Polytropic star structure analysis under Bonnor–Ebert gas sphere astrophysical configuration thorough investigating analytical solutions to the related Lane–Emden equation

In this paper, Bonnor–Ebert gas sphere model of polytropic stars has been investigated through an analytical approach. Two confirmed and well-established methods have been used: the Enhanced Lagrangian Formulation Method ELFM and the Boubaker Polynomials Expansion Scheme BPES. Solutions to the related generalized Lane–Emden equation of the second kind have been expressed and plotted. Results have given evidence to the relevance of the dimensionless Bonnor–Ebert radius, in good agreement with some recently proposed profiles.     

Signal transduction in T lymphocytes--a comparison of the data from space, the free fall machine and the random positioning machine.

In this paper we discuss the effect of microgravity on T cells and we present the data of studies with two new machines for 0 g simulations. Several experiments in space show that mitogenic T cell activation is lost at 0 g. Immunocytochemistry indicates that such effect is associated with changes of the cytoskeleton. Biochemical studies suggest that the lack of expression of the interleukin-2 receptor is one of the major causes of the loss of activity. In fact, interleukin-2 is the third signal required for full activation. In order to deepen our investigations we are now working with the free-fall machine, FFM, invented by D. Mesland, and with the random positioning machine, RPM, or three-dimensional clinostat, developed by T. Hoson. The FFM produces periods of free-fall lasting approximately 800 ms followed by bounces of 15-30 g lasting 45-60 ms. The RPM eliminates the effect of gravity by rotating biological specimen randomly around two orthogonal axes. While the FFM failed to reproduce the results obtained with T lymphocytes in space, the data from the RPM are in good agreement with those in real microgravity. In fact, the inhibition of the mitotic index in the RPM is 89% compared to static controls. The RPM (as the FFM) can carry markedly larger specimen than the fast rotating clinostat and thus allows to conduct comprehensive studies to select suitable biological objects for further investigations in space.     

Influence of the 27-day solar flux variations on the ionosphere parameters measured at Irkutsk in 2003–2005

We present an investigation of the influence of the 27-day solar flux variations, caused by solar rotation, on the ionosphere parameters such as the F2 layer critical frequency (foF2) and the total electron content (TEC). Our observational data were obtained with the Irkutsk Digisonde (DPS-4) located at 52.3 North and 104.3 East during the period from 2003 to 2005. In addition, we use TEC data from the Global Ionosphere Maps (GIM) based on Global Positioning System (GPS) satellites. The solar radiation flux at a wavelength of 10.7 cm (F10.7 index) is used as an index characterizing the solar activity level. A good correlation between observed ionosphere parameters and solar activity variations is found especially in autumn-to-winter season. We estimate the impact of the 27-day solar flux variations on the day-to-day variability and determine the time delay of the ionosphere response.