Solar and geomagnetic activity dependence of 150-km echoes observed by the Equatorial Atmosphere Radar in Indonesia

The occurrence characteristics of 150-km echoes in low-latitude regions are studied using the Equatorial Atmosphere Radar (EAR) in Indonesia. The long-term observation of the 150-km echoes by the EAR enables us to study the occurrence characteristics of 150-km echoes statistically. It is shown that the occurrence rate of the 150-km echoes observed by the EAR shows a semiannual variation with two peaks in solstices and a negative correlation with both the EUV flux and ΣKp index, that is, the solar and the geomagnetic activity. Geomagnetic activity correlates with the occurrence rate of 150-km echoes observed one day after when the ΣKp was measured. However, the occurrence rate is always low during the high solar activity period regardless of the geomagnetic activity. While the seasonal variation and the solar activity dependence of the occurrence of 150-km echoes are consistent with previous studies, this is the first time a negative correlation with geomagnetic activity is reported

中間圏大気重力波のレーダー観測

京都大学0048新制・課程博士工学博士甲第4017号工博第1027号新制||工||721(附属図書館)UT51-63-J251京都大学大学院工学研究科電子工学専攻(主査)教授 加藤 進, 教授 木村 磐根, 教授 松本 紘学位規則第5条第1項該当Kyoto UniversityDFA

Statistical Analysis of Medium-Scale Traveling Ionospheric Disturbances Over Japan Based on Deep Learning Instance Segmentation

Medium-scale traveling ionospheric disturbances (MSTIDs) are observed as parallelly arrayed wavelike perturbations of Total Electron Content (TEC) in ionospheric F region leading to satellite navigation error and communication signal scintillation. The observation method for MSTIDs, detrended TEC (dTEC) map, summarizes the perturbation component of TEC having the merits of full-time and two-dimensional. However, previous automatic processing methods for dTEC map cannot discriminate MSTIDs from other irregular ionospheric perturbations intelligently. With the development of artificial intelligence in recent years, deep learning approach is expecting to clarify the controversy of MSTID external dependence (season and solar/geomagnetic activity) under debating for decades. Therefore, this research proposes a real-time processing algorithm for dTEC maps based on Mask Region-Convolutional Neural Network (R-CNN) model of deep learning instance segmentation to detect wavelike perturbations intelligently with an accuracy of about 80% and a processing speed of about 8 fps. Then isolated perturbations are eliminated and only MSTID waveforms are chosen to obtain statistical characteristics of MSTIDs. With this algorithm, we analyzed up to 1, 209, 600 dTEC maps from 1997 to 2019 over Japan automatically and established a database of hourly averaged MSTID characteristics. This research introduces the partial correlation coefficient for the first time to clarify the solar/geomagnetic activity dependence of MSTID characteristics which is independent with each other

Complementing regional ground GNSS-STEC computerized ionospheric tomography (CIT) with ionosonde data assimilation

A near-real-time computerized ionospheric tomography (CIT) technique was developed over the East Asian sector to specify the 3-D electron density field. The technique is based on a plethora of Global Navigation Satellite System observables within the region of interest which is bounded horizontally 110°–160°E and 10°–60°N and extending from 80 to 25, 000 km in altitude. Prior to deployment, studies validated the CIT results using ionosonde, middle-upper atmosphere radar and occultation data and found the technique to adequately reconstruct the regional ionosphere vertical structure. However, with room for improvement in estimating the peak height and avoiding physically unrealistic negative densities in the final solution, we present preliminary results from a technique that addresses these issues by incorporating CIT results into a data assimilation (DA) technique. The DA technique adds ionosonde bottomside measurements into CIT results, thereby improving the accuracy of the reconstructed bottomside 3-D structure. More specifically, on average CIT NmF2 and hmF2 improve by more than 60%. Further, during analysis, ionospheric electron densities are assumed to be better described by probability log-normal distribution, which introduces the positivity constraint that is mandatory in ionospheric imaging

Nighttime Midlatitude E-F Coupling in Geomagnetic Conjugate Ionospheres: A Double Thin Shell Model and a Multi-Source Data Investigation

Geomagnetic conjugate mid-latitude nighttime ionospheres are frequently simultaneously populated with electrified nighttime medium-scale traveling ionospheric disturbances (MSTIDs). Earlier observations and theoretical analysis have underscored the ionosphere E-F coupling and the postulation of coupled conjugate hemispheres, playing a pivotal role in the formation of electrified MSTIDs. In this paper, the conjugate MSTIDs are studied to elucidate the causes and effects of E-F coupling in the interhemispheric coupled ionosphere. The hemisphere-coupled ionospheres over Japan and Australia are observed and analyzed using total electron content (TEC) measurements, supplemented with multi-source observations from ionosondes, Ionospheric Connection Explorer (neutral wind), Constellation Observing System for Meteorology, Ionosphere, and Climate (electron density), and Swarm (magnetic field). A double-thin-shell model is introduced to analyze the ionospheric responses in E and F regions during the coupling process. For the first time, observation results provide the evidence that F-region geomagnetic conjugate irregularities in both hemispheres are mainly driven by the Es layers in the summer hemisphere. The Es layer in the summer hemisphere subsequently triggers local E-F coupling and inter-hemispheric coupling. In the winter hemisphere, Es layers show amplitude reduction or even dissipation during the interhemispheric coupling process. Furthermore, thermospheric winds, non-equipotential magnetic field lines, and background TEC are presumed candidates for the inter-hemispheric asymmetry in MSTIDs amplitudes and growth rates

Supplementary material for the article: Beškoski, V. P.; Yamamoto, A.; Nakano, T.; Yamamoto, K.; Matsumura, C.; Motegi, M.; Beškoski, L. S.; Inui, H. Defluorination of Perfluoroalkyl Acids Is Followed by Production of Monofluorinated Fatty Acids. Science of the Total Environment 2018, 636, 355–359. https://doi.org/10.1016/j.scitotenv.2018.04.243

Supplementary material for: [https://doi.org/10.1016/j.scitotenv.2018.04.243]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2168

KCl Concentration Dependence on the ATPase Activity of Crab Actomyosion.

KCl concentration dependence on the ATPase activity of myofibrils and of myosin B was studied using crab muscle. 1 ) Without addition of bivalent cations, the ATPase activities of these actomyosin systems were vrey low. 2 ) By addition of 100 μM Ca++ or 2 mM Mg++ these ATPase activities were activated.3) These activated ATPases were decreased with increasing the KCl concentration. From these results, it was indicated that the actomyosin system of a crab is essentially similar to that of a rabbit