| 1. |
- Löfgren, N., et al.
(författare)
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Remote sessions and frequency analysis for improved insight into cerebral function during pediatric and neonatal intensive care.
- 2003
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Ingår i: IEEE transactions on information technology in biomedicine. - 1089-7771 .- 1558-0032. ; 7:4, s. 283-90
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Tidskriftsartikel (refereegranskat)abstract
- A project involving recording and analysing EEG together with cardiovascular signals and temperature has been initiated. The aim of this project is to establish difficulties and possibilities involved with implementing a system for remote sessions and analysing EEG in correlation with other physiological signals. One objective is to find indicators of cerebral function during postasphyxia neonatal intensive care and pediatric cardiopulmonary bypass surgery with hypothermia. Remote sessions for joint interpretation have been carried out between pediatricians and clinical neurophysiologists, and EEG has been analyzed using frequency analyzing tools. One result is the discovery of reversible spectral changes coinciding with blood pressure falls, which may indicate loss of autoregulation function. This finding is one outcome from initial use of a system, developed during the project to facilitate communication about, and analysis of the recorded signals. Thus, already from a limited number of remote sessions and the use of basic signal processing techniques, important results have been achieved and better insight has been gained of how cerebral function is affected by cardiopulmonary bypass surgery. In this paper, we present our experiences from introducing a system for remote consultations, and evaluate the use for such a system in the current applications.
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| 2. |
- Grigoriev, I. A., et al.
(författare)
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Explicit algebraic and differential Reynolds stress model application to homogeneously sheared and compressed turbulence
- 2015
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Ingår i: Proceedings - 15th European Turbulence Conference, ETC 2015. - : TU Delft.
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Konferensbidrag (refereegranskat)abstract
- An explicit algebraic and differential Reynolds stress models (EARSM and DRSM) are used to investigate the influence of homogeneous shear and compression on the behaviour of turbulence in the limit of rapid distortion theory (RDT). EARSM is shown to give realizable results and to preserve RDT regime, unlike the eddy-viscosity model (EVM). The DRSM version of our model is in reasonable agreement with RDT theory.
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| 3. |
- Mancarella, Francesco, et al.
(författare)
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Angular momentum blockade in nanoscale high-T-c superconducting grains
- 2013
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Ingår i: Superconductors Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 26:12
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the angular momentum blockade in small d-wave superconducting grains in an external field. We find that abrupt changes in the angular momentum state of the condensate, angular momentum blockade, occur as a result of changes in the angular momentum of the condensate in an external magnetic field. The effect represents a direct analogy with the Coulomb blockade. We use the Ginzburg-Landau formalism to illustrate how a magnetic field induces a deviation from the d-wave symmetry which is described by a (d(x2-y2)+id(xy))-order parameter. We derive the behavior of the volume magnetic susceptibility as a function of the magnetic field, and corresponding magnetization jumps at critical values of the field that should be experimentally observable in superconducting grains.
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| 4. |
- Thordstein, Magnus, et al.
(författare)
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Spectral analysis of burst periods in EEG from healthy and post-asphyctic full-term neonates
- 2004
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Ingår i: Clin Neurophysiol. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 115:11, s. 2461-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate whether the periodic EEG patterns seen in healthy and sick full term neonates (trace alternant and burst suppression, respectively) have different frequency characteristics. METHODS: Burst episodes were selected from the EEGs of 9 healthy and 9 post-asphyctic full-term neonates and subjected to power spectrum analysis. Powers in two bands were estimated; 0-4 and 4-30 Hz, designated low- and high-frequency activity, respectively (LFA, HFA). The spectral edge frequency (SEF) was also assessed. RESULTS: In bursts, the LFA power was lower in periods of burst suppression as compared to those of trace alternant. The parameter that best discriminated between the groups was the relative amount of low- and high-frequency activity. The SEF parameter had a low sensitivity to the group differences. In healthy neonates, the LFA power was higher over the posterior right as compared to the posterior left region. CONCLUSIONS: Spectral power of low frequencies differs significantly between the burst episodes of healthy and sick neonates. SIGNIFICANCE: These results can be used when monitoring cerebral function in neonates.
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| 5. |
- Vestergren, Anders, et al.
(författare)
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Effect of columnar disorder on the superconducting transition of a type-II superconductor in zero applied magnetic field
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:5
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of random columnar disorder on the superconducting phase transition of a type-II superconductor in zero applied magnetic field using numerical simulations of three dimensional XY and vortex loop models. We consider both an unscreened model, in which the bare magnetic penetration length is approximated as infinite, and a strongly screened model, in which the magnetic penetration length is of order the vortex core radius. We consider both equilibrium and dynamic critical exponents. We show that, as in the disorder free case, the equilibrium transitions of the unscreened and strongly screened models lie in the same universality class, however scaling is now anisotropic. We find for the correlation length exponent nu=1.2+/-0.1, and for the anisotropy exponent zeta=1.3+/-0.1. We find different dynamic critical exponents for the unscreened and strongly screened models.
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| 6. |
- Vestergren, Anders, et al.
(författare)
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Simulation of vortex noise in superconductors in weak applied magnetic fields
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:14
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic-field dependence of flux noise spectra in superconductors is studied by Monte Carlo simulation of vortex dynamics in two- and three-dimensional vortex models. Without an applied magnetic field the flux noise power spectra typically vary with frequency approximately like 1/f(3/2). In this paper we show that in the presence of a weak magnetic field, the spectra instead typically vary approximately like 1/f in a range of temperatures and frequencies. Both types of behavior have been observed in different experiments.
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| 7. |
- Wallin, Linda, 1982, et al.
(författare)
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Span of control and the significance for public sector managers' job demands: A multilevel study.
- 2014
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Ingår i: Economic and Industrial Democracy. - 0143-831X .- 1461-7099. ; 35:3, s. 455-481
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this article is to investigate how span of control influences seven job demands common amongst operational public sector managers. Self-administrated surveys were collected from 434 managers organized in 37 municipal operations, i.e. management teams in a set of public organizations in Sweden, and complemented with register data. Multilevel analyses were performed and it was shown unfavorable to have a large number of subordinates for the majority of job demands investigated. Furthermore, managers who were members of management teams with a higher average span of control experience some job demands to an even higher extent. Thus, the results of this study demonstrate that span of control is a key upstream component of managers’ job demands and emphasize the value of a reasonable number of subordinates.
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