scholarly journals Morphology of NmF2 nighttime increases in the Eurasian sector

2000 ◽  
Vol 18 (6) ◽  
pp. 618-628 ◽  
Author(s):  
A. V. Mikhailov ◽  
T. Yu. Leschinskaya ◽  
M. Förster
Keyword(s):  
Solar Activity ◽  
Statistical Analysis ◽  
Electric Fields ◽  
Solar Maximum ◽  
Occurrence Probability ◽  
Summer Peak ◽  
Longitudinal Sector ◽  
Electric Fields And Currents ◽  
Two Peaks ◽  
Second Peak

Abstract. A statistical analysis of two peaks (pre-midnight and post-midnight) occurrence in NmF2 daily variations was made on a latitudinal chain of four ionosonde stations in the Eurasian longitudinal sector. Overall 6182 cases of the first and 5600 cases of the second peak occurrence were analyzed using all available foF2 observations for the years of solar maximum and minimum. Well-pronounced and systematic variations with season and solar activity were revealed in the occurrence probability of the peaks, their amplitude and timing. The pattern of both peaks occurrence is similar during winter and equinoxes for midlatitude stations implying one and the same mechanism of their formation. The pre-midnight summer peak shows specific variations in particular during solar maximum pointing to a different mechanism controlling its appearance. Possible mechanisms of both peaks formation are discussed.Key words: Ionosphere (electric fields and currents; ionosphere-magnetosphere interactions; mid-latitude ionosphere)

scholarly journals Seasonal activity of ixodid ticks in Podilskyi region

2020 ◽  
Vol 22 (100) ◽  
pp. 66-70
Author(s):  
V. A. Levytska
Keyword(s):  
Climate Change ◽  
Veterinary Medicine ◽  
Statistical Analysis ◽  
Economic Globalization ◽  
Ixodid Ticks ◽  
Seasonal Activity ◽  
Average Temperature ◽  
Two Peaks ◽  
Second Peak ◽  
Experimental Plots

Ixodid ticks are the most important arthropod hematophagies in veterinary medicine. The spread of ticks and tick borne diseases is linked to human activities, including habitat change, deforestation, economic globalization, international animal movements, urbanization and climate change. The research was conducted from March 2018 to March 2019 in Khmelnytsky region. In total were collected 2086 D. reticulatus ticks and 658 I. ricinus ticks. During the studies, two peaks of seasonal activity of both species of ticks were observed according to the average number of specimens in the three study areas. Spring activity began in March, and the peak was observed in April. Males were found to be more active in March and the first half of April, while females dominated males from late May to late June. The second peak of activity in the study area began in mid-September. Since the beginning of September, the activity of ticks has increased almost eight times compared to August. The peak of autumn activity was observed in late October and early November. Active females dominated males from early October to late autumn. From mid-June to mid-September, single specimens of ticks were detected. During the winter, no ticks were found in the experimental plots. On average, in all experimental areas of Khmelnytsky region, ticks were active at a temperature of 10.8 to 27.8 °C (average temperature – 21.6 ± 6.57 °C) and humidity – 39.90–78.20 % (average humidity – 61.79 %). Statistical analysis performed for all study areas showed that air temperature significantly affected the activity of both species of ticks. However, correlations between the number of ticks collected and humidity throughout the study area and in different areas were not observed separately. The largest number of ticks was collected during the period when daylight lasted approximately 12–14 hours; in turn, the lowest number of ticks was detected on days with more than 15 hours of daylight. Statistical analysis confirmed the correlation between the length of daylight and the activity of ticks of both species.

scholarly journals The study of multipeaked type-I X-ray bursts in the neutron star low-mass X-ray binary 4U 1636 − 536 with RXTE

2020 ◽  
Vol 501 (1) ◽  
pp. 168-178
Author(s):  
Chen Li ◽  
Guobao Zhang ◽  
Mariano Méndez ◽  
Jiancheng Wang ◽  
Ming Lyu
Keyword(s):  
Neutron Star ◽  
Flux Ratio ◽  
Light Curves ◽  
Type I ◽  
X Ray ◽  
Soft State ◽  
Peak Flux ◽  
Low Mass ◽  
Two Peaks ◽  
Second Peak

ABSTRACT We have found and analysed 16 multipeaked type-I bursts from the neutron-star low-mass X-ray binary 4U 1636 − 53 with the Rossi X-ray Timing Explorer (RXTE). One of the bursts is a rare quadruple-peaked burst that was not previously reported. All 16 bursts show a multipeaked structure not only in the X-ray light curves but also in the bolometric light curves. Most of the multipeaked bursts appear in observations during the transition from the hard to the soft state in the colour–colour diagram. We find an anticorrelation between the second peak flux and the separation time between two peaks. We also find that in the double-peaked bursts the peak-flux ratio and the temperature of the thermal component in the pre-burst spectra are correlated. This indicates that the double-peaked structure in the light curve of the bursts may be affected by enhanced accretion rate in the disc, or increased temperature of the neutron star.

Computational assessment of effects of electric fields and currents in tokamak edge plasmas

1995 ◽  
Vol 220-222 ◽  
pp. 982-986 ◽  
Author(s):  
M. Baelmans ◽  
D. Reiter ◽  
R.R. Weynants ◽  
R. Schneider
Keyword(s):  
Electric Fields ◽  
Tokamak Edge ◽  
Edge Plasmas ◽  
Electric Fields And Currents

scholarly journals Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India

2002 ◽  
Vol 20 (12) ◽  
pp. 1977-1985 ◽  
Author(s):  
R. Sridharan ◽  
C. V. Devasia ◽  
N. Jyoti ◽  
Diwakar Tiwari ◽  
K. S. Viswanathan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Solar Eclipse ◽  
Equatorial Ionosphere ◽  
Hf Radar ◽  
F Region ◽  
Large Enhancement ◽  
Temporal Structures ◽  
E Region ◽  
Field Lines ◽  
Electric Fields And Currents

Abstract. The effects on the electrodynamics of the equatorial E- and F-regions of the ionosphere, due to the occurrence of the solar eclipse during sunset hours on 11 August 1999, were investigated in a unique observational campaign involving ground based ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5° N; 77° E; dip lat. 0.5° N), India. The study revealed the nature of changes brought about by the eclipse in the evening time E- and F-regions in terms of (i) the sudden intensification of a weak blanketing ES-layer and the associated large enhancement of the VHF backscattered returns, (ii) significant increase in h' F immediately following the eclipse and (iii) distinctly different spatial and temporal structures in the spread-F irregularity drift velocities as observed by the HF radar. The significantly large enhancement of the backscattered returns from the E-region coincident with the onset of the eclipse is attributed to the generation of steep electron density gradients associated with the blanketing ES , possibly triggered by the eclipse phenomena. The increase in F-region base height immediately after the eclipse is explained as due to the reduction in the conductivity of the conjugate E-region in the path of totality connected to the F-region over the equator along the magnetic field lines, and this, with the peculiar local and regional conditions, seems to have reduced the E-region loading of the F-region dynamo, resulting in a larger post sunset F-region height (h' F) rise. These aspects of E-and F-region behaviour on the eclipse day are discussed in relation to those observed on the control day.Key words. Ionosphere (electric fields and currents; equatorial ionosphere; ionospheric irregularities)

scholarly journals Regional estimation of electric fields and currents in the polar ionosphere

1995 ◽  
Vol 22 (3) ◽  
pp. 283-286 ◽  
Author(s):  
Mariko Sato ◽  
Y. Kamide ◽  
A. D. Richmond ◽  
A. Brekke ◽  
S. Nozawa
Keyword(s):  
Electric Fields ◽  
Polar Ionosphere ◽  
Regional Estimation ◽  
Electric Fields And Currents

scholarly journals The effect of the stratospheric QBO on the neutral density of the D region

2015 ◽  
Vol 58 (3) ◽  
Author(s):  
Selçuk Sağır ◽  
Ramazan Atıcı ◽  
Osman Özcan ◽  
Nurullah Yüksel
Keyword(s):  
Statistical Analysis ◽  
Solar Maximum ◽  
Unit Root Test ◽  
Multiple Regression Model ◽  
Neutral Density ◽  
Solar Cycles ◽  
Ion Chemistry ◽  
Integration Test ◽  
D Region ◽  
The Relationship

<p>A multiple regression model, which defines relationship between two variables, is used to perform a statistical analysis of the relationship between the stratospheric QBO and the neutral density of the D region (N<sub>n</sub>D) at altitudes of 75 km and 90 km for Singapore station. While performing the analysis, the solar maxima and solar minima epochs of the sun for 21st, 22nd and 23rd solar cycles (SCs) are taken into account. Before applying the model for the statistical analysis of the relationship, the stationary of the variables is investigated by using the unit root test. The relationship between the variables is also investigated by using the co-integration test. The relationship between N<sub>n</sub>D measured at 75 km altitude and QBO obtained at altitude of 10 hPa is observed that it is positive for solar maximum epoch at 21st and 23rd SCs and for solar minimum epoch at 21st SC and is negative at the other epochs. The relationship between N<sub>n</sub>D measured at 90 km altitude and QBO is observed to be negative at both the solar maxima expect for solar maximum of 23rd SC and the solar minima epochs. The relationship between variables is positive for both phases (east and west) of QBO. Thus, QBO leads to a statistical change in the N<sub>n</sub>D. It may also give rise to changes on the ion chemistry of the D region.</p>

scholarly journals Reflectance Spectrum of a Color Blue Generated by Curved Multilayer and Iridescent of the Elytron of the Calidea Signata Bug

2016 ◽  
Vol 12 (36) ◽  
pp. 1
Author(s):  
Issaka Ouedraogo ◽  
Serge Wendsida Igo ◽  
Priscilla Simonis ◽  
Alioune Ouedraogo ◽  
Belkacem Zeghmati
Keyword(s):  
Multilayer Structure ◽  
Reflectance Spectrum ◽  
Main Peak ◽  
Blue Color ◽  
Transfer Matrices ◽  
Microscopy Characterization ◽  
Two Peaks ◽  
Second Peak ◽  
Scanning Electron Microscopy Characterization ◽  
Scanning Electron

This paper focuses on the study of the origins of blue iridescent reflections of the elytron of Calidea Signata, of the pentatomidae family which is commonly known as bug. Indeed, we use the spectrophotometry measurements, scanning electron microscopy characterization technique, and a ray tracing code program combined with the transfer matrices method, to explain the structure which is responsible for the color of the blue reflections and the iridescent effect. Thus, we noticed that the color of the bug as a result of two peaks. The first and main peak is located at 485.5 nm, corresponding to the blue color. The second peak, is less intense at 525 nm, corresponding to the green-blue color. The numerical reproduction of the reflectance spectrum gives 510.25 nm for the main peak, and 539.5 nm for the secondary peak. These results confirm that the multilayer structure is responsible for the blue color of the Calidea Signata bug. Lastly, the curve of the multilayer is responsible for the iridescence.

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