The theory and practice of polarography in melts

Some of the problems of using solid micro-electrodes in molten salts are discussed. The technique of high-temperature polarography is described and some of the anomalous features of the results are examined.     

Driven production of cold antihydrogen and the first measured distribution of antihydrogen states

Cold antihydrogen is produced when antiprotons are repeatedly driven into collisions with cold positrons within a nested Penning trap. Efficient antihydrogen production takes place during many cycles of positron cooling of antiprotons. A first measurement of a distribution of antihydrogen states is made using a preionizing electric field between separated production and detection regions. Surviving antihydrogen is stripped in an ionization well that captures and stores the freed antiproton for background-free detection.     

Background-free observation of cold antihydrogen with field-ionization analysis of its states

A background-free observation of cold antihydrogen atoms is made using field ionization followed by antiproton storage, a detection method that provides the first experimental information about antihydrogen atomic states. More antihydrogen atoms can be field ionized in an hour than all the antimatter atoms that have been previously reported, and the production rate per incident high energy antiproton is higher than ever observed. The high rate and the high Rydberg states suggest that the antihydrogen is formed via three-body recombination.     

On a matroid identity

The purpose of this note is to prove an identity for generalized Tutte-Grothendieck invariants, at least two special cases of which have already proved to be of considerable use. In addition, one of these special cases is used to strengthen results of Lindström on the critical exponent of a representable matroid and the chromatic number of a regular matroid.