric distance. The simulations are run with parameters suited to make predictions for comet 67P/Churyumov-Gerasimenko when it is at a heliocentric distance of 1.45 AU. It is found that the shape of the ion trajectories depends on the location of the source, and that a velocity distribution that is observed at a given point in space is influenced by the spatial structure of the source. Charged dust grains with radii in the 1-10 nm range are accelerated from the nucleus to a distance of 2.9 x 104 km in between 15 min and 2 h approximately. Dust particles smaller than 10 nm in radius are accelerated to speeds over 10 km/s.
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6.
  • Gunell, H., et al. (författare)
  • Ion acoustic waves at comet 67P/Churyumov-Gerasimenko : Observations and computations
  • 2017
  • Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 600
  • Tidskriftsartikel (refereegranskat)abstract
    • Context. On 20 January 2015 the Rosetta spacecraft was at a heliocentric distance of 2.5 AU, accompanying comet 67P/Churyumov-Gerasimenko on its journey toward the Sun. The Ion Composition Analyser (RPC-ICA), other instruments of the Rosetta Plasma Consortium, and the ROSINA instrument made observations relevant to the generation of plasma waves in the cometary environment.Aims. Observations of plasma waves by the Rosetta Plasma Consortium Langmuir probe (RPC-LAP) can be explained by dispersion relations calculated based on measurements of ions by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA), and this gives insight into the relationship between plasma phenomena and the neutral coma, which is observed by the Comet Pressure Sensor of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument (ROSINA-COPS).Methods. We use the simple pole expansion technique to compute dispersion relations for waves on ion timescales based on the observed ion distribution functions. These dispersion relations are then compared to the waves that are observed. Data from the instruments RPC-LAP, RPC-ICA and the mutual impedance probe (RPC-MIP) are compared to find the best estimate of the plasma density.Results. We find that ion acoustic waves are present in the plasma at comet 67P/Churyumov-Gerasimenko, where the major ion species is H2O+. The bulk of the ion distribution is cold, k(B)T(i) = 0.01 eV when the ion acoustic waves are observed. At times when the neutral density is high, ions are heated through acceleration by the solar wind electric field and scattered in collisions with the neutrals. This process heats the ions to about 1 eV, which leads to significant damping of the ion acoustic waves.Conclusions. In conclusion, we show that ion acoustic waves appear in the H2O+ plasmas at comet 67P/Churyumov-Gerasimenko and how the interaction between the neutral and ion populations affects the wave properties.
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7.
  • Gunell, Herbert, et al. (författare)
  • Plasma waves confined to the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko
  • 2017
  • Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 469, s. S84-S92
  • Tidskriftsartikel (refereegranskat)abstract
    • Ion acoustic waves were observed in the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft on 2015 August 3, when the comet was 1.25 au from the Sun. Wave spectra recorded by the Langmuir probe (RPC-LAP), peak near 200 Hz, decrease for higher frequencies and reach the noise floor at approximately 1.5 kHz. These waves were observed only when the spacecraft was in the diamagnetic cavity or at its boundary, which is identified as a sharp drop in magnetic field magnitude, measured by RPC-MAG. The plasma, on both sides of the boundary, is dominated by a cold (a few hundred K) water group ion population, one cold (k(B)T(e) similar to 0.1 eV) and one warm (k(B)T(e) similar to 10 eV) electron population. The observations are interpreted in terms of current-driven ion acoustic waves, generated by currents that flow through bulges on the boundary of the diamagnetic cavity.
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8.
  • Gunell, H., et al. (författare)
  • Waves in high-speed plasmoids in the magnetosheath and at the magnetopause
  • 2014
  • Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 32:8, s. 991-1009
  • Tidskriftsartikel (refereegranskat)abstract
    • Plasmoids, defined here as plasma entities with a higher anti-sunward velocity component than the surrounding plasma, have been observed in the magnetosheath in recent years. During the month of March 2007 the Cluster spacecraft crossed the magnetopause near the subsolar point 13 times. Plasmoids with larger velocities than the surrounding magnetosheath were found on seven of these 13 occasions. The plasmoids approach the magnetopause and interact with it. Both whistler mode waves and waves in the lower hybrid frequency range appear in these plasmoids, and the energy density of the waves inside the plasmoids is higher than the average wave energy density in the magnetosheath. When the spacecraft are in the magnetosphere, Alfvenic waves are observed. Cold ions of ionospheric origin are seen in connection with these waves, when the wave electric and magnetic fields combine with the Earth's dc magnetic field to yield an E x B/B-2 drift speed that is large enough to give the ions energies above the detection threshold.
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9.
  • Maggiolo, R., et al. (författare)
  • Effect of the Surface Roughness of Icy Grains on Molecular Oxygen Chemistry in Molecular Clouds
  • 2019
  • Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 882:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Molecular cloud and protosolar nebula chemistry involves a strong interaction between the gas phase and the surface of icy grains. The exchanges between the gas phase and the solid phase depend not only on the adsorption and desorption rates but also on the geometry of the surface of the grains. Indeed, for sufficient levels of surface roughness, atoms and molecules have a significant probability to collide with the grain icy mantle several times before being potentially captured. In consequence, their net sticking probability may differ from their sticking probability for a single collision with the grain surface. We estimate the effectiveness of the recapture on uneven surfaces for the various desorption processes at play in astrophysical environments. We show that surface roughness has a significant effect on the desorption rates. We focus in particular on the production of O-2 since unexpectedly large amounts of it, probably incorporated in the comet when it formed, have been detected in the coma of comet 67P by the Rosetta probe. Our results suggest that the higher escape probability of hydrogen compared to heavier species on rough surfaces can contribute to enhancing the production of O-2 in the icy mantles of grains while keeping its abundance low in the gas phase and may significantly decrease the desorption probability of molecules involved in the O-2 chemical network.
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10.
  • Maggiolo, R., et al. (författare)
  • The earth's magnetic field enhances solar energy deposition in the upper atmosphere
  • 2022
  • Ingår i: Journal of Geophysical Research - Space Physics. - : John Wiley & Sons. - 2169-9380 .- 2169-9402. ; 127:12
  • Tidskriftsartikel (refereegranskat)abstract
    • The presence of a large-scale planetary magnetic field is thought to be a protective factor for atmospheres, preventing them from being blown off by the solar wind. We focus on one key aspect of atmospheric escape: how does a planetary magnetic fields affect the energy transfer from the Sun to the atmosphere? We estimate the solar wind energy currently dissipated in the Earth's atmosphere using empirical formulas derived from observations. We show that it is significantly higher than the energy dissipated in the atmosphere of a hypothetical unmagnetized Earth. Consequently, we conclude that the Earth's magnetic field enhances the solar energy dissipation in the Earth's atmosphere and that, contrary to the old paradigm, an intrinsic magnetic field does not necessarily reduces atmospheric loss.
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