Abstract: Nucleic acids encoding the .beta.-chain of the human granulocyte-macrophage colony stimulating factor (GM-CSF) receptor, as well as the .beta.-chain itself, are provided. The .beta.-chain may be expressed with the .alpha.-chain in cellular hosts to form compositions useful in screening agonists and antagonists of human GM-CSF.

Abstract: Nucleic acids encoding the .beta. chain of the human granulocyte-macrophage colony stimulating factor (GM-CSF) receptor, as well as the .beta. chain itself, are provided. The .beta. chain may be expressed with the .alpha. chain in cellular hosts to form compositions useful in screening agonists and antagonists of human GM-CSF.

Abstract: An apparatus for measuring the size distribution of particles by making use of centrifugal force field, comprising a mechanism for making a suspension revolve, an optical unit for detecting a light absorption by the suspension, and a micro-computer. The suspension suspends test particles whose size distribution is to be measured. The optical unit measures a time-dependent particle concentration variation due to the particle movements forced in a centrifugal force field produced by the revolution of the suspension. The micro-computer is provided with a memory for storing equations to obtain the size distribution of particles from the measured particle concentration variation and equations for correcting adverse effects by non-parallel particle movements in a centrifugal force field, to give a particle size distribution free from the error arising from the non-parallel movements of particles.