Summary
Background
Vonoprazan is a novel potassium‐competitive acid blocker which may provide clinical benefit in acid‐related disorders.
Aim
To verify the non‐inferiority of vonoprazan vs. ...lansoprazole in patients with erosive oesophagitis (EE), and to establish its long‐term safety and efficacy as maintenance therapy.
Methods
In this multicentre, randomised, double‐blind, parallel‐group comparison study, patients with endoscopically confirmed EE (LA Classification Grades A–D) were randomly allocated to receive vonoprazan 20 mg or lansoprazole 30 mg once daily after breakfast. The primary endpoint was the proportion of patients with healed EE confirmed by endoscopy up to week 8. In addition, subjects who achieved healed EE in the comparison study were re‐randomised into a long‐term study to investigate the safety and efficacy of vonoprazan 10 or 20 mg as maintenance therapy for 52 weeks.
Results
Of the 409 eligible subjects randomised, 401 completed the comparison study, and 305 entered the long‐term maintenance study. The proportion of patients with healed EE up to week 8 was 99.0% for vonoprazan (203/205) and 95.5% for lansoprazole (190/199), thus verifying the non‐inferiority of vonoprazan (P < 0.0001). Vonoprazan was also effective in patients with more severe EE (LA Classification Grades C/D) and CYP2C19 extensive metabolisers. In the long‐term maintenance study, there were few recurrences (<10%) of EE in patients treated with vonoprazan 10 or 20 mg. Overall, vonoprazan was well‐tolerated.
Conclusions
The non‐inferiority of vonoprazan to lansoprazole in EE was verified in the comparison study, and vonoprazan was well‐tolerated and effective during the long‐term maintenance study.
Using the Arase and Van Allen Probes satellite observations, we investigate the nonlinear electromagnetic ion cyclotron (EMIC) rising‐tone (RT) emissions with an increase of the solar wind dynamic ...pressure in the dayside magnetosphere. We find that EMIC RT emissions are accompanied by the extended dayside uniform zone (DUZ) over |MLAT| < 25° due to the dayside magnetospheric compression by an increase in Pdyn. Using the observed plasma and magnetic field data, we modeled the threshold amplitude for the nonlinear EMIC waves and compared it with the observation. The small gradient of the ambient magnetic field strongly contributes to the reduction in the threshold amplitude of nonlinear wave growth compared to other parameters. When the threshold amplitude falls to comparable level of pre‐existing EMIC waves, EMIC RT emissions are immediately triggered, suggesting direct evidence that the DUZ is the preferred condition to cause the nonlinear EMIC RT emission in the dayside magnetosphere.
Plain Language Summary
Electromagnetic ion cyclotron (EMIC) waves play an important role in controlling the dynamics of charged particles in the inner magnetosphere. Especially, nonlinear EMIC rising‐tone (RT) emissions can cause the rapid loss of relativistic electrons and ring current ions. Here, we present direct evidence demonstrating that the distortion of the dayside magnetic field causes nonlinear EMIC RT emission in response to the intensification of the solar wind dynamic pressure. Remarkably, these nonlinear EMIC waves are generated through a reduction in the threshold wave amplitudes by the distortion of the magnetic fields, even in the absence of any significant change in the pre‐existing EMIC wave amplitude. The present result provides new insights into a triggering process of nonlinear plasma waves in the magnetosphere.
Key Points
Electromagnetic ion cyclotron (EMIC) waves with rising‐tone (RT) elements were observed in the dayside magnetosphere during an increase in the solar wind dynamic pressure
Increasing solar wind dynamic pressure extends the dayside uniform zone of the magnetic field to higher magnetic latitudes
The uniform zone leads to the reduction of the nonlinear threshold wave amplitude, which triggers nonlinear EMIC RT emissions
Whether aseismic transients occur as the next earthquake approaches or not is an important problem in the area of disaster mitigation by geophysical observation. We conducted a series of rate‐state ...(aging law) earthquake sequence simulations with inertial effects and revealed that A/B (direct effect/evolution effect) is a key parameter controlling the complexity of interseismic behavior in a seismogenic patch. Interseismically, a creep front invades a locked patch. If A/B≤0.4, nucleation takes place as soon as the linear stability of the coherent creep is violated, and no significant aseismic transient occurs. If A/B≥0.4, nucleation size is given by the energy balance criterion, and if A/B≥0.6, aseismic transients occur after the violation of linear stability and before the creeping region is able to host the nucleation. Thus, not only A − B but also A/B must be selected carefully to obtain realistic results in numerical simulations.
Key PointsNucleation size is estimated by 3‐D rate‐state earthquake sequence simulationsLarge A/B causes complex interseismic behavior of a seismogenic patchSSEs occur in the later interseismic period for A/B larger than 0.6
We conduct a statistical analysis on nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) using the Super Dual Auroral Radar Network (SuperDARN) Hokkaido East (43.53°N, 143.61°E) ...high‐frequency (HF) radar data from 2009 to 2019 and the SuperDARN Hokkaido West (43.54°N, 143.61°E) HF radar data from 2016 to 2019. We analyze the line‐of‐sight Doppler velocity data, corresponding to the magnitude of the polarization electric field associated with nighttime MSTIDs. We find that the propagation direction of the nighttime MSTIDs is mainly southwestward and rotates clockwise with progressing local time. In addition, we identify a negative correlation between the nighttime MSTIDs amplitude and the solar F10.7 index. These tendencies can be explained by the Perkins instability, which is considered to be associated with the growth of nighttime MSTIDs. This study is the first to find the solar activity dependence of the polarization electric field fluctuations associated with the nighttime MSTIDs.
Plain Language Summary
Medium‐scale traveling ionospheric disturbances (MSTIDs) are propagating wave‐like electron density disturbances in the ionosphere. Previous studies have shown nighttime MSTIDs propagate mainly southwestward and the propagation direction changes clockwise with progressing local time at mid‐latitude. However, statistical studies using long‐term data are few in number, and long‐term trends, such as solar activity dependence, are still unknown. In this study, we report the results of statistical analysis on the characteristics of nighttime MSTIDs using long‐term data from the Super Dual Auroral Radar Network (SuperDARN) Hokkaido pair of radars. The nighttime MSTIDs in the northern region of Hokkaido have the same propagation characteristics with the MSTIDs in the other midlatitude region. In addition, the nighttime MSTID amplitude has a negative correlation with solar activity.
Key Points
Long‐term analysis on nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) was conducted using the SuperDARN Hokkaido pair of radars
Seasonal and local time dependences were analyzed and these results were consistent with theoretical expectations of the Perkins instability
Negative correlation between the MSTID amplitude and solar activity was found
Abstract
In this paper, a simple method to improve sampling efficiency of the generalized hybrid Monte Carlo (GHMC) method is presented. Compared to the standard GHMC method, our method is found to ...allow us to safely increase the time increment for solving an equation-of-motion in the GHMC calculations by a factor of 4. We have demonstrated various algorithmic parameter dependence on the sampling efficiency of a hydrated alanine dipeptide.
Abstract Pulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby ...depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.
Resonant interactions of energetic electrons with electromagnetic whistler‐mode waves (whistlers) contribute significantly to the dynamics of electron fluxes in Earth's outer radiation belt. At low ...geomagnetic latitudes, these waves are very effective in pitch angle scattering and precipitation into the ionosphere of low equatorial pitch angle, tens of keV electrons and acceleration of high equatorial pitch angle electrons to relativistic energies. Relativistic (hundreds of keV), electrons may also be precipitated by resonant interaction with whistlers, but this requires waves propagating quasi‐parallel without significant intensity decrease to high latitudes where they can resonate with higher energy low equatorial pitch angle electrons than at the equator. Wave propagation away from the equatorial source region in a non‐uniform magnetic field leads to ray divergence from the originally field‐aligned direction and efficient wave damping by Landau resonance with suprathermal electrons, reducing the wave ability to scatter electrons at high latitudes. However, wave propagation can become ducted along field‐aligned density peaks (ducts), preventing ray divergence and wave damping. Such ducting may therefore result in significant relativistic electron precipitation. We present evidence that ducted whistlers efficiently precipitate relativistic electrons. We employ simultaneous near‐equatorial and ground‐based measurements of whistlers and low‐altitude electron precipitation measurements by ELFIN CubeSat. We show that ducted waves (appearing on the ground) efficiently scatter relativistic electrons into the loss cone, contrary to non‐ducted waves (absent on the ground) precipitating only <150 keV electrons. Our results indicate that ducted whistlers may be quite significant for relativistic electron losses; they should be further studied statistically and possibly incorporated in radiation belt models.
Key Points
Near‐equatorial and ground‐based measurements of whistler‐mode waves are accompanied by relativistic electron precipitation
In the presence (absence) of ducted wave propagation, as monitored by propagation to the ground, the precipitating electron energies are above (below) 150 keV
Ducted whistler‐mode waves may play a key role in relativistic electron loss in the inner magnetosphere
Poleward Moving Auroral Arcs and Pc5 Oscillations Sakurai, T.; Wright, A. N.; Takahashi, K. ...
Journal of geophysical research. Space physics,
August 2022, 2022-08-00, 20220801, Letnik:
127, Številka:
8
Journal Article
Recenzirano
Odprti dostop
We present an example of one‐to‐one correspondence between poleward moving auroral arcs (PMAAs) and Pc5 oscillations observed at the Time History of Events and Macroscale Interactions during ...Substorms (THEMIS) Ground Based Observatory station Gillam. The PMAAs consisted of four successive intensifications (named PMAA1, PMAA2, PMAA3 and PMAA4) with a period of 3∼4 min over the magnetic latitudes from 68° to 70° in the auroral oval and varied coherently with the H‐component of magnetic field Pc5 oscillations. PMAA1 and PMAA2 appeared clearly at the magnetic latitude ∼69°, and the following two PMAAs, which were dimmer, appeared at the magnetic latitude ∼68°. PMAA1 and PMAA2 exhibited features of field‐line resonances with the maximum luminosity at the magnetic latitude ∼69.5° and ∼69.4°, respectively. The ground Pc5 oscillations were concurrent with toroidal mode Pc5 oscillation observed at the THEMIS‐D, ‐E, and ‐A satellites at ∼4 MLT in the outer magnetosphere. The magnetic and electric field oscillations at THEMIS were synchronized with the PMAAs. The magnetic energy of the THEMIS Pc5 oscillations is estimated using a numerical model of damped toroidal oscillations and compared with the kinetic energy of precipitating electrons associated with the field aligned current carried by the toroidal oscillations. The result reveals that the Pc5 magnetic energy is much larger than the kinetic energy, implying the magnetic energy is important for producing auroral emissions in the ionosphere. We also perform a simulation of the relationship between PMAAs and toroidal mode Pc5 oscillations. The simulation explains the observed spatial and temporal structures of the PMAAs.
Plain Language Summary
Aurora are a fascinating phenomenon observed in the polar region of the earth. The auroral emission is caused by the excitation of neutral oxygen atoms and nitrogen molecules in the ionosphere through collision with precipitating electrons from higher altitudes traveling along the magnetic field lines. The precipitating electrons need to have energies of order keV in order to produce auroral emissions. The energy is higher than that of solar wind electrons even after they are heated on passing through the bow shock in front of the magnetosphere. However, how the electrons gain the required high energy is not fully understood. The present study discusses a possible mechanism for the electron acceleration through analysis of the relationship between periodic auroral brightening detected by an all‐sky imager and ultralow frequency hydromagnetic (Alfvén) waves detected by the THEMIS spacecraft and a ground magnetometer. The emphasis is placed on the importance of the magnetic energy of Alfvén waves. We find that the magnetic energy is larger than the kinetic energy of the precipitating electrons, implying that the magnetic energy is important for acceleration of auroral electrons. A simulation of this process explains the spatial and temporal structure of the observed auroral emissions.
Key Points
We observed concurrent occurrence of poleward moving auroral arcs (PMAAs) and Pc5 oscillations on the ground and in the magnetosphere
We evaluated magnetic energy of Pc5 oscillations and compared it with kinetic energy of precipitating electrons along the field line
The magnetic energy of Pc5 oscillations is important for auroral emission and simulated the spatial and temporal structures of PMAAs
Polypropylene (PP) is a widely used synthetic fiber. Due to its advantages, PP has been used for numerous applications. However, the utilization of PP is limited by poor dye-ability. To improve this, ...the fiber is typically composited with polyester (PET), which is dyed with a disperse dye using either the conventional method or with a high technology such as Supercritical carbon dioxide (scCO2). In this investigation, the sheath-core polyester/co-polypropylene composite fibers (PET/co-PP fibers) were annealed at 150 °C for 1 h and dyed with three types of disperse dyes using scCO2 at the various dyeing temperatures and pressures. Optical and scanning electron microscopes (SEM) were used to examine the cross section of the fibers. Extraction of disperse dye in the fibers was carried out followed by quantification of the dye contents. SEM images showed the order distribution of core-PET which was affected due to molecular re-orientation after annealing. Dye content in the fibers varied with the type of fiber, dyeing temperatures and pressures. Remarkably increased dye contents were found from 100 to 120 °C. The dye-ability of the fibers was found to be more profound for pressure variation than for the variation of temperature. No dye content was found in the fibers dyed at 50 MPa, but significant increases in the dye content were observed at higher pressures. Images from optical microscope confirmed that high color depth was found in fibers dyed at higher pressure than obviously seen in PET core. However, uniformly dyed PET/co-PP fibers were, typically observed.
•Polyester/co-polypropylene fibers were annealed and dyed with disperse dyes using scCO2.•Dye content in fibers increased with increasing temperature and pressure.•Annealing process caused low dye content in the fibers.
Abstract
Both solar wind and ionospheric sources contribute to the magnetotail plasma sheet, but how their contribution changes during a geomagnetic storm is an open question. The source is critical ...because the plasma sheet properties control the enhancement and decay rate of the ring current, the main cause of the geomagnetic field perturbations that define a geomagnetic storm. Here we use the solar wind composition to track the source and show that the plasma sheet source changes from predominantly solar wind to predominantly ionospheric as a storm develops. Additionally, we find that the ionospheric plasma during the storm main phase is initially dominated by singly ionized hydrogen (H
+
), likely from the polar wind, a low energy outflow from the polar cap, and then transitions to the accelerated outflow from the dayside and nightside auroral regions, identified by singly ionized oxygen (O
+
). These results reveal how the access to the magnetotail of the different sources can change quickly, impacting the storm development.
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