| 1. |
- Cavalieri, A L, et al.
(författare)
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Clocking femtosecond X rays.
- 2005
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Ingår i: Phys Rev Lett. - 0031-9007. ; 94:11
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Tidskriftsartikel (refereegranskat)abstract
- Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.
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| 2. |
- Svanberg, Sune, et al.
(författare)
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Applications of terawatt lasers
- 1994
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Ingår i: LASER SPECTROSCOPY - XITH INTERNATIONAL CONFERENCE. - : AIP. - 1551-7616 .- 0094-243X. - 1563962624 ; :290, s. 264-269
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Konferensbidrag (refereegranskat)
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| 3. |
- Crona-Larsson, G, et al.
(författare)
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Effect of luxation injuries on permanent teeth.
- 1991
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Ingår i: Endodontics & dental traumatology. - 0109-2502. ; 7:5, s. 199-206
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Tidskriftsartikel (refereegranskat)abstract
- Trauma to the supporting tissues of the teeth are among the most common dental injuries, leading to such complications as pulp canal obliteration, necrosis and root resorption. The aim of this investigation was to study the outcome for young permanent teeth subjected to luxation injuries. From 108 dental records 171 teeth with injuries to the supporting tissue were selected. The material comprised 130 subluxated, 15 extruded, 9 intruded, 15 exarticulated and 6 laterally luxated teeth in children aged 6-19 years. Apart from luxation, 59 teeth (35%) had additional crown and root fractures. 65% of the teeth recovered without complications. 78% of the subluxated teeth and 24% of the luxated teeth showed uneventful posttraumatic healing. Concomitant uncomplicated crown fractures or root fractures without displacement of the coronal fragment did not interfere with the healing. Of 60 teeth with healing complications, 52 (87%) were subsequently recorded as healed, the remaining 8 were extracted or had progressive root resorption. Loss of pulp vitality and external root resorptions were the most often recorded complications (28% and 17% of the total material respectively). Pulp canal obliteration was noted in 3% of the cases. Extent of injury and degree of tooth maturity were found to be related to healing complications.
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| 4. |
- Crona-Larsson, G, et al.
(författare)
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Luxation injuries to permanent teeth -- a retrospective study of etiological factors.
- 1989
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Ingår i: Endodontics & dental traumatology. - 0109-2502. ; 5:4, s. 176-9
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Tidskriftsartikel (refereegranskat)abstract
- Trauma to permanent teeth with luxation injuries often leads to clinical treatment problems. Traumatic injury patients in local clinics are often limited in number. The aim of this investigation was to retrospectively study the etiological factors in luxation injuries to permanent teeth in relation to sex, age, time of year and diagnosis. A total of 108 files from patients, aged 6 to 19 years, with 196 teeth with luxation injuries, were collected. The maxillary central incisors represented 70% of all teeth injured and 70% of the teeth belonged to children between 8 and 12 years of age. Falls (34%) and bicycle-riding (30%) were the most frequent reasons for trauma, followed by sports (14%) and assaults (13%). Boys were more often involved in trauma. Girls were as often involved in sports accidents as boys. Subluxation was the most frequent diagnosis (77%), followed by extrusion, intrusion, exarticulation and lateral luxation. Accidents were reported most frequently during spring and early summer. A slight increase was also noted during autumn.
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| 5. |
- Gaffney, K J, et al.
(författare)
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Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb
- 2005
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 95:12
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Tidskriftsartikel (refereegranskat)abstract
- The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.
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| 6. |
- Gyan, D. S., et al.
(författare)
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Low-temperature nanoscale heat transport in a gadolinium iron garnet heterostructure probed by ultrafast x-ray diffraction
- 2022
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Ingår i: Structural Dynamics-Us. - : AIP Publishing. - 2329-7778. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Time-resolved x-ray diffraction has been used to measure the low-temperature thermal transport properties of a Pt/Gd3Fe5O12//Gd3Ga5O12 metal/oxide heterostructure relevant to applications in spin caloritronics. A pulsed femtosecond optical signal produces a rapid temperature rise in the Pt layer, followed by heat transport into the Gd3Fe5O12 (GdIG) thin film and the Gd3Ga5O12 (GGG) substrate. The time dependence of x-ray diffraction from the GdIG layer was tracked using an accelerator-based femtosecond x-ray source. The ultrafast diffraction measurements probed the intensity of the GdIG (1 -1 2) x-ray reflection in a grazing-incidence x-ray diffraction geometry. The comparison of the variation of the diffracted x-ray intensity with a model including heat transport and the temperature dependence of the GdIG lattice parameter allows the thermal conductance of the Pt/GdIG and GdIG//GGG interfaces to be determined. Complementary synchrotron x-ray diffraction studies of the low-temperature thermal expansion properties of the GdIG layer provide a precise calibration of the temperature dependence of the GdIG lattice parameter. The interfacial thermal conductance of the Pt/GdIG and GdIG//GGG interfaces determined from the time-resolved diffraction study is of the same order of magnitude as previous reports for metal/oxide and epitaxial dielectric interfaces. The thermal parameters of the Pt/GdIG//GGG heterostructure will aid in the design and implementation of thermal transport devices and nanostructures. (C) 2022 Author(s).
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| 7. |
- Johansson, S. G, et al.
(författare)
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Comparison of New Experimental and Astrophysical F-values For Some Ru-ii Lines, Observed In Hst Spectra of Chi-lupi
- 1994
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 421:2, s. 809-815
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Tidskriftsartikel (refereegranskat)abstract
- We report on experimental absolute oscillator strengths for 18 UV lines of Ru II, obtained by combining laser-induced fluorescence measurements of radiative lifetimes and branching fractions from line intensities in a calibrated Fourier-transform spectrum. HST/GHRS observations of the spectrum of the sharp-lined B star chi Lupi contain six of these lines, for which ''astrophysical'' relative f-values have been determined. The agreement is within 0.10 dex for a Ru abundance of log N(Ru)/N(H) = -7.90, which is 2.3 dex above the solar abundance.
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| 8. |
- Larsson, P G, et al.
(författare)
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Advantage or disadvantage of episiotomy compared with spontaneous perineal laceration.
- 1991
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Ingår i: Gynecologic and obstetric investigation. - : S. Karger AG. - 0378-7346 .- 1423-002X. ; 31:4, s. 213-6
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Tidskriftsartikel (refereegranskat)abstract
- In a prospective clinical investigation of 2,144 deliveries, we elucidate the indications for episiotomy and how different methods of anesthesia affect the frequency of episiotomy and the perineal problems after episiotomy compared with those after spontaneous perineal laceration. We found a significantly higher infection rate (p less than 0.001) and a longer healing period in the episiotomy group. These differences remain even if only primigravida or the indication, imminent perineal laceration, is studied. The results indicate that many women will unnecessarily suffer after an episiotomy. The patient's subjective problems are significantly increased, both immediately and at the 3-month postoperative follow-up.
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| 9. |
- Lundberg, Hans, et al.
(författare)
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Experimental Pd II oscillator strengths and the palladium abundance in the HgMn-type star chi Lupi
- 1996
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 469:1, s. 388-392
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Tidskriftsartikel (refereegranskat)abstract
- Experimental oscillator strengths for 19 ultraviolet lines of Pd II have been derived from measurements of line intensities in calibrated Fourier transform spectra, combined with picosecond-pulse laser measurements of radiative lifetimes. Five of these 19 lines, in addition to other Pd nr lines, are present in Hubble Space Telescope/Goddard High-Resolution Spectrograph echelle spectra of the chemically peculiar HgMn star chi Lupi, yielding a palladium abundance of log (N-Pd) = +5.0, which is 3.3 dex above the solar abundance. Theoretical oscillator strengths have been calculated for all strong ultraviolet transitions associated with the lowest odd-parity configuration of Pd II.
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| 10. |
- Trigo, M., et al.
(författare)
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Fourier-transform inelastic X-ray scattering from time- and momentum-dependent phonon-phonon correlations
- 2013
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Ingår i: Nature Physics. - 1745-2473. ; 9:12, s. 790-794
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Tidskriftsartikel (refereegranskat)abstract
- The macroscopic characteristics of a material are determined by its elementary excitations, which dictate the response of the system to external stimuli. The spectrum of excitations is related to fluctuations in the density-density correlations and is typically measured through frequency-domain neutron(1) or X-ray(2-4) scattering. Time-domain measurements of these correlations could yield a more direct way to investigate the excitations of solids and their couplings both near to and far from equilibrium. Here we show that we can access large portions of the phonon dispersion of germanium by measuring the diffuse scattering from femtosecond X-ray free-electron laser pulses. A femtosecond optical laser pulse slightly quenches the vibrational frequencies, producing pairs of high-wavevector phonons with opposite momenta. These phonons manifest themselves as time-dependent coherences in the displacement correlations(5) probed by the X-ray scattering. As the coherences are preferentially created in regions of strong electron-phonon coupling, the time-resolved approach is a natural spectroscopic tool for probing low-energy collective excitations in solids, and their microscopic interactions.
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