| 1. |
- Kozlowska, K., et al.
(författare)
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Patterns of healthy lifestyle and positive health attitudes in older Europeans
- 2008
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Ingår i: The Journal of Nutrition, Health & Aging. - 1279-7707 .- 1760-4788. ; 12:10, s. 728-733
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To determine (i) the extent to which recommended lifestyle healthy behaviors are adopted and the existence of positive attitudes to health; (ii) the relative influence of socio-demographic variables on multiple healthy lifestyle behaviors and positive attitudes to health; (iii) the association between healthy lifestyle behaviors and positive attitudes to health. Design: two distinct healthy behavioral measures were developed: (i) healthy lifestyles based on physical activity, no cigarette smoking, no/moderate alcohol drinking, maintaining a "healthy" weight and having no sleeping problems and (ii) positive health attitudes based on having positive emotional attitudes, such as: self-perceived good health status, being calm, peaceful and happy for most of the time, not expecting health to get worse and regular health check-ups. A composite healthy lifestyle index, ranging from 0 (none of behaviors met) to 5 (all behaviors met) was calculated by summing up the individual's scores for the five healthy lifestyle items. Afterwards, each individual's index was collapsed into three levels: 0-2 equivalent to 'level 1' (subjectively regarded as 'too low'), a score of 3 equivalent to 'level 2' ('fair') and 4-5 as 'level 3' satisfactory 'healthy lifestyle' practices. The same procedure was applied to the positive health attitudes index. Multinomial logistic regression analyses by a forward selection procedure were used to calculate the adjusted odds ratio (OR) with 95% confidence interval (95% CI). Participants: a multi-national sample consisting of 638 older Europeans from 8 countries, aged 65-74 and 75+, living alone or with others. Results and conclusions: maintaining a "healthy" weight was the most frequently cited factor in the healthy lifestyles index and therefore assumed to be the most important to the older Europeans in the study; positive attitudes to health were relatively low; participants achieved a 'satisfactory' level for healthy lifestyles index (level 3) more frequently than a satisfactory level for positive attitudes to health; having a satisfactory 'healthy lifestyle' was directly related to having a satisfactory level of positive attitudes to health based on the positive health attitudes index; income and geographical location in Europe appeared to be key predictors for meeting both the recommended healthy lifestyle factors in the index and having positive health attitudes however, the composition and nature of the study sample should be taken into consideration when considering the impact of the location on healthy lifestyles and attitudes to health across Europe.
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| 2. |
- Geilhufe, J., et al.
(författare)
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Extracting depth information of 3-dimensional structures from a single-view X-ray Fourier-transform hologram
- 2014
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Ingår i: Optics Express. - 1094-4087. ; 22:21, s. 24959-24969
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate how information about the three-dimensional structure of an object can be extracted from a single Fourier-transform Xray hologram. In contrast to lens-based 3D imaging approaches that provide depth information of a specimen utilizing several images from different angles or via adjusting the focus to different depths, our method capitalizes on the use of the holographically encoded phase and amplitude information of the object's wavefield. It enables single-shot measurements of 3D objects at coherent X-ray sources. As the ratio of longitudinal resolution over transverse resolution scales proportional to the diameter of the reference beam aperture over the X-ray wavelength, we expect the approach to be particularly useful in the extreme ultraviolet and soft-X-ray regime. (C) 2014 Optical Society of America
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| 3. |
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| 4. |
- Schmising, C. von Korff, et al.
(författare)
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Imaging Ultrafast Demagnetization Dynamics after a Spatially Localized Optical Excitation
- 2014
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Ingår i: Physical Review Letters. - 1079-7114. ; 111:21
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Tidskriftsartikel (refereegranskat)abstract
- Ultrashort, coherent x-ray pulses of a free-electron laser are used to holographically image the magnetization dynamics within a magnetic domain pattern after creation of a localized excitation via an optical standing wave. We observe a spatially confined reduction of the magnetization within a couple of hundred femtoseconds followed by its slower recovery. Additionally, the experimental results show evidence of a spatial evolution of magnetization, which we attribute to ultrafast transport of nonequilibrium spin-polarized electrons for early times and to a fluence-dependent remagnetization rate for later times.
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| 5. |
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| 6. |
- Stiel, H., et al.
(författare)
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2D and 3D Nanoscale Imaging Using High Repetition Rate Laboratory-Based Soft X-Ray Sources
- 2018
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Ingår i: X-Ray Lasers 2016 - Proceedings of the 15th International Conference on X-Ray Lasers. - Cham : Springer International Publishing. - 9783319730240 ; 202, s. 265-272
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Konferensbidrag (refereegranskat)abstract
- In this contribution, we report about tomographic nanoscale imaging using a laser-produced plasma-based laboratory transmission X-ray microscope (LTXM) in the water window. The soft X-ray radiation of the LTXM is provided by a high average power laser-produced (1.3 kHz repetition rate, 0.5 ns pulse duration, 140 W average power) plasma source, a multilayer condenser mirror, an objective zone plate, and a back-illuminated CCD camera as a detector. In the second part of the contribution, we will present recent results on holography and coherent diffraction imaging using our high repetition rate X-ray laser. We will discuss advantages of these methods and its potential for nanoscale imaging.
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| 7. |
- von Korff Schmising, C., et al.
(författare)
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Imaging Non-Local Magnetization Dynamics
- 2016
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Ingår i: Synchrotron Radiation News. - : Informa UK Limited. - 0894-0886 .- 1931-7344. ; 29:3, s. 26-31
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Tidskriftsartikel (refereegranskat)abstract
- Many fundamental processes in magnetism take place on a nanometer length and sub-picosecond time scale. An important example of such phenomena in magnetism is ultrafast, spin-polarized transport of laser-excited hot electrons, which is now being recognized as playing a crucial role for novel spintronic devices and for optically induced magnetic switching. Recent experimental examples include the demonstration of all-optical helicity dependent control of spin-polarized currents at interfaces [1], the design of novel and efficient terahertz emitters [2], and nanoscale spin reversal in chemically heterogeneous GdFeCo driven by non-local transfer of angular momentum [3]. In particular, for advanced information technologies with bit densities already exceeding 1 terabit per square inch with bit cell dimensions of (15 × 38 nm2) [4], it is of fundamental importance to understand and eventually control the mechanisms responsible for optically induced spin dynamics on the nanoscale.
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| 8. |
- Blanco-Cano, Xochitl, et al.
(författare)
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Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation
- 2018
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Ingår i: Annales Geophysicae. - : COPERNICUS GESELLSCHAFT MBH. - 0992-7689 .- 1432-0576. ; 36:4, s. 1081-1097
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present the first identification of foreshock cavitons and the formation of spontaneous hot flow anomalies (SHFAs) with the Vlasiator global magnetospheric hybrid-Vlasov simulation code. In agreement with previous studies we show that cavitons evolve into SHFAs. In the presented run, this occurs very near the bow shock. We report on SHFAs surviving the shock crossing into the down-stream region and show that the interaction of SHFAs with the bow shock can lead to the formation of a magnetosheath cavity, previously identified in observations and simulations. We report on the first identification of long-term local weakening and erosion of the bow shock, associated with a region of increased foreshock SHFA and caviton formation, and repeated shock crossings by them. We show that SHFAs are linked to an increase in suprathermal particle pitch-angle spreads. The realistic length scales in our simulation allow us to present a statistical study of global caviton and SHFA size distributions, and their comparable size distributions support the theory that SHFAs are formed from cavitons. Virtual spacecraft observations are shown to be in good agreement with observational studies.
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| 9. |
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| 10. |
- Correa, J., et al.
(författare)
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The PERCIVAL detector : first user experiments
- 2023
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 30, s. 242-250
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Tidskriftsartikel (refereegranskat)abstract
- The PERCIVAL detector is a CMOS imager designed for the soft X-ray regime at photon sources. Although still in its final development phase, it has recently seen its first user experiments: ptychography at a free-electron laser, holographic imaging at a storage ring and preliminary tests on X-ray photon correlation spectroscopy. The detector performed remarkably well in terms of spatial resolution achievable in the sample plane, owing to its small pixel size, large active area and very large dynamic range; but also in terms of its frame rate, which is significantly faster than traditional CCDs. In particular, it is the combination of these features which makes PERCIVAL an attractive option for soft X-ray science.
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| 11. |
- Hoilijoki, S., et al.
(författare)
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Properties of Magnetic Reconnection and FTEs on the Dayside Magnetopause With and Without Positive IMF Bx Component During Southward IMF
- 2019
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Ingår i: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 124:6, s. 4037-4048
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes properties and behavior of magnetic reconnection and flux transfer events (FTEs) on the dayside magnetopause using the global hybrid-Vlasov code Vlasiator. We investigate two simulation runs with and without a sunward (positive)B-x component of the interplanetary magnetic field (IMF) when the IMF is southward. The runs are two-dimensional in real space in the noon-midnight meridional (polar) plane and three-dimensional in velocity space. Solar wind input parameters are identical in the two simulations with the exception that the IMF is purely southward in one but tilted 45 degrees toward the Sun in the other. In the purely southward case (i.e., without B-x) the magnitude of the magnetos heath magnetic field component tangential to the magnetopause is larger than in the run with a sunward tilt. This is because the shock normal is perpendicular to the IMF at the equatorial plane, whereas in the other run the shock configuration is oblique and a smaller fraction of the total IMF strength is compressed at the shock crossing. Hence, the measured average and maximum reconnection rate are larger in the purely southward run. The run with tilted IMF also exhibits a north-south asymmetry in the tangential magnetic field caused by the different angle between the IMF and the bow shock normal north and south of the equator. Greater north-south asymmetries are seen in the FTE occurrence rate, size, and velocity as well; FTEs moving toward the Southern Hemisphere are larger in size and observed less frequently than FTEs in the Northern Hemisphere.
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| 12. |
- Johlander, Andreas, 1990-, et al.
(författare)
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Ion Acceleration Efficiency at the Earth's Bow Shock : Observations and Simulation Results
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 914:2
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Tidskriftsartikel (refereegranskat)abstract
- Collisionless shocks are some of the most efficient particle accelerators in heliospheric and astrophysical plasmas. Here we study and quantify ion acceleration at Earth's bow shock with observations from NASA's Magnetospheric Multiscale (MMS) satellites and in a global hybrid-Vlasov simulation. From the MMS observations, we find that quasiparallel shocks are more efficient at accelerating ions. There, up to 15% of the available energy goes into accelerating ions above 10 times their initial energy. Above a shock-normal angle of similar to 50 degrees, essentially no energetic ions are observed downstream of the shock. We find that ion acceleration efficiency is significantly lower when the shock has a low Mach number (M ( A ) < 6) while there is little Mach number dependence for higher values. We also find that ion acceleration is lower on the flanks of the bow shock than at the subsolar point regardless of the Mach number. The observations show that a higher connection time of an upstream field line leads to somewhat higher acceleration efficiency. To complement the observations, we perform a global hybrid-Vlasov simulation with realistic solar-wind parameters with the shape and size of the bow shock. We find that the ion acceleration efficiency in the simulation shows good quantitative agreement with the MMS observations. With the combined approach of direct spacecraft observations, we quantify ion acceleration in a wide range of shock angles and Mach numbers.
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| 13. |
- Pfau, Bastian, et al.
(författare)
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Influence of stray fields on the switching-field distribution for bit-patterned media based on pre-patterned substrates
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 105:13
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Tidskriftsartikel (refereegranskat)abstract
- Using a direct imaging method, we experimentally investigate the reversal of magnetic islands in a bit-patterned media sample based on a pre-patterned substrate. Due to systematic variation of the island distances in the media, we are able to study the influence of the dipolar interaction on the switching-field distribution of the island ensemble. The experimental findings are explained by an analytical magnetostatic model that allows us to quantify the different components of the demagnetizing field in the system and to distinguish intrinsic and dipolar broadening of the switching-field distribution. Besides the well-known dipolar broadening due to stray fields from neighboring islands, we find strong influence from the magnetized trench material on the island switching. (C) 2014 Author(s).
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