scholarly journals Ground-Based GNSS and Satellite Observations of Auroral Ionospheric Irregularities during Geomagnetic Disturbances in August 2018

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7749
Author(s):  
Irina Zakharenkova ◽  
Iurii Cherniak ◽  
Andrzej Krankowski
Keyword(s):  
Auroral Oval ◽  
Ionospheric Irregularities ◽  
Polar Cap ◽  
Geomagnetic Disturbances ◽  
Main Ionospheric Trough ◽  
Large Expansion ◽  
Space Weather Event ◽  
High Degree ◽  
Degree Of Similarity ◽  
Gnss Observations

The 25–26 August 2018 space weather event occurred during the solar minimum period and surprisingly became the third largest geomagnetic storm of the entire 24th solar cycle. We analyzed the ionospheric response at high latitudes of both hemispheres using multi-site ground-based GNSS observations and measurements onboard Swarm and DMSP satellites. With the storm development, the zones of intense ionospheric irregularities of auroral origin largely expanded in size and moved equatorward towards midlatitudes as far as ~55–60° magnetic latitude (MLAT) in the American, European, and Australian longitudinal sectors. The main ionospheric trough, associated with the equatorward side of the auroral oval, shifted as far equatorward as 45–50° MLAT at both hemispheres. The interhemispheric comparison revealed a high degree of similarity in a large expansion of the auroral irregularities oval towards midlatitudes, in addition to asymmetrical differences in terms of larger intensity of plasma density gradients and structures over the Southern auroral and polar cap regions. Evolution of the intense ionospheric irregularities and equatorward expansion of the auroral irregularities oval were well correlated with increases of geomagnetic activity and peaks of the auroral electrojet index.

scholarly journals On the occurrence and motion of decametre-scale irregularities in the sub-auroral, auroral, and polar cap ionosphere

2003 ◽  
Vol 21 (8) ◽  
pp. 1847-1868 ◽  
Author(s):  
M. L. Parkinson ◽  
J. C. Devlin ◽  
H. Ye ◽  
C. L. Waters ◽  
P. L. Dyson ◽  
...  
Keyword(s):  
Electric Fields ◽  
Spectral Width ◽  
Auroral Oval ◽  
Auroral Zone ◽  
Ionospheric Irregularities ◽  
Lower Latitude ◽  
Doppler Velocity ◽  
Auroral Ionosphere ◽  
Polar Cap ◽  
Sunspot Maximum

Abstract. The statistical occurrence of decametre-scale ionospheric irregularities, average line-of-sight (LOS) Doppler velocity, and Doppler spectral width in the sub-auroral, auroral, and polar cap ionosphere ( - 57°L to - 88°L) has been investigated using echoes recorded with the Tasman International Geospace Environment Radar (TIGER), a SuperDARN radar located on Bruny Island, Tasmania (147.2° E, 43.4° S geographic; - 54.6 °L). Results are shown for routine soundings made on the magnetic meridian beam 4 and the near zonal beam 15 during the sunspot maximum interval December 1999 to November 2000. Most echoes were observed in the nightside ionosphere, typically via 1.5-hop propagation near dusk and then via 0.5-hop propagation during pre-midnight to dawn. Peak occurrence rates on beam 4 were often > 60% near magnetic midnight and ~ - 70 °L. They increased and shifted equatorward and toward pre-midnight with increasing Kp (i.e. Bz southward). The occurrence rates remained very high for Kp > 4, de-spite enhanced D-region absorption due to particle precipitation. Average occurrence rates on beam 4 exhibited a relatively weak seasonal variation, consistent with known longitudinal variations in auroral zone magnetic activity (Basu, 1975). The average echo power was greatest between 23 and 07 MLT. Two populations of echoes were identified on both beams, those with low spectral width and a mode value of ~ 9 ms-1 (bin size of 2 ms-1) concentrated in the auroral and sub-auroral ionosphere (population A), and those with high spectral width and a mode value of ~ 70 ms-1 concentrated in the polar cap ionosphere (population B). The occurrence of population A echoes maximised post-midnight because of TIGER’s lower latitude, but the subset of the population A echoes observed near dusk had characteristics reminiscent of "dusk scatter" (Ruohoniemi et al., 1988). There was a dusk "bite out" of large spectral widths between ~ 15 and 21 MLT and poleward of - 67 °L, and a pre-dawn enhancement of large spectral widths between ~  03 and 07 MLT, centred on ~ - 61 °L. The average LOS Doppler velocities revealed that frequent westward jets of plasma flow occurred equatorward of, but overlapping, the diffuse auroral oval in the pre-midnight sector.Key words. Ionosphere (auroral ionosphere; electric fields and currents, ionospheric irregularities)

scholarly journals Characterization of multi-scale ionospheric irregularities using ground-based and space-based GNSS observations

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
YuXiang Peng ◽  
Wayne A Scales ◽  
Michael D Hartinger ◽  
Zhonghua Xu ◽  
Shane Coyle
Keyword(s):  
Formation Flying ◽  
Satellite System ◽  
Ionospheric Irregularities ◽  
Mission Design ◽  
Electron Content ◽  
Total Electron ◽  
Spatial And Temporal Scales ◽  
Multi Scale ◽  
Global Navigation Satellite ◽  
Gnss Observations

AbstractIonospheric irregularities can adversely affect the performance of Global Navigation Satellite System (GNSS). However, this opens the possibility of using GNSS as an effective ionospheric remote sensing tool. Despite ionospheric monitoring has been undertaken for decades, these irregularities in multiple spatial and temporal scales are still not fully understood. This paper reviews Virginia Tech’s recent studies on multi-scale ionospheric irregularities using ground-based and space-based GNSS observations. First, the relevant background of ionospheric irregularities and their impact on GNSS signals is reviewed. Next, three topics of ground-based observations of ionospheric irregularities for which GNSS and other ground-based techniques are used simultaneously are reviewed. Both passive and active measurements in high-latitude regions are covered. Modelling and observations in mid-latitude regions are considered as well. Emphasis is placed on the increased capability of assessing the multi-scale nature of ionospheric irregularities using other traditional techniques (e.g., radar, magnetometer, high frequency receivers) as well as GNSS observations (e.g., Total-Electron-Content or TEC, scintillation). Besides ground-based observations, recent advances in GNSS space-based ionospheric measurements are briefly reviewed. Finally, a new space-based ionospheric observation technique using GNSS-based spacecraft formation flying and a differential TEC method is demonstrated using the newly developed Virginia Tech Formation Flying Testbed (VTFFTB). Based on multi-constellation multi-band GNSS, the VTFFTB has been developed into a hardware-in-the-loop simulation testbed with external high-fidelity global ionospheric model(s) for 3-satellite formation flying, which can potentially be used for new multi-scale ionospheric measurement mission design.

Using Cluster Analysis to Improve Marketing Experiments

1971 ◽  
Vol 8 (3) ◽  
pp. 340-347 ◽  
Author(s):  
George S. Day ◽  
Roger M. Heeler
Keyword(s):  
Cluster Analysis ◽  
Space Representation ◽  
Reduced Space ◽  
High Degree ◽  
Degree Of Similarity ◽  
Sensitive Experiment ◽  
Selection Of

When the selection of a sample of stores or cities requires a high degree of similarity among the test units in order to ensure a sensitive experiment, the sample may no longer represent the market. These conflicting requirements can be satisfied by choosing the sample from clusters displayed in a reduced space representation of the market.

Are Tetranychus macfarlanei Baker & Pritchard and Tetranychus malaysiensis Ehara (Acari: Tetranychidae) one species? Morphological and molecular evidences for synonymy between these two spider mite species and a note on invasiveness of T. macfarlanei on okra and eggplant in India

2017 ◽  
Vol 22 (4) ◽  
pp. 467
Author(s):  
Mahran Zeity ◽  
Nagappa Srinivas ◽  
Chinnamade Channegowde Gowda
Keyword(s):  
Spider Mite ◽  
Morphological Characters ◽  
Molecular Data ◽  
Mite Species ◽  
Coi Gene ◽  
High Similarity ◽  
Mitochondrial Coi ◽  
Mitochondrial Coi Gene ◽  
High Degree ◽  
Degree Of Similarity

Study of morphological characters of Tetranychus macfarlanei Baker & Pritchard and Tetranychus malaysiensis Ehara revealed high similarity by comparing all the important characters in addition to the characters pointed out by Ehara to separate those two species. Molecular phylogeny of seven Indian populations of T. macfarlanei and one population of T. malaysiensis from Philippines along with few distantly related species of Tetranychus was attempted. High degree of similarity between these two species at mitochondrial COI gene (96%) as well as ITS2 (rDNA) (96–99%) region was evident. Based on both morphological features and molecular data, T. malaysiensis is proposed as a junior synonym of T. macfarlanei based on ICZN’s law of priority. Also more female characters are prompted in this study to distinctly discriminate T. macfarlanei from its most resembling species, Tetranychus ludeni Zacher. Tetranychus macfarlanei has emerged as a pest of several cultivated crop plants in India. 

Jesus in the World of Religions a Preliminary Plotting of a Route Map

1998 ◽  
Vol 5 (3) ◽  
pp. 311-334
Author(s):  
Gerhard Van Den Heever
Keyword(s):  
Comparative Study ◽  
The World ◽  
High Degree ◽  
The Relationship ◽  
Degree Of Similarity

AbstractIn a comparative study the issue is raised about the relationship between the construction of the saviour-image in Christianity, Buddhism, Zoroastrianism and Hinduism. The historical links between these traditions are highlighted and then the article proceeds to argue that when compared, the projections of the images of Jesus and Buddha, Jesus and Zoroaster and Jesus and Krishna exhibit a high degree of similarity. In the process questions are asked about the nature of religion and the value of comparative study.

Dexmedetomidine upregulates the expression of miR-493-5p, inhibiting growth and inducing the apoptosis of lung adenocarcinoma cells by targeting RASL11B

2021 ◽  
pp. 1-8
Author(s):  
Bo Xu ◽  
Yiling Qian ◽  
Chunxiao Hu ◽  
Yongsheng Wang ◽  
Hong Gao ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Luciferase Reporter ◽  
Adenocarcinoma Cell Line ◽  
Expression Levels ◽  
Lung Adenocarcinoma Cell Line ◽  
Adenocarcinoma Cells ◽  
Reporter Assays ◽  
Lung Adenocarcinoma Cells ◽  
High Degree ◽  
Degree Of Similarity

Numerous studies have indicated that microRNAs (miRNAs) play critical roles in the development and progression of cancer. However, how changes to the expression levels of miRNAs in response to dexmedetomidine affects the progression of lung cancer remains poorly understood. In this study, we treated the lung adenocarcinoma cell line-A549 with dexmedetomidine and then examined the changes to the expression levels of miRNAs. We found that one of the most significantly upregulated miRNAs was miR-493-5p, which has an important role in the growth and apoptosis of lung adenocarcinoma (LUAD) cells. In addition, bioinformatics searches and luciferase reporter assays revealed that miR-493-5p targets RASL11B, which has a high degree of similarity to RAS. Finally, database searches revealed that RASL11B is associated with survival of LUAD cells. In conclusion, dexmedetomidine causes changes to the expression levels of miRNAs in LUAD, including significant upregulation of miR-493-5p. MiR-493-5p targets RASL11B, thereby inhibiting cell growth and inducing apoptosis in LUAD.

scholarly journals Origin, Traject and Distribution of Renal Arteries (Arteriae renalis) in Chinchilla lanigera

2018 ◽  
Vol 75 (1) ◽  
pp. 129
Author(s):  
Cristian MARTONOS ◽  
Cristian DEZDROBITU ◽  
Florin STAN ◽  
Aurel DAMIAN ◽  
Alexandru GUDEA
Keyword(s):  
Renal Artery ◽  
Renal Arteries ◽  
Left Renal Artery ◽  
Lateral Part ◽  
Formaldehyde Solution ◽  
Anatomical Dissection ◽  
The Right ◽  
High Degree ◽  
Aorta Abdominalis ◽  
Degree Of Similarity

For the present study a number of 5 female chinchilla carcasses were used. The animals were slaughtered for commercial purpuses (fur). The anatomical dissection started with the identification of the aorta (Aorta abdominalis). The next step was the intra-arterial injection of a colouring substance. The carcasses was fixed in the formaldehyde solution and subsequently the renal arteries were dissected. The first renal artery was the right renal artery (Arteria renalis dextra) and, at 0,5 cm caudally, the left renal artery (Arteria renalis sinister) arose . The origin of those arteries were disposed on the lateral part of the abdominal aorta.The origin, traject and distribution of renal arteries on the studied species have a high degree of similarity with the literature dates described for leporids.

scholarly journals Aurora and open magnetic flux during isolated substorms, sawteeth, and SMC events

2007 ◽  
Vol 25 (8) ◽  
pp. 1865-1876 ◽  
Author(s):  
A. D. DeJong ◽  
X. Cai ◽  
R. C. Clauer ◽  
J. F. Spann
Keyword(s):  
Magnetic Flux ◽  
Temporal Variations ◽  
Auroral Oval ◽  
Polar Cap ◽  
Expansion Phase ◽  
Magnetospheric Convection ◽  
Open Magnetic Flux ◽  
Open Flux ◽  
The Individual

Abstract. Using Polar UVI LBHl and IMAGE FUV WIC data, we have compared the auroral signatures and polar cap open flux for isolated substorms, sawteeth oscillations, and steady magnetospheric convection (SMC) events. First, a case study of each event type is performed, comparing auroral signatures and open magnetic fluxes to one another. The latitude location of the auroral oval is similar during isolated substorms and SMC events. The auroral intensity during SMC events is similar to that observed during the expansion phase of an isolated substorm. Examination of an individual sawtooth shows that the auroral intensity is much greater than the SMC or isolated substorm events and the auroral oval is displaced equatorward making a larger polar cap. The temporal variations observed during the individual sawtooth are similar to that observed during the isolated substorm, and while the change in polar cap flux measured during the sawtooth is larger, the percent change in flux is similar to that measured during the isolated substorm. These results are confirmed by a statistical analysis of events within these three classes. The results show that the auroral oval measured during individual sawteeth contains a polar cap with, on average, 150% more magnetic flux than the oval measured during isolated substorms or during SMC events. However, both isolated substorms and sawteeth show a 30% decrease in polar cap magnetic flux during the dipolarization (expansion) phase.

scholarly journals Histological and morphometric study of the uterus of the lowland bison

2017 ◽  
Vol 73 (10) ◽  
pp. 661-665
Author(s):  
Katarzyna Olbrych ◽  
Karolina Barszcz ◽  
Bartłomiej Bartyzel ◽  
Tomasz Szara ◽  
Marta Kupczyńska
Keyword(s):  
Morphometric Study ◽  
European Bison ◽  
Histological Structure ◽  
Group I ◽  
Epithelium Thickness ◽  
Polish Law ◽  
And Function ◽  
High Degree ◽  
Sexually Mature ◽  
Degree Of Similarity

Summary The European bison belongs to endangered species. Its restitution requires a complete knowledge of the structure and function of its genital organs. The aim of this study was a histological and morphometric examination of the uterus of immature and adult females. Material for the study came from 55 females living in the Białowieża Forest. According to the Polish law, the post mortem use of tissues does not require an approval from an ethics committee. The animals were divided into 2 groups: group I included 36 prepubertal females aged from 2 months to 1.5 years, while group II consisted of 19 sexually mature females aged 2 to 20 years. The samples were stained with haematoxylin and eosin (H&E). Histological and morphometric examinations included measurements of the height of the epithelium, thickness of the endometrium, thickness of the myometrium, thickness of the inner and outer muscular layers, and thickness of the perimetrium. The results were analyzed using the STATISTICA 12.0™ software. Statistically significant differences were found between the two groups in all morphometric parameters examined. The results revealed a high degree of similarity of the histological structure of the uterus between European bison and domestic cattle.

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