| 1. |
- Johansen, T.H., et al.
(författare)
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Transition from elastic to dissipative motion in a magnet-high-Tc superconductor system
- 1991
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 70:12, s. 7496-7499
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Tidskriftsartikel (refereegranskat)abstract
- Using quasistatic harmonic excitations, we have measured the lateral force between a permanent magnet and a Bi-based ceramic high-Tc superconductor (HTSC) for lateral displacement amplitudes down to 1 µm. We find clear evidence for a transition from elastic (nondissipative) to inelastic interaction, and attribute the effect to flux pinning. The crossover amplitude can easily reach several micrometers, with the consequence that the lateral disturbance of a levitated magnet will decay to this amplitude, whereas further damping will be extremely slow. For applications of HTSCs in magnetic bearing systems this can be a very relevant aspect of the interaction, and it can set the limit for precision positioning of levitated objects
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| 2. |
- Yang, Z.J., et al.
(författare)
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Study of flux motion in Bi-based superconductors by a pendulum
- 1992
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Ingår i: Journal of Superconductivity. - 0896-1107 .- 1572-9605. ; 5:2, s. 127-135
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Tidskriftsartikel (refereegranskat)abstract
- Using a computerized mechanical pendulum, we have studied the lateral magnetic flux motion of the Bi-based high-T c superconductors in the quasi-static magnetic field (0.1 Hz) for the range 1 μm to 0.35 mm. The effect of d.c. and a.c. transport currents on the flux motion has also been investigated. We argue that the lateral magnetic stiffness is a measure of the pinning potential of the fluxoids in the superconductors. The pinning energy barrier ε is estimated to be about 0.3 eV based on the stiffness measurements, which is comparable with the data from the YBa2Cu3O7-χ superconductors.
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| 3. |
- Michaelsen, K F, et al.
(författare)
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Serum bone gamma-carboxyglutamic acid protein in a longitudinal study of infants : lower values in formula-fed infants.
- 1992
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Ingår i: Pediatric Research. - : Springer Science and Business Media LLC. - 0031-3998 .- 1530-0447. ; 31:4 Pt 1, s. 401-5
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Tidskriftsartikel (refereegranskat)abstract
- Bone gamma-carboxyglutamic acid protein [BGP (osteocalcin)] is a protein synthesized by osteoblasts and incorporated in the bone matrix. Serum BGP is a sensitive marker of bone formation, and it parallels the growth velocity curve during childhood and adolescence. Serum BGP was measured at the age of 2, 6, and 9 mo in a cohort study of nutrition and growth in 91 healthy infants. At 2 mo, the mean BGP value (+/- SD) was 275 +/- 87 ng/mL in infants exclusively breast-fed, and 80 +/- 44 ng/mL in formula-fed infants. At 6 mo, the values were 142 +/- 58 ng/mL and 55 +/- 30 ng/mL, and at 9 mo 75 +/- 39 ng/mL and 45 +/- 19 ng/mL in partially breast-fed and formula-fed infants, respectively. The differences were significant (p less than 0.001) at all three ages. At 2 and 9 mo, breast-milk intake was measured by test-weighing. Serum BGP was positively correlated to breast milk intake (mL/kg body wt) at 2 mo (r = 0.59, p less than 0.001) and 9 mo (r = 0.41, p = 0.06). When breast-feeding was stopped, the high BGP concentrations were not sustained. There were no significant differences in linear growth velocity between breast-fed and formula-fed infants and no correlation between BGP values and linear growth velocity. We speculate that either a factor in human milk or the level of minerals in human milk causes the high BGP values. Moreover, if the higher values are associated with increased osteoblast activity, then the remodeling or the mineralization of bone might be different in infants not being breast-fed.
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| 4. |
- Michaelsen, K F, et al.
(författare)
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Serum bone Gla Protein (BGP, Osteocalcin) in Infants : Values Positively Correlated with Human Milk Intake.
- 1992
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Ingår i: Mechanisms Regulating Lactation and Infant Nutrient Utilization. - : Wiley-Liss. - 0471561347 ; , s. 419-423
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Bone gamma-carboxyglutamic acid protein [BGP (osteocalcin)] is a protein synthesized by osteoblasts and incorporated in the bone matrix. Serum BGP is a sensitive marker of bone formation, and it parallels the growth velocity curve during childhood and adolescence. Serum BGP was measured at the age of 2, 6, and 9 mo in a cohort study of nutrition and growth in 91 healthy infants. At 2 mo, the mean BGP value (+/- SD) was 275 +/- 87 ng/mL in infants exclusively breast-fed, and 80 +/- 44 ng/mL in formula-fed infants. At 6 mo, the values were 142 +/- 58 ng/mL and 55 +/- 30 ng/mL, and at 9 mo 75 +/- 39 ng/mL and 45 +/- 19 ng/mL in partially breast-fed and formula-fed infants, respectively. The differences were significant (p less than 0.001) at all three ages. At 2 and 9 mo, breast-milk intake was measured by test-weighing. Serum BGP was positively correlated to breast milk intake (mL/kg body wt) at 2 mo (r = 0.59, p less than 0.001) and 9 mo (r = 0.41, p = 0.06). When breast-feeding was stopped, the high BGP concentrations were not sustained. There were no significant differences in linear growth velocity between breast-fed and formula-fed infants and no correlation between BGP values and linear growth velocity. We speculate that either a factor in human milk or the level of minerals in human milk causes the high BGP values. Moreover, if the higher values are associated with increased osteoblast activity, then the remodeling or the mineralization of bone might be different in infants not being breast-fed.
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