Slow and Fast Muscle Fibers

On the basis of the clear-cut differentiation used in fast (twitch) and slow (tonic) muscles of the frog, both the fast E.D.L. and the slow soleus muscle should be considered twitch muscles. However, they reveal a marked differential behavior in their contracture responses to ACh and caffeine. Moreover, all the slow muscles I have studied (i.e.. the L.D.A. of the chicken, the rectus abdominis of the frog, and the soleus of the rat) show a higher rate of proteosynthesis. This may be related to the basic function of slow muscles concerned with long-lasting maintenance of tension, the extreme being, for example, the contracture responses observed in reaction to ACh. There may be a relation of rate of protein metabolism to the mobility of protein-bound Ca⁺⁺ in the sarcoplasmatic reticulum. The differences in contracture behavior are apparent already three days after birth of the animals. All this may indicate a basic differentiation of two main groups of muscle fibers. Neural long-term influences operate in the development of this differentiation in contracture behavior of fast and slow muscle fibers. The mechanisms by which the nerve cell affects this behavior have still to be uncovered

Current developments in electrochemical storage systems for satellites

The need for batteries with greater power capacity and service life for power satellites is examined. The Ni/Cd and Ni/H batteries now being used must be upgraded to meet advanced space requirements. Improvements in power capacity, service life, and cycle count for various satellites in LEO and GEO orbits are discussed. The Ni/Cd and Ni/H cell reactions are explained, and the solubility and volume changes for various charged and uncharged masses are described. A chart of the energy content and cycle count for various cell systems is presented, and the factors which cause aging and failure in the Ni/Cd and Ni/H cell systems are discussed. The advantages of the Ni/H battery are given and the need for more developed electrochemical storage systems because of an increase in the mass of satellites is explained. The requirements for space batteries and the work currently done by NASA and West Germany on advanced batteries are discussed

Rectenna session: Micro aspects

Two micro aspects of the rectenna design are addressed: evaluation of the degradation in net rectenna RF to DC conversion efficiency due to power density variations across the rectenna (power combining analysis) and design of Yagi-Uda receiving elements to reduce rectenna cost by decreasing the number of conversion circuits (directional receiving elements). The first of these micro aspects involves resolving a fundamental question of efficiency potential with a rectenna, while the second involves a design modification with a large potential cost saving