No abstract

A newborn without any signs of Down's syndrome was found to have an acute proliferation that remitted without drug therapy. Chromosomal analysis of blood, bone marrow, and skin cells revealed that the child was a constitutional mosaic with normal cells and a low number of cells in which one no. 21 chromosome was replaced by a probably isochromosome for the no. 21 long arm: 46,XY/46,XY,i(21q). The abnormal cell line of the mosaic appeared to be selectively involved in this proliferation.

SummaryAn experimental investigation has been made of the minimum detectable echo power from meteor traiJs, using radar techniques at 69 Mc/s, with incoherent detection.For optimum signal-to-noise ratio the pulse width must exceed the cathode-ray tube spot width. Extraterrestrial noise is predominant at 69 Mc/s, and the receiver noise figure is found to be of-only second order importance. Variations in the effective aerial temperature introduce corresponding variations in the observed meteor rate, and must therefore be considered when meteor rates are being compared.Using artificial echoes, a minimum detectable signal-to-noise ratio of 8 db is found. The most important parameter is the total received signal energy. Both these results are in agreement with published theories. No further reduction in the size of the smallest observable meteor is likely thro\lgh receiver improvement. The important features of the receiver are described.

A newborn without any signs of Down's syndrome was found to have an acute proliferation that remitted without drug therapy. Chromosomal analysis of blood, bone marrow, and skin cells revealed that the child was a constitutional mosaic with normal cells and a low number of cells in which one no. 21 chromosome was replaced by a probably isochromosome for the no. 21 long arm: 46,XY/46,XY,i(21q). The abnormal cell line of the mosaic appeared to be selectively involved in this proliferation.