| 1. |
- Campbell, PJ, et al.
(författare)
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Pan-cancer analysis of whole genomes
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 578:7793, s. 82-
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Tidskriftsartikel (refereegranskat)abstract
- Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1–3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4–5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10–18.
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| 2. |
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| 3. |
- Barucca, G., et al.
(författare)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
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| 4. |
- Barucca, G., et al.
(författare)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
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| 5. |
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| 6. |
- Buntgen, U., et al.
(författare)
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Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure the 14C content in 484 individual tree rings formed in the periods 770–780 and 990–1000 CE. Distinct 14C excursions starting in the boreal summer of 774 and the boreal spring of 993 ensure the precise dating of 44 tree-ring records from five continents. We also identify a meridional decline of 11-year mean atmospheric radiocarbon concentrations across both hemispheres. Corroborated by historical eye-witness accounts of red auroras, our results suggest a global exposure to strong solar proton radiation. To improve understanding of the return frequency and intensity of past cosmic events, which is particularly important for assessing the potential threat of space weather on our society, further annually resolved 14C measurements are needed.
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| 11. |
- Aurelle, D., et al.
(författare)
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Biodiversity, climate change, and adaptation in the Mediterranean
- 2022
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Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- Potential for, and limits to, adaptation to environmental changes are critical for resilience and risk mitigation. The Mediterranean basin is a mosaic of biodiversity-rich ecosystems long affected by human influence, whose resilience is now questioned by climate change. After reviewing the different components of biological adaptation, we present the main characteristics of marine and terrestrial biodiversity in the Mediterranean basin and of the pressures they face. Taking climatic trends into consideration, we discuss the adaptive potential of a range of ecosystems dominated by species without active dispersal. We argue that the high heterogeneity of Mediterranean landscapes and seascapes constitutes a laboratory for the study of adaptation when environmental conditions change rapidly and may provide opportunities for adaptation and adaptability of species and ecosystems. Adaptive management in the Mediterranean can and should harness the nature-based solutions offered by both ecological and evolutionary processes for increasing the resilience of ecosystems to climate change.
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| 12. |
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| 15. |
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| 16. |
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| 17. |
- Ravelli, A, et al.
(författare)
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2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: A European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organisation Collaborative Initiative
- 2016
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Ingår i: Annals of the rheumatic diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 75:3, s. 481-489
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Tidskriftsartikel (refereegranskat)abstract
- To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA). A multistep process, based on a combination of expert consensus and analysis of real patient data, was conducted. A panel of 28 experts was first asked to classify 428 patient profiles as having or not having MAS, based on clinical and laboratory features at the time of disease onset. The 428 profiles comprised 161 patients with systemic JIA—associated MAS and 267 patients with a condition that could potentially be confused with MAS (active systemic JIA without evidence of MAS, or systemic infection). Next, the ability of candidate criteria to classify individual patients as having MAS or not having MAS was assessed by evaluating the agreement between the classification yielded using the criteria and the consensus classification of the experts. The final criteria were selected in a consensus conference. Experts achieved consensus on the classification of 391 of the 428 patient profiles (91.4%). A total of 982 candidate criteria were tested statistically. The 37 best-performing criteria and 8 criteria obtained from the literature were evaluated at the consensus conference. During the conference, 82% consensus among experts was reached on the final MAS classification criteria. In validation analyses, these criteria had a sensitivity of 0.73 and a specificity of 0.99. Agreement between the classification (MAS or not MAS) obtained using the criteria and the original diagnosis made by the treating physician was high (κ=0.76). We have developed a set of classification criteria for MAS complicating systemic JIA and provided preliminary evidence of its validity. Use of these criteria will potentially improve understanding of MAS in systemic JIA and enhance efforts to discover effective therapies, by ensuring appropriate patient enrollment in studies.
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| 18. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Minoia, F, et al.
(författare)
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Development and initial validation of the MS score for diagnosis of macrophage activation syndrome in systemic juvenile idiopathic arthritis
- 2019
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Ingår i: Annals of the rheumatic diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 78:10, s. 1357-1362
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Tidskriftsartikel (refereegranskat)abstract
- To develop and validate a diagnostic score that aids in identifying macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (sJIA).MethodsThe clinical and laboratory features of 362 patients with sJIA-associated MAS and 404 patients with active sJIA without evidence of MAS were collected in a multinational collaborative project. Eighty percent of the study population was used to develop the score and the remaining 20% constituted the validation sample. A Bayesian Model Averaging approach was used to assess the role of each clinical and laboratory variables in the diagnosis of MAS and to obtain the coefficients of selected variables. The final score, named MAS/sJIA (MS) score, resulted from the linear combination of these coefficients multiplied by the values of each variable. The cut-off that best discriminated MAS from active sJIA was calculated by means of receiver operating characteristic (ROC) curve analysis. Score performance was evaluated in both developmental and validation samples.ResultsThe MS score ranges from −8.4 to 41.8 and comprises seven variables: central nervous system dysfunction, haemorrhagic manifestations, active arthritis, platelet count, fibrinogen, lactate dehydrogenase and ferritin. A cut-off value ≥−2.1 revealed the best performance in discriminating MAS from active sJIA, with a sensitivity of 0.85, a specificity of 0.95 and a kappa value of 0.80. The good performance of the MS score was confirmed in the validation sample.ConclusionThe MS score is a powerful and feasible tool that may assist practitioners in making a timely diagnosis of MAS in patients with sJIA.
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| 34. |
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| 35. |
- Minoia, F, et al.
(författare)
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Dissecting the heterogeneity of macrophage activation syndrome complicating systemic juvenile idiopathic arthritis
- 2015
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Ingår i: The Journal of rheumatology. - : The Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 42:6, s. 994-1001
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Tidskriftsartikel (refereegranskat)abstract
- To seek insights into the heterogeneity of macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (sJIA) through the analysis of a large patient sample collected in a multinational survey.Methods.International pediatric rheumatologists and hemato-oncologists entered their patient data, collected retrospectively, in a Web-based database. The demographic, clinical, laboratory, histopathologic, therapeutic, and outcome data were analyzed in relation to (1) geographic location of caring hospital, (2) subspecialty of attending physician, (3) demonstration of hemophagocytosis, and (4) severity of clinical course.Results.A total of 362 patients were included by 95 investigators from 33 countries. Demographic, clinical, laboratory, and histopathologic features were comparable among patients seen in diverse geographic areas or by different pediatric specialists. Patients seen in North America were given biologics more frequently. Patients entered by pediatric hemato-oncologists were treated more commonly with biologics and etoposide, whereas patients seen by pediatric rheumatologists more frequently received cyclosporine. Patients with demonstration of hemophagocytosis had shorter duration of sJIA at MAS onset, higher prevalence of hepatosplenomegaly, lower levels of platelets and fibrinogen, and were more frequently administered cyclosporine, intravenous immunoglobulin (IVIG), and etoposide. Patients with severe course were older, had longer duration of sJIA at MAS onset, had more full-blown clinical picture, and were more commonly given cyclosporine, IVIG, and etoposide.Conclusion.The clinical spectrum of MAS is comparable across patients seen in different geographic settings or by diverse pediatric subspecialists. There was a disparity in the therapeutic choices among physicians that underscores the need to establish uniform therapeutic protocols.
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| 36. |
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| 37. |
- Sofou, E, et al.
(författare)
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Evidence of somatic hypermutation in the antigen binding sites of patients with CLL harboring IGHV genes with 100% germline identity
- 2022
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Ingår i: Frontiers in oncology. - : Frontiers Media SA. - 2234-943X. ; 12, s. 1079772-
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Tidskriftsartikel (refereegranskat)abstract
- Classification of patients with chronic lymphocytic leukemia (CLL) based on the somatic hypermutation (SHM) status of the clonotypic immunoglobulin heavy variable (IGHV) gene has established predictive and prognostic relevance. The SHM status is assessed based on the number of mutations within the IG heavy variable domain sequence, albeit only over the rearranged IGHV gene excluding the variable heavy complementarity determining region 3 (VH CDR3). This may lead to an underestimation of the actual impact of SHM, in fact overlooking the most critical region for antigen-antibody interactions, i.e. the VH CDR3. Here we investigated whether SHM may be present within the VH CDR3 of cases bearing ‘truly unmutated’ IGHV genes (i.e. 100% germline identity across VH FR1-VH FR3) employing Next Generation Sequencing. We studied 16 patients bearing a ‘truly unmutated’ CLL clone assigned to stereotyped subsets #1 (n=12) and #6 (n=4). We report the existence of SHM within the germline-encoded 3’IGHV, IGHD, 5’IGHJ regions of the VH CDR3 in both the main IGHV-IGHD-IGHJ gene clonotype and its variants. Recurrent somatic mutations were identified between different patients of the same subset, supporting the notion that they represent true mutational events rather than technical artefacts; moreover, they were located adjacent to/within AID hotspots, pointing to SHM as the underlying mechanism. In conclusion, we provide immunogenetic evidence for intra-VH CDR3 variations, attributed to SHM, in CLL patients carrying ‘truly unmutated’ IGHV genes. Although the clinical implications of this observation remain to be defined, our findings offer a new perspective into the immunobiology of CLL, alluding to the operation of VH CDR3-restricted SHM in U-CLL.
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| 38. |
- Strefford, J. C., et al.
(författare)
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Distinct patterns of novel gene mutations in poor-prognostic stereotyped subsets of chronic lymphocytic leukemia : the case of SF3B1 and subset #2
- 2013
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 0887-6924 .- 1476-5551. ; 27:11, s. 2196-2199
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have revealed recurrent mutations of the NOTCH1, SF3B1 and BIRC3 genes in chronic lymphocytic leukemia (CLL), especially among aggressive, chemorefractory cases. Nevertheless, it is currently unknown whether their presence may differ in subsets of patients carrying stereotyped B-cell receptors and also exhibiting distinct prognoses. Here, we analyzed the mutation status of NOTCH1, SF3B1 and BIRC3 in three subsets with particularly poor prognosis, that is, subset # 1, # 2 and # 8, aiming to explore links between genetic aberrations and immune signaling. A remarkably higher frequency of SF3B1 mutations was revealed in subset # 2 (44%) versus subset # 1 and # 8 (4.6% and 0%, respectively; P<0.001). In contrast, the frequency of NOTCH1 mutations in subset # 2 was only 8%, lower than the frequency observed in either subset # 1 or # 8 (19% and 14%, respectively; P 0.04 for subset # 1 versus # 2). No associations were found for BIRC3 mutations that overall were rare. The apparent non-random association of certain mutations with stereotyped CLL subsets alludes to subset-biased acquisition of genomic aberrations, perhaps consistent with particular antigen/antibody interactions. These novel findings assist in unraveling specific mechanisms underlying clinical aggressiveness in poor-prognostic stereotyped subsets, with far-reaching implications for understanding their clonal evolution and implementing biologically oriented therapy.
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| 39. |
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| 40. |
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| 41. |
- Sutton, LA, et al.
(författare)
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Comparative analysis of targeted next-generation sequencing panels for the detection of gene mutations in chronic lymphocytic leukemia: an ERIC multi-center study
- 2021
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 106:3, s. 682-691
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Tidskriftsartikel (refereegranskat)abstract
- Next-generation sequencing (NGS) has transitioned from research to clinical routine, yet the comparability of different technologies for mutation profiling remains an open question. We performed a European multicenter (n=6) evaluation of three amplicon-based NGS assays targeting 11 genes recurrently mutated in chronic lymphocytic leukemia. Each assay was assessed by two centers using 48 pre-characterized chronic lymphocytic leukemia samples; libraries were sequenced on the Illumina MiSeq instrument and bioinformatics analyses were centralized. Across all centers the median percentage of target reads ≥100x ranged from 94.2-99.8%. To rule out assay-specific technical variability, we first assessed variant calling at the individual assay level i.e. pairwise analysis of variants detected amongst partner centers. After filtering for variants present in the paired normal sample and removal of PCR/sequencing artefacts, the panels achieved 96.2% (Multiplicom), 97.7% (TruSeq) and 90% (HaloPlex) concordance at a VAF >0.5%. Reproducibility was assessed by looking at the inter-laboratory variation in detecting mutations and 107/115 (93% concordance) of mutations were detected by all 6 centers, while the remaining 8/115 (7%) variants were undetected by a single center and 6/8 of these variants concerned minor subclonal mutations (VAF <5%). We sought to investigate low-frequency mutations further by using a high-sensitivity assay containing unique molecular identifiers, which confirmed the presence of several minor subclonal mutations. Thus, while amplicon-based approaches can be adopted for somatic mutation detection with VAFs >5%, after rigorous validation, the use of unique molecular identifiers may be necessary to reach a higher sensitivity and ensure consistent and accurate detection of low-frequency variants.
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| 42. |
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| 43. |
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| 44. |
- Agathangelidis, A, et al.
(författare)
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Immunoglobulin gene sequence analysis in chronic lymphocytic leukemia: the 2022 update of the recommendations by ERIC, the European Research Initiative on CLL
- 2022
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 36:8, s. 1961-1968
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Tidskriftsartikel (refereegranskat)abstract
- The somatic hypermutation (SHM) status of the clonotypic immunoglobulin heavy variable (IGHV) gene is a critical biomarker for assessing the prognosis of patients with chronic lymphocytic leukemia (CLL). Importantly, independent studies have documented that IGHV SHM status is also a predictor of responses to therapy, including both chemoimmunotherapy (CIT) and novel, targeted agents. Moreover, immunogenetic analysis in CLL has revealed that different patients may express (quasi)identical, stereotyped B cell receptor immunoglobulin (BcR IG) and are classified into subsets based on this common feature. Patients in certain stereotyped subsets display consistent biology, clinical presentation, and outcome that are distinct from other patients, even with concordant IGHV gene SHM status. All of the above highlights the relevance of immunogenetic analysis in CLL, which is considered a cornerstone for accurate risk stratification and clinical decision making. Recommendations for robust immunogenetic analysis exist thanks to dedicated efforts by ERIC, the European Research Initiative on CLL, covering all test phases, from the pre-analytical and analytical to the post-analytical, pertaining to the analysis, interpretation, and reporting of the findings. That said, these recommendations apply to Sanger sequencing, which is increasingly being superseded by next generation sequencing (NGS), further underscoring the need for an update. Here, we present an overview of the clinical utility of immunogenetics in CLL and update our analytical recommendations with the aim to assist in the refined management of patients with CLL.
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| 45. |
- Baliakas, Panagiotis, et al.
(författare)
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Clinical effect of stereotyped B-cell receptor immunoglobulins in chronic lymphocytic leukaemia: a retrospective multicentre study
- 2014
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Ingår i: The Lancet Haematology. - 2352-3026. ; 1:2, s. 74-84
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Tidskriftsartikel (refereegranskat)abstract
- Background About 30% of cases of chronic lymphocytic leukaemia (CLL) carry quasi-identical B-cell receptor immunoglobulins and can be assigned to distinct stereotyped subsets. Although preliminary evidence suggests that B-cell receptor immunoglobulin stereotypy is relevant from a clinical viewpoint, this aspect has never been explored in a systematic manner or in a cohort of adequate size that would enable clinical conclusions to be drawn. Methods For this retrospective, multicentre study, we analysed 8593 patients with CLL for whom immunogenetic data were available. These patients were followed up in 15 academic institutions throughout Europe (in Czech Republic, Denmark, France, Greece, Italy, Netherlands, Sweden, and the UK) and the USA, and data were collected between June 1, 2012, and June 7, 2013. We retrospectively assessed the clinical implications of CLL B-cell receptor immunoglobulin stereotypy, with a particular focus on 14 major stereotyped subsets comprising cases expressing unmutated (U-CLL) or mutated (M-CLL) immunoglobulin heavy chain variable genes. The primary outcome of our analysis was time to first treatment, defined as the time between diagnosis and date of first treatment. Findings 2878 patients were assigned to a stereotyped subset, of which 1122 patients belonged to one of 14 major subsets. Stereotyped subsets showed significant differences in terms of age, sex, disease burden at diagnosis, CD38 expression, and cytogenetic aberrations of prognostic significance. Patients within a specific subset generally followed the same clinical course, whereas patients in different stereotyped subsets-despite having the same immunoglobulin heavy variable gene and displaying similar immunoglobulin mutational status-showed substantially different times to first treatment. By integrating B-cell receptor immunoglobulin stereotypy (for subsets 1, 2, and 4) into the well established Dohner cytogenetic prognostic model, we showed these, which collectively account for around 7% of all cases of CLL and represent both U-CLL and M-CLL, constituted separate clinical entities, ranging from very indolent (subset 4) to aggressive disease (subsets 1 and 2). Interpretation The molecular classification of chronic lymphocytic leukaemia based on B-cell receptor immunoglobulin stereotypy improves the Dohner hierarchical model and refines prognostication beyond immunoglobulin mutational status, with potential implications for clinical decision making, especially within prospective clinical trials.
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| 46. |
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| 47. |
- Baliakas, Panagiotis, et al.
(författare)
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Not all IGHV3-21 chronic lymphocytic leukemias are equal: prognostic considerations.
- 2015
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 125:5, s. 856-859
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Tidskriftsartikel (refereegranskat)abstract
- An unresolved issue in chronic lymphocytic leukemia (CLL) is whether IGHV3-21 gene usage, in general, or the expression of stereotyped B-cell receptor immunoglobulin defining subset #2 (IGHV3-21/IGLV3-21), in particular, determines outcome for IGHV3-21-utilizing cases. We reappraised this issue in 8593 CLL patients of whom 437 (5%) used the IGHV3-21 gene with 254/437 (58%) classified as subset #2. Within subset #2, immunoglobulin heavy variable (IGHV)-mutated cases predominated, whereas non-subset #2/IGHV3-21 was enriched for IGHV-unmutated cases (P = .002). Subset #2 exhibited significantly shorter time-to-first-treatment (TTFT) compared with non-subset #2/IGHV3-21 (22 vs 60 months, P = .001). No such difference was observed between non-subset #2/IGHV3-21 vs the remaining CLL with similar IGHV mutational status. In conclusion, IGHV3-21 CLL should not be axiomatically considered a homogeneous entity with adverse prognosis, given that only subset #2 emerges as uniformly aggressive, contrasting non-subset #2/IGVH3-21 patients whose prognosis depends on IGHV mutational status as the remaining CLL.
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| 48. |
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| 49. |
- Björklund, J., et al.
(författare)
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Scientific Merits and Analytical Challenges of Tree-Ring Densitometry
- 2019
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Ingår i: Reviews of geophysics. - 8755-1209 .- 1944-9208. ; 57:4, s. 1224-1264
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Forskningsöversikt (refereegranskat)abstract
- X-ray microdensitometry on annually resolved tree-ring samples has gained an exceptional position in last-millennium paleoclimatology through the maximum latewood density (MXD) parameter, but also increasingly through other density parameters. For 50 years, X-ray based measurement techniques have been the de facto standard. However, studies report offsets in the mean levels for MXD measurements derived from different laboratories, indicating challenges of accuracy and precision. Moreover, reflected visible light-based techniques are becoming increasingly popular, and wood anatomical techniques are emerging as a potentially powerful pathway to extract density information at the highest resolution. Here we review the current understanding and merits of wood density for tree-ring research, associated microdensitometric techniques, and analytical measurement challenges. The review is further complemented with a careful comparison of new measurements derived at 17 laboratories, using several different techniques. The new experiment allowed us to corroborate and refresh long-standing wisdom but also provide new insights. Key outcomes include (i) a demonstration of the need for mass/volume-based recalibration to accurately estimate average ring density; (ii) a substantiation of systematic differences in MXD measurements that cautions for great care when combining density data sets for climate reconstructions; and (iii) insights into the relevance of analytical measurement resolution in signals derived from tree-ring density data. Finally, we provide recommendations expected to facilitate futureinter-comparability and interpretations for global change research.
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| 50. |
- Björklund, Jesper, 1979, et al.
(författare)
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Scientific Merits and Analytical Challenges ofTree-Ring Densitometry
- 2019
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Ingår i: Reviews of Geophysics. - : American Geophysical Union (AGU). - 8755-1209 .- 1944-9208. ; 57:4, s. 1224-1264
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Tidskriftsartikel (refereegranskat)abstract
- X-ray microdensitometry on annually resolved tree-ring samples has gained an exceptional position in last-millennium paleoclimatology through the maximum latewood density (MXD) parameter, but also increasingly through other density parameters. For 50 years, X-ray based measurement techniques have been the de facto standard. However, studies report offsets in the mean levels for MXD measurements derived from different laboratories, indicating challenges of accuracy and precision. Moreover, reflected visible light-based techniques are becoming increasingly popular, and wood anatomical techniques are emerging as a potentially powerful pathway to extract density information at the highest resolution. Here we review the current understanding and merits of wood density for tree-ring research, associated microdensitometric techniques, and analytical measurement challenges. The review is further complemented with a careful comparison of new measurements derived at 17 laboratories, using several different techniques. The new experiment allowed us to corroborate and refresh "long-standing wisdom" but also provide new insights. Key outcomes include (i) a demonstration of the need for mass/volume-based recalibration to accurately estimate average ring density; (ii) a substantiation of systematic differences in MXD measurements that cautions for great care when combining density data sets for climate reconstructions; and (iii) insights into the relevance of analytical measurement resolution in signals derived from tree-ring density data. Finally, we provide recommendations expected to facilitate futureinter-comparability and interpretations for global change research.
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