Precision measurements of 14C in AMS — some results and prospects

Some of the factors affecting the precision in AMS measurements will be discussed and the specific developments undertaken to reduce the errors at the ETH facility are described. Based on a large number of ¹⁴C measurements we show the present limitations of our system and consider what improvements might be possible. Further, a comparison is made between high precision measurements of ¹⁴C and current achievements relating to Be, Al and Cl.     

Properties of milligram size samples prepared for AMS 14C dating at ETH

We have investigated the ion beam characteristics (intensities, yields, duration and stability) of a variety of targets prepared for radiocarbon dating by AMS. The target preparation techniques include: organic matter pyrolysis products mixed with silver, high pressure temperature ‘graphites’, CO reduction by cracking, magnesium reduction of CO₂ and direct dating of extractives. Values for minimum sample amounts, sample preparation times, contamination as judged by background and precision of determination are given and the overall performance is evaluated.     

Serum enzyme activity and physical condition

Following the WHO tri-axial classification of mental disorders, which set out possibilities for differential classification and diagnosis among the syndromes, the present article suggests complementary axes upon which educational therapy can be based in the psychoses of autism and allied disorders. They are offered as a basis of common ground for discussion in multidisciplinary teams.     

Cell classification by laser light scattering: identification and separation of unstained leukocytes

We have used a flow-system cell sorter to separate unfixed, unstained human leukocyte cells into morphologically distinct populations based only on the intensity of 488-nm wavelength laser light simultaneously scattered by each cell at two different angles. Three populations were observed as distinct peaks in a two-parameter pulse-height distribution and were then physically sorted into separate classes and stained for cytological examination. The three groups consisted of lymphocytes, monocytes, and neutrophils. Each group contained between 77 and 98 per cent of a single cell type. Blood from an irradiated monkey was also sorted and showed the presence of a fourth peak which consisted of 61 per cent eosinophils. Thus, multiangle light-scattering information from unfixed, unstained cells may be a promising technique for rapid morphologic analysis and may have application, for example, as a highspeed automated leukocyte differential. We anticipate that this method may be useful in other clinical applications where morphologic differences are diagnostically important. One of the principal advantages of the method is elimination of fixation and staining of the samples; this is a nondestructive testing technique.     

The treated prevalence of mental illness in the Republic of Ireland--the three county case register study

In-patient data show high rates for mental illness in the Republic of Ireland, particularly for schizophrenia. 'One-day prevalence' figures from the Three County psychiatric case register have been compared with similar data from the Camberwell register. The results confirm much higher contact rates in Ireland.     

Anticonvulsant nature of marihuana smoking

Marihuana smoking, in conjunction with therapeutic doses of phenobarbital and diphenylhydantoin, was apparently necessary for controlling seizures in one 24-year-old epileptic patient.