A Maximum of Temperature in the Middle Ionosphere
J. FUCHS1 has already pointed out the fact that from the change of electron-density (N) with height (h) conclusions as to the temperature in the ionosphere can be drawn. It was, however, not possible then to carry out exact calculations for two reasons: first, the electron-density was only known to be dependent on the apparent height (h′), and secondly, the process of electron loss was not known in more detail, so that Fuchs had to calculate with a recombination-coefficient constant as to space and time.
A study of lymphocyte behavior in cultures of fibroblast-like lymphoreticular cells.
Abstract Fibroblast-like reticular cells were isolated from mouse lymph node and spleen and maintained in culture. These cells were found to be highly phagocytic and possess receptors for the Fc portion of immunoglobulin and for activated complement. These cells, unlike fibroblasts from other sources, were found to bind both syngeneic and allogeneic thymocytes and peripheral lymphocytes in large numbers. Thymocytes consistently bind in larger numbers than peripheral lymphocytes and there appears to be a qualitative difference in this binding. Identification of the bound cells using immunofluorescent techniques showed that more than 90% of bound peripheral lymphocytes are B cells. Microcinematographic studies suggest that lymphocytes, normally very nonadhesive, move readily over and between confluent layers of reticular cells. The significance of these observations to lymphocyte recirculation and positioning is discussed.
Diffusion of ions in the ionosphere
(1) Introduction—The variation of ionic density in the ionosphere with height at any time of the day has been the subject of a number of theoretical studies by E. O. Hulburt and S. Chapman, amongst others. Chapman's discussion is based on the supposition that the disappearance of electrons in the ionosphere is due entirely to electron-positive ion recombinations, and Appleton and Naismith [see 1 of “References” at end of paper] find that this simple theory agrees well with the observed variation of the maximum electron-density in the E- and F1-layers. His theory, however, does not take into account the possible influence of the downward diffusion of ions and an approximately equal number of electrons. Hulburt [2], summing up the results of his investigation, remarks that as regards the variation of ionic density “there is an uncertainty in the case of F2 and F1 which may or may not turn out to be important.