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| 2. |
- Lizárraga, Raquel, et al.
(författare)
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Crystal and magnetic structure investigation of TbNi5-xCux (x=0,0.5,1.0,1.5,2.0) : Experiment and theory
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:9, s. 094419-
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Tidskriftsartikel (refereegranskat)abstract
- The effect of Cu substitution on the structural and magnetic properties of TbNi5-xCux (x=0,0.5,1.0,1.5,2.0) have been investigated by x-ray diffraction, magnetization measurements and neutron powder and single crystal diffraction. The electronic and the magnetic structures of TbNi5 were studied using first principles theory. All samples were found to have the CaCu5-type structure, space group P6/mmm. The lattice parameters increase monotonically with increasing Cu concentration. The Curie temperature T-c has a maximum value of 29 K at x=1.0. The magnetic structure of TbNi5 at 10 K is incommensurate with a helimagnetic component [wave vector q similar to 2 pi/c(0,0,0.02)] perpendicular to a ferromagnetic one. In contrast, the substituted TbNi5-xCux alloy is ferromagnetic. All magnetic moments are observed to be located on the Tb atoms. The magnetocrystalline anisotropy in the ab plane is observed to be strongly increased by the Cu substitution, whereas the magnetization decreases with the Cu concentration. The observed magnetic structure of TbNi5 is consistent with first principles calculations regarding both the magnetic moments and the helimagnetic structure. The microscopical origin of the helimagnet is analyzed and correlated to the Fermi surface topology.
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| 3. |
- Magnussen, S., et al.
(författare)
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What people believe about memory
- 2006
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Ingår i: Memory. - : Informa UK Limited. - 0965-8211 .- 1464-0686. ; 14:5, s. 595-613
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Tidskriftsartikel (refereegranskat)abstract
- Two representative samples of adult Norwegians (n=2000) were asked a set of general and specific questions regarding their beliefs and opinions about human memory. The results indicate that on many questions, such as time of the earliest memories, inhibiting effects of collaboration, and memory for dramatic versus ordinary events, the views of the general public concurred with current research findings, and people in general had realistic views about their own memory performance. On other questions, such as the reliability of olfactory as compared with visual and auditory memory, the memory of small children in comparison with that of adults, the likelihood of repression of adult traumatic memories, and on more general questions such as the possibility of training memory and the capacity limitations of long-term memory, a large proportion of the participants expressed views that are less supported by scientific evidence. Implications of these findings are briefly discussed. © 2006 Psychology Press Ltd.
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| 5. |
- Holmström, Petter, et al.
(författare)
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Intersubband photonic devices by group-III nitrides
- 2007
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Ingår i: Optoelectronic Materials And Devices II. - : SPIE. - 9780819469458 ; , s. N7821-N7821
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Konferensbidrag (refereegranskat)abstract
- The characteristics of intersubband transitions in III-nitride quantum wells are promising for detectors and all-optical switches through a high intrinsic speed (similar to 1 THz), and can also provide a high optical saturation power and a desired small negative chirp parameter in electroabsorption modulators. The high LO-phonon energy allows to improve the operating temperature of THz emitters. Recent achievements and prospects for intersubband III-nitride photonic devices, mainly for lambda=1.55 mu m, are briefly reviewed. Further, means to enhance material quality by achieving crack-free growth of GaN/AlN multiple-quantum-well (MQW) structures, and by employing intersubband transitions in multiple-quantum-disk (MQD) structures incorporated into dislocation free GaN nanocolumns are discussed. We investigate the occurrence of cracks in MBE-grown GaN/AlN MQWs on GaN MOVPE templates with respect to the buffer layer, the number of QWs and the temperature reduction rate after growth. Intersubband absorption in GaN/AlN MQDs in the wavelength range 1.38-1.72 mu m is demonstrated in three samples grown on Si(111).
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| 6. |
- Normen, L, et al.
(författare)
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A phytosterol database: Fatty foods consumed in Sweden and the Netherlands
- 2007
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Ingår i: Journal of Food Composition and Analysis. - : Elsevier BV. - 0889-1575. ; 20:3-4, s. 193-201
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to quantify seven specific dietary phytosterols (PS) (campesterol, β-sitosterol, stigmasterol, brassicasterol, 5-avenasterol, β-sitostanol and campestanol) in fatty foods. Gas–liquid chromatography procedure was applied to 87 items of Swedish and Dutch origin. In general, β-sitosterol was the dominating phytosterol (60% represented the median total concentration), followed by campesterol (24%), stigmasterol (7%) and 5-avenasterol (5%), brassicasterol (3%), β-sitostanol (1%) and campestanol (<0.1%). The median total content of PS for the 42 fat spreads and margarines was 204 mg/100 g with minimum 73 mg/100 g in a low-fat margarine and maximum 775 mg/100 g in a polyunsaturated fat spread. Among 19 plant oils, median total PS content was 348 mg/100 g, with minimum 39 mg/100 g in palm oil and maximum 978/100 g in corn oil. Median value for 12 nuts and seeds was 144 mg/100 g, with minimum 68 mg/100 g in coconut rasps and maximum 404 mg/100 g in sesame seeds. Median value for total PS was 100 mg/100 g among 14 miscellaneous fatty foods with minimum 11 mg/100 g in Dutch non-dairy ice cream and maximum 484 mg/100 g in mayonnaise. The results are discussed against a background of methodological aspects with the chosen analytical procedure and the importance of setting up valid PS databases for epidemiological studies.
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