Designs and Perfect Codes
A Steiner triple system of order n (briefly STS(n)) is a family of 3-element blocks (subsets or triples) of the set N={1,2,..., n} such that each not ordered pair of elements of N appears in exactly one block. 
 
Two STS-s of order n are called isomorphic if there exists a permutation on the set N which transforms them into one another. It is well known that STS(n) exists if and only if n≡1 or 3 (mod 6).
There exist Steiner triple systems of order 15 that do not occur in a perfect binary one‐error‐correcting code
The codewords at distance three from a particular codeword of a perfect binary one‐error‐correcting code (of length 2m−1) form a Steiner triple system. It is a longstanding open problem whether every Steiner triple system of order 2m−1 occurs in a perfect code. It turns out that this is not the case; relying on a classification of the Steiner quadruple systems of order 16 it is shown that the unique anti‐Pasch Steiner triple system of order 15 provides a counterexample. © 2006 Wiley Periodicals, Inc. J Combin Designs 15: 465–468, 2007
Comparison of model prediction with measurements of galactic background noise at L-band
The spectral window at L-band (1.413 GHz) is important for passive remote sensing of surface parameters such as soil moisture and sea surface salinity that are needed to understand the hydrological cycle and ocean circulation. Radiation from celestial sources (mostly galactic) is strong in this window, and an accurate accounting of this background radiation is often needed for calibration. This paper presents a comparison of the background radiation predicted by a model developed from modern radio astronomy measurements with measurements made with several modern L-band remote sensing radiometers. The comparison validates the model and illustrates the magnitude of the correction necessary in remote sensing applications.