[en] This paper presents an overview of planning for and construction of the power supply and distribution systems for a major new gas centrifuge uranium enrichment plant near Portsmouth, Ohio. Unusually reliable systems are dictated by requirements for continuity of production. Alternate power supply and primary distribution system plans are compared on the basis of cost and overall performance. Based on results of the studies, power supply is provided by three one-mile 345 kV pipe-type cables from an existing major substation and connected to three 70 MVA transformers to supply a 13.8 kV underground distribution system. Reliability criteria are based on contingency planning so that no electric load will be interrupted by failure of any element in the system

No abstract available

[en] Two techniques for simulating lung nodules in nodule detection studies were evaluated. In one technique, radiographs were obtained with plastic beads placed on the surface of a chest phantom to simulate lung nodules. In the second technique, the same plastic beads were radiographed against a uniform background, and their radiographic images were then superimposed photographically onto a radiograph of the same chest phantom. Nodule detection rates determined by four different film readers were significantly different for films prepared by the two different techniques. The differences in detection rates are explained by differences in nodule contrast due to film sensitometric characteristics and scattered radiation effects. Photographic superpositioning does not mimic these effects accurately, as they affect clinical chest films. For this reason, it is suggested that nodule simulation films prepared by the photographic superpositioning technique cannot be used to predict nodule detection rates for clinical chest radiography. Other aspects of lung nodule simulation techniques also are discussed

[en] In an effort to evaluate the potential cost-effectiveness of three-dimensional (3D) display equipment, we compared the speed and accuracy of experienced radiologists identifying in sliced uppercase letters from CT scans with 2D and pseudo-3D display. CT scans of six capital letters were obtained and printed as a 2D display or as a synthesized pseudo-3D display (Pixar). Six observes performed a timed identification task. Radiologists read the 3D display an average of 16 times faster than the 2D, and the average error rate of 2/6 (± 0.6/6) for 2D interpretations was totally eliminated. This degree of improvement in speed and accuracy suggests that the expense of 3D display may be cost-effective in a defined clinical setting

No abstract available

[en] Accumulation of adenosine (Ado) and/or deoxyadenosine (dAdo) in adenosine deaminase deficiency is thought to mediate the immunodeficiency associated with the genetic disease in humans. To study the mechanism by which immune function is impaired, we are using analogs which are not substrates for the deaminase. The analogs and their doses (mg/kg/day, IP) are: an Ado analog, Tubercidin (2); and two dAdo analogs, 2-chlorodeoxy-adenosine (50) and 2-fluoro, arabinosyl AMP (250). CTL were generated by injecting C57B1/6 mice with 2.5 x 10⁷ P815 mastocytoma cells, IP. Groups of mice were then treated once daily on days 9-11 with the analogs. On day 12, the animals were sacrificed and spleen cell suspensions were enriched for CTL by passage through nylon wool columns. CTL were measured against ⁵¹Cr-labeled P815 targets using a standard ⁵¹Cr-release assay. Primary antibody response was assessed in AKR mice following immunization with a T-dependent (sheep erythrocytes) or T-independent (TNP-Ficoll) antigen. Animals were treated with the analogs on days 1-3. On day 4, spleen cells were removed and assayed for antibody response in a plaque-forming assay. The dAdo analogs, but not tubercidin, inhibited the immune functions at these near-maximally tolerated doses. Treatment of the mice with the deaminase inhibitor, deoxycoformycin (1 mg/kg/day), was not inhibitory to these responses

[en] The authors undertook this study to correlate the computed tomographic (CT) and magnetic resonance (MR) appearances of gallstones with the rate of stone dissolution in m-tert-butyl-ether (MTBE). Gallstones from 40 patients underwent in vitro CT and 1.5-T MR imaging, and six CT and five MR patterns were identified. The stones were subjected to dissolution in MTBE and residual weight and fragment size were recorded at intervals until 24 hours. MR patterns failed to correlate with dissolution. CT pattern evaluation showed the least dissolution in homogeneous dense (90 HU) or moderately dense (60-89 HU) stones, while those with central high density (127-204 HU) and those that were rimmed and faint (30-59 HU) or isodense with bile patterns showed the greatest dissolution, with a mean residual of 9% or less of the original weight at 4 hours. Other features correlating with dissolution were the CT density of homogeneous stones or of the rim portion of rimmed stones. No correlation was found between the thickness of peripheral rims and dissolution. The authors conclude that CT appearances can be used to predict the solubility of gallstones in MTBE

[en] Most reports on manganese porphyrins as MR imaging contrast agents have focused on a water-soluble compound, Mn-TPPS4. Phototherapy researchers have noted that lipophilic components of hematoporphyrin derivative sensitize normal brain tissue to light-stimulated photodestruction. This observation suggests that a lipophilic paramagnetic agent might be useful for brain contrast enhancement. The current experiments were designed to test the MR imaging effects of a lipid-soluble compound, Mn-mesoporphyrin. An intravenous injection of 0.05 μmoles/kg was administered to rats with a well-characterized astrocytic glioma implanted into the right cerebral hemisphere. MR imaging experiments performed at 2 T on a General Electric CSI-II system revealed T1 relaxation shortening in both normal brain and tumor. Delayed images at 24 hours revealed persistent selective contrast agent enhancement at the gross tumor site

[en] Iodinated contrast media is used daily in numerous diagnostic radiology procedures. However, the influence of these compounds on the cytotoxicity of X-rays has only recently been questioned. In this study, CHO cells were assayed for cell survival after exposure to either diatrizoate or iothalamate singly or in combination with irradiation with either 100 KVP X-rays, 250 KVP X-rays; or 9 MeV electrons. Cell survival was unaffected by contrast media alone. However, in the presence of contrast media, radiation cytotoxicity with either 100 KVP or 250 KVP X-rays was enhanced. This enhancement was dependent on concentration of iodine present at the time or irradiation, with the D/sub o/ decreasing from 118 rad when no iodine was present to 83 rad when 19 mg/ml of iodine was present. The increased effectiveness of the X-irradiation results from increased radiation dose obtained from the secondary irradiation of the interaction of low-energy X-rays and iodine. At 9MeV, where the effective cross section of iodine and oxygen are the same thus eliminating the iodine photoelectric effect, no increased cytotoxicity was observed in the presence of the iodinated compounds

[en] The authors have developed arteriosclerotic disease of the iliac vessels in the Yucatan microswine in order to test angioplasty devices. Arteriosclerosis was achieved by a combination of a high cholesterol diet and multiple balloon injuries to the iliac vessels. Of the 15 animals, seven have been sacrificed 31--35 weeks after having been placed on the diet, five are still living at 29--35 weeks, and three died during the study. Angiography was obtained in all seven animals before sacrifice, and findings were correlated with the histology. Angiography shows varying degrees of iliac artery stenosis and occlusion. In three of four swine, vessel thrombosis was associated with plaque formation that included calcification, necrosis, and foam cells. Three swine showed patent arteries; histology showed all had intimal hyperplasia (complex plaque formation was present in one). The microswine represents an excellent animal model of human arteriosclerosis to help develop and evaluate angioplastic devices