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- Cunha, M. S., et al.
(författare)
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Rotation and pulsation in Ap stars : first light results from TESS sectors 1 and 2
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 487:3, s. 3523-3549
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Tidskriftsartikel (refereegranskat)abstract
- We present the first results from the Transiting Exoplanet Survey Satellite (TESS) on the rotational and pulsational variability of magnetic chemically peculiar A-type stars. We analyse TESS 2-min cadence data from sectors 1 and 2 on a sample of 83 stars. Five new rapidly oscillating Ap (roAp) stars are announced. One of these pulsates with periods around 4.7 min, making it the shortest period roAp star known to date. Four out of the five new roAp stars are multiperiodic. Three of these and the singly periodic one show the presence of rotational mode splitting. Individual frequencies are provided in all cases. In addition, seven previously known roAp stars are analysed. Additional modes of oscillation are found in some stars, while in others we are able to distinguish the true pulsations from possible aliases present in the ground-based data. We find that the pulsation amplitude in the TESS filter is typically a factor of 6 smaller than that in the B filter, which is usually used for ground-based observations. For four roAp stars we set constraints on the inclination angle and magnetic obliquity, through the application of the oblique pulsator model. We also confirm the absence of roAp-type pulsations down to amplitude limits of 6 and 13 mu mag, respectively, in two of the best characterized non-oscillating Ap (noAp) stars. We announce 27 new rotational variables along with their rotation periods, and provide different rotation periods for seven other stars. Finally, we discuss how these results challenge state-of-the-art pulsation models for roAp stars.
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- Bertl, Kristina, et al.
(författare)
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Does the time-point of orthodontic space closure initiation after tooth extraction affect the incidence of gingival cleft development? A randomized controlled clinical trial.
- 2020
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Ingår i: Journal of Periodontology. - : John Wiley & Sons. - 0022-3492 .- 1943-3670. ; 91:5, s. 572-581
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Tidskriftsartikel (refereegranskat)abstract
- Background: Gingival clefts (GC) develop frequently during orthodontic space closure and may compromise the treatment outcome. This study assessed whether the time-point of orthodontic space closure initiation, after permanent tooth extraction, affects the incidence of GC. Methods: In 25 patients requiring bilateral premolar extraction due to orthodontic reasons, one premolar, chosen at random, was extracted 8 weeks before space closure initiation (“delayed movement”, DM), while the contralateral premolar was extracted one week before (“early movement”, EM) (“treatment group”). Presence/absence of GC after 3 and 6 months (“time-point”) was recorded and any association with various parameters (i.e., treatment group, time-point, gender, jaw, craniofacial growth, gingival biotype, buccal bone dehiscence after extraction, space closure) was statistically assessed. Results: Twenty-one patients contributing with 26 jaws were finally included in the analysis. Overall, GC were frequent after 3 (DM: 53.9%; EM: 69.2%) and 6 months (DM: 76.9%; EM: 88.5%). EM (p=0.014) and larger space closure within the study period (p=0.001) resulted in a significantly higher incidence of GC. Further, there was a tendency for GC development in the presence of buccal bone dehiscence (p=0.052) and thin gingival biotype (p=0.054). “Fast movers” (herein cases with a tooth movement ≥ 1mm per month) developed a GC in > 90% of the cases already after 3 months. “Slow movers” developed a GC only in 25 and 70% after 3m and FE, respectively. Conclusions: GC development is a frequent finding during orthodontic space closure and seems to occur more frequently with early tooth movement initiation and in “fast movers”.
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- Nemec, H., et al.
(författare)
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Bulk-like transversal electron mobility in heavily n-doped InP nanowires probed by terahertz spectroscopy
- 2014
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Ingår i: 2014 39th International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2014. - 9781479938773
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Konferensbidrag (refereegranskat)abstract
- Waveguiding of excitation beam and propagation of THz beam in a complex gradient environment were studied in an array of InP nanowires. Measurements by time-resolved THz spectroscopy accompanied by Monte-Carlo calculations of the response of localized charges enabled determination of transversal electron mobility.
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- Nemec, Hynek, et al.
(författare)
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Charge carrier dynamics in alternating polyfluorene copolymer : Fullerene blends probed by terahertz spectroscopy
- 2008
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:16, s. 6558-6563
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Tidskriftsartikel (refereegranskat)abstract
- Time-resolved terahertz spectroscopy is used for investigation of photoinduced charge carrier dynamics in blends of a polyfluorene copolymer (poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl- 2',1',3-benzo-thiadiazole)]) and an electron acceptor ([6,6]-phenyl-C61-butyric acid methyl ester). The transient far-infrared response appears instantaneously after photoexcitation. We show that the transient conductivity spectrum is dominated by two major contributions: response of separated charge carriers and response of coupled polaron pairs. © 2008 American Chemical Society.
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