| 1. |
- Gilbert, F., et al.
(författare)
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Sediment reworking by the burrowing polychaete Hediste diversicolor modulated by environmental and biological factors across the temperate North Atlantic. A tribute to Gaston Desrosiers
- 2021
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 541
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Tidskriftsartikel (refereegranskat)abstract
- Particle mixing and irrigation of the seabed by benthic fauna (bioturbation) have major impacts on ecosystem functions such as remineralization of organic matter and sediment-water exchange. As a tribute to Prof. Gaston Desrosiers by the Nereis Park association, eighteen laboratories carried out a collaborative experiment to acquire a global snapshot of particle reworking by the polychaete Hediste diversicolor at 16 sites surrounding the Northern Atlantic. Organisms and soft sediments were collected during May - July at different geographical locations and, using a common laboratory protocol, particulate fluorescent tracers (`luminophores') were used to quantify particle transport over a 10-day period. Particle mixing was quantified using the maximum penetration depth of tracers (MPD), particle diffusive coefficients (D-b), and non-local transport coefficients (r). Non-local coefficients (reflecting centimeter scale transport steps) ranged from 0.4 to 15 yr(-1), and were not correlated across sites with any measured biological (biomass, biovolume) or environmental parameters (temperature, grain size, organic matter). Maximum penetration depths (MPD) averaged similar to 10.7 cm (6.5-14.5 cm), and were similar to the global average bioturbation depth inferred from short-lived radiochemical tracers. MPD was also not correlated with measures of size (individual biomass), but increased with grain size and decreased with temperature. Bio-diffusion (D-b) correlated inversely with individual biomass (size) and directly with temperature over the environmental range (Q(10) similar to 1.7; 5-21 degrees C). The transport data were comparable in magnitude to rates reported for localized H. diversicolor populations of similar size, and confirmed some but not all correlations between sediment reworking and biological and environmental variables found in previous studies. The results imply that measures of particle reworking activities of a species from a single location can be generally extrapolated to different populations at similar conditions.
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| 2. |
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| 3. |
- MAGNUSSON, J, et al.
(författare)
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FLUX PINNING IN YBA2CU3O7 THIN-FILMS GROWN BY DC MAGNETRON SPUTTERING
- 1992
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Ingår i: Cryogenics (Guildford). - : Elsevier BV. - 0011-2275 .- 1879-2235. ; 32, s. 1084-1088
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of YBa2Cu3O7 (YBCO) were deposited on single crystalline LaAlO3 substrates using d.c. magnetron sputtering. The quality of the films has been assessed by X-ray diffraction; YBa2Cu3O7 grows epitaxially with the c-axis parallel to the substrate normal. For some choices of the deposition parameters in the sputtering process, it was found that secondary phases were precipitated in the films. By a deliberate choice of deposition parameters, semi-coherently grown Y2O3 (yttria) inclusions could be obtained. They had square platelet or cubical shapes with sizes from 5 - 20 nm and thickness approximately 10 nm. The superconducting properties of the YBa2Cu3O7 films were investigated using SQUID magnetometry. Magnetization measurements on films with different densities of semicoherent Y2O3 inclusions indicate an enhanced flux pinning capability with increasing inclusion density.
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| 4. |
- NISKANEN, K, et al.
(författare)
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ANGULAR DEPENDENT MAGNETIC-PROPERTIES OF SINGLE-CRYSTAL BI-SR-CA-CU-O
- 1991
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 185, s. 2207-2208
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Tidskriftsartikel (refereegranskat)abstract
- The field, time and temperature dependence of the longitudinal component of the magnetization of a single crystal of BiSrCaCuO has been investigated by SQUID-magnetometry as a function of the tilt angle between the crystallographic c-axis and the applied magnetic field. We here discuss the results on the field and angular dependence of the magnetic response in zero field cooled magnetization experiments at low fields.
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| 5. |
- NISKANEN, K, et al.
(författare)
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ANISOTROPY IN SINGLE CRYSTALLINE BISRCACUO
- 1992
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Ingår i: Superconductors Science and Technology. - 0953-2048 .- 1361-6668. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The longitudinal component of the magnetization of a single crystal of Bi2.2Sr1.7CaCu2O8 has been investigated by SQUID-magnetometry when the magnetic field is applied at different angles 0-degrees-90-degrees with respect to the crystallographic c-axis. The anisotropy of the system, deduced from the magnetization and relaxation rate data, indicates a mass anisotropy m(c)/m(ab) of order 20, a strikingly low value compared to what has been found from torque and magnetoresistance measurements m(c)/m(ab) almost-equal-to 3000.
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| 6. |
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| 7. |
- NISKANEN, K, et al.
(författare)
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NONLOGARITHMIC MAGNETIC-RELAXATION IN BI-SR-CA-CU-O SINGLE-CRYSTALS
- 1991
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Ingår i: Superconductors Science and Technology. - 0953-2048 .- 1361-6668. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- The time dependence of the low field susceptibility of a Bi2.2Sr1.7CaCu2O8 single crystal has been investigated in the field range 0.1-300 gauss and at temperatures 0.25 less-than-or-equal-to T/T(c) less-than-or-equal-to 0.9. The relaxation of the magnetization is found to change from a logarithmic to a non-logarithmic form as the applied field is increased, implying that a conventional flux creep model cannot sufficiently describe the behaviour.
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| 8. |
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| 9. |
- NORLING, P, et al.
(författare)
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MAGNETIC-RELAXATION OF INTERGRANULAR CRITICAL-STATE IN SINTERED YBA2CU3O7-DELTA
- 1994
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Ingår i: Physica. C, Superconductivity. - : Elsevier BV. - 0921-4534 .- 1873-2143. ; 221, s. 169-176
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Tidskriftsartikel (refereegranskat)abstract
- The relaxation of the zero-field-cooled magnetisation of three sintered samples of YBa2Cu3O7-delta has been measured at low fields. Special attention was paid to the low-field regime where the motion of intergranular vortices is dominating the decay of the magnetisation. From the measured data the apparent activation energy for flux jumps, U0, was calculated. The extracted values fall in the range 0.6-2 eV, considerably higher than what has been found for the intragranular flux creep but in the same range as reported by others for intergranular creep. The samples showed somewhat different behaviours and the sample with the most homogeneous morphology had the lowest value of U0. This can be explained within theories for pinning in granular superconductors.
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| 10. |
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