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Trace metals and polycyclic aromatic hydrocarbons (PAH) were analyzed in sediment cores from three central Alberta lakes to determine the contributions of local coal-fired power plants to contaminant loadings. In Wabamun Lake, with four power plants built since 1950 within a 35-km radius, sediment concentrations of mercury, copper, lead, arsenic and selenium have increased by 1.2- to 4-fold. Trace metal enrichments were less pronounced in Lac Ste. Anne and Pigeon Lake, situated 20 km north and 70 km south of Wabamun Lake, respectively. Total Hg flux to Wabamun Lake sediments (21–32μg m−2 yr−1) has increased 6-fold since 1950, compared to 2- and 1.5-fold increases in Lac Ste. Anne and Pigeon Lake, respectively, since circa 1900. Total PAH flux to surface sediments was 730–1100μg m−2 yr−1 in Wabamun Lake, 290–420μg m−2 yr−1 in Lac Ste. Anne, and 140–240μg m−2 yr−1 in Pigeon Lake. Without adoption of pollution-abatement technology that compensates for increases in generating capacity, continued expansion of coal-burning industry in Alberta will result in increased contaminant deposition, primarily from local sources.

The water chemistry of the euphotic zone in 12 lakes within burned and reference watersheds on Alberta's Boreal Plain was surveyed two years post-fire. Five burned and four reference lakes were located in the Boreal Foothills (mean elevation = 1048 m) and three reference lakes were situated at lower elevations in the Boreal Mixedwood ecoregion (748 m). Mean dissolved organic carbon (DOC) concentration in lake water from burned watersheds was 1.4-fold higher than in lake water from reference Foothills watersheds, whereas lake colour increased with the area of catchment burned divided by lake volume (r = 0.98). Reference Mixedwood lakes had higher mean total phosphorus (TP, 1.8-fold) and chlorophyll a (chl a; 4.4-fold) concentrations than reference Foothills lakes. Ten additional lakes from a previous study in boreal Alberta were used to further compare water chemistry between ecoregions. Boreal Mixedwood lakes (n = 13) had higher TP (2.3-fold), chl a (3-fold), and Ca2+ + Mg2+ (3.3-fold) concentrations than Boreal Foothills lakes (n = 9). Our data suggest an influence of forest fire on lake chemistry in the Boreal Foothills, and demonstrate the need for an ecoregion approach to detect the impacts of watershed disturbance on the Boreal Plain. Key words: watershed disturbance, forest fire, lake nutrients, lake elevation, phosphorus, chlorophyll a, anions, cations, dissolved organic carbon.

Objective: To describe preserved cognitive skills in patients with dementia. Design: Case series. Setting: Community clinic. Patients: Five patients who met National Institute of Neurological and Communicative Disorders and Stroke—Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease and were claimed to retain a cognitive skill. Interventions: None. Main Outcome Measures: Standard neuropsychological tests and individualized measures of patients' skilled behaviors. For patients who remained skilled at games, performance was compared with that of normal controls in direct competition. For the patient-trombonist, raters compared premorbid and postmorbid recordings of his play. Results: One patient continued to play the trombone in a Dixieland band, although he could not name wellknown numbers that he played. Another continued to solve adult jigsaw puzzles. A third patient retained skill at canasta, the fourth at dominoes. The fifth patient remained a skillful contract bridge player, although he could not name the suits or articulate simple bidding rules. Four patients had impaired performance on standard anterograde and remote memory and naming tests but performed normally on pursuit rotor and letter fluency tests. Mini-Mental State Examination scores for these patients ranged from 10 to 22. One patient refused neuropsychological testing but displayed his skill. Conclusions: Together with previous studies of preserved piano playing or painting skills, our findings indicate that a broad range of complex cognitive abilities may be preserved in patients with dementia of the Alzheimer type who cannot perform simpler actions.

The three-detector TRIAD 88 is a variable cylindrical FOV whole-body SPECT system designed for both brain as well as body organ imaging. The system performance was assessed in terms of physical indices and clinical quality. Measures of low contrast resolution using contrast-detail curves, high contrast resolution using LSFs and associated frequency descriptors, display characteristics, system sensitivity, energy resolution and uniformity analysis were utilized. In addition, images of Carlson phantom, Hoffman brain phantom and clinical brain images were used to compare two collimators subjectively. Measurements and calculations were obtained for two sets of parallel hole collimators, i.e., LEUR_PAR and LEHR_PAR. Of special interest is the consistency among the three detectors. The planar and volume sensitivities for the LEUR_PAR collimator were about 58% of those of the LEHR_PAR collimator. The planar spatial resolution of the two collimators differed by about 14%. The display was characterized by a logistic model HD curve. The planar contrast-detail curves demonstrated no statistical difference in lesion detectability between the two collimator types, however SPECT phantom and clinical images demonstrated improved performance with the LEUR_PAR collimator. Images of Hoffman single slice brain and Carlson phantoms and Tc-99m (HMPAO) brain images demonstrated excellent image quality. There was similarity in performance parameters of the three detector heads.

131I labeled iodo-antipyrine and 99mTc labeled erythrocytes were used to measure water content in lungs. These radioactive tracers were injected into 10 rabbits with normal lungs and 11 rabbits with injured lungs. Blood samples were drawn and the subjects were killed. The lungs were removed, weighed and homogenized. Samples of blood and lung homogenate were assayed for 131I and 99mTc. Samples were also weighed before and after drying to a constant weight at 70-75 degrees C. Extravascular lung water was determined by the dual isotope technique and again by gravimetric analysis. The average ratio of the results from the 2 different methods is 1.03 +/- 0.15. The 2 methods were compared by regression analysis and the correlation coefficient was 0.92 +/- 0.09. Our investigation suggests the possibility of measurement of lung water with equilibrium distribution of iodo-antipyrine.

This paper traces the development of interference regulations from the original requirement that waves be pure and sharp to the present complex formula for attenuation of spurious emissions. It also shows how different philosophies of regulation developed. In broadcasting, the regulations grew up around the concept of a "protected service area." In the communication service, on the other hand, regulations developed in the direction of limiting the bandwidth and confining emissions within the authorized band. The paper also traces the history of ISM regulation with its philosophy of assigned frequencies on which unlimited radiation is permitted with an associated requirement for severe limitation of radiation on other frequencies. It also discusses the "low-power rules" which establish the conditions under which low-power equipment may be operated without becoming a source of interference. The paper describes briefly the voluntary work in this area by industry, and touches on local regulations concerning interference.

The Seventh Plenary Assembly of the International Radio Consultative Committee (CCIR) was held in London from September 3 through October 7, 1953. Although many members of the Institute may be unfamiliar with the work of this Committee, it may have far-reaching effects upon the progress of radio. The London meeting approved 165 documents, each of them a possible subject for a technical paper. The purpose of this paper is to give a brief outline of the work accomplished in that assembly and to describe briefly the organization and functions of the CCIR.

The paper gives a definition of an automatically controlled as distinguished from a remotely controlled substation, and also analyzes the duties of the attendant in the starting, loading, and shutting down, of apparatus in hand-operated stations. It states that the changes in the conditions of the electric circuit which the attendant observes may also be utilized to operate control relays, and as reliable devices are already available to protect the machines against overload and runaway, his assistance in these matters is no longer necessary. The paper then proceeds on the assumption that converting apparatus should be automatically controlled and that the conditions which have heretofore governed both the design and location of substations can be modified to advantage in many cases. It advocates a reduction in size and an increase in the number of stations and endeavors by example to show the large saving in feeder copper which the proposed arrangement permits. Finally, a description is given of the automatically controlled substations installed on the lines of the Elgin & Belvidere Electric Railroad.

The effects of commonly used cardiac drugs on cardiac imaging with thallium-201-labeled thallous chloride were studied. This retrospective study included 62 men ranging in age from 37 to 70 years who had cardiac imaging attempted with thallium during an eight-month period. Seven drugs were being used by at least eight patients each--propranolol, nitroglycerin ointment, isosorbide dinitrate, digoxin, hydrochlorothiazide, potassium chloride, and quinidine. Myocardial-to-background (M/Bk) ratios were calculated for each patient. No drug consistently affected the M/Bk ratios. The lowest M/Bk ratio was found in patients receiving digoxin, but there was no significant difference between the M/Bk ratios for patients taking digoxin (1.38 +/- 0.16) and those not taking digoxin (1.45 +/- 0.10) (0.05 less than p less than 0.10, Student's t test). It is concluded that the drugs studied do not affect cardiac imaging with thallous chloride Tl 201.

Tc-99m gluceptate renal imaging was compared with the intravenous urogram in 41 patients. While the specificity of the examination was essentially the same for both techniques, the sensitivity for the detection of renal mass lesions was better with gluceptate imaging. The study suggests the desirability of a shift in emphasis from the IVU to the Tc-99m gluceptate scintigram in the early evaluation of suspected renal mass lesions, and merits further clinical evaluation.

During 1985, low-level radioactive waste disposal has become a critical concern. The issue has been forced by the threatened closure of the three commercial disposal sites. The medical community has used radioactive isotopes for decades in nuclear medicine, radiation therapy, radioimmunoassay, and biomedical research. Loss of disposal capacity for radioactive wastes generated by these activities, by the suppliers of radioisotopes, and by pharmaceutical companies will have a profound impact on the medical profession.

The effect of chronic administration of sulfonylurea compounds on the insulogenic responsiveness of beta cells was studied in normal dogs who received hypoglycemia-maintaining dosages of tolbutamide daily for several weeks. Insulin concentration in pancreaticoduodenal venous blood was measured during infusion of glucose at a rate causing physiologic increase in arterial glucose concentration. Neither fasting plasma insulin level nor its enhancement during progressive hyperglycemia was significantly greater in tolbutamide-treated animals than in the control group. The data indicate that prolonged exposure of nondiabetic canine beta cells to effective concentrations of sulfonylurea does not increase their insulin-secretory responsiveness to glycemic stimulus. Whether these agents impinge similarly or differently upon diabetic human islets awaits elucidation. It was parenthetically observed that dogs treated with tolbutamide for several weeks required more than twice the usual amount of Nembutal to maintain surgical anesthesia.

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The Television Allocations Study Organization was established by the television industry in September, 1956, at the request of the Federal Communications Commission, to make a thorough analysis of the engineering aspects of problems relating to the television broadcast allocations. This paper relates the needs underlying the request and gives a brief history of television allocations, culminating in the events leading to the formation of TASO.