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  • 1
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A variety of experiments have been performed on the TFTR tokamak [Wilson et al., Plasma Physics and Controlled Nuclear Fusion Research 1988 (IAEA, Vienna, 1989), Vol. 1, p. 691] utilizing ion cyclotron range of frequencies (ICRF) heating. Of special interest has been the insight into plasma performance gained by utilizing a different heating scheme other than the usual neutral beam injection (NBI). Utilizing ICRF heating allows control over the power deposition profile independent of the plasma fueling profile. In addition, by varying the minority concentration the power split between ion and electron heating can be varied. Confinement has been examined in high recycling gas fueled discharges, low recycling supershot plasmas, and peaked density pellet fueled discharges. Global confinement is found not to be affected by the method or localization of plasma heating, but the calculated local diffusivities vary with the power deposition profile to yield similar global values. In addition, sawtooth stabilization observed with ICRF heating has been investigated and found to occur in qualitative agreement with theory. ICRF sawtooth stabilized discharges exhibit peaked temperature and density profiles and have a safety factor q that appears to fall well below unity on axis.
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  • 2
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Heating and current drive with ICRF is one of the major missions of TPX and is crucial to its success. In contrast to the integrated nature of core diagnostic programs, diagnostics that measure ICRF propagation and edge interactions are often assigned lower priority, have not been included in the base diagnositics set, or were included as upgrades. This can result in an incomplete and unoptimized set of measurements. Thus it is important that an integrated set of diagnostics (engineered along with the antenna design), capable of fully diagnosing the interaction, propagation, and absorption of the ICRF be available for TPX. The parameters of interest include: coupling of the ICRF antenna to the plasma, launched spectrum, wave propagation, edge plasma interactions, electron heating, and current drive, and fast ion power deposition and losses. The diagnostic set should be designed so it can be upgraded for control of loading and spectrum by providing feedback information for adjusting phase, power level, fuel gas injection, and plasma position. The proposed set focuses on wave propagation, launched spectrum, absorption, and measuring and comparing the plasma edge properties in the near vicinity of the antenna with that measured at a large toroidal distance from them; thus many would be installed as toroidally separated indentical sets. In addition to the planned core diagnostic set, the ICRF specific diagnostics proposed for TPX include: edge density reflectometers, RF fluctuation reflectometers, fixed and moveable Langmuir probes, visible and IR cameras with spectroscopic line filters, rf magnetic loop probes, local ion energy analyzer, direct ion loss detectors, charge exchange analyzers, fast response ECE, and edge temperature ECE. The anticipated approach is one in which individual diagnostics could be provided by industry, universities, or laboratories but overall coordination, driven by specific ICRF issues, would be required. © 1995 American Institute of Physics.
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fast reciprocating ion cyclotron range of frequencies (ICRF) probe was installed and operated on TORE SUPRA during 1992/1993. The body of the probe was originally used on the ATF experiment at Oak Ridge National Laboratory. The probe was adapted for use on TORE SUPRA, and mounted on one of the two fast reciprocating probe mounts. The probe consists of two orthogonal single-turn wire loops, mounted so that one loop senses toroidal rf magnetic fields and the other senses poloidal rf magnetic fields. The probe began operation in June, 1993. The probe active area is approximately 5 cm long by 2 cm, and the reciprocating mount has a slow stroke (5 cm/s) of 30 cm and a fast stroke (1.5 m/s) of about 10 cm. The probe was operated at distances from the plasma edge ranging from 30 to −5 cm (i.e., inside the last closed flux surface). The probe design, electronics, calibration, data acquisition, and data processing are discussed. First data from the probe are presented as a function of ICRF power, distance from the plasma, loop orientation, and other plasma parameters. Initial data show parametric instabilities do not play an important role for ICRF in the TORE SUPRA edge and scrape-off-layer (SOL) plasmas. Additionally it is observed that the probe signal has little or no dependence on position in the SOL/plasma edge. © 1995 American Institute of Physics.
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  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fast reciprocating ion cyclotron range of frequencies (ICRF) probe was installed and operated on TORE SUPRA during 1992/1993. The body of the probe was originally used on the ATF experiment at Oak Ridge National Laboratory. The probe was adapted for use on TORE SUPRA, and mounted on one of the two fast reciprocating probe mounts. The probe consists of two orthogonal single-turn wire loops, mounted so that one loop senses toroidal rf magnetic fields and the other senses poloidal rf magnetic fields. The probe began operation in June, 1993. The probe active area is approximately 5 cm long by 2 cm, and the reciprocating mount has a slow stroke (5 cm/s) of 30 cm and a fast stroke (1.5 m/s) of about 10 cm. The probe was operated at distances from the plasma edge ranging from 30 to −5 cm (i.e., inside the last closed flux surface). The probe design, electronics, calibration, data acquisition, and data processing are discussed. First data from the probe are presented as a function of ICRF power, distance from the plasma, loop orientation, and other plasma parameters. Initial data show parametric instabilities do not play an important role for ICRF in the TORE SUPRA edge and scrape-off-layer (SOL) plasmas. Additionally it is observed that the probe signal has little or no dependence on position in the SOL/plasma edge. © 1995 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 35 (1998), S. 492-497 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Eggs of Forster's terns (Sterna forsteri) collected in 1991 from nesting colonies on Crescent Island (Columbia River) and the Potholes Reservoir in south central Washington generally contained low residues of organochlorine pesticides and metabolites, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, and polychlorinated biphenyls (PCBs). Hepatic cytochrome P450 enzyme activity in pipped embryos of Forster's terns from the two colonies seemed unaffected by contaminants. At Crescent Island, examination of 23 Forster's tern eggs with large embryos (19 viable [10 pipped] and four dead [two pipped]) revealed developmental abnormalities in two viable pipped embryos (missing maxilla and deformed pelvic girdle) and a viable prepipping embryo (shortened beak). Our limited sample sizes and number of compounds analyzed preclude us from determining whether or not the abnormalities are related to contaminants. No abnormalities were noted in 10 pipped eggs (nine viable and one dead at collection) of Forster's terns collected from the Potholes Reservoir colony. Eggs of Caspian terns (Sterna caspia) collected from Crescent Island in 1991 also contained generally low residues of contaminants, only one developmental abnormality was noted, and limited data indicated that cytochrome P450 enzyme activity apparently was unaffected by contaminants. Organochlorine contaminants were generally low in addled eggs of American white pelicans (Pelecanus erythrorhynchos) collected from Crescent Island in 1994.
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  • 6
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. During the winter of 1993–1994, male lesser scaup (Aythya affinis) were collected on the heavily polluted Indiana Harbor Canal, East Chicago, Indiana, and examined for several bioindicators of chemical exposure. Livers were analyzed for activities of three cytochrome P450–associated monooxygenases and four measures of oxidative stress. Blood and spleen were analyzed by flow cytometry for chromosomal damage. In a concurrent study, scaup tissues were analyzed for organic and inorganic contaminants. Ethoxyresorufin-O-dealkylase (EROD) activity in livers of scaup collected in January 1994 was significantly higher than in livers of scaup collected in March 1994 or in livers of reference birds. Three hepatic monooxygenase activities were each significantly correlated with polycyclic aromatic hydrocarbon (PAH) concentrations in scaup carcasses. Thiobarbituric acid (TBA) activity in scaup livers was positively correlated with iron, boron, and lead concentrations in livers and polychlorinated biphenyl concentrations in carcasses. TBA activity was negatively correlated with protein-bound thiol activity and mercury concentrations in livers. The coefficient of variation of DNA content in scaup blood cells was correlated with PAH concentrations in scaup carcasses. This is the first field study with birds to demonstrate a correlation between liver monooxygenase activity and carcass PAH concentrations and to show a direct correlation between PAH concentrations in tissues and somatic chromosomal damage in blood.
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  • 7
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Pea Patch Island in Delaware Bay is the site of the largest heronry north of Florida. From 1989–93, the population of nine species of wading birds numbered approximately 12,000 pairs, but has recently declined to about 7,000 pairs. Because Delaware Bay is a major shipping channel and receives anthropogenic releases of toxic substances from agricultural, industrial, and municipal point and nonpoint sources, contaminant exposure and effects to the heronry have been an ongoing concern. In 1997, pipping (early hatching stage) black-crowned night herons (Nycticorax nycticorax) were collected from separate nests at Pea Patch Island and from a coastal reference site, Middle Island in Rehoboth Bay, Delaware. There was no evidence of malformations or hepatic histopathological lesions in embryos, and their body and liver weights did not differ between sites. Biomarkers of petroleum hydrocarbons, polyhalogenated contaminant, and metal exposure (cytochrome P450 induction and oxidative stress responses) did not differ (p 〉 0.05) between sites, although activities of benzyloxy-O-dealkylase and ethoxyresorufin-O-dealkylase were somewhat elevated in 3 of the 15 embryos collected from Pea Patch Island. Concentrations of 21 organochlorine pesticides and metabolites were relatively low at both sites, with p,p′-DDE values well below the threshold associated with eggshell thinning. Although total PCB concentration was modestly elevated (p 〈 0.05) in Pea Patch Island heron embryos, levels of arylhydrocarbon receptor-active PCB congeners, polychlorinated dibenzodioxins and dibenzofurans, and toxic equivalents were low and did not differ between sites. Concentrations of Cd and Mn in pipping embryos from Pea Patch Island were slightly greater (p 〈 0.05) than values observed in Middle Island embryos, but levels of these and the other metals and metalloids (e.g., Hg and Se) were below values associated with toxicity. In conclusion, it seems unlikely that chlorinated hydrocarbon and metal contaminant exposure constitutes a direct threat to the reproductive success of black-crowned night herons at Pea Patch Island. However, low-level exposure to these contaminants may constitute one of many stressors that in combination could adversely affect the stability of the wading bird population at this large heronry.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 30 (1996), S. 93-99 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The toxicity of four chemical forms of selenium (seleno-L-methionine, seleno-DL-methionine, selenized yeast, and high selenium wheat) was compared in day-old mallard ducklings (Anas platyrhynchos). In the first experiment, in which the basal diet was 75% wheat, survival after 2 weeks was lower for ducklings fed 30 μg/g selenium as seleno-L-methionine (36%) than for ducklings fed 30 μg/g selenium as seleno-DL-methionine (100%) or 30 μg/g selenium from high selenium yeast (88%). The concentration of selenium at 2 weeks in the livers of survivors was similar for ducklings fed 15 μg/g selenium as seleno-DL-methionine (12 μg/g, wet weight), seleno-L-methionine (11 μg/g), and high selenium wheat (11 μg/g), but was lower when the selenium came from selenized yeast (6.2μg/g). When fed 30 μg/g selenium from the various sources, the selenium concentrations in liver were 20 μg/g for seleno-DL-methionine, 19 μg/g for seleno-L-methionine, and 9.9 μg/g for selenized yeast. In a second experiment, in which the basal diet was a commercial duck feed, survival after 2 weeks was 100% in ducklings fed 30 μg/g selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. Selenium concentrations in liver were similar for ducklings fed the 30-μg/g selenium diets as the DL or L forms of selenomethionine (27 and 25 μg/g), but lower for ducklings fed selenized yeast (13 μg/g). The greater toxicity of the L form of selenomethionine was probably related to the palatability or nutritional nature of the wheat-based diet used in experiment 1, but the exact reason for the difference between the DL and L forms is unknown. Biologically incorporated selenium, derived from high selenium wheat, was no more toxic than selenium derived from the two purified forms of selenomethionine, and the selenium in selenized yeast was not as toxic as that in the two forms of selenomethionine.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 30 (1996), S. 93-99 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The toxicity of four chemical forms of selenium (seleno-L-methionine, seleno-DL-methionine, selenized yeast, and high selenium wheat) was compared in day-old mallard ducklings (Anas platyrhynchos). In the first experiment, in which the basal diet was 75% wheat, survival after 2 weeks was lower for ducklings fed 30 μg/g selenium as seleno-L-methionine (36%) than for ducklings fed 30 μg/g selenium as seleno-DL-methionine (100%) or 30 μg/g selenium from high selenium yeast (88%). The concentration of selenium at 2 weeks in the livers of survivors was similar for ducklings fed 15 μg/g selenium as seleno-DL-methionine (12 μg/g, wet weight), seleno-L-methionine (11 μg/g), and high selenium wheat (11 μg/g), but was lower when the selenium came from selenized yeast (6.2 μg/g). When fed 30 μg/g selenium from the various sources, the selenium concentrations in liver were 20 μg/g for seleno-DL-methionine, 19 μg/g for seleno-L-methionine, and 9.9 μg/g for selenized yeast. In a second experiment, in which the basal diet was a commercial duck feed, survival after 2 weeks was 100% in ducklings fed 30 μg/g selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. Selenium concentrations in liver were similar for ducklings fed the 30-μg/g selenium diets as the DL or L forms of selenomethionine (27 and 25 μg/g), but lower for ducklings fed selenized yeast (13 μg/g). The greater toxicity of the L form of selenomethionine was probably related to the palatability or nutritional nature of the wheat-based diet used in experiment 1, but the exact reason for the difference between the DL and L forms is unknown. Biologically incorporated selenium, derived from high selenium wheat, was no more toxic than selenium derived from the two purified forms of selenomethionine, and the selenium in selenized yeast was not as toxic as that in the two forms of selenomethionine.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 39 (2000), S. 221-232 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Sediment ingestion has been identified as an important exposure route for toxicants in waterfowl. The toxicity of lead-contaminated sediment from the Coeur d'Alene River Basin (CDARB) in Idaho was examined on posthatching development of mallard (Anas platyrhynchos) ducklings for 6 weeks. Day-old ducklings received either untreated control diet, clean sediment (24%) supplemented control diet, CDARB sediment (3,449 μg/g lead) supplemented diets at 12% or 24%, or a positive control diet containing lead acetate equivalent to that found in 24% CDARB. The 12% CDARB diet resulted in a geometric mean blood lead concentration of 1.41 ppm (WW) with over 90% depression of red blood cell ALAD activity and over threefold elevation of free erythrocyte protoporphyrin concentration. The 24% CDARB diet resulted in blood lead of 2.56 ppm with over sixfold elevation of protoporphyrin and lower brain weight. In this group the liver lead concentration was 7.92 ppm (WW), and there was a 40% increase in hepatic reduced glutathione concentration. The kidney lead concentration in this group was 7.97 ppm, and acid-fast inclusion bodies were present in the kidneys of four of nine ducklings. The lead acetate positive control group was more adversely affected in most respects than the 24% CDARB group. With a less optimal diet (mixture of two thirds corn and one third standard diet), CDARB sediment was more toxic; blood lead levels were higher, body growth and liver biochemistry (TBARS) were more affected, and prevalence of acid-fast inclusion bodies increased. Lead from CDARB sediment accumulated more readily in duckling blood and liver than reported in goslings, but at given concentrations was generally less toxic to ducklings. Many of these effects are similar to ones reported in wild mallards and geese within the CDARB.
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