| 1. |
- Bonanni, Valentina, et al.
(author)
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First order reversal curve analysis of graded anisotropy FePtCu films
- 2010
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:20
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Journal article (peer-reviewed)abstract
- The reversal mechanisms of graded anisotropy FePtCu films have been investigated by alternating gradient magnetometer (AGM) and magneto-optical Kerr effect (MOKE) measurements with first-order reversal curve (FORC) techniques. The AGM-FORC analysis, which clearly shows the presence of soft and hard components, is unable to resolve how these phases are distributed throughout the film thickness. MOKE-FORC measurements, which preferentially probe the surface of the film, reveal that the soft components are indeed located toward the top surface. Combining AGM-FORC with the inherent surface sensitivity of MOKE-FORC analysis allows for a comprehensive analysis of heterogeneous systems such as graded materials.
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| 2. |
- Bonetti, Stefano, 1982-, et al.
(author)
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Experimental evidence of self-localized and propagating spin wave modes in obliquely magnetized current-driven magnetic nanocontacts
- 2010
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:21, s. 217204-
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Journal article (peer-reviewed)abstract
- Through detailed experimental studies of the angular dependence of spin wave excitations in nanocontact-based spin-torque oscillators, we demonstrate that two distinct spin wave modes can be excited, with different frequency, threshold currents, and frequency tunability. Using analytical theory and micromagnetic simulations we identify one mode as an exchange-dominated propagating spin wave, and the other as a self-localized nonlinear spin wave bullet. Wavelet-based analysis of the simulations indicates that the apparent simultaneous excitation of both modes results from rapid mode hopping induced by the Oersted field.
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| 3. |
- Elmlund, Dominika, 1981-, et al.
(author)
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Ab initio structure determination from electron microscopic images of single molecules coexisting in different functional states
- 2010
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In: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 18:7, s. 777-786
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Journal article (peer-reviewed)abstract
- We have developed methods for ab initio three-dimensional (3D) structure determination from projection images of randomly oriented single molecules coexisting in multiple functional states, to aid the study of complex samples of macromolecules and nanoparticles by electron microscopy (EM). New algorithms for the determination of relative 3D orientations and conformational state assignment of single-molecule projection images are combined with well-established techniques for alignment and statistical image analysis. We describe how the methodology arrives at homogeneous groups of images aligned in 3D and discuss application to experimental EM data sets of the Escherichia coli ribosome and yeast RNA polymerase II.
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| 4. |
- Fang, Yeyu, et al.
(author)
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FORC studies of exchange biased NiFe in L1_0(111) FePt-based spin valve
- 2010
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In: Journal of Physics Conference Series. - BRISTOL : IOP Publishing. - 1742-6588 .- 1742-6596. ; 200:7, s. 072002-
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Journal article (peer-reviewed)abstract
- We use First-Order Reversal Curves (FORC) to study the switching distribution and exchange bias in L10 (111) FePt-based spin valves with a layer structure of Ta (6)/Pt (3)/L10 (111) Fe53Pt47 (20)/Co50Fe50 (1.5)/Cu (4.5)/Co50Fe50 (2)/Ni80Fe20 (3) (in nm). We find that the switching of the free layer magnetization is strongly influence by the magnetic state of the FePt/CoFe fixed layer, as evidenced by tunable coercivity and exchange bias fields.
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| 5. |
- Flisberg, Anders, 1958, et al.
(author)
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Does indomethacin for closure of patent ductus arteriosus affect cerebral function?
- 2010
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In: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 99:10, s. 1493-1497
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Journal article (peer-reviewed)abstract
- Objective: To study whether indomethacin used in conventional dose for closure of patent ductus arteriosus affects cerebral function measured by Electroencephalograms (EEG) evaluated by quantitative measures. Study design: Seven premature neonates with haemodynamically significant persistent ductus arteriosus were recruited. EEG were recorded before, during and after an intravenous infusion of 0.2 mg/kg indomethacin over 10 min. The EEG was analysed by two methods with different degrees of complexity for the amount of low-activity periods (LAP, "suppressions") as an indicator of affection of cerebral function. Results: Neither of the two methods identified any change in the amount of LAPs in the EEG as compared to before the indomethacin infusion. Conclusion: Indomethacin in conventional dose for closure of patent ductus arteriosus does not affect cerebral function as evaluated by quantitative EEG.
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| 6. |
- Flisberg, Anders, 1958, et al.
(author)
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EEG and spectral edge frequency : analysis in posthypoxic newborn piglets
- 2010
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In: Neuro - endocrinology letters. - : Brain Research Promotion. - 0172-780X. ; 31:2, s. 181-186
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To evaluate the frequency content of the electroencephalogram (EEG) during recovery after a severe hypoxic insult in newborn piglets. METHODS: EEG was continuously monitored in nine newborn piglets exposed to a severe hypoxic period. Power spectra in five frequency bands were calculated using Fourier transformation. Spectral edge frequency 90 (SEF90) was defined as the frequency below which 90% of the power in the EEG was located. The piglets were divided into two groups; Group 1 represented piglets with some EEG recovery and Group 2 represented piglets without any EEG recovery. RESULTS: The recovery of the EEG in Group 1 had the same time course in all frequency bands. SEF90 indicates recovery earlier than the value of total power. But SEF90 also signals activity in the EEGs that were almost completely suppressed. When SEF90 was calculated during periods of periodic EEG activity during the very early phase of recovery, the values fell within the same range as during the control period. CONCLUSION: Spectral analysis of continuous EEG in newborn piglets exposed to very severe hypoxia showed that no specific frequency band of the EEG preceded the other ones during recovery. The results of the SEF90 measure, demonstrates the need for critical analysis of the raw EEG before any reliable estimation of cerebral function can be made.
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| 7. |
- Holmgren, Kristina, 1955, et al.
(author)
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The association between poor organizational climate and high work commitments, and sickness absence in a general population of women and men
- 2010
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In: Journal of Occupational and Environmental Medicine. - : Lippincott Williams & Wilkins. - 1076-2752 .- 1536-5948. ; 52:12, s. 1179-1185
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Journal article (peer-reviewed)abstract
- Objectives: To investigate the association between organizational climate and work commitment, and sickness absence in a general population of workers and consecutively selected employed sick-listed. Methods: Questionnaire data used in this cross-sectional study consisted of two cohorts: (1) randomly selected individuals in a general working population cohort (2763) and (2) consecutively selected employed sick-listed cohort (3044) for more than 14 days over 2 months. Results: Poor organizational climate was associated with increased odds of belonging to the employed sick-listed cohort among both women and men, while high work commitments were associated with increased odds only among women. The increased adjusted odds ratio for the combinations of poor organizational climate and high work commitment was 1.80 (confidence interval 1.36 to 2.37) among women and 2.74 (confidence interval 1.84 to 4.08) among men. Conclusions: These results support the magnitude of combining organizational climate and work commitment.
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| 8. |
- Jacksén, Johan, et al.
(author)
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Capillary electrophoresis separation and matrix-assisted laser desorption/ionization mass spectrometry characterization of bovine serum albumin fluorescein isothiocyanate conjugates
- 2010
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In: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878:15-16, s. 1125-1134
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Journal article (peer-reviewed)abstract
- A protocol using enzymatic digestion, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and capillary electrophoresis with laser induced fluorescence detection (CE-LIF) for the investigation of the binding of the fluorescent contact allergen fluorescein isothiocyanate (FITC) to the 66 kDa large protein bovine serum albumin (BSA), as a model system for protein-hapten binding in the skin, is presented. Mass spectra of BSA-FITC digestions, using trypsin and chymotrypsin, respectively, provided sequence coverage of 97%. To investigate the number of FITC-bound peptides using CE-LIF separation, three different buffer salts at four different pH levels were evaluated. The use of 20 mM sodium citrate pH 6.5 as well as 20 mM sodium phosphate pH 6.5 or pH 7.5 as background electrolyte revealed high numbers of peptides with at least one bound FITC. The effect of the electrolyte counter ion on MALDI-MS was investigated and was found to have effect on the MALDI spectra signal-to-noise (S/N) at 50 mM but not at 10 m M. Of the 60 theoretical FITC-binding sites in BSA this MALDI-MS protocol presents 30 defined. 28 possible and 2 non-binding sites for FITC. (C) 2010 Elsevier B.V. All rights reserved.
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| 9. |
- Kadigrobov, Anatoli M., 1937, et al.
(author)
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Thermoelectrical manipulation of nanomagnets
- 2010
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 107:12, s. 123706-
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Journal article (peer-reviewed)abstract
- We investigate the interplay between the thermodynamic properties and spin-dependent transport in a mesoscopic device based on a magnetic multilayer (F/f/F), in which two strongly ferromagnetic layers (F) are exchange-coupled through a weakly ferromagnetic spacer (f) with the Curie temperature in the vicinity of room temperature. We show theoretically that the Joule heating produced by the spin-dependent current allows a spin-thermoelectronic control of the ferromagnetic-to-paramagnetic (f/N) transition in the spacer and, thereby, of the relative orientation of the outer F-layers in the device (spin-thermoelectric manipulation of nanomagnets). Supporting experimental evidence of such thermally-controlled switching from parallel to antiparallel magnetization orientations in F/f(N)/F sandwiches is presented. Furthermore, we show theoretically that local Joule heating due to a high concentration of current in a magnetic point contact or a nanopillar can be used to reversibly drive the weakly ferromagnetic spacer through its Curie point and thereby exchange couple and decouple the two strongly ferromagnetic F-layers. For the devices designed to have an antiparallel ground state above the Curie point of the spacer, the associated spin-thermionic parallel to antiparallel switching causes magnetoresistance oscillations whose frequency can be controlled by proper biasing from essentially dc to GHz. We discuss in detail an experimental realization of a device that can operate as a thermomagnetoresistive switch or oscillator.
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| 10. |
- Luheshi, Leila M., et al.
(author)
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Sequestration of the A beta Peptide Prevents Toxicity and Promotes Degradation In Vivo
- 2010
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In: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 8:3, s. e1000334-
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Journal article (peer-reviewed)abstract
- Protein aggregation, arising from the failure of the cell to regulate the synthesis or degradation of aggregation-prone proteins, underlies many neurodegenerative disorders. However, the balance between the synthesis, clearance, and assembly of misfolded proteins into neurotoxic aggregates remains poorly understood. Here we study the effects of modulating this balance for the amyloid-beta (A beta) peptide by using a small engineered binding protein (Z(A beta 3)) that binds with nanomolar affinity to A beta, completely sequestering the aggregation-prone regions of the peptide and preventing its aggregation. Co-expression of Z(A beta 3) in the brains of Drosophila melanogaster expressing either A beta(42) or the aggressive familial Alzheimer's disease (AD) associated E22G variant of A beta(42) abolishes their neurotoxic effects. Biochemical analysis indicates that monomer A beta binding results in degradation of the peptide in vivo. Complementary biophysical studies emphasize the dynamic nature of A beta aggregation and reveal that Z(A beta 3) not only inhibits the initial association of A beta monomers into oligomers or fibrils, but also dissociates pre-formed oligomeric aggregates and, although very slowly, amyloid fibrils. Toxic effects of peptide aggregation in vivo can therefore be eliminated by sequestration of hydrophobic regions in monomeric peptides, even when these are extremely aggregation prone. Our studies also underline how a combination of in vivo and in vitro experiments provide mechanistic insight with regard to the relationship between protein aggregation and clearance and show that engineered binding proteins may provide powerful tools with which to address the physiological and pathological consequences of protein aggregation.
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