One of the causes of power loss in a free-space optical communication link is beam motion or received spot wander. The power spectrum of the spot motion indicates that most of the frequency content is less than ~500 Hz. A fast steering mirror (FSM) controlled by a position-sensing detector (PSD) has the potential to correct for a significant portion of the focal spot position fluctuations and thus the power loss. A FSM controlled with a Germanium PSD was installed on the receiver at the NRL Chesapeake Bay free-space lasercomm test facility. Results are presented from the initial tests performed using this system to measure and correct for wander of an optical beam propagated across the bay (20 mile round-trip).

Abstract5-Fluoroanthranilic acid (FAA)-resistant mutants were selected in homothallic diploids of three Saccharomyces species, taking care to isolate mutants of independent origin. Mutations were assigned to complementation groups by interspecific complementation with S. cerevisiae tester strains. In all three species, trp3, trp4 and trp5 mutants were recovered. trp1 mutants were also recovered if the selection was imposed on a haploid strain. Thus, FAA selection may be more generally applicable than was previously described.

THERE is no doubt that applanation tonometry gives more accurate information about the level of intra-ocular pressure than does indentation tonometry. This increased accuracy is due to the fact that applanation readings approach very closely to the levels of pressure in the undisturbed eye (Po), owing to the small volume of fluid displaced by the application of the tonometer (Goldmann, 1957).An indentation tonometer, on the other hand, which compresses the eye with a considerable weight (16-5 G in the case of a standard Schiotz tonometer), raises the intra-ocular pressure considerably and the level of Po can only be obtained by reference to conversion tables which assume that the eye responds in a standard way to the application of the tonometer (Grant, 1951).It is now recognized that the effect of the application of a Schiotz tonometer may vary, not only from eye to eye, but also in the same eye from time to time. This variability of effect is related to what we call "scleral rigidity", a complex of factors which includes not only the resistance of the ocular coats to deformation, but also the compressibility of the vascular contents of the eye, and the ease with which fluid is expressed through the drainage channels, both of aqueous and blood (Perkins and Gloster, 1957).The currently accepted conversion charts for Schiotz tonometers (the 1955 scale) are based on Friedenwald's work and assume an average scleral rigidity (Friedenwald, 1957). When the scleral rigidity is within the normal range, Schiotz tonometers (provided that they are of standard construction) may be expected to give readings of intra-ocular pressure which are of an acceptable standard of accuracy.The purpose of this present paper is to attempt to assess the relationship between the readings of applanation and Schiotz tonometers. Before doing so, however, it seems necessary to draw attention to certain established facts about Schiotz tonometers, and in particular, tonometers of the mechanical type. Some of these considerations do not apply to electronic tonometers.Schiotz "Range" When Schiotz (1920) and later Friedenwald (1957) constructed their conversion charts for Schi6tz tonometers, the results were obtained under laboratory con-*

Tonometry has long been considered a satisfactory and accurate aid to the diagnosis of chronic simple glaucoma and, since the publication of a paper by Grant (I 950), tonography has been acclaimed as a useful additional refinement. The results of tonography have been expressed either alone as an indicator of facility of aqueous outflow (C) or combined with a measure of intraocular pressure (Po) and expressed as Po/C, the coefficient of outflow.Many of the observers who have confirmed Grant's findings have failed to state clearly their criteria for the diagnosis of chronic simple glaucoma. For example, Tuovinen (I96I) implied that the diagnosis was, in part, based on tonometry and tonography, so that his argument about the effectiveness of the tests depends on the prior assumption that the tests are effective.We will show that confidence in the results of tonometry and tonography is misplaced, especially in those reports in the literature, for example Paterson (i966), where these measurements taken at certain levels are accepted as diagnostic of chronic simple glaucoma. Previous studies of tonography should have warned us against this practice. Gloster (i966) found that in Io8 normal eyes all exceeded O I2 in C value, and only 4 per cent.had values lower than O I5. His experience in thirty glaucomatous eyes showed that the tests were less discriminating. C values were higher than OI2 in 73 per cent. and higher than 0 I5 in 54 per cent.In our study we have made tonometric and tonographic observations and calculated the coefficient of outflow in four groups of eyes: non-glaucomatous, 'suspicious', untreated glaucoma, and treated glaucoma.

ASCO Leadership Development Program members were tasked by the ASCO Board of Directors to explore how to optimize integration of key aspects of oncology care in order to facilitate continuous quality improvement for the practicing oncologist. This Perspective summarizes their findings.