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Volume3, Issue1

Postremum

EDITORIAL

Page 1PDFEditorial

S. B. Lisesivdin


ARTICLES

Page 2: PDFSpecial relativity with synchrony parameters

B. Rothenstein, M. Costache

Abstract: We show that the transformation equations for the space-time coordinates of the same event, derived on the basis of the constancy of the round trip speed of light, could be derived by performing the Lorentz-Einstein transformations of the event generated by a subluminal one way signal when it arrives at the location of the clock to be synchronized with the clock located at the origin of the inertial reference frame. Considering that it propagates with speed cf=c/n (n>1), n dependent “general transformation equations are derived. Particular values of n are considered, leading to absolute simultaneity.


Page 13: PDFMagnetic phase diagram of semimagnetic semiconductor Cu2(1-x)MnxGa2Se4 systems

R. Masrour, M. Hamedoun, A. Benyoussef, A. Hourmatallah, K. Bouslykhane, N. Benzakour

Abstract: The magnetic properties of the Cu2(1-x)MnxGa2Se4 systems in the range 0.75<x<1 have been studied by mean field theory and high-temperature series expansions (HTSE). By using the first theory, we have evaluated the nearest neighbour and the next-nearest exchange interaction J1(x) and J2(x) respectively. The intra-planar and the inter-planar interactions are deduced. The corresponding classical exchange energy for magnetic structure is obtained for this system. The second theory combined with the Padé approximants (P.A) method are applied to the Cu2(1-x)MnxGa2Se4 systems; we have obtained the magnetic phase diagram (TN versus dilution x) in the range 0.75<x<1. The obtained theoretical results are in agreement with experimental results obtained by magnetic measurements. The critical exponents associated with the magnetic susceptibility and the correlation lengths are deduced in the range order 0.75<x<1.


Page 19: PDFSignificance of two types of high-speed solar wind streams in modulating cosmic ray intensity 

R. K. Mishra, R. Agarwal

Abstract: One of the most dynamical interplanetary phenomena of solar terrestrial physics is definitely the passage of solar wind streams near the Earth environment. In this work, we have identified the two types of high-speed solar wind streams using the spacecraft data during high amplitude days. The behaviour of high-speed solar wind streams during high amplitude anisotropic wave trains is investigated for the period 1981-1994. The two types of high-speed solar wind streams (corotating streams and flare-generated streams) produce significant deviations in cosmic ray intensity during high amplitude anisotropic wave trains. On the onset of both types of streams the cosmic ray intensity reaches its minimum during high amplitude events and then increases statistically. It has been observed that both types of solar wind streams (Corotating and Flare generated) produce significant deviations in cosmic ray intensity during high amplitude anisotropic wave train events.


Page 25PDFSignificance of interplanetary plasma and magnetic field features in modulating cosmic rays

R. K. Mishra, R. Agarwal

Abstract: This work deals with the time evolution of the three harmonics of the unusual diurnal variation of cosmic ray intensity during high amplitude anisotropic wave trains. The relation of these harmonics to interplanetary parameters such as Dst-index, Ap-index, solar wind speed and interplanetary magnetic field (Bz) is investigated in order to found the possible origin of these anisotropic wave trains and to develop a suitable theoretical model. The first three harmonics of high amplitude anisotropic wave trains of cosmic ray intensity over the period 1991-1994 have been investigated for Deep River neutron monitoring station. It is noteworthy that the amplitude of all the three harmonics remains high whereas, the direction of first harmonic shift towards earlier hours and towards later hours for second and third harmonic compared to quite day annual average. The Bz component of interplanetary magnetic field, the disturbance storm time index (Dst) and geomagnetic activity index (Ap) shows good impact on direction of first harmonic, amplitude of third harmonic and direction of third harmonic respectively. High amplitude anisotropic wave train events seem to weakly dependent on solar wind velocity.