OFFICIAL USE OF WY -4- Fluorescent transmission scanning of the thyroid by irradiating the thyroid with an Americium source which emits 60 kev gammas is being investigated in phantoms. The technique looks promising. The instrumentation group now has a 3-inch diameter germanium crystal and a germanium scanning camera is being developed. Dr. Stanton Cohn described studies on the neutron activation of the skeleton tollowed by whole body counting to estimate the various constituents of the skeleton. They use either 14 Mg¥gneutrons from a conventional generator or the 4.5 MeV neutrons from a Pu, Be source, As might be anticipated, a major problem is obtaining uniform fluences throughout the body. In terms of getting a uniform distribution of thermal neutrons which are the ones captured by bhe chemical constituents, 14 MeV neutrons give the best distribution. Cf, being of very low energy, gives a rather Byer result. At the present time they are using 14 50 curie sources of Pu mixed with Be. A moderator is fit very closely around the patient's body to give uniform affluences of thermal neutrons. Calibrations have been worked out for the content of calcium, phosphorus, chlorine and sodium. The total radiation doses to the patients are about 300 millirem from the Pu, Be sources. Diseases that have been investigated include a great variety of bone diseases such as osteoporosis, Padgett's disease, parathyroid dysfunctions and other hormonal dysfunctions. Calcitonin is used as a specific therapy for a number of these diseases and they find that they are able to measure the patient's response quite adequately using their activation method. Dr. George Woodwell described some of the present activities of the ecology group. In the past they studied intensively one of the onsite forests. They are now interested in studying an estuary. Their previous studies on the forest produced some interesting observations. One of the things they looked at was the carbon budget. Most forests or productive fields have a net production of about 200 grams of carbon per square meter per year. If one takes out the loss to decay and to animals, the net production in the forest they studied was about 500 grams per square meter per year. Mature forests, of course, come into an equilibrium and there is no net production of carbon. In comparison to forests, estuaries are much more complicated because of imports and exports to the estuary. It is not known whether estuaries typically reach an equilibrium value. The group headed by Dr. Wocdwell is presently studying Flax Pond which is relatively simple to study hecause there is no input by way of a river or stream running into it, It is simply a tidal pond connected to Long Island Sound. Woodwell pointed out that it is commonly believed that estuaries are very productive in terms of producing organic matter. His studies suggest that this is not so. They have studied the exchanpes with the ocean and most of the exchange is in the form of dissolved organic material. This amounts to 1-12 mg per liter, while small particulate materials amount to about 1/10th of this. They find that by studying the input from and the output to the ocean, they OFFICIAL USE ONLY