Measurement of 227Ac impurity in 225Ac using decay energy spectroscopy.

225Ac is a valuable medical radionuclide for targeted α therapy, but 227Ac is an undesirable byproduct of an accelerator-based synthesis method under investigation. Sufficient detector sensitivity is critical for quantifying the trace impurity of 227Ac, with the 227Ac/225Ac activity ratio predicted to be approximately 0.15% by end-of-bombardment (EOB). Superconducting transition edge sensor (TES) microcalorimeters offer high resolution energy spectroscopy using the normal-to-superconducting phase transition to measure small changes in temperature. By embedding 225Ac production samples in a gold foil thermally coupled to a TES microcalorimeter we can measure the decay energies of the radionuclides embedded with high resolution and 100% detection efficiency. This technique, known as decay energy spectroscopy (DES), collapses several peaks from α decays into single Q-value peaks. In practice there are more complex factors in the interpretation of data using DES, which we will discuss herein. Using this technique we measured the EOB 227Ac impurity to be (0.142 ± 0.005)% for a single production sample. This demonstration has shown that DES is a useful tool for quantitative measurements of complicated spectra.

Epidemic diphtheria in Ukraine, 1991-1997.

In 1991, Ukraine experienced a return of epidemic diphtheria after decades of control that had resulted in <40 sporadic cases reported every year. Increased incidence was first recorded in Kiev, Lviv, and Odessa. By 1993, the epidemic had spread to >50% of the oblasts (provinces) in the country, and by 1995, all regions were affected. In 1995, at the peak of the epidemic, >5,000 cases and >200 deaths were reported. As in Russia, >80% of these cases were diagnosed in persons 16-59 years old. In 1993, the government of Ukraine initiated a program of increased immunization among children and at-risk adults, and by 1995, a mass immunization strategy was adopted in an effort to arrest the epidemic, which was increasing exponentially. In 1996, the number of cases started to decrease, and data from 1998 indicate that the downward trend has continued. It is likely that the diphtheria epidemic in Ukraine started among children, who had been left vulnerable due to inadequate childhood immunizations, and then quickly spread to inadequately protected adults.

Low-back injuries in a heavy industry. I. Worker and workplace factors.

The costs and circumstances of low-back strains, low-back impact injuries, and non-low-back injuries among field employees of an offshore petroleum drilling company, 1979-1985, were compared. The objectives were to identify worker and workplace factors associated with low-back injuries, to identify factors differentially associated with lost-time injuries, and to formulate recommendations for the control of low-back injuries. Low-back-impact injuries resulted largely from falls. Efforts to prevent falls would have a potential to reduce other serious consequences as well as back injuries. Workers performing the heaviest physical labor were at highest risk of low-back strains. Based on activities precipitating the injury, modifications of work site, equipment, and procedures to help reduce low-back strains are recommended. Only job was a predictor of whether a low-back strain was likely to be associated with lost time. Even this association was lacking for low-back impact injuries. Cost control by preventing the small proportion of high cost injuries may not be feasible. Rather, subsets of low-back injuries defined, for example, by work site or activity can suggest options for intervention.