Comparisons of exha-cellular fluid (w) volume estimates made by isotope dilution and electrical impedance techniques have been made in a group of 16 children. For each patient an estimate of BCF volume (V,) was obtained from measurements of the blood clearance of 99Tc"-diethylene triamine penta-acetate @PI A) which was compared with WO estimates (V,l and Vi) of FCF volume obtained from measurements of the whole-body electrical impedance at 50 frequencies in the range 1 kkh to 1.348 MHz and a third estimate Vh based on patient heighr L, alone. The observed frequency response of the impedance measurements was fined to a thee. element equivalent-circuit model of whole-body impedance and gave a value of the ECF resistance R. V i 1 was obtained from Vi, = 4 ( L z / R ) + b. Viz was given by C ( W ? L~/ R )~~~ where W is the patient weight and Vh was given by dLZ + e. The constants (1, b. e, d, e were determined by comparison with V, and were equal to 0.335 IClm-' (standard error = 0.01 0.42 1 (0.25 I), 0.33 1 (~2~k g -~m -~)~i~ 0.007 1 (s2'kg-1m-4)1n, 4.92 I m-' (2.8 x 1m-l). 0.13 1 (0.41 1). respectively. 91, Viz. Vh were linearly correlated with V, 0' = 0.98, 0.99. 0.95, respectively, p < 0.001), and upper and lower levels of agreement were given by 50.95 1 (V,and Vi), 1.44 1 and -1.12 1 (V, and Viz), k1.5 1 (V, and Vh), respectively. Thus inclusion of the impedance data accounted for gmter volume variation. but differences between the techniques were not signficant (paired t-test and Man"-Whimey analysis) suggesting that more accurate and detailed measurements are quired.

No abstract

No abstract

The possibility of an optical disk capacity of 28GB/side is studied. The read-write characteristics of a phase-change optical disk are examined using a thin cover layer, a blue laser diode, high NA objective lens and the PRML method. The wide tilt margins of high-density recording are achieved.

No abstract