Reconstruction of Current Flow and Imaging of Current-Limiting Defects in Polycrystalline Superconducting Films     

AE Pashitski  A Gurevich  AA Polyanskii  DC Larbalestier  A Goyal  ED Specht  DM Kroeger  JA DeLuca  JE Tkaczyk 《Science (New York, N.Y.)》1997,275(5298):367-369

Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.  相似文献   

S. 1720 vs. S. 1777     

Meyerhoff HA 《Science (New York, N.Y.)》1946,103(2667):161-162

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Induced responses to herbivory and increased plant performance   总被引：5，自引：0，他引：5  

AA Agrawal 《Science (New York, N.Y.)》1998,279(5354):1201-1202

Plant resistance to herbivores was induced in a field experiment to evaluate the consequences of induced responses for subsequent herbivory and plant fitness. Induction early in the season resulted in halving of herbivory by chewing herbivores and a reduction in the abundance of phloem-feeding aphids when compared with controls. A correlate of lifetime plant fitness, seed mass, was enhanced by over 60 percent for individuals that were induced.  相似文献   

Pyrrolizidine alkaloid poisoning in yaks. First report and confirmation by identification of sulphurbound pyrrolic metabolites of the alkaloids in preserved liver tissue     

H. WINTER  AA SEAWRIGHT  AR MATTOCKS  R. JUKES  U. TSHEWANG  BJ GURUNG 《Australian veterinary journal》1990,67(11):411-412

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Comparison of worm control strategies in grazing sheep in Denmark.     

ME Boa  SM Thamsborg  AA Kassuku  HO B?gh 《Acta veterinaria Scandinavica》2001,42(1):57-69

Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed.  相似文献   

Pyrrolizidine alkaloid poisoning of yaks: diagnosis of pyrrolizidine alkaloid exposure by the demonstration of sulphur-conjugated pyrrolic metabolites of the alkaloid in circulating haemoglobin     

H WINTER  AA SEAWRIGHT  J HRDLICKA  AR MATTOCKS  R JUKES  KINZANG WANGDI  KB GURUNG 《Australian veterinary journal》1993,70(8):312-313

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On the Floor of the Senate     

Meyerhoff HA 《Science (New York, N.Y.)》1946,103(2674):382

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THE PRE-OLIGOCENE STRATIGRAPHY OF PORTO RICO     

Meyerhoff HA 《Science (New York, N.Y.)》1930,71(1838):322-323

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Domestic Control of Atomic Energy     

Meyerhoff HA 《Science (New York, N.Y.)》1946,103(2666):133-136

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SCIENTIFIC RESEARCH BILLS BEFORE THE UNITED STATES SENATE     

Meyerhoff HA 《Science (New York, N.Y.)》1945,102(2652):411-416

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