scholarly journals Investigation of the relationship between optical auroral forms and HF radar E region backscatter

2000 ◽  
Vol 18 (6) ◽  
pp. 608-617 ◽  
Author(s):  
S. E. Milan ◽  
M. Lester ◽  
N. Sato ◽  
H. Takizawa ◽  
J.-P. Villain
Keyword(s):  
Spectral Characteristics ◽  
Hf Radar ◽  
Vhf Radar ◽  
The Past ◽  
Optical Signature ◽  
E Region ◽  
Coherent Backscatter ◽  
First Time ◽  
The Relationship ◽  
East West

Abstract. The SuperDARN HF radars have been employed in the past to investigate the spectral characteristics of coherent backscatter from L-shell aligned features in the auroral E region. The present study employs all-sky camera observations of the aurora from Husafell, Iceland, and the two SuperDARN radars located on Iceland, Þykkvibær and Stokkseyri, to determine the optical signature of such backscatter features. It is shown that, especially during quiet geomagnetic conditions, the backscatter region is closely associated with east-west aligned diffuse auroral features, and that the two move in tandem with each other. This association between optical and radar aurora has repercussions for the instability mechanisms responsible for generating the E region irregularities from which radars scatter. This is discussed and compared with previous studies investigating the relationship between optical and VHF radar aurora. In addition, although it is known that E region backscatter is commonly observed by SuperDARN radars, the present study demonstrates for the first time that multiple radars can observe the same feature to extend over at least 3 h of magnetic local time, allowing precipitation features to be mapped over large portions of the auroral zone.Key words: Ionosphere (particle precipitation; plasma waves and instabilities)

Die Bundeswehr und die Belgischen Streitkräfte in Deutschland

2021 ◽  
Author(s):  
Jonas Springer
Keyword(s):  
Local Level ◽  
Military Training ◽  
Armed Forces ◽  
History Of ◽  
Military Training Areas ◽  
The Military ◽  
First Time ◽  
The Relationship ◽  
Peak Phase ◽  
East West

This study is dedicated to the regional history of the East-West conflict on the basis of the relationship between the Germany military and the Belgian armed forces stationed in Germany. The central question it addresses is which factors were largely responsible for the interdependence between actors and institutions of both armies. In addition to analysing the limited time of the peak phase of Belgian military deployment in the Federal Republic 1946–1990, the book concentrates regionally on the military training areas of Vogelsang in the Eifel and the Wahner Heide near Cologne as military contact zones. For this purpose, the author evaluates unpublished archival sources at the local level for the first time.

scholarly journals V. Bryusov’s Letters to His Fiancée

Literary Fact ◽  
2021 ◽  
pp. 8-30
Author(s):  
Monika V. Orlova
Keyword(s):  
Young People ◽  
Full Text ◽  
Terminally Ill ◽  
The Past ◽  
The Future ◽  
State Of Mind ◽  
First Time ◽  
The Village ◽  
The Relationship

The publication includes V.Ya. Bryusov’s letters to his fiancée I.M. Runt (1876 –1965) from June 9 to September 9, 1897. 11 correspondences, including the final telegram sent from Kursk, were written and sent from Aachen (Germany), Moscow and several Ukrainian localities. The letter 10 is accompanied by the full text of I.M. Runt’s only surviving letter to Bryusov, sent from Moscow to the village of Bolshye Sorochintsy and received by the poet a few months later at home. The relationship between the young people before the wedding were complicated. While the poet was preparing for the wedding in Moscow, he summed up the past contacts with “mes amantes”, and his state of mind was painful. Shortly before meeting his future wife, Bryusov broke up with the former governess of his family E.I. Pavlovskaya, who was terminally ill. A few days before the wedding he decided to go to say goodbye to Pavlovskaya to her homeland, Ukraine. In his letters to the future wife the poet tried to smooth out the tension of the situation, perhaps anticipating that he would be bounded with I.M. Runt 30 Литературный факт. 2021. № 2 (20) by a long-term relationship, where life and literature are closely interconnected. The letters are published for the first time.

scholarly journals Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region

2005 ◽  
Vol 23 (3) ◽  
pp. 773-779 ◽  
Author(s):  
A. K. Patra ◽  
S. Sripathi ◽  
P. B. Rao ◽  
K. S. V. Subbarao
Keyword(s):  
Low Latitude ◽  
Vhf Radar ◽  
Radar Echoes ◽  
First Results ◽  
E Region ◽  
Gradient Drift ◽  
Drift Instability ◽  
Relationship Of ◽  
The Relationship ◽  
Field Aligned Irregularities

Abstract. The first results of simultaneous observations made on the low-latitude field-aligned irregularities (FAI) using the MST radar located at Gadanki (13.5° N, 79.2° E, dip 12.5°) and the Es parameters using an ionosonde at a nearby station Sriharikota (13.7° N, 80.1° E, dip 12.6°) are presented. The observations show that while the height of the most intense radar echoes is below the virtual height of Es (h'Es) during daytime, it is found to be either below or above during nighttime. The strength of the FAI is better correlated with the top penetration frequency (ftEs) and the blanketing frequency (fbEs) during the night (r=0.4 in both cases) as compared to the day (r=0.35 and -0.04, respectively). Furthermore, the signal strength of FAI is reasonably correlated with (ftEs-fbEs) during daytime (r=0.59) while very poorly correlated during nighttime (r=0.18). While the radar observations in general appear to have characteristics close to that of mid-latitudes, the relationship of these with the Es parameters are poorer than that of mid-latitudes. The observations reported here, nevertheless, are quite consistent with the expectations based on the gradient drift instability mechanism.

The relationship between semblance and eigenstructure velocity estimators

Geophysics ◽  
1992 ◽  
Vol 57 (8) ◽  
pp. 1027-1033 ◽  
Author(s):  
R. Lynn Kirlin
Keyword(s):  
Seismic Signal ◽  
Resolving Power ◽  
Velocity Spectrum ◽  
Visual Appearance ◽  
The Past ◽  
Spectral Estimators ◽  
Velocity Spectra ◽  
Subspace Separation ◽  
First Time ◽  
The Relationship

This short presentation gives for the first time a formulation of the semblance coefficient in terms of data covariance matrix eigenstructure. Because the high‐resolution wavefront or spectral eigenstructure methods have received so much interest over the past decade, it is necessary to analytically tie the conventionally used semblance produce to eigenstructure, thereby allowing the seismic signal analyst an opportunity to relate the various displays of velocity spectra using more than visual appearance. The eigenstructure form of semblance is compared to a number of the now well‐known eigenstructure‐based spectral estimators that separate signal and noise (vector) subspaces. Because of the inclusion of noise‐space energy in the coherence measure, conventional semblance does not have the resolving power of the newer methods. We suggest an enhanced semblance, based on the signal and noise subspace separation concept. A brief simulation verifies the visual improvement in the velocity spectrum obtained from the enhanced version.

scholarly journals Multi-frequency observations of E-region HF radar aurora

2003 ◽  
Vol 21 (3) ◽  
pp. 761-777 ◽  
Author(s):  
S. E. Milan ◽  
M. Lester ◽  
N. Sato
Keyword(s):  
Doppler Shift ◽  
Hf Radar ◽  
Low Flow ◽  
Wave Number ◽  
Electron Drift ◽  
Doppler Shifts ◽  
Ion Acoustic ◽  
E Region ◽  
Coherent Backscatter ◽  
Acoustic Speed

Abstract. Multi-frequency observations of E-region coherent backscatter from decametre waves reveal that auroral echoes tend to comprise two spectral components superimposed, one at low Doppler shifts, below 250 ms-1, and the other Doppler shifted to near the ion-acoustic speed or above, up to 800 ms-1. The low Doppler shift component occurs at all look directions; Doppler shifts near the ion acoustic speed occur when looking at low flow angles along the direction of the electron drift in the electrojet, and Doppler shifts in excess of the ion acoustic speed occur at intermediate flow angles. The latter population appears most commonly at radar frequencies near 10–12 MHz, with its occurrence decreasing dramatically at higher frequencies. The velocity of the high Doppler shift echoes increases with increasing radar frequency, or irregularity wave number k. The velocity of the low Doppler shift population appears to be suppressed significantly below the line-of-sight component of the electron drift. Initial estimates of the altitude from which scatter occurs suggest that the high Doppler shift echoes originate from higher in the E-region than the low Doppler shift echoes, certainly in the eastward electrojet. We discuss these observations with reference to the theories of de/stabilization of two-stream waves by electron density gradients and electrostatic ion cyclotron waves excited by field-parallel electron drifts.Key words. Ionosphere (ionospheric irregularities)

Islam in France and France in the Territory of Islam in the Late 18th — First Half of the 19th Century

Istoriya ◽  
2021 ◽  
Vol 12 (5 (103)) ◽  
pp. 0
Author(s):  
Evgeniya Prusskaya
Keyword(s):  
19Th Century ◽  
North Africa ◽  
Diplomatic Relations ◽  
The Past ◽  
Colonial Experience ◽  
Muslim Majority ◽  
19Th Century France ◽  
The 19Th Century ◽  
First Time ◽  
The Relationship

In the first half of the 19th century France began an active colonial penetration into the region of the Middle East and North Africa, to the territories inhabited mainly by Muslims. Despite its rich colonial experience in the past and long-standing trade and diplomatic relations with the Ottoman Empire, France for the first time met Islam so closely and faced the necessity to govern the territories inhabited by a Muslim majority. This article provides an overview of the relationship between France and Islam at the end of the 18th and first half of the 19th centuries, analyzes the process of awakening interest in this religion among the French and examines the first political steps towards Islam, undertaken by the French authorities during this unstable period, which saw three revolutions in France.

scholarly journals A first comparison of irregularity and ion drift velocity measurements in the E-region

2006 ◽  
Vol 24 (9) ◽  
pp. 2375-2389 ◽  
Author(s):  
R. A. Makarevich ◽  
F. Honary ◽  
V. S. C. Howells ◽  
A. V. Koustov ◽  
S. E. Milan ◽  
...  
Keyword(s):  
Drift Velocity ◽  
Hf Radar ◽  
Electron Velocity ◽  
Velocity Measurements ◽  
Vhf Radar ◽  
Positive Correlation ◽  
Ion Drift ◽  
E Region ◽  
Ion Velocity ◽  
Large Flow

Abstract. E-region irregularity velocity measurements at large flow angles with the STARE Finland coherent VHF radar are considered in context of the ion and electron velocity data provided by the EISCAT tristatic radar system, CUTLASS Finland coherent HF radar, and IMAGE fluxgate magnetometers. The data have been collected during a special experiment on 27 March 2004 during which EISCAT was scanning between several E- and one F-region altitudes along the magnetic field line. Within the E-region, the EISCAT measurements at two altitudes of 110 and 115 km are considered while the electron velocity is inferred from the EISCAT ion velocity measurements at 278 km. The line-of-sight (l-o-s) VHF velocity measured by STARE VHF los is compared to the ion and electron velocity components (Vi0 comp and Ve0 comp) along the STARE l-o-s direction. The comparison with Ve0 comp for the entire event shows that the measurements exhibit large scatter and small positive correlation. The correlation with Ve0 comp was substantial in the first half of the interval under study when Ve0 comp was larger in magnitude. The comparison with Vi0 comp at 110 and 115 km shows a considerable positive correlation, with VHF velocity being typically larger (smaller) in magnitude than Vi0 comp at 110 km (115 km) so that VVHF los appears to be bounded by the ion velocity components at two altitudes. It is also demonstrated that the difference between VVHF los and Vi0 comp at 110 km can be treated, in the first approximation, as a linear function of the effective backscatter height heff also counted from 110 km; heff varies in the range 108–114 km due to the altitude integration effects in the scattering cross-section. Our results are consistent with the notion that VHF velocity at large flow angles is directly related to the ion drift velocity component at an altitude heff.

scholarly journals A Pilot Study on Effects of Acupuncture and Moxibustion by Hyperspectral Imaging Technique

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Dong Zhang ◽  
Yin-long Li ◽  
Shu-you Wang ◽  
Xiao-dong Bai ◽  
Xiao-jing Song ◽  
...  
Keyword(s):  
Hyperspectral Imaging ◽  
Light Absorption ◽  
Spectral Characteristics ◽  
Control Group ◽  
Wave Band ◽  
Absorption Intensity ◽  
Acupuncture And Moxibustion ◽  
And Control ◽  
First Time ◽  
The Relationship

This study was to observe the effects of acupuncture and moxibustion on spectrum features of acupoint using hyperspectral imaging (HSI) technique. HSI of the Neiguan (PC6) in the acupuncture groups, moxibustion groups, and control groups was scanned by the hyperspectral imager to analyze the spectrum features and the variations within the wavelength of 400–1000 nm and explore the relationship between the spectral characteristics and effects of acupuncture and moxibustion. The light absorption intensity was slightly reduced within the wave band of 540–590 nm after acupuncture. The absorption intensity of PC6 before moxibustion was significantly higher than that after moxibustion, and the maximum reduction was found at the wavelength of 580 nm with 20.5% reduction,P<0.05. There was no significant change of the spectrum of palm and PC6 and the spectrum curves of the acupoint were basically identical in control group. The light absorption intensity of PC6 of human body was weakened after Acu-mox. Specific wavelengths were all exhibited at 580 nm and the effect of moxibustion was more significant. HSI technique can be used to measure the spectral characteristics of the acupoint areas. This first time research would be significant and beneficial for study on the effect of acupuncture and moxibustion.

scholarly journals The spectral characteristics of E-region radar echoes co-located with and adjacent to visual auroral arcs

2002 ◽  
Vol 20 (6) ◽  
pp. 795-805 ◽  
Author(s):  
S. E. Milan ◽  
N. Sato ◽  
M. Lester ◽  
T. K. Yeoman ◽  
Y. Murata ◽  
...  
Keyword(s):  
Electric Fields ◽  
Spectral Characteristics ◽  
Hf Radar ◽  
Radar Backscatter ◽  
Acoustic Instability ◽  
Radar Echoes ◽  
Close Relationship ◽  
E Region ◽  
Auroral Arcs ◽  
Gradient Drift

Abstract. Simultaneous all-sky camera and HF radar observations of the visual and E-region radar aurora in the west-ward electrojet suggest a close relationship between a pair of parallel east-west-aligned auroral arcs, separated by ~ 30 km, and a region of strong radar backscatter. Poleward of this a broader region of radar backscatter is observed, though the spectral characteristics of the echoes in these two regions differ considerably. We suggest that the visual aurorae and their radar counterparts are produced in a region of upward field-aligned current (FAC), whereas the backscatter poleward of this is associated with downward FAC. Relatively low electric fields ( ~ 10 mV m-1) are observed in the vicinity of the arc system, suggesting that in this case, two-stream waves are not directly generated through the electrodynamics of the arc. Rather, the generation of irregularities is most probably associated with the gradient drift instability operating within horizontal electron density gradients produced by the filamentary nature of the arc FAC system. The observation of high Doppler shift echoes superimposed on slow background flow within the region of backscatter poleward of the visual aurora is argued to be consistent with previous suggestions that the ion-acoustic instability threshold is reduced in the presence of upwelling thermal electrons carrying downward FAC.Key words. Ionosphere (auroral ionosphere; ionospheric irregularities; particle precipitation)

Introduction

2006 ◽  
Vol 14 (3) ◽  
pp. 369-372
Author(s):  
NICHOLAS CANNY
Keyword(s):  
Nineteenth Century ◽  
Social Preferences ◽  
The West ◽  
The Past ◽  
National Archives ◽  
Public Record ◽  
The Moment ◽  
National Libraries ◽  
First Time ◽  
The Relationship

This Focus addresses the relationship between historians and the societies they serve, particularly since the later nineteenth century when, for the first time, historians began to define themselves as a distinct professional group. One of the conclusions that emerges from the four case studies pursued here is that the independence of judgement which professionalism implies, founders the moment it is perceived by a wider public that historians are no longer providing them with the moral guidance they expect from those who have studied their pasts. It is also shown that the challenges and responses did not prove identical in any two sets of circumstances. This introduction also makes reference to general challenges to which individual contributors do not necessarily refer, but which have impacted on the work and independence of all historians.Historians, both now and in the past, have been aware that what they write is, of necessity, influenced by their personal circumstances as also by their political and social preferences. Perhaps out of recognition of this, some writers of history in all centuries, and possibly from every culture, have celebrated their ability to shape policy in the present by citing experiences from past times. Then, in the nineteenth century, as governments in the west established Public Record Offices, National Archives and National Libraries, it came to be accepted in that part of the world that historians were professionals who, having undertaken a prescribed course of training, were uniquely equipped to assess how politicians and diplomats in the past had conducted their business.

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