Browsing by Subject "ACCELERATION"

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  • Bode, Hannes F.; Heikkinen, Aino; Lundgren, Sara; Kaprio, Jaakko; Ollikainen, Miina (2022)
    DNA methylation-based age acceleration (DNAmAA) is associated with cancer, with both cancer tissue and blood showing increased DNAmAA. We aimed to investigate whether DNAmAA is associated with cancer risk within twin pairs discordant for cancer, and whether DNAmAA has the potential to serve as a biomarker for such. The study included 47 monozygotic and 48 same-sex-dizygotic cancer-discordant twin pairs from the Finnish Twin Cohort study with blood samples available between 17 and 31 years after the cancer diagnosis. We studied all cancers (95 pairs), then separately breast cancer (24 pairs) and all sites other than breast cancer (71 pairs). DNAmAA was calculated for seven models: Horvath, Horvath intrinsic epigenetic age acceleration, Hannum, Hannum intrinsic epigenetic age acceleration, Hannum extrinsic epigenetic age acceleration, PhenoAge and GrimAge. Within-pair differences in DNAmAA were analyzed by paired t tests and linear regression. Twin pairs sampled before cancer diagnosis did not differ significantly in DNAmAA. However, the within-pair differences in DNAmAA before cancer diagnosis increased significantly the closer the cancer diagnosis was, and this acceleration extended for years after the diagnosis. Pairs sampled after the diagnosis differed for DNAmAA with the Horvath models capturing cancer diagnosis-associated DNAmAA across all three cancer groupings. The results suggest that DNAmAA in blood is associated with cancer diagnosis. This may be due to epigenetic alterations in relation to cancer, its treatment or associated lifestyle changes. Based on the current study, the biomarker potential of DNAmAA in blood appears to be limited.
  • Zhou, Zhipeng; Kyritsakis, Andreas; Wang, Zhenxing; Li, Yi; Geng, Yingsan; Djurabekova, Flyura (2021)
    Vacuum breakdown, also known as vacuum discharge, is a common phenomenon in nature and is gaining an increasingly important role in modern technologies. In spite of a remarkable advance in our understanding of the nature of the breakdown, the role of the anode, i.e. the positively charged electrode, in the development of the breakdown is still completely unclear. In this paper, we employ a streak camera with picosecond time resolution to observe precisely the evolution of anodic glow from different anode materials. The results show that the choice of the anode material does not affect either the delay time between the cathodic and anodic flares or the formation of the conductive channel. Furthermore, we show that the heating of the anode surface by runaway electron currents is not sufficient to evaporate enough atoms for the anodic glow. On the other hand, we show that the neutrals for the anodic flare can be produced by the ions from the expanding cathode plasma by sputtering. Finally, the coincidence in time of the voltage collapse and the anode glow is consistent with the fast expansion of the cathode plasma, which causes both the voltage collapse and the anode glow when it reaches the anode, and densifies by sputtering and reflection. However, the two events are not in direct dependence of one another, since the order of their appearance is random, implying that a fully conductive channel can be established without any light emission from the anode.
  • Laine, Sonja; Hotulainen, Risto; Tirri, Kirsi (2019)
    This study examined Finnish elementary school teachers' (N = 212) attitudes toward the gifted and their education. On a general level, teachers' attitudes toward gifted education were slightly positive. Teachers saw that gifted students have social value and that they need special services. The results of teachers' attitudes toward specific gifted education options were in line with earlier Finnish research, because teachers supported differentiated teaching but were more negative toward acceleration or separating the gifted into their own groups. However, despite the strong support for differentiated teaching for the gifted, teachers' positions toward practice were more skeptical.
  • An, Xin; Liu, Terry Z.; Bortnik, Jacob; Osmane, Adnane; Angelopoulos, Vassilis (2020)
    Upstream of shocks, the foreshock is filled with hot ions. When these ions are concentrated and thermalized around a discontinuity, a diamagnetic cavity bounded by compressional boundaries, referred to as a foreshock transient, forms. Sometimes, the upstream compressional boundary can further steepen into a secondary shock, which has been observed to accelerate particles and contribute to the primary shock acceleration. However, secondary shock formation conditions and processes are not fully understood. Using particle-in-cell simulations, we reveal how secondary shocks are formed. From 1D simulations, we show that electric fields play a critical role in shaping the shock's magnetic field structure, as well as in coupling the energy of hot ions to that of the shock. We demonstrate that larger thermal speed and concentration ratio of hot ions favor the formation of a secondary shock. From a more realistic 2D simulation, we examine how a discontinuity interacts with foreshock ions leading to the formation of a foreshock transient and a secondary shock. Our results imply that secondary shocks are more likely to occur at primary shocks with higher Mach number. With the secondary shock's previously proven ability to accelerate particles in cooperation with a planetary bow shock, it is even more appealing to consider them in particle acceleration of high Mach number astrophysical shocks.
  • Battarbee, Markus; Blanco-Cano, Xochitl; Turc, Lucile; Kajdic, Primoz; Johlander, Andreas; Tarvus, Vertti; Fuselier, Stephen; Trattner, Karlheinz; Alho, Markku; Brito, Thiago; Ganse, Urs; Pfau-Kempf, Yann; Akhavan-Tafti, Mojtaba; Karlsson, Tomas; Raptis, Savvas; Dubart, Maxime; Grandin, Maxime; Suni, Jonas; Palmroth, Minna (2020)
    The foreshock is a region of space upstream of the Earth's bow shock extending along the interplanetary magnetic field (IMF). It is permeated by shock-reflected ions and electrons, low-frequency waves, and various plasma transients. We investigate the extent of the He2+ foreshock using Vlasiator, a global hybrid-Vlasov simulation. We perform the first numerical global survey of the helium foreshock and interpret some historical foreshock observations in a global context. The foreshock edge is populated by both proton and helium field-aligned beams, with the proton foreshock extending slightly further into the solar wind than the helium foreshock and both extending well beyond the ultra-low frequency (ULF) wave foreshock. We compare our simulation results with Magnetosphere Multiscale (MMS) Hot Plasma Composition Analyzer (HPCA) measurements, showing how the gradient of suprathermal ion densities at the foreshock crossing can vary between events. Our analysis suggests that the IMF cone angle and the associated shock obliquity gradient can play a role in explaining this differing behaviour. We also investigate wave-ion interactions with wavelet analysis and show that the dynamics and heating of He2+ must result from proton-driven ULF waves. Enhancements in ion agyrotropy are found in relation to, for example, the ion foreshock boundary, the ULF foreshock boundary, and specular reflection of ions at the bow shock. We show that specular reflection can describe many of the foreshock ion velocity distribution function (VDF) enhancements. Wave-wave interactions deep in the foreshock cause de-coherence of wavefronts, allowing He2+ to be scattered less than protons.
  • Liu, C.M.; Vaivads, A.; Graham, D.B.; Khotyaintsev, Yu V.; Fu, H.S.; Johlander, A.; André, M.; Giles, B.L. (2019)
    Electrostatic solitary waves (ESWs) have been reported inside reconnection jets, but their source and role remain unclear hitherto. Here we present the first observational evidence of ESWs generation by cold ion beams inside the jet, by using high-cadence measurements from the Magnetospheric Multiscale spacecraft in the Earth's magnetotail. Inside the jet, intense ESWs with amplitude up to 30 mV m(-1) and potential up to similar to 7% of the electron temperature are observed in association with accelerated cold ion beams. Instability analysis shows that the ion beams are unstable, providing free energy for the ESWs. The waves are observed to thermalize the beams, thus providing a new channel for ion heating inside the jet. Our study suggests that electrostatic turbulence can play an important role in the jet dynamics.
  • Battarbee, Markus; Dalla, Silvia; Marsh, Mike S. (2018)
    Understanding the transport of solar energetic particles (SEPs) from acceleration sites at the Sun into interplanetary space and to the Earth is an important question for forecasting space weather. The interplanetary magnetic field (IMF), with two distinct polarities and a complex structure, governs energetic particle transport and drifts. We analyze for the first time the effect of a wavy heliospheric current sheet (HCS) on the propagation of SEPs. We inject protons close to the Sun and propagate them by integrating fully 3D trajectories within the inner heliosphere in the presence of weak scattering. We model the HCS position using fits based on neutral lines of magnetic field source surface maps (SSMs). We map 1 au proton crossings, which show efficient transport in longitude via HCS, depending on the location of the injection region with respect to the HCS. For HCS tilt angles around 30 degrees-40 degrees, we find significant qualitative differences between A+ and A- configurations of the IMF, with stronger fluences along the HCS in the former case but with a distribution of particles across a wider range of longitudes and latitudes in the latter. We show how a wavy current sheet leads to longitudinally periodic enhancements in particle fluence. We show that for an A+ IMF configuration, a wavy HCS allows for more proton deceleration than a flat HCS. We find that A- IMF configurations result in larger average fluences than A+ IMF configurations, due to a radial drift component at the current sheet.
  • Sanchez-Diaz, E.; Rouillard, A. P.; Davies, J. A.; Lavraud, B.; Sheeley, N. R.; Pinto, R. F.; Kilpua, E.; Plotnikov, I.; Genot, V. (2017)
    The origin of the slow solar wind is still a topic of much debate. The continual emergence of small transient structures from helmet streamers is thought to constitute one of the main sources of the slow wind. Determining the height at which these transients are released is an important factor in determining the conditions under which the slow solar wind forms. To this end, we have carried out a multipoint analysis of small transient structures released from a north-south tilted helmet streamer into the slow solar wind over a broad range of position angles during Carrington Rotation 2137. Combining the remote-sensing observations taken by the Solar-TErrestrial RElations Observatory (STEREO) mission with coronagraphic observations from the SOlar and Heliospheric Observatory (SOHO) spacecraft, we show that the release of such small transient structures (often called blobs), which subsequently move away from the Sun, is associated with the concomitant formation of transient structures collapsing back toward the Sun; the latter have been referred to by previous authors as "raining inflows." This is the first direct association between outflowing blobs and raining inflows, which locates the formation of blobs above the helmet streamers and gives strong support that the blobs are released by magnetic reconnection.
  • Kalliokoski, Milla M. H.; Kilpua, Emilia K. J.; Osmane, Adnane; Turner, Drew L.; Jaynes, Allison N.; Turc, Lucile; George, Harriet; Palmroth, Minna (2020)
    The energetic electron content in the Van Allen radiation belts surrounding the Earth can vary dramatically at several timescales, and these strong electron fluxes present a hazard for spacecraft traversing the belts. The belt response to solar wind driving is, however, largely unpredictable, and the direct response to specific large-scale heliospheric structures has not been considered previously. We investigate the immediate response of electron fluxes in the outer belt that are driven by sheath regions preceding interplanetary coronal mass ejections and the associated wave activity in the inner magnetosphere. We consider the events recorded from 2012 to 2018 in the Van Allen Probes era to utilise the energy- and radial-distance-resolved electron flux observations of the twin spacecraft mission. We perform a statistical study of the events by using the superposed epoch analysis in which the sheaths are superposed separately from the ejecta and resampled to the same average duration. Our results show that the wave power of ultra-low frequency Pc5 and electromagnetic ion cyclotron waves, as measured by a Geostationary Operational Environmental Satellite (GOES), is higher during the sheath than during the ejecta. However, the level of chorus wave power, as measured by the Van Allen Probes, remains approximately the same due to similar substorm activity during the sheath and ejecta. Electron flux enhancements are common at low energies (<1 MeV) throughout the outer belt (L = 3-6), whereas depletion predominantly occurs at high energies for high radial distances (L > 4). It is distinctive that the depletion extends to lower energies at larger distances. We suggest that this L-shell and energy-dependent depletion results from the magnetopause shadowing that dominates the losses at large distances, while the wave-particle interactions dominate closer to the Earth. We also show that non-geoeffective sheaths cause significant changes in the outer belt electron fluxes.
  • Kilpua, E. K. J.; Turner, D. L.; Jaynes, A.; Hietala, H.; Koskinen, H. E. J.; Osmane, A.; Palmroth, M.; Pulkkinen, T. I.; Vainio, R.; Baker, D.; Claudepierre, S. (2019)
    We study the response of the outer Van Allen radiation belt during an intense magnetic storm on 15-22 February 2014. Four interplanetary coronal mass ejections (ICMEs) arrived at Earth, of which the three last ones were interacting. Using data from the Van Allen Probes, we report the first detailed investigation of electron fluxes from source (tens of kiloelectron volts) to core (megaelectron volts) energies and possible loss and acceleration mechanisms as a response to substructures (shock, sheath and ejecta, and regions of shock-compressed ejecta) in multiple interacting ICMEs. After an initial enhancement induced by a shock compression of the magnetosphere, core fluxes strongly depleted and stayed low for 4 days. This sustained depletion can be related to a sequence of ICME substructures and their conditions that influenced the Earth's magnetosphere. In particular, the main depletions occurred during a high-dynamic pressure sheath and shock-compressed southward ejecta fields. These structures compressed/eroded the magnetopause close to geostationary orbit and induced intense and diverse wave activity in the inner magnetosphere (ULF Pc5, electromagnetic ion cyclotron, and hiss) facilitating both effective magnetopause shadowing and precipitation losses. Seed and source electrons in turn experienced stronger variations throughout the studied interval. The core fluxes recovered during the last ICME that made a glancing blow to Earth. This period was characterized by a concurrent lack of losses and sustained acceleration by chorus and Pc5 waves. Our study highlights that the seemingly complex behavior of the outer belt during interacting ICMEs can be understood by the knowledge of electron dynamics during different substructures.
  • Oleynik, Philipp; Vainio, Rami; Hedman, Hannu-Pekka; Punkkinen, Arttu; Punkkinen, Risto; Salomaa, Lassi; Säntti, Tero; Tuominen, Jarno; Virtanen, Pasi; Bosser, Alexandre; Janhunen, Pekka; Kilpua, Emilia; Palmroth, Minna; Praks, Jaan; Slavinskis, Andris; Kakakhel, Syed R.U.; Peltonen, Juhani; Plosila, Juha; Tammi, Jani; Tenhunen, Hannu; Westerlund, Tomi (2020)
    The Particle Telescope (PATE) of FORESAIL-1 mission is described. FORESAIL-1 is a CubeSat mission to polar Low Earth Orbit. Its scientific objectives are to characterize electron precipitation from the radiation belts and to observe energetic neutral atoms (ENAs) originating from the Sun during the strongest solar flares. For that purpose, the 3-unit CubeSat carries a particle telescope that measures energetic electrons in the nominal energy range of 80-800 keV in seven energy channels and energetic protons at 0.3-10 MeV in ten channels. In addition, particles penetrating the whole telescope at higher energies will be measured in three channels: one >800 keV electron channel, two integral proton channels at >10 MeV energies. The instrument contains two telescopes at right angles to each other, one measuring along the spin axis of the spacecraft and one perpendicular to it. During a spin period (nominally 15 s), the rotating telescope will, thus, deliver angular distributions of protons and electrons, at 11.25-degree clock-angle resolution, which enables one to accurately determine the pitch-angle distribution and separate the trapped and precipitating particles. During the last part of the mission, the rotation axis will be accurately pointed toward the Sun, enabling the measurement of the energetic hydrogen from that direction. Using the geomagnetic field as a filter and comparing the rates observed by the two telescopes, the instrument can observe the solar ENA flux for events similar to the only one so far observed in December 2006. We present the Geant4-simulated energy and angular response functions of the telescope and assess its sensitivity showing that they are adequate to address the scientific objectives of the mission. (C) 2019 COSPAR. Published by Elsevier Ltd. All rights reserved.
  • Hayes, Laura A.; Gallagher, Peter T.; Dennis, Brian R.; Ireland, Jack; Inglis, Andrew; Morosan, Diana E. (2019)
    Solar flares often display pulsating and oscillatory signatures in the emission, known as quasi-periodic pulsations (QPP). QPP are typically identified during the impulsive phase of flares, yet in some cases, their presence is detected late into the decay phase. Here, we report extensive fine structure QPP that are detected throughout the large X8.2 flare from 2017 September 10. Following the analysis of the thermal pulsations observed in the Geostationary Operational Environmental Satellite/X-ray sensor and the 131 angstrom channel of Solar Dynamics Observatory/Atmospheric Imaging Assembly, we find a pulsation period of similar to 65 s during the impulsive phase followed by lower amplitude QPP with a period of similar to 150 s in the decay phase, up to three hours after the peak of the flare. We find that during the time of the impulsive QPP, the soft X-ray source observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager rapidly rises at a velocity of approximately 17 km s(-1) following the plasmoid/coronal mass ejection eruption. We interpret these QPP in terms of a manifestation of the reconnection dynamics in the eruptive event. During the long-duration decay phase lasting several hours, extended downward contractions of collapsing loops/plasmoids that reach the top of the flare arcade are observed in EUV. We note that the existence of persistent QPP into the decay phase of this flare are most likely related to these features. The QPP during this phase are discussed in terms of magnetohydrodynamic wave modes triggered in the post-flaring loops.
  • Kalliokoski, Milla; Kilpua, Emilia; Osmane, Adnane; Jaynes, Allison N.; Turner, Drew L.; George, Harriet; Turc, Lucile; Palmroth, Minna (2022)
    Coronal mass ejection driven sheath regions are one of the key drivers of drastic outer radiation belt responses. The response can however be significantly different based on the sheath properties and the associated inner magnetospheric wave activity. We performed two case studies on the effects of sheaths on outer belt electrons of various energies using data from the Van Allen Probes. One sheath caused a major geomagnetic disturbance and the other had only a minor impact. We especially investigated the phase space density (PSD) of seed, core, and ultrarelativistic electrons to determine the dominant energization and loss processes taking place during the events. Both sheaths produced substantial variation in the electron fluxes from tens of kiloelectronvolts up to ultrarelativistic energies. The responses were however the opposite: the geoeffective sheath mainly led to enhancement, while the nongeoeffective one caused a depletion throughout most of the outer belt. The case studies highlight that both inward and outward radial transport driven by ultra-low frequency waves played an important role in both electron energization and loss. Additionally, PSD radial profiles revealed a local peak that indicated significant acceleration to core energies by chorus waves during the geoeffective event. The distinct responses and different mechanisms in action during these events were related to the timing of the peaked solar wind dynamic pressure causing magnetopause compression, and the differing levels of substorm activity. The most remarkable changes in the radiation belt system occurred in key sheath sub-regions near the shock and the ejecta leading edge.
  • Daglis, Ioannis A.; Chang, Loren C.; Dasso, Sergio; Gopalswamy, Nat; Khabarova, Olga; Kilpua, Emilia; Lopez, Ramon; Marsh, Daniel; Matthes, Katja; Nandy, Dibyendu; Seppala, Annika; Shiokawa, Kazuo; Thieblemont, Remi; Zong, Qiugang (2021)
    In October 2017, the Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) Bureau established a committee for the design of SCOSTEP's Next Scientific Programme (NSP). The NSP committee members and authors of this paper decided from the very beginning of their deliberations that the predictability of the Sun-Earth System from a few hours to centuries is a timely scientific topic, combining the interests of different topical communities in a relevant way. Accordingly, the NSP was christened PRESTO - PREdictability of the variable Solar-Terrestrial cOupling. This paper presents a detailed account of PRESTO; we show the key milestones of the PRESTO roadmap for the next 5 years, review the current state of the art and discuss future studies required for the most effective development of solar-terrestrial physics.
  • Johlander, Erik Andreas; Battarbee, Markus; Turc, Lucile; Ganse, Urs; Pfau-Kempf, Yann; Grandin, Maxime; Suni, Jonas Emil; Tarvus, Vertti Aleksanteri; Bussov, Maarja; Zhou, Hongyang; Alho, Markku Juhani; Dubart, Maxime; George, Harriet Elizabeth; Papadakis, Konstantinos; Palmroth, Minna (2022)
    Shock waves in collisionless plasmas are among the most efficient particle accelerators in space. Shock reformation is a process important to plasma heating and acceleration, but direct observations of reformation at quasi-parallel shocks have been lacking. Here, we investigate Earth's quasi-parallel bow shock with observations by the four Magnetospheric Multiscale spacecraft. The multi-spacecraft observations provide evidence of short large-amplitude magnetic structures (SLAMS) causing reformation of the quasi-parallel shock. We perform an ion-kinetic Vlasiator simulation of the bow shock and show that SLAMS reforming the bow shock recreates the multi-spacecraft measurements. This provides a method for identifying shock reformation in the future.
  • Osmane, Adnane; Lejosne, Solene (2021)
    Radial diffusion in planetary radiation belts is a dominant transport mechanism resulting in the energization and losses of charged particles by large-scale electromagnetic fluctuations. In this study, we revisit the radial diffusion formalism by relaxing the assumption of zero correlation time in the spectrum of fluctuations responsible for the transport of charged particles. We derive a diffusion coefficient by assuming fluctuations that (1) are time homogeneous, (2) too small to trap the particles, and (3) can decorrelate on timescales comparable to the transit time of the particles. We demonstrate through self-similar solutions of the Fokker-Planck equation that autocorrelation time tc much larger than the linear transit time/particle drift period tau(L) = WL D1 results in characteristic time for transport independent of the drift frequency and faster than for short correlation time. In both instances, that is for short (t(L)>> t(c)) and long (t(L) similar to t(s), with s <1. However, in the absence of sources and sinks, particle transport for both short and long autocorrelation times result in equilibrium distribution along L* with differences of less than 10% across lower magnetic drift shells. The main consequence of incorporating finite correlation time appears in intermediate times much longer than the drift period but before the distribution function reaches equilibrium and indicates the importance of quantifying observationally the spectral properties of fluctuations for the modeling of planetary radiation belts.
  • Wijsen, N.; Aran, A.; Sanahuja, B.; Pomoell, J.; Poedts, S. (2020)
    Aims. We study the effect of the magnetic gradient and curvature drifts on the pitch-angle dependent transport of solar energetic particles (SEPs) in the heliosphere, focussing on similar to 3-36 MeV protons. By considering observers located at different positions in the heliosphere, we investigate how drifts may alter the measured intensity-time profiles and energy spectra. We focus on the decay phase of solar energetic proton events in which a temporal invariant spectrum and disappearing spatial intensity gradients are often observed; a phenomenon known as the "reservoir effect" or the "SEP flood". We study the effects of drifts by propagating particles both in nominal and non-nominal solar wind conditions.Methods. We used a three-dimensional (3D) particle transport model, solving the focused transport equation extended with the effect of particle drifts in the spatial term. Nominal Parker solar wind configurations of different speeds and a magnetohydrodynamic (MHD) generated solar wind containing a corotating interaction region (CIR) were considered. The latter configuration gives rise to a magnetic bottle structure, with one bottleneck at the Sun and the other at the CIR. We inject protons from a fixed source at 0.1 AU, the inner boundary of the MHD model.Results. When the drift induced particle net-flux is zero, the modelled intensity-time profiles obtained at different radial distances along an IMF line show the same intensity fall-off after the prompt phase of the particle event, which is in accordance with the SEP flood phenomenon. However, observers magnetically connected close to the edges of the particle injection site can experience, as a result of drifts, a sudden drop in the intensities occurring at different times for different energies such that no SEP flood phenomenon is established. In the magnetic bottle structure, this effect is enhanced due to the presence of magnetic field gradients strengthening the nominal particle drifts. Moreover, anisotropies can be large for observers that only receive particles through drifts, illustrating the importance of pitch-angle dependent 3D particle modelling. We observe that interplanetary cross-field diffusion can mitigate the effects of particle drifts.Conclusions. Particle drifts can substantially modify the decay phase of SEP events, especially if the solar wind contains compression regions or shock waves where the drifts are enhanced. This is, for example, the case for our CIR solar wind configuration generated with a 3D MHD model, where the effect of drifts is strong. A similar decay rate in different energy channels and for different observers requires the mitigation of the effect of drifts. One way to accomplish this is through interplanetary cross-field diffusion, suggesting thus a way to determine a minimum value for the cross-field diffusion strength.
  • Hemila, Harri; Chalker, Elizabeth (2015)
    BACKGROUND: A previous meta-analysis found that high dose zinc acetate lozenges reduced the duration of common colds by 42%, whereas low zinc doses had no effect. Lozenges are dissolved in the pharyngeal region, thus there might be some difference in the effect of zinc lozenges on the duration of respiratory symptoms in the pharyngeal region compared with the nasal region. The objective of this study was to determine whether zinc acetate lozenges have different effects on the duration of common cold symptoms originating from different anatomical regions. METHODS: We analyzed three randomized trials on zinc acetate lozenges for the common cold administering zinc in doses of 80-92 mg/day. All three trials reported the effect of zinc on seven respiratory symptoms, and three systemic symptoms. We pooled the effects of zinc lozenges for each symptom and calculated point estimates and 95% confidence intervals (95% CI). RESULTS: Zinc acetate lozenges shortened the duration of nasal discharge by 34% (95% CI: 17% to 51%), nasal congestion by 37% (15% to 58%), sneezing by 22% (-1% to 45%), scratchy throat by 33% (8% to 59%), sore throat by 18% (-10% to 46%), hoarseness by 43% (3% to 83%), and cough by 46% (28% to 64%). Zinc lozenges shortened the duration of muscle ache by 54% (18% to 89%), but there was no difference in the duration of headache and fever. CONCLUSIONS: The effect of zinc acetate lozenges on cold symptoms may be associated with the local availability of zinc from the lozenges, with the levels being highest in the pharyngeal region. However our findings indicate that the effects of zinc ions are not limited to the pharyngeal region. There is no indication that the effect of zinc lozenges on nasal symptoms is less than the effect on the symptoms of the pharyngeal region, which is more exposed to released zinc ions. Given that the adverse effects of zinc in the three trials were minor, zinc acetate lozenges releasing zinc ions at doses of about 80 mg/day may be a useful treatment for the common cold, started within 24 hours, for a time period of less than two weeks.
  • Turner, D. L.; Kilpua, E. K. J.; Hietala, H.; Claudepierre, S. G.; O'Brien, T. P.; Fennell, J. F.; Blake, J. B.; Jaynes, A. N.; Kanekal, S.; Baker, D. N.; Spence, H. E.; Ripoll, J.-F.; Reeves, G. D. (2019)
    A statistical study was conducted of Earth's radiation belt electron response to geomagnetic storms using NASA's Van Allen Probes mission. Data for electrons with energies ranging from 30 keV to 6.3 MeV were included and examined as a function of L-shell, energy, and epoch time during 110 storms with SYM-H 1 MeV also revealed a marked increase in likelihood of a depletion at all L-shells through the outer belt (3.5 1-MeV electrons throughout the outer belt, while storms driven by full CMEs and stream interaction regions are most likely to produce an enhancement of MeV electrons at lower (L <similar to 5) and higher (L > similar to 4.5) L-shells, respectively. CME sheaths intriguingly result in a distinct enhancement of similar to 1-MeV electrons around L similar to 5.5, and on average, CME sheaths and stream interaction regions result in double outer belt structures.
  • Zhao, L-L; Zank, G. P.; He, J. S.; Telloni, D.; Hu, Q.; Li, G.; Nakanotani, M.; Adhikari, L.; Kilpua, E. K. J.; Horbury, T. S.; O'Brien, H.; Evans, Bradley; Angelini, Corrado (2021)
    Aims. An interplanetary coronal mass ejection (ICME) event was observed by the Solar Orbiter at 0.8 AU on 2020 April 19 and by Wind at 1 AU on 2020 April 20. Futhermore, an interplanetary shock wave was driven in front of the ICME. Here, we focus on the transmission of the magnetic fluctuations across the shock and we analyze the characteristic wave modes of solar wind turbulence in the vicinity of the shock observed by both spacecraft. Methods. The observed ICME event is characterized by a magnetic helicity-based technique. The ICME-driven shock normal was determined by magnetic coplanarity method for the Solar Orbiter and using a mixed plasma and field approach for Wind. The power spectra of magnetic field fluctuations were generated by applying both a fast Fourier transform and Morlet wavelet analysis. To understand the nature of waves observed near the shock, we used the normalized magnetic helicity as a diagnostic parameter. The wavelet-reconstructed magnetic field fluctuation hodograms were used to further study the polarization properties of waves. Results. We find that the ICME-driven shock observed by Solar Orbiter and Wind is a fast, forward oblique shock with a more perpendicular shock angle at the Wind position. After the shock crossing, the magnetic field fluctuation power increases. Most of the magnetic field fluctuation power resides in the transverse fluctuations. In the vicinity of the shock, both spacecraft observe right-hand polarized waves in the spacecraft frame. The upstream wave signatures fall within a relatively broad and low frequency band, which might be attributed to low frequency MHD waves excited by the streaming particles. For the downstream magnetic wave activity, we find oblique kinetic Alfven waves with frequencies near the proton cyclotron frequency in the spacecraft frame. The frequency of the downstream waves increases by a factor of similar to 7-10 due to the shock compression and the Doppler effect.