We present computer experiments of electrostatic solitary waves (ESW) observed by Geotail in the magnetotail. ESW correspond to broadband electrostatic noise, and they are excited through electron two‐stream instabilities along a static magnetic field. We performed one‐dimensional electrostatic particle simulations involving two electron beams and an ion beam traveling along the static magnetic field. We vary the density ratio of the electron beams and the thermal velocities of the electron and ion beams. The values of these parameters strongly affect diffusion processes of the electron beams, and accordingly, different types of electrostatic waves are generated. We studied four different cases: cold bistream instability, weak‐beam instability, bump‐on‐tail instability, and warm bistream instability. For these electron beam instabilities, we performed two different runs with cold and hot ions, respectively. The cold bistream instability gives ESW for hot ions and ion acoustic waves for cold ions. The weak‐beam instability gives Langmuir waves, while the bump‐on‐tail instability gives ESW. The amplitudes of the waves excited by the weak‐beam and bump‐on‐tail instabilities are small and do not induce nonlinear decay to ion acoustic waves even in the presence of cold ions. The warm bistream instability gives electron hole modes regardless of the value of the ion temperature. The electron hole mode is a normal mode in the presence of a two‐hump electron distribution, and it is regarded as narrowband electrostatic noise. It also leads to formation of ESW, if the phase velocity of the electron hole mode is much larger than the ion drift velocity. A necessary condition for ESW formation through the bump‐on‐tail instability is derived theoretically, and its significance to Geotail observations is discussed.

Abstract. We performed computer simulations of electrostatic solitary waves (ESW), which correspond to broadband electrostatic noise (BEN), observed by Geotail spacecraft in the magnetotail. According to Geotail/WFC data analysis, ESW are composed of sequences of impulsive solitary waves, and their potentials are revealed to have uniform structures in the direction perpendicular to the ambient magnetic field. We performed a series of two-dimensional electrostatic particle simulations with a cold electron beam drifting against background hot electrons along the ambient magnetic field. In these simulations, spatial potentials are excited by the initial electron beam instability. They coalesce with each other and form potential troughs uniform in the direction perpendicular to the ambient magnetic field, as predicted by the Geotail observations. We varied the magnitude of the ambient magnetic field and found that this parameter critically affects the ESW formation process. These simulation results indicate that ESW are excited by the electron beam instability in the presence of the static magnetic field with a certain magnitude. ESW are also subject to the enhanced thermal fluctuations due to the limited number of superparticles in the simulations.

BackgroundNonalcoholic steatohepatitis (NASH) is an active form of nonalcoholic fatty liver disease. Risk factors for NASH include type 2 diabetes mellitus (T2DM) and obesity. Sodium–glucose cotransporter 2 (SGLT2) inhibitors used to treat T2DM prevent glucose reabsorption in the kidney and increase glucose urinary excretion. Dapagliflozin is a potent, selective SGLT2 inhibitor that reduces hyperglycemia in patients with T2DM and has been demonstrated to reduce some complications associated with NASH in rodent models.ObjectiveTo assess the efficacy and safety profile of dapagliflozin for the treatment of NASH-associated with T2DM.MethodsIn this single-arm, nonrandomized, open-label study, 16 patients with percutaneous liver biopsy-confirmed NASH and T2DM were enrolled to be prescribed dapagliflozin 5 mg/d for 24 weeks. Of these, 11 patients were evaluable. Patients with chronic liver disease other than NASH were excluded. Body composition, laboratory variables related to liver tests and metabolism, and glucose homeostasis were assessed at baseline and periodically during the study. Changes from baseline were evaluated with the Wilcoxon signed-rank test.ResultsAdministration of dapagliflozin for 24 weeks was associated with significant decreases in body mass index (P < 0.01), waist circumference (P < 0.01), and waist-to-hip ratio (P < 0.01). Changes in body composition were driven by reductions in body fat mass (P < 0.01) and percent body fat (P < 0.01), without changes in lean mass or total body water. Liver tests (ie, serum concentrations of aspartate aminotransferase, alanine aminotransferase, ferritin, and type IV collagen 7S) also significantly improved during the study. Insulin concentrations decreased (P < 0.01 by Week 24) in combination with significant reductions in fasting plasma glucose (P < 0.01) and glycated hemoglobin (P < 0.01) levels and increases in adiponectin (P < 0.01) levels from Week 4 onward.ConclusionsDapagliflozin was associated with improvements in body composition, most likely a reduction in visceral fat, which occurred together with improvements in liver tests and metabolic variables in patients with NASH-associated with T2DM.UMIN Clinical Trial Registry identifier: UMIN000023574.

Abstract. We study the formation mechanism of two-dimensional solitary waves observed in the auroral region via two-dimensional electrostatic particle simulations. The FAST satellite observed very strong "solitary waves" in the downward current regions of the mid-altitude auroral zone, and the Polar satellite also succeeded in detecting solitary waves in the polar region. These "solitary waves" are reported to have isolated two-dimensional structures. The present simulation study demonstrates that such isolated two-dimensional "solitary waves" can be generated by a simple electron two-stream instability. We performed two simulation runs; one was a run without ion dynamics, and the other was a run with ion dynamics. By comparing these two runs, we found isolated two-dimensional potentials are generated due to the ion dynamics. In these simulations an initial electron beam instability first forms solitary potentials isolated in the parallel direction. When the ion dynamics are neglected, these potentials become coherent in the perpendicular direction, forming one-dimensional structures. Owing to the ion dynamics, however, quasi-perpendicular lower hybrid waves are strongly excited through coupling with parallel drifting electron potentials. Potentials are divided in the perpendicular direction by these lower hybrid waves, forming isolated two-dimensional potentials. In a long time evolution, these isolated two-dimensional potentials are gradually aligned in the perpendicular direction, and the perpendicular potential energy decreases. Finally, they again become one-dimensional potentials coherent in the direction perpendicular to the ambient magnetic field.

Background/Aims: The clinical characteristics of esophageal eosinophilia (EE), which is essential for diagnosis of eosinophilic esophagitis (EoE), have not been fully clarified in a Japanese population. The aim of this study was to analyze the reliability of symptoms and endoscopic findings for diagnosing EE in Japanese individuals. Methods: We prospectively enrolled subjects who complained of esophageal symptoms suggesting EoE and/or those with endoscopic findings of suspected EoE at the outpatient clinics of 12 hospitals. Diagnostic utility was compared between the EE and non-EE groups using logistic regression analysis. Results: A total of 349 patients, including 319 with symptoms and 30 with no symptoms but endoscopic findings suggesting EoE were enrolled. Of those with symptoms, 8 (2.5%) had EE, and 3 were finally diagnosed with EoE. Of those without symptoms but endoscopic findings, 4 had EE. Among 8 symptomatic patients, 7 had abnormal endoscopic findings suspicious of EoE. Although dysphagia was a major symptom in EE, none of the presenting symptoms was useful for diagnosis of EE. Among the endoscopic findings, linear furrow was the most reliable (OR = 41.583). Conclusion: EE is uncommon among patients with esophageal symptoms in Japanese individuals. The most useful endoscopic finding for diagnosis of EE was linear furrow, whereas subjective symptoms were not supportive.