| 1. |
- Bagger-Sjoback, Dan, et al.
(författare)
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High-frequency hearing, tinnitus, and patient satisfaction with stapedotomy: A randomized prospective study
- 2015
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Ingår i: Scientific Reports. - : Nature Publishing Group: Open Access Journals - Option C / Nature Publishing Group. - 2045-2322. ; 5:13341
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Tidskriftsartikel (refereegranskat)abstract
- Otosclerosis is a common disorder that leads to conductive hearing loss. Most patients with otosclerosis also have tinnitus, and surgical treatment is known to improve hearing as well as tinnitus. Some patients however experience worsening of tinnitus after the operation, but there are no known factors that allow surgeons to predict who will be at risk. In this prospective observational study on 133 patients undergoing stapedotomy, we show that postoperative air conduction thresholds at very high stimulus frequencies predict improvement of tinnitus, as assessed with proportional odds logistic regression models. Young patients were significantly more likely to experience reduction of tinnitus and patients whose tinnitus became better were also more satisfied with the outcome of the operation. These findings have practical importance for patients and their surgeons. Young patients can be advised that surgery is likely to be beneficial for their tinnitus, but a less positive message should be conveyed to older patients.
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| 2. |
- Bagger-Sjöbäck, Dan, et al.
(författare)
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A Randomised, Double Blind Trial of N-Acetylcysteine for Hearing Protection during Stapes Surgery
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Background Otosclerosis is a disorder that impairs middle ear function, leading to conductive hearing loss. Surgical treatment results in large improvement of hearing at low sound frequencies, but high-frequency hearing often suffers. A likely reason for this is that inner ear sensory cells are damaged by surgical trauma and loud sounds generated during the operation. Animal studies have shown that antioxidants such as N-Acetylcysteine can protect the inner ear from noise, surgical trauma, and some ototoxic substances, but it is not known if this works in humans. This trial was performed to determine whether antioxidants improve surgical results at high frequencies. Methods We performed a randomized, double-blind and placebo-controlled parallel group clinical trial at three Swedish university clinics. Using block-stratified randomization, 156 adult patients undergoing stapedotomy were assigned to intravenous N-Acetylcysteine (150 mg/kg body weight) or matching placebo (1:1 ratio), starting one hour before surgery. The primary outcome was the hearing threshold at 6 and 8 kHz; secondary outcomes included the severity of tinnitus and vertigo. Findings One year after surgery, high-frequency hearing had improved 2.7 +/- 3.8 dB in the placebo group (67 patients analysed) and 2.4 +/- 3.7 dB in the treated group (72 patients; means +/- 95% confidence interval, p = 0.54; linear mixed model). Surgery improved tinnitus, but there was no significant intergroup difference. Post-operative balance disturbance was common but improved during the first year, without significant difference between groups. Four patients receiving N-Acetylcysteine experienced mild side effects such as nausea and vomiting. Conclusions N-Acetylcysteine has no effect on hearing thresholds, tinnitus, or balance disturbance after stapedotomy.
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| 3. |
- Cerny, Petr, et al.
(författare)
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Zirconium and hafnium in minerals of the columbite and wodginite groups from granitic pegmatites
- 2007
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Ingår i: Canadian Mineralogist. - : Mineralogical Association of Canada. - 0008-4476 .- 1499-1276. ; 45:2, s. 185-202
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Tidskriftsartikel (refereegranskat)abstract
- Niobium-tantalum-oxide minerals from five localities with moderately to highly fractionated granitic pegmatites were examined for their Zr and Hf contents. Wodginite was found to contain up to 9.59 ZrO2 and 1.15 wt.% HfO2 and columbite-group minerals, up to 1.26 and 0. 12 wt.%, respectively. The Zr/Hf value is decidedly high in columbite-group minerals (13 to 6) relative to wodginite (4 to 1). Coexisting wodginite-group and columbite-group minerals behave similarly with respect to the overall behavior of Zr + Hf and with respect to the partitioning of Zr versus Hf. In individual pegmatite bodies, no systematic changes in Zr + Hf or Zr/Hf are discernible among the various zones. However, a positive correlation of Zr + Hf with Sri, Mn and Ta is locally observed, and a negative correlation with Ti. No clear trends are shown by Zr/Hf. The Zr/Hf value in the (Nb,Ta)-oxide minerals generally corresponds to its range in associated zircon-hafnon. Considerable depolymerization of highly fractionated, (F, B, P)- and H2O-rich pegmatite-forming melts, in part alkaline in boundary layers (particularly significant in final stages of consolidation), is responsible for shifting oxygen coordination of Zr and Hf from [8]- to [6]-fold. Consequently, the abundance of zircon decreases, and the (Nb,Ta)-oxide minerals become geochemically significant carriers of Zr and Hf. This effect apparently operates not only in granitic pegmatites but also in other granite-related environments.
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| 4. |
- Romer, Rolf, et al.
(författare)
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Implications of U-Pb ages of columbite-tantalites from granitic pegmatites for the Palaeoproterozoic accretion of 1.90-1.85 Ga magmatic arcs to the Baltic Shield
- 1994
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Ingår i: Precambrian Research. - : Elsevier BV. - 0301-9268 .- 1872-7433. ; 67:1-2, s. 141-158
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Tidskriftsartikel (refereegranskat)abstract
- The Palaeoproterozoic growth of the Baltic Shield involved the accretion of several ~1.90-1.85 Ga old magmatic arcs to the southwest of the Archaean craton and the deformation and migmatization of sedimentary basins located between the arcs. During crustal thickening after the collision of the arcs, the sedimentary basin fill became intruded by peraluminous two-mica granites. Locally, columbite-bearing pegmatites are genetically associated with these granites. Columbites from lithium-cesium-tantalum-type (LCT-type) pegmatites from the Stockholm area (Sormland gneisses) yield U-Pb ages at 1815-1820 Ma, while niobium-yttrium-fluorine-type (MYF-type) pegmatites from the same area are younger (1795±2 Ma, 2σ). Farther to the north, LCT-type pegmatites from the central Bothnian Basin, that correspond geochemically and mineralogically to those of the Stockholm area, yield U-Pb columbite ages at 1795-1800 Ma, while LCT-type pegmatites in the sedimentary basin between Skelleftea and Lulea yield less well constrained U-Pb columbite ages at 1765-1775 Ma. LCT-type pegmatites are mainly associated with crustal melts that form during postcollisional thickening of continental crust. They represent markers for the time when the Palaeoproterozoic Baltic Shield suffered sufficient thickening to yield voluminous anatectic melts. The U-Pb columbite ages from the LCT-type pegmatites indicate that comparable phases of postcollisional crustal thickening of the Svecofennian area of the Baltic Shield occurred later to the north
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| 5. |
- Romer, Rolf L., et al.
(författare)
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Crystal-chemical and genetic controls of U-Pb systematics of columbite-tantalite
- 1996
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Ingår i: Mineralogy and Petrology. - 0930-0708 .- 1438-1168. ; 57:3-4, s. 243-260
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Tidskriftsartikel (refereegranskat)abstract
- Columbite-tantalite can accommodate considerable amounts of uranium and excludes lead almost completely. It is thus potentially suited for U-Pb dating. Discordias generally yield closely constrained upper intercept ages. Yet, in a few cases, the U-Pb system of columbite-tantalite gives poorly constrained ages due to excess scatter or inverse discordance. These anomalous features do not show any relation with gross mineral chemistry or pegmatite fractionation. Recrystallization or the presence of exsolutions and inclusions generally do not result in anomalous and scattered U-Pb systematics, unless the inclusions are uraninite or secondary Nb, Ta-bearing phases. Open-system behavior of uraninite, whose occurrence seems to be related to the local host-rock-influenced redox conditions during pegmatite crystallization, often results in inverse discordance. Secondary Nb, Ta-bearing phases that accept Pb and U derived from uraninite inclusions into their structure may inherit this inverse discordance.
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| 6. |
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| 7. |
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| 8. |
- Romer, Rolf L., et al.
(författare)
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U-Pb columbite ages of pegmatites from Sveconorwegian terranes in southwestern Sweden
- 1996
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Ingår i: Precambrian Research. - : Elsevier BV. - 0301-9268 .- 1872-7433. ; 76:1/2, s. 15-30
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Tidskriftsartikel (refereegranskat)abstract
- Post-kinematic and post-metamorphic rare-mineral pegmatites in the Sveconorwegian Province of southwestern Sweden yield U-Pb columbite ages at 1041.4+ or -1.6 Ma (2 ), 1038.7+ or -3.4 Ma, 1029.7+ or -1.4 Ma, and 984.3+ or -6.4 Ma. The contrasting age of spatially close pegmatites with equivalent rare-mineral assemblages demonstrates that spatial and mineralogical coincidence does not imply genetic kinship, but rather reflects the repeated prevalence of comparable pressure and temperature conditions favourable for the formation of rare-mineral pegmatites. Furthermore, our data demonstrate that the pegmatites are more than 50 Ma older than the nearby Bohus Granite that earlier had been considered to be genetically related to the pegmatites. These new U-Pb columbite age data together with earlier U-Pb data from southern Norway and Sweden define a zonal pattern with increasingly younger ages to the east. These pegmatites are interpreted to have formed in relation to the thermal peak in the host or underlying terranes as they were stacked on each other in a piggy-back style during eastward thrusting onto the Baltic Shield. The youngest of these pegmatites (980 Ma) gives a minimum age for the cessation of thrusting. We interpret the 941.6+ or -1.4 Ma old Riddaho pegmatite of the Eastern Gneiss region to be related to the post-collisional extension of the Sveconorwegian Province. This event exposed high-grade gneisses in the Eastern Gneiss region and eventually resulted in the emplacement of voluminous melts in the internal allochthonous belt of the Sveconorwegian orogen.
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| 9. |
- Romer, Rolf L., et al.
(författare)
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U-Pb columbite chronology of post-kinematic Palaeoproterozoic pegmatites in Sweden
- 1997
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Ingår i: Precambrian Research. - 0301-9268 .- 1872-7433. ; 82:1-2, s. 85-99
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Tidskriftsartikel (refereegranskat)abstract
- Rare-element pegmatites of the lithium-cesium-tantalum (LCT) family originate from crustal melts derived from orogenically-thickened continental crust and yield a minimum estimate for the age of orogenic thickening. Pegmatites of this type from the Palaeoproterozoic Bothnian Basin of central Sweden formed during the short age interval between 1803 and 1794 Ma, even though the dated pegmatites are spread over a large area. In contrast, LCT-family pegmatites from a much smaller area in south-central Sweden seem to encompass a much larger age range between 1820 and 1815 Ma (Mysingen-Utö pegmatites) and ca. 1780 Ma (Skrumpetorp pegmatites). This broad age range is matched by the age distribution of migmatitic granites (1846-1779 Ma). The ages of LCT-type pegmatites and migmatitic granites are compatible with earlier findings that Svecofennian crustal thickening started earlier to the south and, in addition, indicate that this thickened crust persisted during the compression and thickening of the northern area. Niobium-yttrium-fluorine (NYF)-type pegmatites and related granites, which could be related to crustal thinning or could reflect melting at a deeper crustal level, overlap in age with LCT-type pegmatites in south-central Sweden. The NYF-type pegmatites are coeval or younger when both pegmatite types occur in the same subareas.
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| 10. |
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