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- Levy, J. S., et al.
(författare)
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Decadal topographic change in the McMurdo Dry Valleys of Antarctica : Thermokarst subsidence, glacier thinning, and transfer of water storage from the cryosphere to the hydrosphere
- 2018
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Ingår i: Geomorphology. - : Elsevier BV. - 0169-555X .- 1872-695X. ; 323, s. 80-97
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Tidskriftsartikel (refereegranskat)abstract
- Recent local-scale observations of glaciers, streams, and soil surfaces in the McMurdo Dry Valleys of Antarctica (MDV) have documented evidence for rapid ice loss, glacial thinning, and ground surface subsidence associated with melting of ground ice. To evaluate the extent, magnitude, and location of decadal-scale landscape change in the MDV, we collected airborne lidar elevation data in 2014-2015 and compared these data to a 2001-2002 airborne lidar campaign. This regional assessment of elevation change spans the recent acceleration of warming and melting observed by long-term meteorological and ecosystem response experiments, allowing us to assess the response of MDV surfaces to warming and potential thawing feedbacks. We find that locations of thermokarst subsidence are strongly associated with the presence of excess ground ice and with proximity to surface or shallow subsurface (active layer) water. Subsidence occurs across soil types and landforms, in low-lying, low-slope areas with impeded drainage and also high on steep valley walls. Glacier thinning is widespread and is associated with the growth of fine-scale roughness. Pond levels are rising in most closed-basin lakes in the MDV, across all microclimate zones. These observations highlight the continued importance of insolation-driven melting in the MDV. The regional melt pattern is consistent with an overall transition of water storage from the local cryosphere (glaciers, permafrost) to the hydrosphere (dosed basin lakes and ponds as well as the Ross Sea). We interpret this regional melting pattern to reflect a transition to Arctic and alpine-style, hydrologically mediated permafrost and glacial melt.
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| 2. |
- Mathsson Alm, Linda, et al.
(författare)
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The performance of anti-cyclic citrullinated peptide assays in diagnosing rheumatoid arthritis : a systematic review and meta-analysis
- 2018
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Ingår i: Clinical and Experimental Rheumatology. - 0392-856X .- 1593-098X. ; 36:1, s. 144-152
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Forskningsöversikt (refereegranskat)abstract
- Objective. We assessed the ability of anti-cyclic citrullinated peptide (CCP) tests to diagnose rheumatoid arthritis (RA), comparing the effect of manufacturer assay type, study design (single-and two-gated) and duration of disease (early vs. established). Methods. We searched seven data-bases for relevant diagnostic studies containing data on CCP tests in known or suspected RA patients. We used a bi-variate model to produce summary estimates for test sensitivity, specificity, and positive and negative likelihood ratios. Summary Receiver Operating Characteristic (sROC) curves were derived to compare early versus established RA. Results. 83 studies were identified and included. For individual manufacturer tests there was considerable variation in both pooled sensitivity (range 67-83%) and specificity (range 90-96%) estimates. This heterogeneity was also observed when grouping studies into two-gated and single-gated designs. Study design and disease duration impacted on sensitivity, with single-gated study designs and early RA patients resulting in lower estimates than two-gated and established disease, respectively. Conclusion. This review highlights the large number of CCP tests that are now commercially available and the considerable variation in their diagnostic performance. This variation, although partly influenced in this analysis by the study design (single-gated vs. two-gated), seems to have different levels of impact depending on the manufacturers. The Thermo Fisher Scientific EliA and Inova Diagnostics Quanta Lite (CCP2) tests showed the least between-study variation in sensitivity and specificity suggesting they have the most consistent diagnostic performance overall.
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