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  • 1
    Electronic Resource
    Electronic Resource
    Critical-state magnetization of type-II superconductors in rectangular slab and cylinder geometries (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 3945-3952 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A scheme is described for analytical calculation of critical-state magnetization M of superconductors in the geometry of long rectangular slabs and cylindrical specimens in a parallel magnetic field. The simplicity of the general scheme is demonstrated by deriving compact expressions for the ascending and descending field branches of M in the exponential model Jc=jc0 exp(−B/B0) and in the Kim, Hempstead, and Strnad model [Phys. Rev. 129, 528 (1963)], Jc=jc0/(1+B/B0). The analyses focus on the vertical width ΔM of large field magnetization hysteresis loops. While Bean's result [Phys. Rev. Lett. 8, 250 (1962)], Jc∝ΔM, today is used extensively to infer the critical current, it is well known that the method lacks consistency when a field dependence is seen in ΔM. For the two models it is shown explicitly that in the expansion of the functional relation ΔM(Jc), Bean's result corresponds to the lowest-order term. Also to the next order in the functional expansion we find a unifying form of expressing the model behaviors. This term contains the second derivative of J2c(B) with a prefactor that depends on the sample geometry. A model-independent proof for the two first terms in the expansion of ΔM(Jc) is also given, which allows the significance of size and shape, i.e., thickness and aspect ratio, to be discussed on a general basis. New methods to extract Jc from ΔM data, one of them without having to invoke specific critical-state models, are indicated. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358576
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  • 2
    Electronic Resource
    Electronic Resource
    Flux patterns of multifilamentary Ag-sheathed (Pb,Bi)2Sr2Ca2Cu3O10+δ tapes : The 7th joint MMM-intermag conference on magnetism and magnetic materials (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 6798-6800 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Flux patterns of multifilamentary Ag-sheathed (Pb,Bi)2Sr2Ca2Cu3O10+δ tapes comprising 19 filaments are visualized by means of magneto-optic imaging. In low fields, the shielding currents are seen to flow mainly in the outermost filaments. With increasing external magnetic field, the inner filaments also contribute to the current flow. To compare the local flux distribution with the integral magnetization values, magnetization loops are measured by a SQUID magnetometer on the same sample following the fields used in the magneto-optic imaging (± 120 mT) and covering fields up to ±5 T at various temperatures. The magnetization loops also reveal that the multifilamentary tapes show the anomalous position of the central peak, but always less pronounced than in monofilamentary tapes. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367865
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  • 3
    Electronic Resource
    Electronic Resource
    Burning of high Tc bridges (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3147-3149 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Burning of superconducting thin film bridges by large transport currents (up to densities of 2×107 A/cm2) is investigated by magneto-optical imaging of flux distribution and low-temperature scanning electron microscopy providing Tc maps. It is shown that the destruction is preceded by significant penetration of magnetic field inside a weak-pinning region. In bridges containing extended defects magneto-optic investigation is sufficient to locate the incipient burning region. In high-quality bridges free from such defects only a combination of the two techniques will allow prediction of the place of fatal destruction. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120272
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  • 4
    Electronic Resource
    Electronic Resource
    Magneto-optic observation of anomalous Meissner current flow in superconducting thin films with slits (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3590-3592 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Slits patterned into a YBa2Cu3O7−δ thin film were observed to obstruct Meissner sheet currents leading to an imbalance in the local Meissner screening properties. The new phenomenon was studied with magneto-optic imaging where twin lobes of opposite flux polarity were seen to form near the slits and inside the Meissner region. The lobe closest to the sample edge is always polarized opposite to the applied field. At weak fields, the anomalous flux generation is reversible. At higher fields, but still sufficiently small to keep the vortex penetration front away from the slits, the anomalous current starts nucleating flux lines which become trapped when the field is removed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117216
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic analysis of population structure of tusk in the North Atlantic (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: To study the population structure of tusk Brosme brosme in the North Atlantic, samples from six fishing grounds were collected: St Kilda; Storegga; Faroe Islands; Rockall bank; Davis Strait and East Greenland. In addition two samples from the Norwegian coast; Kragerø and Øygarden, were included. Nine enzymes and haemoglobin were analysed by starch gel and agar gel electrophoresis. In addition isoelectric focusing (IEF) was carried out. At least 22 loci were represented. Polymorphisms were shown in eight loci and average heterozygosity was found to be about 0.05. Highest heterozygosity was found in haemoglobin analysed by Smithies buffer pH 8.6. Malate dehydrogenase (MDH-2) analysed in IEF (pH 3.5-9.5), and haemoglobin were found as valuable tools for studies of stock structure in tusk. In the Greenland samples only one of the MDH-2 heterozygotes was found, while in the East Atlantic both the observed heterozygotes were more frequent. The frequencies of the the Hb*b allele were about 0.40 and 0.70 in the samples from east and west Atlantic respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb06058.x
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  • 6
    Electronic Resource
    Electronic Resource
    Ontogeny of haemoglobin polymorphism in cod (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Haemoglobins of 0-group cod from 30 to 150 mm length were analysed by agar gel electrophoresis and isoelectric focusing to identify the lower size limit for determination of the haemoglobin polymorphisms in cod; both the main system which has been known for more than 30 years and the recently described subgroups. The juvenile fish studied had higher concentration of the HbII-component (split into three bands at these fish sizes) compared to older fish. The main haemoglobin types could be distinguished clearly and reliably at a fish size of about 35 mm and above. The subgroups of the HbI-components, however, could not be identified reliably until the cod were about 80 mm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb06043.x
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  • 7
    Electronic Resource
    Electronic Resource
    Feeding, Ichthyophonus sp. infection, distribution and growth history of Norwegian spring-spawning herring in summer (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 50 (1997), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: After its collapse in the late 1960s, 1991 was the first year of systematic herring investigations after the Norwegian Sea stock returned to the traditional summer-feeding areas. Of 11 prey groups three dominated the diet; Calanus finmarchicus, Parathemisto spp. and Sebastes spp. There was a high prevalence of Ichthyophonus sp. at stations in the central and western parts of the Norwegian Sea where the cpue was low. This suggests that infected individuals were unable to return from the feeding to the wintering area of the Norwegian fjords. Highest cpue were recorded between 68–73° N and 5–15° E. Age groups 2, 3 and 8 were most frequently caught and age group 8 (the 1983 year class) dominated the samples. Herring occurred in dense concentrations where C. finmarchicus dominated diet. 0-group fish dominated diet at stations along the coast from 66–73° N and out to c. 300 km off the coast. Mature herring overlapped in distribution with 0-group fish and Sebastes spp. contributed largely to herring diet in this area. The first rich year-class after the collapse, the 1983 year class, had a faster growth than rich year classes from past herring periods, but slower than poor ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1997.tb01956.x
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  • 8
    Electronic Resource
    Electronic Resource
    Magneto-optic study of spatial magnetic-field distribution relaxation in an HTSC film strip after transport current turn-on (1999)
    Springer
    Physics of the solid state 41 (1999), S. 877-880 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper provides the first demonstration of the efficiency of applying the magneto-optic method to studies of the spatial and temporal magnetic-field relaxation in an YBa2Cu3O7 film strip after the transport current is switched on. It is shown that the evolution of magnetic flux distribution is adequately described in terms of a modified Bean model with time-dependent critical current. At a time 50 ms after the current is switched on, the critical current of the samples studied decreases by ≈15%. This proves the significance of thermally activated magnetic flux motion (creep) in the regime investigated. The magnetic vortex pinning energy has been estimated as U 0≈20 kT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1130894
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  • 9
    Electronic Resource
    Electronic Resource
    Magnetic Levitation With High-T c Superconducting Thin Films (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 519-524 
    Details
    ISSN: 1572-9605
    Keywords: HTSC thin film ; levitation force ; magnetic stiffness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The levitation force between a permanent magnet and a superconducting thin film was investigated experimentally. The configuration consisted of a cylindrical NdFeB permanent magnet placed above a circular YBa2Cu3O7−δ disk with common cylinder axis. Precise measurements were made of the vertical force F z and the magnetic stiffness κ z as a function of the magnet–superconductor separation at 77 K. Several features contrasting the levitation force produced using bulk superconductors were observed. Thin films produced very high values for F z and κ z per unit volume of superconducting material. The hysteretic behavior of F z during decreasing and increasing separation resulted in loops of nearly symmetrical shape, which also contain a peak in the repulsive force branch. The observations are analyzed and explained with good quantitative agreement using recent theories for flux penetration in thin superconductors in transverse magnetic fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022618825582
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  • 10
    Electronic Resource
    Electronic Resource
    Aleochara suffusa andA. bilineata (Col.: Staphylinidae) as parasitoids of brassica root flies in northern Norway (1995)
    Springer
    BioControl 40 (1995), S. 163-167 
    Details
    ISSN: 1573-8248
    Keywords: Aleochara ; Delia ; Brassica ; parasitoids ; coexistence ; niche separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A sample ofDelia puparia collected in late autumn from a brassica field at Tromsø, northern Norway, was investigated to study the level of parasitism byAleochara. BothA. suffusa andA. bilineata were reared from puparia of the cabbage root fly,Delia radicum, and the bean seed flies,D. florilega and/orD. platura. Only two specimens ofA. bilineata emerged from puparia of the turnip root fly,D. floralis. BothAleochara species hibernated in the larval state and both pupated inside the host puparium. Most specimens ofA. suffusa emerged from small hosts (D. florilega/D. platura), whereas the majority of A.bilineata emerged from host species of larger size (D. radicum/D. floralis). The time to develop from first instar larva to adult was similar for bothA. suffusa andA. bilineata. Parasitoids developing in large hosts emerged later than those in small hosts, the delay being the same for both species ofAleochara.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02373065
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