Two groups of 11-week-old swine (40 miniature and 40 domestic swine) received a single oral administration of 1.9 X 10(8) Bq (5.2 mCi) of 241Am citrate, and groups of eight animals, four of each type, were killed and sampled at 1, 2, 4, 8, 16, 24, 48, 72, and 96 h and 30 days later. Uptake and excretion patterns of the radioactivity appeared to occur in three phases: rapid uptake, rapid excretion, and then a slower excretion. All animals were systematically dissected, and the eviscerated carcasses were autoclaved for separation of bone and muscle. The predominant site of deposition was bone, and autoclaving had little effect on releasing 241Am from either bone or muscle. The maximum fractional gastrointestinal absorption of 1.1 X 10(-3) occurred 8 h after radionuclide administration. The tissue distribution data suggest partitions of 50, 20, and 30%, for bone, liver, and other soft tissues, respectively. Two metabolic models were evaluated: a modified Mewhinney-Griffith model and the ICRP 30 model to compare the biological data with model predictions. All models underestimated the actual early time data, but the fits to the experimental results were better at later times.

An urn contains balls ofs different colors. The problem of the reinforcement of a specified color and random depletion of balls has been considered by Shenton (1981, 1983). In this paper, the theory is applied to the biological age dependent half-life of radioactive iodine in man; the data of Cook and Snyder (1965) is used. The intake of radioactive iodine and its retention subsequently is studied.

Balls are removed one-at-a-time at equal time intervals from an urn initially containing w0 white balls and a large numberb of black balls and each black or white ball is immediately replaced by a black ball. The distribution of the number of white balls remaining aftert iterations (under certain limiting operations) is taken from the literature. The problem is to use this result to find the time required to remove a fixed number of white ballsw1 from the urn. We then find the mean and variance of this distribution and also look at the special case whenw1 = w0.

We have derived two different models representing the metabolic behavior of both inorganic and methyl mercury. Simple three- and four-compartment models fit the short-term data very well. However, it was necessary to add long-term compartments to the data so the model would be in keeping with the long-term data as observed in Reference Man, ICRP Publication 23 and in industrial experience (ICRP75). One concept not used in our models is biotransformation. It has been established that in the rat methyl mercury undergoes a biotransformation that cleaves the carbon-methyl bond and releases inorganic mercury (No 70; No 71). However, we were unable to find any human data. Since methylation of inorganic mercury is known to occur, it might be expected that methylation would occur in mammals. Rowland et al. have shown that the contents of the rat cecum can synthesize methyl mercury from mercuric chloride (Row 77). Furthermore, they also showed that bacteria from human feces can cause methylation. Clearly, a model incorporating biotransformation would be useful but it must await further experimental evidence.

A chain-like arrangement of four urns (a catenary system) into which different color balls (white, corresponding to radio atoms, and black, corresponding to stable atoms) are being transferred is used to simulate the transport of atoms down the GI tract of man and animals. Into the first urn (stomach) are placedwo white balls andr black balls while in the 2nd (small intestines) and 3rd (large intestines) urn, onlyr blacks are put in, with no whites. A sample of sizer is transferred from the 1st, 2nd and 3rd urns to the 2nd, 3rd and 4th (infinite universe) urns. From the random variable difference equations the first and second moments for the distribution of the number of radio atoms present in each urn are obtained. The variance of the contents of radioatoms in the excretion urn is

Coupling between electronic and nuclear degrees of freedom in Rhodamine 800 has been studied using fluorescence line narrowing (FLN) and three-pulse photon echo peak shift (3PEPS). From the FLN measurement we extract the Huang-Rhys S-factors and frequencies of 16 Franck-Condon active vibrations clustered in two groups centred around 350 cm−1 and 1400 cm−1. The five modes below 500 cm−1 covered by the excitation pulse spectral band create a complex beating pattern in the 3PEPS measurements. After determining the reorganisation energy of the modes involved in the peak shift measurement we are able to obtain the S-factors of the modes. The S-factors from two different experiments are in good agreement. The dephasing rates of these vibrations deviate significantly from the band-gap law. We propose that the main channel for the dephasing of the modes above 225 cm−1 is a second order process involving one phonon and a molecular vibration.

A model is presented for the internal radiation dose to the small intestine wall of miniature swine given Americium 241 citrate by oral intubation. The model incorporates the uptake of the Am-241 by the intestinal wall. About equal contributions of dose to the small intestine were observed from the intestinal contents and the wall itself. (ACR)

A two urn Polya-type scheme is considered in whichr black balls (corresponding to the stable form of an element) are added to urn one at every stage and the same number of balls are removed at random at every stage from the same urn. In between these two operations, which form a stage or iteration, a fixed number of balls is exchanged at random between urns one and two. Urn one has a given initial number of white balls (corresponding to a radioactive form of the same element). The problem of interest is to study the stochastic aspect of the number of white balls remaining in urn one (and/or urn two) aftern iterations.

TWENTY-FIFTH ANNUAL MEETING OF THE HEALTH PHYSICS SOCIETY: Abstracts of papers presented at the meeting: PDF Only