Observations of Cosmic Noise at 9·15 Mc/s

Abstract

SummaryFrom observations made at a frequency of 9· 15 Mc/s, with an aerial of beam width 29° between half-power points and directed to Dec. -32°, a curve of equivalent aerial temperature, as a function of sidereal time, is derived.The temperatures observed were of the order of 10· OK. The curve is compared with curves derived for similar conditions by calculation from the results of observations at 18·3 Mc/s and at 100 Mc/s_ It is found that the equivalent temperatures increase rapidly with decreasing frequency, but the ratio of maximum to minimum temperature decreases with frequency.It is shown that" atmospheric" noise levels observed by the standard techniques sometimes contain a large contribution from cosmic noise at this frequency.

Palindromic units are part of a new bacterial interspersed mosaic element (BIME)

“…Because of its palindromic nature, part of the PU sequence (32 out of the 40 nucleotides of the consensus) could adopt a 'stem and loop' structure (nucleotides 4-35 in fig. 1), and evidences for the formation of this secondary structure at the level of RNA was obtained from in vitro studies (6). The fact that the palindrome is not perfect has an important consequence: the PU can be oriented and we distinguish the right end and the left end of PU (see details in fig.…”

“…Two years later, an extensive search revealed that a large number of intergenic sequences in Escherichia coli and in Salmonella enteritica serotype Typhimurium were homologous to PU DNA, so that PU amounted to almost 1 % of the genomic DNA (2,3). A number of laboratories kept the name PU family for these sequences (2,4), while others called them REP for Repetitive Extragenic Palindromes (5,6). It was latter shown that the consensus sequence from Escherichia coli PU (3 and upper part in fig.…”

The Observation and Interpretation of Radio Emission from Some Bright Galaxies

“…No observations are available at this frequency, the nearest being those of Higgins and Shain (1954) at a frequency of 9·5 Mc/s. If their results are extrapolated to the lower frequency a brightness temperature of about 5 x10 6 oK is obtained near the galactic centre.…”